Language：English   Publishing type：Doctoral thesis  

Our previous report indicated that vascular injury enhances vascular remodeling in fetal growth restriction (FGR) mice. The angiotensin II type 2 receptor (AT2R) is relatively highly expressed in fetal mice. Therefore, we investigated the roles of AT2R in FGR-induced cardiovascular disease using AT2R knockout (AT2KO) mice. Dams (wild-type and AT2KO mice) were fed an isocaloric diet containing 20% protein (NP) or 8% protein (LP) until delivery. Arterial blood pressure, body weight, and histological changes in organs were investigated in offspring. The birth weight of offspring from dams fed an LP diet (LPO) was significantly lower than that of offspring from dams fed an NP diet. The heart/body and kidney/body weight ratios in AT2KO-LPO at 12 weeks of age were significantly higher than those in the other groups. Greater thickness of the left ventricular wall, larger cardiomyocyte size and enhancement of perivascular fibrosis were observed in AT2KO-LPO. Interestingly, mRNA expression of collagen I and inflammatory cytokines was markedly higher in the AT2KO-LPO heart at 6 weeks of age but not at 12 weeks of age. AT2R signaling may be involved in cardiovascular disorders of adult offspring with FGR. Regulation of AT2R could contribute to preventing future cardiovascular disease in FGR offspring.

DOI： 10.1038/s41440-017-0004-2

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis  

BACKGROUND: The classical renin-angiotensin system is known as the angiotensin (Ang)-converting enzyme/Ang II/Ang type 1 receptor axis, which induces various organ damage including cognitive decline. The angiotensin-converting enzyme 2/Ang-(1-7)/Mas axis is known to exert antagonistic actions against the classical renin-angiotensin system axis in the cardiovascular system. However, its roles in the brain remain unclear. We examined possible roles of the angiotensin-converting enzyme 2/Ang-(1-7)/Mas axis in cognitive function, employing vascular cognitive impairment model mice. METHODS AND RESULTS: Male 10-week-old C57BL6 (wild-type mice, Mas1 knockout mice, Ang II type 2 receptor knockout mice, and Ang II type 2 receptor/Mas1 double knockout mice were subjected to bilateral carotid artery stenosis (BCAS) surgery. Six weeks after treatment, they were subjected to cognitive tasks. Brain samples were used for histopathological analysis. Cognitive function was significantly impaired in wild-type and double knockout mice after BCAS. On the other hand, the cognitive function of Mas1 knockout mice was maintained in spite of the reduction of cerebral blood flow with BCAS. Total cell number in the dentate gyrus region was significantly reduced after BCAS in wild-type but not in Mas1 knockout mice. The number of doublecortin-positive cells in the subgranular zone was not significantly different between wild-type and Mas1 knockout mice. Ang-(1-7) administration did not improve cognitive function in all mice after BCAS surgery. CONCLUSIONS: Lack of the Mas receptor may have a protective effect against chronic brain ischemia when the Ang II type 2 receptor exists.

DOI： 10.1161/JAHA.117.008121

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The Morris water maze test (MWM) is a useful tool to evaluate rodents' spatial learning and memory, but the outcome is susceptible to various experimental conditions. Thigmotaxis is a commonly observed behavioral pattern which is thought to be related to anxiety or fear. This behavior is associated with prolonged escape latency, but the impact of its frequency in the early stage on the final outcome is not clearly understood. We analyzed swim path trajectories in male C57BL/6 mice with or without bilateral common carotid artery stenosis (BCAS) treatment. There was no significant difference in the frequencies of particular types of trajectories according to ischemic brain surgery. The mouse groups with thigmotaxis showed significantly prolonged escape latency and lower cognitive score on day 5 compared to those without thigmotaxis. As the next step, we made a convolutional neural network (CNN) model to recognize the swim path trajectories. Our model could distinguish thigmotaxis from other trajectories with 96% accuracy and specificity as high as 0.98. These results suggest that thigmotaxis in the early training stage is a predictive factor for impaired performance in MWM, and machine learning can detect such behavior easily and automatically.

DOI： 10.1371/journal.pone.0197003

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The Morris water maze test (MWM) is one of the most popular and established behavioral tests to evaluate rodents' spatial learning ability. The conventional training period is around 5 days, but there is no clear evidence or guidelines about the appropriate duration. In many cases, the final outcome of the MWM seems predicable from previous data and their trend. So, we assumed that if we can predict the final result with high accuracy, the experimental period could be shortened and the burden on testers reduced. An artificial neural network (ANN) is a useful modeling method for datasets that enables us to obtain an accurate mathematical model. Therefore, we constructed an ANN system to estimate the final outcome in MWM from the previously obtained 4 days of data in both normal mice and vascular dementia model mice. Ten-week-old male C57B1/6 mice (wild type, WT) were subjected to bilateral common carotid artery stenosis (WT-BCAS) or sham-operation (WT-sham). At 6 weeks after surgery, we evaluated their cognitive function with MWM. Mean escape latency was significantly longer in WT-BCAS than in WT-sham. All data were collected and used as training data and test data for the ANN system. We defined a multiple layer perceptron (MLP) as a prediction model using an open source framework for deep learning, Chainer. After a certain number of updates, we compared the predicted values and actual measured values with test data. A significant correlation coefficient was derived form the updated ANN model in both WT-sham and WT-BCAS. Next, we analyzed the predictive capability of human testers with the same datasets. There was no significant difference in the prediction accuracy between human testers and ANN models in both WT-sham and WT-BCAS. In conclusion, deep learning method with ANN could predict the final outcome in MWM from 4 days of data with high predictive accuracy in a vascular dementia model.

DOI： 10.1371/journal.pone.0191708

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

There is a growing interest in identifying natural food ingredients that may serve to prevent dementia such as that due to Alzheimer disease (AD). Peptides derived from food proteins have been demonstrated to have various physiological activities such as a hypotensive action. Recent findings have indicated possible associations of hypertension with AD progression, and suggest that angiotensin converting enzyme (ACE) inhibitors with potential to pass through the blood brain barrier (BBB) may reduce the risk of AD. In this study, we investigated the effect of milk peptide (CH-3) on cognitive function in AD model mice. CH-3 contains a tripeptide (methionine-lysine-proline, MKP) that has been found to have a strong ACE inhibitory effect and the potential to pass through the BBB. Adult male ddY mice were used in this study, and an animal model of AD was induced by intracerebroventricular (ICV) injection of A beta 1-42. CH-3 (250 mg/kg/day) or MKP (0.5 mg/kg/day) was orally administered every day starting 2 days before ICV injection. At 3 weeks after ICV injection, cognitive function was evaluated by the Morris water maze test. Brain samples were obtained after behavioral testing, and expression of inflammatory cytokines and NADPH oxidase subunits was measured by real-time quantitative RT-PCR. ICV injection of A beta 1-42 significantly impaired cognitive function compared with that in PBS-injected mice. Daily administration of CH-3 markedly attenuated this A beta 1-42-induced cognitive decline. A beta 1-42 injection significantly enhanced the expression of tumor necrosis factor-alpha (TNF-alpha), inducible nitric oxide synthase (iNOS) and p22(phox) in the mouse hippocampus compared with PBS injection, and showed a tendency to increase the expression of monocyte chemoattractant protein-1 (MCP-1), p47(phox) and gp91(phox), whereas CH-3 treatment markedly reduced A beta 1-42-induced TNF-alpha, MCP-1, iNOS, p47(phox) and gp91(phox) expression. Finally, administration of MKP also attenuated A beta 1-42-induced cognitive impairment with an increase in cerebral blood flow. The present study demonstrated that repeated oral administration of CH-3 to AD model mice not only improved cognitive function but also suppressed the expression of inflammatory cytokines and production of oxidative stress, and suggests its therapeutic potential for preventing cognitive impairment in AD.

DOI： 10.1371/journal.pone.0171515

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The classical renin-angiotensin system (RAS), known as the angiotensin (Ang)-converting enzyme (ACE)/Ang II/Ang II type 1 (AT1) receptor axis, induces various organ damages including cognitive decline. On the other hand, the ACE2/Ang-(1-7)/Mas receptor axis has been highlighted as exerting antagonistic actions against the classical RAS axis in the cardiovascular system. However, the roles of the ACE2/Ang-(1-7)/Mas axis in cognitive function largely remain to be elucidated, and we therefore examined possible roles of ACE2 in cognitive function. Male, 10-week-old C57BL6 (wild type, WT) mice and ACE2 knockout (KO) mice were subjected to the Morris water maze task and Y maze test to evaluate cognitive function. ACE2KO mice exhibited significant impairment of cognitive function, compared with that in WT mice. Superoxide anion production increased in ACE2KO mice, with increased mRNA levels of NADPH oxidase subunit, p22phox, p40phox, p67phox, and gp91phox in the hippocampus of ACE2KO mice compared with WT mice. The protein level of SOD3 decreased in ACE2KO mice compared with WT mice. The AT1 receptor mRNA level in the hippocampus was higher in ACE2KO mice compared with WT mice. In contrast, the AT2 receptor mRNA level in the hippocampus did not differ between the two strains. Mas receptor mRNA was highly expressed in the hippocampus compared with the cortex. Brain-derived neurotrophic factor (BDNF) mRNA and protein levels were lower in the hippocampus in ACE2KO mice compared with WT mice. Taken together, ACE2 deficiency resulted in impaired cognitive function, probably at least in part because of enhanced oxidative stress and a decrease in BDNF.

DOI： 10.1038/npjamd.2016.24.

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

We previously reported interferon regulatory factor (IRF) 1 plays physiological roles in "growth"-regulated angiotensin II type 2 (AT2) receptor expression in fibroblasts. Here, we investigated whether IRF-1 is involved in attenuation of vascular remodeling in association with AT2 receptor upregulation. Neointimal area in injured artery after 14 days of cuff placement was significantly increased in IRF-1 knockout mice (IRF-1KO) and AT2 receptor knockout mice (AT2KO) compared with wild-type mice (WT: C57BL/6J). Treatment with compound 21 attenuated neointima formation in both WT and IRF-1KO. AT2 receptor mRNA expression after 7 days of cuff placement was significantly decreased in IRF-1KO compared with WT; however, IRF-1 expression did not differ between AT2KO and WT. Apoptotic changes in injured artery after 14 days of cuff placement were significantly attenuated in IRF-1KO, with a decrease in interleukin-1β-converting enzyme and inducible nitric oxide synthase mRNA levels. These results indicate IRF-1 is one of the key transcriptional factors for the prevention of neointimal formation involving AT2 receptors.

DOI： 10.1016/j.jash.2016.07.005

PubMed

researchmap

DOI： 10.1097/01.hjh.0000500554.97597.16

PubMed

researchmap

DOI： 10.1097/01.hjh.0000500987.39434.12

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

We investigated the possibility that coadministration of rosuvastatin and compound 21 (C21), a selective angiotensin II type 2 (AT2) receptor agonist, could exert synergistic preventive effects on vascular injury. Vascular injury was induced by polyethylene cuff placement on the femoral artery in 9-week-old male C57BL/6J mice. Mice were treated with rosuvastatin and/or with C21 after cuff placement. Neointima formation was determined 14 days after the operation and cell proliferation, and superoxide anion production and expression of inflammatory cytokines were examined 7 days after cuff placement. Neointima formation was significantly attenuated by the treatment of rosuvastatin (5 mg kg(-1) day(-1)) or C21 (10 μg kg(-1) day(-1)), associated with the decreases in proliferating cell nuclear antigen (PCNA) labeling index, oxidative stress, and the expression of inflammatory markers. Treatment with a noneffective dose of rosuvastatin (0.5 mg kg(-1) day(-1)) plus a low dose of C21 (1 μg kg(-1) day(-1)) inhibited the PCNA labeling index, superoxide anion production, mRNA expressions of NAD(P)H subunits, and mRNA and protein expressions of inflammatory markers associated with marked inhibition of neointima formation. Angiotensin II type 1 (AT1) receptor mRNA expression did not differ the groups. By contrast, AT2 receptor mRNA expression was increased by administration of C21 at the dose of 10 μg kg(-1) day(-1) but not by C21 at the dose of 1 μg kg(-1) day(-1) or rosuvastatin. The combination of rosuvastatin and AT2 receptor agonist exerted synergistic preventive effects on vascular remodeling associated with the decreases in cell proliferation, oxidative stress, and inflammatory reaction. That could be a powerful approach to vascular disease prevention.

DOI： 10.1124/jpet.116.233148

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Angiotensin II type 2 (AT(2)) receptor stimulation could exert beneficial effects on vascular remodeling. Previously, we reported that AT(2) receptor stimulation ameliorated insulin resistance in diabetic mice accompanied by PPAR gamma activation which also plays a variety of crucial roles in the vasculature. Therefore, this study aimed to investigate the vascular protective effect of the AT(2) receptor with activation of PPAR gamma involving AT(2) receptor-interacting protein (ATIP).
Vascular injury was induced by polyethylene-cuff placement around the femoral artery in C57BL/6J mice. Treatment with compound 21 (C21), an AT(2) receptor agonist, decreased neointimal formation, cell proliferation, and the mRNA levels of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF)-alpha, and interleukin-1 beta, and phosphorylation of nuclear factor-kappa B, and increased PPAR gamma DNA-binding activity in the injured artery, whereas these inhibitory effects of C21 were attenuated by co-treatment with a PPAR gamma antagonist, GW9662. Treatment of vascular smooth muscle cells (VSMC) with C21 prepared from smAT(2) transgenic mice, which highly express the AT(2) receptor in VSMC, increased both PPAR gamma activity and its DNA-binding activity determined by dual-luciferase assay and electrophoresis mobility shift assay (EMSA), respectively. We observed that ATIP was involved in PPAR gamma complex formation, and that transfection of siRNA of ATIP1 attenuated the AT(2) receptor-mediated increase in PPAR gamma activity in VSMC. In response to AT(2) receptor stimulation, ATIP was translocated from the plasma membrane to the nucleus.
Our results suggest a new mechanism by which AT(2) receptor stimulation activates PPAR gamma, thereby resulting in amelioration of vascular intimal proliferation, and that ATIP plays an important role in AT(2) receptor-mediated PPAR gamma activation.

DOI： 10.1093/ajh/hpv168

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Browning of white adipose tissue (WAT) has been highlighted as a new possible therapeutic target for obesity, diabetes and lipid metabolic disorders, because WAT browning could increase energy expenditure and reduce adiposity. The new clusters of adipocytes that emerge with WAT browning have been named 'beige' or 'brite' adipocytes. Recent reports have indicated that the renin-angiotensin system (RAS) plays a role in various aspects of adipose tissue physiology and dysfunction. The biological effects of angiotensin II, a major component of RAS, are mediated by two receptor subtypes, angiotensin II type 1 receptor (AT1R) and type 2 receptor (AT2R). However, the functional roles of angiotensin II receptor subtypes in WAT browning have not been defined. Therefore, we examined whether deletion of angiotensin II receptor subtypes (AT1aR and AT2R) may affect white-to-beige fat conversion in vivo. AT1a receptor knockout (AT1aKO) mice exhibited increased appearance of multilocular lipid droplets and upregulation of thermogenic gene expression in inguinal white adipose tissue (iWAT) compared to wild-type (WT) mice. AT2 receptor-deleted mice did not show miniaturization of lipid droplets or alteration of thermogenic gene expression levels in iWAT. An in vitro experiment using adipose tissue-derived stem cells showed that deletion of the AT1a receptor resulted in suppression of adipocyte differentiation, with reduction in expression of thermogenic genes. These results indicate that deletion of the AT1a receptor might have some effects on the process of browning of WAT and that blockade of the AT1 receptor could be a therapeutic target for the treatment of metabolic disorders.

DOI： 10.1371/journal.pone.0167704

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Background
Stroke is a leading cause of death and disability; however, meta-analysis of randomized controlled trials of blood pressure-lowering drugs in acute stroke has shown no definite evidence of a beneficial effect on functional outcome. Accumulating evidence suggests that angiotensin II type 1 receptor blockade with angiotensin II type 2 (AT(2)) receptor stimulation could contribute to protection against ischemic brain damage. We examined the possibility that direct AT(2) receptor stimulation by compound 21 (C21) initiated even after stroke can prevent ischemic brain damage.
Methods
Stroke was induced by middle cerebral artery (MCA) occlusion, and the area of cerebral infarction was measured by magnetic resonant imaging. C21 (10 mu g/kg/day) treatment was initiated immediately after MCA occlusion by intraperitoneal injection followed by treatment with C21 once daily.
Results
We observed that ischemic area was enlarged in a time dependent fashion and decreased on day 5 after MCA occlusion. Treatment with C21 initiated after MCA occlusion significantly reduced the ischemic area, with improvement of neurological deficit in a time-dependent manner without affecting blood pressure. The decrease of cerebral blood flow after MCA occlusion was also ameliorated by C21 treatment. Moreover, treatment with C21 significantly attenuated superoxide anion production and expression of proinflammatory cytokines, monocyte chemoattractant protein 1, and tumor necrosis factor a. Interestingly, C21 administration significantly decreased blood-brain barrier permeability and cerebral edema on the ischemic side.
Conclusions
These results provide new evidence that direct AT2 receptor stimulation with C21 is a novel therapeutic approach to prevent ischemic brain damage after acute stroke.

DOI： 10.1093/ajh/hpu015

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The possible counteracting effect of angiotensin (Ang)-converting enzyme (ACE)2/Ang-(1-7)/Mas axis against the ACE/Ang II/Ang II type 1 (AT1) receptor axis in blood pressure control has been previously described. We examined the possibility that this pathway might be involved in the anti-hypertensive effect of a newly developed AT1 receptor blocker (ARB), azilsartan, and compared azilsartan's effects with those of another ARB, olmesartan. Transgenic mice carrying the human renin and angiotensinogen genes (hRN/hANG-Tg) were given azilsartan or olmesartan. Systolic and diastolic blood pressure, as determined by radiotelemetry, were significantly higher in hRN/hANG-Tg mice than in wild-type (WT) mice. Treatment with azilsartan or olmesartan (1 or 5 mg kg(-1) per day) significantly decreased systolic and diastolic blood pressure, and the blood pressure-lowering effect of azilsartan was more marked than that of olmesartan. The urinary Na concentration decreased in an age-dependent manner in hRN/hANG-Tg mice. Administration of azilsartan or olmesartan increased urinary Na concentration, and this effect was weaker with olmesartan than with azilsartan. Azilsartan decreased ENaC-α mRNA expression in the kidney and decreased the ratio of heart to body weight. Olmesartan had a similar but less-marked effect. ACE2 mRNA expression was lower in the kidneys and hearts of hRN/hANG-Tg mice than in WT mice. This decrease in ACE2 mRNA expression was attenuated by azilsartan, but not by olmesartan. These results suggest that the hypotensive and anti-hypertrophic effects of azilsartan may involve activation of the ACE2/Ang-(1-7)/Mas axis with AT1 receptor blockade.

DOI： 10.1038/hr.2014.49

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Cross talk between the angiotensin-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II type 1 (AT1) receptor axis and the ACE2/Ang-(1-7)/Mas axis plays a role in the pathogenesis of cardiovascular remodeling. Furthermore, possible stimulation of the Ang II type 2 (AT2) receptor by Ang-(1-7) has been highlighted as a new pathway. Therefore, we examined the possibility of whether the ACE2/Ang-(1-7)/Mas axis and Ang-(1-7)/AT2 receptor axis are involved in the inhibitory effects of AT1 receptor blockers on vascular remodeling. Wild-type, Mas-knockout, and AT2 receptor knockout mice were used in this study. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. Some mice were treated with azilsartan, an AT1 receptor blocker, or Ang-(1-7). Neointimal formation 2 weeks after cuff placement was more marked in Mas-knockout mice compared with wild-type mice. Treatment with azilsartan or Ang-(1-7) attenuated neointimal area, vascular smooth muscle cell proliferation, increases in the mRNA levels of monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-1β, and superoxide anion production in the injured artery; however, these inhibitory effects of azilsartan and Ang-(1-7) were less marked in Mas-knockout mice. Administration of azilsartan or Ang-(1-7) attenuated the decrease in ACE2 mRNA and increased AT2 receptor mRNA but did not affect AT1 receptor mRNA or the decrease in Mas mRNA. The inhibitory effect of Ang-(1-7) on neointimal formation was less marked in AT2 receptor knockout mice compared with wild-type mice. These results suggest that blockade of the AT1 receptor by azilsartan could enhance the activities of the ACE2/Ang-(1-7)/Mas axis and ACE2/Ang-(1-7)/AT2 receptor axis, thereby inhibiting neointimal formation.

DOI： 10.1161/HYPERTENSIONAHA.113.02426

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Type 2 diabetes mellitus (T2DM) is known to be associated with increased risk of cognitive impairment including Alzheimer disease. Recent studies have suggested an interaction between angiotensin II and N-methyl-d-aspartic acid (NMDA) glutamate receptors. We previously reported that stimulation of the angiotensin II type 2 (AT2) receptor exerts brain protective effects. A newly developed AT2 receptor agonist, compound 21 (C21), has enabled examination of the direct effect of AT2 receptor stimulation in vivo. Accordingly, we examined the possible synergistic effect of C21 and memantine on cognitive impairment in T2DM mice, KKAy. KKAy were divided into four groups; (1) control, (2) treatment with C21 (10 μg/kg/day), (3) treatment with memantine (20mg/kg/day), and (4) treatment with both for 4 weeks, and subjected to Morris water maze tasks. Treatment with C21 or memantine alone at these doses tended to shorten escape latency compared to that in the control group. C21 treatment increased cerebral blood flow (CBF), but memantine did not influence CBF. Treatment with C21 or C21 plus memantine increased hippocampal field-excitatory postsynaptic potential (f-EPSP). Moreover, treatment with memantine or C21 increased acetylcholine level, which was lower in KKAy than in wild-type mice, and C21 plus memantine treatment enhanced memantine or C21-induced acetylcholine secretion. This study provides an insight into new approaches to understand the interaction of angiotensin II and neurotransmitters. We can anticipate a new therapeutic approach against cognitive decline using C21 and memantine.

DOI： 10.1016/j.ejphar.2013.12.015

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

We demonstrated that angiotensin II type 2 (AT2) receptor-interacting protein (ATIP) 1 ameliorates inflammation-mediated vascular remodeling independent of the AT2 receptor, leading us to explore the possibility of whether ATIP1 could exert anti-inflammatory effects and play a role in other pathophysiological conditions. We examined the possible anti-inflammatory effects of ATIP1 in adipose tissue associated with amelioration of insulin resistance. In mice fed a high-cholesterol diet, adipose tissue macrophage (ATM) infiltration and M1-to-M2 ratio were decreased in ATIP1 transgenic mice (ATIP1-Tg) compared with wild-type mice (WT), with decreased expression of inflammatory cytokines such as tumor necrosis factor-α and monocyte chemoattractant protein-1 in white adipose tissue (WAT), but an increase in interleukin-10, an anti-inflammatory cytokine. Moreover, 2-[(3)H]deoxy-d-glucose (2-[(3)H]DG) uptake was significantly increased in ATIP1-Tg compared with WT. Next, we examined the roles of ATIP1 in BM-derived hematopoietic cells, employing chimeric mice produced by BM transplantation into irradiated type 2 diabetic mice with obesity, KKAy, as recipients. ATM infiltration and M1-to-M2 ratio were decreased in ATIP1 chimera (ATIP1-tg as BM donor), with improvement of insulin-mediated 2-[(3)H]DG uptake and amelioration of inflammation in WAT. Moreover, serum adiponectin concentration in ATIP1 chimera was significantly higher than that in WT chimera (WT as BM donor) and KKAy chimera (KKAy as BM donor). These results indicate that ATIP1 could exert anti-inflammatory effects in adipose tissue via macrophage polarization associated with improvement of insulin resistance, and ATIP1 in hematopoietic cells may contribute to these beneficial effects on adipose tissue functions in type 2 diabetes.

DOI： 10.1371/journal.pone.0060067

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

Additional beneficial effects of angiotensin II type 1 (AT(1)) receptor blockers beyond AT(1) receptor blockade have been highlighted. Irbesartan is reported to act as an antagonist of the monocyte chemoattractant protein-1 (MCP-1) receptor, C-C chemokine receptor 2 (CCR2). We examined the possible synergistic effects of the combination of irbesartan with rosuvastatin on preventing vascular remodeling focusing on the MCP-1/CCR2 pathway. We observed that administration of irbesartan and CCR2 antagonist, propagermanium, at noneffective doses, decreased the neointima with a decrease in PCNA labeling index in the injured mouse femoral artery induced by cuff placement. We also observed that administration of a noneffective dose of rosuvastatin with propagermanium decreased the neointima area, suggesting that the inhibitory effect of rosuvastatin on neointima formation is at least partly attributable to blockade of the MCP-1/CCR2 pathway. Moreover, we demonstrated that the combination of irbesartan with rosuvastatin decreased neointima formation. MCP-1 mRNA level was significantly increased in injured femoral arteries, and administration of irbesartan with rosuvastatin decreased the mRNA levels of MCP-1, TNF alpha, and IL-1 beta, and increased PPAR gamma mRNA expression. These results suggest that the synergistic inhibitory effects of irbesartan with rosuvastatin on neointima formation may involve attenuation of MCP-1/CCR2 signaling. J Am Soc Hypertens 2012;6(6):375-384. (C) 2012 American Society of Hypertension. All rights reserved.

DOI： 10.1016/j.jash.2012.10.002

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Objectives: The role of angiotensin II type 2 (AT(2)) receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT(2) receptor stimulation by compound 21 (C21) might contribute to possible insulin-sensitizing/anti-diabetic effects in type 2 diabetes (T2DM) with PPAR gamma activation, mainly focusing on adipose tissue.
Methods: T2DM mice, KK-Ay, were subjected to intraperitoneal injection of C21 and/or a PPAR gamma antagonist, GW9662 in drinking water for 2 weeks. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[H-3] deoxy-D-glucose in white adipose tissue. Morphological changes of adipose tissues as well as adipocyte differentiation and inflammatory response were examined.
Results: Treatment with C21 ameliorated insulin resistance in KK-Ay mice without influencing blood pressure, at least partially through effects on the PPAR gamma pathway. C21 treatment increased serum adiponectin concentration and decreased TNF-alpha concentration; however, these effects were attenuated by PPAR gamma blockade by co-treatment with GW9662. Moreover, we observed that administration of C21 enhanced adipocyte differentiation and PPAR gamma DNA-binding activity, with a decrease in inflammation in white adipose tissue, whereas these effects of C21 were attenuated by co-treatment with GW9662. We also observed that administration of C21 restored beta cell damage in diabetic pancreatic tissue.
Conclusion: The present study demonstrated that direct AT(2) receptor stimulation by C21 accompanied with PPAR gamma activation ameliorated insulin resistance in T2DM mice, at least partially due to improvement of adipocyte dysfunction and protection of pancreatic beta cells.

DOI： 10.1371/journal.pone.0048387

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

An adverse relationship between suboptimal fetal environments and the development of adult diseases, such as hypertension, type II diabetes, and cardiovascular disease, has been reported in numerous studies. The purpose of this study was to investigate the strain difference of offspring's response to maternal malnutrition during pregnancy and the involvement of the renin-angiotensin system (RAS) in the development of adult hypertension using C57BL/6J (C57) mice and angiotensin II (Ang II) type 1 receptor-associated protein-transgenic (ATRAP-Tg) mice. Pregnant dams were fed an isocaloric diet containing either 20% (normal protein; NP) or 8% (low protein; LP) protein. Birth weight was significantly reduced in C57-LP offspring, but not in ATRAP-Tg-LP offspring. Arterial blood pressure was higher in C57-LP offspring than in the other groups. In contrast, ATRAP-Tg-LP offspring did not show an increase in blood pressure compared with NP offspring. Renal angiotensin II type 1 (AT(1)) receptor expression was not altered by maternal malnutrition, whereas angiotensin II type 2 receptor expression was significantly decreased in C57-LP offspring. In conclusion, these findings suggest that a suboptimal intrauterine environment induces adult hypertension because of an alteration of expression of RAS components, which was partly suppressed by sustained ATRAP overexpression via attenuation of the AT(1) receptor-mediated pathological response.

DOI： 10.1016/j.jash.2012.07.001

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

We reported previously that an angiotensin II type 1 receptor blocker, telmisartan, improved cognitive decline with peroxisome proliferator-activated receptor-γ activation; however, the detailed mechanisms are unclear. Enhanced blood-brain barrier (BBB) permeability with alteration of tight junctions is suggested to be related to diabetes mellitus. Therefore, we examined the possibility that telmisartan could attenuate BBB impairment with peroxisome proliferator-activated receptor-γ activation to improve diabetes mellitus-induced cognitive decline. Type 2 diabetic mice KKA(y) exhibited impairment of cognitive function, and telmisartan treatment attenuated this. Cotreatment with GW9662, a peroxisome proliferator-activated receptor-γ antagonist, interfered with these protective effects of telmisartan against cognitive function. BBB permeability was increased in both the cortex and hippocampus in KKA(y) mice. Administration of telmisartan attenuated this increased BBB permeability. Coadministration of GW9662 reduced this effect of telmisartan. Significant decreases in expression of tight junction proteins and increases in matrix metalloproteinase expression, oxidative stress, and proinflammatory cytokine production were observed in the brain, and treatment with telmisartan restored these changes. Swollen astroglial end-feet in BBB were observed in KKA(y) mice, and this change in BBB ultrastructure was decreased in telmisartan. These effects of telmisartan were weakened by cotreatment with GW9662. In contrast, administration of another angiotensin II type 1 receptor blocker, losartan, was less effective compared with telmisartan in terms of preventing BBB permeability and astroglial end-foot swelling, and coadministration of GW9662 did not affect the effects of losartan. These findings are consistent with the possibility that, in type 2 diabetic mice, angiotensin II type 1 receptor blockade with peroxisome proliferator-activated receptor-γ activation by telmisartan may help with protection against cognitive decline by preserving the integrity of the BBB.

DOI： 10.1161/HYPERTENSIONAHA.112.192401

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

Angiotensin II type 2 (AT(2)) receptor-interacting protein (ATIP), which interacts with the C-terminal tail of the AT(2) receptor, regulates the functions of the AT(2) receptor. We have reported that AT(2) receptor stimulation attenuated vascular senescence. Therefore, we examined the possible negative role of ATIP in regulating vascular senescence. We generated ATIP-transgenic (Tg) mice, and cultured vascular smooth muscle cells (VSMCs). Persistent angiotensin II stimulation induced increases in SA-beta-gal-positive cells and the level of a DNA damage marker, 8-OHdG in VSMC, whereas these effects of angiotensin II were attenuated in VSMC prepared from ATIP-Tg mice. Angiotensin II treatment also upregulated the expression of methyl methanesulfonate-sensitive 2 (MMS2), a DNA repair factor, and Src homology 2 domain-containing protein-tyrosine phosphatase I (SHP-1) activity, whereas these effects of angiotensin II were further enhanced in ATIP-Tg VSMC. In vivo, x-ray irradiation to mice caused increases in SA-beta-gal-positive area and 8-OHdG level in the thoracic aorta; however, these effects were reduced in ATIP-Tg mice, with a significant increase in MMS2 expression. These results suggest that ATIP could inhibit VSMC senescence, involving MMS2 expression and SHP-1 activity. ATIP might be a new therapeutic molecule to treat vascular aging and age-related vascular diseases. J Am Soc Hypertens 2012;6(3):179-184. (C) 2012 American Society of Hypertension. All rights reserved.

DOI： 10.1016/j.jash.2012.01.006

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Patients with type 2 diabetes mellitus (T2DM) exhibit more severe cognitive decline in females compared with males; however, the preventive approach to this gender-specific cognitive decline is still an enigma. Spironolactone is a potassium-sparing diuretic that also acts as an androgen receptor antagonist. Here, we investigated whether spironolactone attenuates cognitive impairment observed in female T2DM mice. Adult wild-type (WT) mice and an obese T2DM model, KKAy mice, were employed in this study. Cognitive function was evaluated by the shuttle avoidance test and Morris water maze test. Administration of spironolactone (50 mg/kg per day in chow) had no significant effect on blood pressure, glucose tolerance or insulin resistance. In WT mice, no significant sex difference in cognitive function was observed; however, treatment with spironolactone improved spatial memory in the water maze, especially in female WT mice. Administration of spironolactone markedly improved the cognitive decline in female KKAy mice up to the level in male KKAy mice. Spironolactone treatment also improved cognitive function in ovariectomized-KKAy mice, but failed to improve it in those with administration of estradiol (200 µg/kg per day). In diabetic mice, spironolactone improved impaired cognitive function observed in female mice, suggesting that spironolactone may prevent cognitive impairment associated with diabetes in females clinically.

DOI： 10.1177/1470320311412810

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis  

We examined the possibility that direct stimulation of the angiotensin II type 2 (AT(2)) receptor by a newly generated direct AT(2) receptor agonist, Compound 21 (C21), enhances cognitive function. Treatment with C21 intraperitoneal injection for 2 weeks significantly enhanced cognitive function evaluated by the Morris water maze test in C57BL6 mice, but this effect was not observed in AT(2) receptor-deficient mice. However, C21-induced cognitive enhancement in C57BL6 mice was attenuated by coadministration of icatibant, a bradykinin B(2) receptor antagonist. Administration of C21 dose dependently increased cerebral blood flow assessed by laser speckle flowmetry and hippocampal field-excitatory postsynaptic potential (f-EPSP) determined by electrophysiological techniques in C57BL6 mice. Furthermore, activation of the AT(2) receptor by C21 promoted neurite outgrowth of cultured hippocampal neurons prepared from fetal transgenic mice expressing green fluorescent protein. Finally, we investigated the pathologic relevance of C21 for spatial learning using an Alzheimer's disease mouse model with intracerebroventricular injection of amyloid-β (1 to 40). We observed that treatment with C21 prevented cognitive decline in this model. These results suggest that a direct AT(2) receptor agonist, C21, enhances cognitive function at least owing to an increase in CBF, enhancement of f-EPSP, and neurite outgrowth in hippocampal neurons.

DOI： 10.1038/jcbfm.2011.133

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Interleukin 17 (IL-17) is known to contribute to the pathogenesis of hypertension, atherosclerosis, and adipocyte differentiation; however, the roles of IL-17 in glucose metabolism remain to be elucidated. Angiotensin II type 1 receptor blockers improve insulin resistance at least in part because of the amelioration of inflammation. Therefore, we examined the possible roles of IL-17 in the pathogenesis of insulin resistance in type 2 diabetes mellitus using a mouse model, KK-Ay, and angiotensin II type 1 receptor-mediated insulin resistance. KK-Ay mice were administered control-IgG(2A) or anti-IL-17 antibody 5 times at a dose of 100 mu g every second day by IP injection. KK-Ay mice were administered telmisartan for 2 weeks. C57BL/6J mice treated with angiotensin II infusion for 2 weeks were administered telmisartan or hydralazine. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[H-3]deoxy-D-glucose in peripheral tissues. Serum IL-17 concentration in KK-Ay mice was significantly higher than that in C57BL/6J mice. Treatment of KK-Ay mice with anti-IL-17 antibody significantly increased 2-[H-3]deoxy-D-glucose uptake in skeletal muscle but not in white adipose tissue and attenuated the increase in blood glucose level after a glucose load. Blockade of IL-17 enhanced the expression of adipocyte differentiation markers and adiponectin. Treatment with telmisartan decreased serum IL-17 concentration in KK-Ay and ameliorated angiotensin II-induced insulin resistance with a decrease in serum IL-17 level in C57BL/6J. In conclusion, IL-17 could play an important role in the pathogenesis of angiotensin II type 1 receptor-induced insulin resistance. (Hypertension. 2012;59[part 2]:493-499.). Online Data Supplement

DOI： 10.1161/HYPERTENSIONAHA.111.183178

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The angiotensin II type 2 (AT(2)) receptor is expressed in bone marrow cells and may affect cell differentiation. We previously reported a beneficial role of the AT(2) receptor in ischemic brain damage. Here, we investigated the effect of AT(2) receptor stimulation in hematopoietic cells on ischemic brain injury using chimeric mice. Chimeric mice were generated by bone marrow transplantation into wild-type mice after irradiation. Bone marrow cells were prepared from wild-type (Agtr2(+)) or AT(2) receptor-deficient mice (Agtr2(-)). Six weeks after bone marrow transplantation, these chimeric mice were subjected to ischemia/reperfusion injury. Both Agtr2(+) and Agtr2(-) chimeric mice did not show a significant change in systolic and diastolic blood pressures, whereas body weight decreased in Agtr2(-) chimera. Twenty-four hours after ischemia/reperfusion injury, ischemic brain damage in Agtr2(-) chimera was exaggerated compared with that in Agtr2(+) chimera. Moreover, cerebral blood flow in the peripheral region before and after ischemia/reperfusion injury was decreased in Agtr2(-) chimera. The inflammatory response in the ipsilateral hemisphere was not significantly different, whereas tumor necrosis factor-α and monocyte chemoattractant protein 1 expressions tended to increase in the Agtr2(-) chimeric brain. Expression of methylmethane sulfonate 2, which has a neuroprotective effect, was lower in the brain of Agtr2(-) chimera. These results indicate that deletion of AT(2) receptor in blood cells has a harmful effect on ischemic brain injury.

DOI： 10.1161/HYPERTENSIONAHA.111.177873

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

The contribution of the renin-angiotensin-aldosterone system (RAAS) to central nervous system (CNS) disorders is not yet fully understood. RAAS has been shown to be involved in the proliferation of astrocytes, which have a role in neuronal damage contributing to neurodegenerative diseases. However, the direct relationship between RAAS and neuronal damage is still unclear. We therefore examined the effect of angiotensin (Ang) II and aldosterone (Aldo) on damage to spinal ganglion neurons (SGNs) by regulating astrocytes. Ang II stimulation significantly increased DNA damage in SGNs in a time-dependent manner. This increase in DNA damage was further enhanced when SGNs were co-cultured with astrocytes. On the other hand, no significant increase was observed in SGNs co-cultured with astrocytes without Ang II stimulation. Moreover, the addition of conditioned medium from Ang II-treated astrocytes exacerbated SGN DNA damage. An Ang II type 1 receptor blocker, valsartan, inhibited Ang II-stimulated DNA damage but not DNA damage induced by conditioned medium prepared from astrocyte cultures. In contrast, an Aldo antagonist, eplerenone, significantly inhibited DNA damage induced by the culture medium from Ang II-treated astrocytes. Ang II-stimulated Aldo secretion in the conditioned medium from astrocytes. Furthermore, the administration of Aldo alone also enhanced DNA damage in SGNs. Finally, flow cytometric analysis showed that Ang II or Aldo treatment markedly increased the percentage of dead SGNs. In conclusion, Ang II- and Aldo-induced neuronal damage in SGNs through astrocytes regulation. Blocking Ang II and Aldo to target astrocytes might be useful for the treatment of CNS disorders.

DOI： 10.1038/hr.2011.38

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Angiotensin II type 1 (AT(1)) receptor blockers (ARBs) are known to prevent the onset of stroke and to attenuate neural damage. Additional beneficial effects of ARBs, independent of AT(1) receptor blockade, have been highlighted. Irbesartan is reported to act as an antagonist of the monocyte chemoattractant protein-1 (MCP-1) receptor, C-C chemokine receptor 2 (CCR2), due to its molecular structure. We examined the possible synergistic effects of co-administration of irbesartan with propagermanium, a CCR2 antagonist, on ischemic brain damage. Administration of propagermanium decreased ischemic brain area after middle cerebral artery occlusion (MCAO). To study the possible synergistic effects of propagermanium with ARBs, we employed non-effective lower doses of irbesartan and losartan. Administration of irbesartan with propagermanium decreased the ischemic brain area more markedly compared with propagermanium alone, but co-administration of losartan did not. MCP-1 mRNA level was significantly increased on the ipsilateral side after MCAO, and administration of irbesartan with propagermanium decreased the MCP-1 level, whereas co-administration of losartan did not. Similar results were obtained for MCP-1 protein level. CCR2 mRNA expression was significantly elevated on the ipsilateral side; however, no significant difference was observed between each group. mRNA levels of other inflammatory cytokines such as TNF-α and IL-1β also significantly increased on the ipsilateral side, but the expression levels were not changed by each drug treatment. Taking these findings together, irbesartan exerts more beneficial effects on ischemic brain damage with an MCP-1 receptor blocker, at least due to its inhibitory effects on MCP-1/CCR2 signaling beyond AT(1) receptor blockade.

DOI： 10.1016/j.bbrc.2011.04.142.

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Type 2 diabetes can impair the outcome of stroke as well as increase stroke risk; however, the sex difference in ischemic brain damage is not well known, and even less is known about the difference in diabetes. We therefore investigated the possible gender difference in brain damage after stroke associated with type 2 diabetes using a mouse model, KKAy. Female KKAy showed a much larger ischemic area compared with male KKAy. NADPH oxidase activity in the brain was also increased more in female than in male mice. Ovariectomy enhanced the ischemic area, and treatment with estradiol markedly attenuated the ischemic area to that in female KKAy, with a reduction of NADPH oxidase activity. Female and OVX mice showed improvement of cerebral blood flow (CBF) at 1 hour after middle cerebral artery (MCA) occlusion, but no significant difference in CBF of the ipsilateral penumbra and ipsilateral core 24 hours after MCA occlusion was observed among each group. Severe ischemic brain damage was observed in female KKAy compared with male KKAy. Estrogen showed a protective effect on the brain, at least partly from attenuation of oxidative stress in the female brain. These findings suggest that brain damage in diabetes mellitus might be more marked in women than in men.

DOI： 10.1016/j.jash.2010.12.003.

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Background Telmisartan is a unique AT(1) receptor blocker with a peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonistic action. Activation of PPAR-gamma could prevent inflammation and brain damage.
Method We investigated the beneficial effect of telmisartan on ischemic brain damage via PPAR-gamma activation as well as AT(1) receptor blockade. Eight-week-old male KK-Ay mice were subjected to middle cerebral artery occlusion. Before middle cerebral artery occlusion, they were administered telmisartan or losartan, with or without GW9662, a PPAR-gamma antagonist, for 2 weeks. Ischemic area, neurological score, oxidative stress, inflammation and cerebral blood flow were assessed 24 h after middle cerebral artery occlusion.
Results Administration of telmisartan, losartan, GW9662 and these AT(1) receptor blockers with GW9662 had no significant effect on blood pressure. KK-Ay mice exhibited a significant increase in the ischemic area compared with C57BL6 mice. Treatment with telmisartan decreased the ischemic area and improved the neurological score compared with the no-treatment group, with an increase in cerebral blood flow and a reduction in superoxide production and expression of inflammatory cytokines. These protective effects of telmisartan were partially attenuated by coadministration of GW9662, although GW9662 treatment alone had no significant effect on ischemic area. Losartan treatment showed a reduction in ischemic area compared with nontreated KK-Ay mice. However, coadministration of GW9662 had no effect on the losartan-mediated reduction in ischemic area.
Conclusion These results suggest that telmisartan has a beneficial effect on stroke partly due to activation of PPAR-gamma as well as AT(1) receptor blockade. J Hypertens 28: 1730-1737 (c) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

DOI： 10.1097/HJH.0b013e32833a551a

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Aims: Sex-specific medicine has been highlighted as a different approach to the diagnosis and treatment of diseases between men and women. Type 2 diabetes has been reported to be a risk factor for cognitive impairment. Here, we investigated the sex difference in cognitive function associated with diabetes using KKAy mice.
Main methods: Cognitive function was evaluated by shuttle avoidance test and Morris water maze test. Changes in gene expression in the brain were evaluated by PCR array and confirmed by quantitative RT-PCR. To evaluate the effect of estradiol, some female KKAy were ovariectomized and treated with or without estradiol.
Key findings: In KKAy mice, female significantly exhibited impaired cognitive function compared with male, while there was no sex difference in these cognitive functions in C57BL6, wild-type mice. Female KKAy mice showed hyperinsulinemia, impaired glucose tolerance and increased oxidative stress compared with male KKAy mice. Female KKAy also showed a significant decrease in peroxisome proliferators-activated receptor (PPAR)-gamma expression in the brain compared with male KKAy. Estradiol treatment improved the insulin resistance and higher superoxide production, but failed to improve the cognitive task performance, serum insulin level and lower expression of PPAR-gamma.
Significance: In diabetic mice, female showed significantly impaired cognitive function, with greater insulin resistance, lower expression of PPAR-gamma and higher superoxide production compared with male. Estrogen had little effect on cognitive function. These results indicate that a sex-specific approach to cognitive impairment is necessary for diabetic patients, especially for women. (C) 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.lfs.2010.03.003

Web of Science

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Emerging new research suggests that the functions of the angiotensin (Ang) II type 1 (AT(1)) receptor are regulated in a complex manner. AT(1) receptor-associated protein (ATRAP) has been reported to reduce AT(1) receptor signaling with enhancement of AT(1) receptor internalization and to regulate the calcineurin/nuclear factor of activated T cells (NFAT) pathway. We examined the possibility that ATRAP could attenuate AT(1) receptor-mediated vascular senescence via inactivation with the calcineurin/NFAT pathway. Ang II stimulation significantly increased senescence-associated beta-galactosidase (SA-beta-gal) -stained cells, oxidative stress, and expression of p53 and p21 in wild-type (WT) vascular smooth muscle cells (VSMC). Moreover, in WT VSMC, Ang II stimulation enhanced NFAT transcriptional activity, which was prevented by CAML-siRNA treatment. NFAT-siRNA treatment attenuated Ang-II-increased SA-beta-gal activity and p53 and p21 expression. Treatment with a calcineurin activity inhibitor, cyclosporin A, reduced Ang-II-induced NFAT transcriptional activity and senescent VSMC. In contrast, VSMC prepared from ATRAP transgenic (ATRAP-Tg) mice exhibited attenuation of Ang-II-induced SA-beta-gal activity, oxidative stress, NFAT transcriptional activity, and expression of p53 and p21. Moreover, ATRAP-Tg VSMC showed a more reduction of Ang-II-induced NFAT transcriptional activity by CAML-siRNA treatment than WT VSMC. Furthermore, we demonstrated that in ATRAP-Tg VSMC, NFAT activity and senescent cells induced by ultraviolet irradiation were decreased compared with those in WT VSMC. Treatment with an AT(1) receptor blocker, valsartan, blocked these senescent cells but did not change NFAT activity in both cells. These results suggest that ATRAP negatively regulates VSMC senescence by reducing AT(1) receptor signaling, and that ATRAP-mediated inactivation of the calcineurin/NFAT pathway could be at least partly involved in prevention of VSMC senescence, irrespective of AT(1) receptor blockade in some conditions. (C) 2009 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.yjmcc.2009.09.006

Web of Science

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis   Publisher：ELSEVIER SCIENCE BV  

We previously reported that angiotensin II type 2 (AT(2)) receptor signaling prevents neural damage and cognitive impairment after focal cerebral ischemia. We investigated the possible roles of the AT(2) receptor in the sex difference, focusing on cognitive function and ischemic brain damage using AT(2) receptor-deficient mice (Agtr2(-)). In Agtr2(-), spatial memory evaluated by the Morris water maze test was impaired in female compared with that in male Aytr2(-) and female wild-type (Agtr2(+)), while no significant sex-different change was observed in Agtr2(+). Interestingly, bromodeoxyuridine incorporation assay showed a significant decrease of hippocampal neurogenesis in female Agtr2(-) compared with that in female Agtr2(+). In contrast, ischemic area after middle cerebral artery (MCA) occlusion was significantly increased in male compared with female mice in Agtr2(-), while no significant sex-different change was observed in Agtr2(+). Male Agtr2(-) mice showed higher AT, receptor expression and significantly impaired cerebral blood flow (CBF) in the ipsilateral side 24 hours after MCA occlusion compared with female Agtr2(-) mice. In conclusion, deletion of the AT(2) receptor showed a sex-different effect such as a severe cognitive impairment with a decrease of hippocampal neurogenesis in females and a larger ischemic brain damage with a decrease of CBF in males. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.brainres.2009.08.068

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

The pathological hallmark of Alzheimer disease is deposition of amyloid-beta protein (A beta) in the brain. Telmisartan is a unique angiotensin II receptor blocker with peroxisome proliferator-activated receptor-gamma (PPAR-gamma) stimulating activity. Activation of PPAR-gamma is expected to prevent inflammation and A beta accumulation in the brain. We investigated the possible preventive effect of telmisartan on cognitive decline in an Alzheimer disease mouse model via PPAR-gamma activation. Here, male ddY mice underwent ICV injection of A beta 1-40. Cognitive function was evaluated by the Morris water maze test. A low dose of telmisartan (0.35 mg/kg per day) was administered in drinking water with or without GW9662, a PPAR-gamma antagonist. Cerebral blood flow was evaluated by laser speckle flowmetry. Inflammatory cytokine levels were measured by quantitative RT-PCR. A beta 1-40 ICV injection significantly impaired cognitive function. Pretreatment with telmisartan improved this cognitive decline to a similar level to that in control mice. Cotreatment with GW9662, a PPAR-gamma antagonist, attenuated this telmisartan-mediated improvement of cognition. Treatment with telmisartan enhanced cerebral blood flow and attenuated the A beta-induced increase in expression of cytokines, such as tumor necrosis factor-alpha and inducible NO synthase in the brain. Interestingly, coadministration of GW9662 cancelled these beneficial effects of telmisartan. A beta 1-40 concentration in the brain was significantly decreased by treatment with telmisartan, whereas administration of GW9662 attenuated the decrease in telmisartan-mediated A beta 1-40 concentration. Taken together, our findings suggest that even a low dose of telmisartan had a preventive effect on cognitive decline in an Alzheimer disease mouse model, partly because of PPAR-gamma activation. (Hypertension. 2009; 54: 782-787.)

DOI： 10.1161/HYPERTENSIONAHA.109.136879

Web of Science

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Recently we have cloned angiotensin II type 2 receptor-interacting protein 1 (ATIP1) as a novel protein that interacts specifically with the C-terminal tail of the angiotensin II type 2 receptor; however, the pathophysiological roles of ATIP1 in vascular remodeling are still unknown. Here, we generated ATIP1-transgenic (ATIP1-Tg) mice expressing mouse ATIP1 and investigated the role of ATIP1 in vascular remodeling using these transgenic mice. ATIP1-Tg mice exhibited no significant difference in blood pressure compared with wild-type (WT) mice. Angiotensin II type 2 receptor mRNA expression in the femoral artery was increased in injured femoral arteries, reaching a peak at 7 days after operation in WT mice, and a similar result of angiotensin II type 2 receptor expression was observed in ATIP1-Tg mice. In ATIP1-Tg mice, neointimal formation of the femoral artery 14 days after cuff placement was significantly smaller than that in WT mice. 5-Bromo-2'-deoxyuridine incorporation was significantly reduced in the injured arteries of ATIP1-Tg mice compared with WT mice. In ATIP1-Tg mice, superoxide anion production and the expression of a proinflammatory cytokine, tumor necrosis factor-alpha, were markedly attenuated. Moreover, cell proliferative signaling, such as extracellular signal-regulated kinase phosphorylation, was significantly attenuated in ATIP1-Tg mice compared with WT mice. Taken together, these results suggest that ATIP1 plays an important role in cuff-induced vascular remodeling in mice. (Hypertension. 2009;53:688-693.)

DOI： 10.1161/HYPERTENSIONAHA.108.128140

Web of Science

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER IRELAND LTD  

Angiotensin (Ang) II, the major effector of the rennin-angiotensin-aldosterone system (RAAS), has multiple functions in regulating cardiovascular hemodynamics and structure. Recent evidence strongly supports that Ang II promotes the onset and progression of vascular senescence, which is associated with vascular functional and structural changes, contributing to age-related vascular diseases. The vast majority of the cardiovascular actions of Ang II, including vascular senescence, are mediated by the Ang II type-1 (AT(1)) receptor. Similar to its growth-promoting process, the signaling mechanisms of AT(1) receptor-mediated vascular senescence-promoting effects involve activation of small G-protein Ras such as Ki-ras2A, mitogen-activated protein kinases (MAPK) such as extracellular signal-regulated kinase 1/2, and transcription factors including nuclear factor (NF)-kappa B and activator protein (AP)-1, and increased generation of reactive oxygen species. Moreover, AT(1) receptor stimulation has been suggested to inactivate cyclin-dependent kinase complexes by up-regulation of cell cycle regulators such as p53 and p21, resulting in cellular senescence. Furthermore, the interaction between Ang II and aldosterone (Aldo) in their contribution to cardiovascular pathophysiology has been highlighted. Aldo can interact with Ang II signaling via a genomic mechanism mediated by the mineralocorticoid receptor (MR). Aldo via MR couples with the AT(1) receptor to elicit the Ras/NF-kappa B, AP-1/p53/p21 pathway involving oxidative stress, leading to synergistic promotion of vascular senescence. Although the precise mechanisms controlling cellular senescence are currently poorly understood, this article reviews recent findings on the signaling mechanisms elicited by RAAS from the perspective of AT, receptor blockers and/or MR blockers in the treatment of age-related vascular diseases. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

DOI： 10.1016/j.arr.2008.12.002.

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Telmisartan is a unique angiotensin receptor blocker (ARB) and partial agonist of peroxisome proliferator-activated receptor (PPAR)-gamma, Here, we investigated the preventive effect of telmisartan on cognitive decline in Alzheimer disease. In ddY mice, intracerebroventricular injection of A beta 1-40 significantly attenuated their cognitive function evaluated by shuttle avoidance test. Pretreatment with a non-hypotensive dose of telmisartan significantly inhibited such cognitive decline. Interestingly, co-treatment with GW9662. a PPAR-gamma antagonist, partially inhibited this improvement of cognitive decline. Another ARB, losartan, which has less PPAR-gamma agonistic effect, also inhibited A beta-injection-induced cognitive decline; however the effect was smaller than that of telmisartan and was not affected by GW9662. Immunohistochemical staining for A beta showed the reduced A beta deposition in telmisartan-treated mice. However, this reduction was not observed in mice co-administered GW9662. These findings Suggest that ARB has a preventive effect on cognitive impairment in Alzheimer disease, and telmisartan, with PPAR-gamma activation, Could exert a stronger effect. (C) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2008.08.032

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Background and Purpose-Protective effects of bone marrow stromal cells (MSCs) on ischemic brain damage have been highlighted. We examined the possibility that deletion of AT(2) receptor could attenuate the cerebroprotective effects of MSC using AT(2) receptor-deficient mice (Agtr2(-)) and the effect of selective AT(1) receptor blocker.
Methods-Wild-type mice (Agtr2(+)) were subjected to 3 hours of focal brain ischemia followed by reperfusion (ischemia-reperfusion injury). Simultaneously, Agtr2(+) -MSC, Agtr2(-) -MSC, or saline was injected through the tail vein.
Results-Survival rates at 6 days after ischemia-reperfusion injury were as follows: approximately 50% in saline-injected mice, 80% in Agtr2(+) -MSC-injected mice, and 20% in Agtr2(-) -MSC-injected mice. Neurological deficit after ischemia-reperfusion injury was improved in Agtr2(+) -MSC-injected mice, but not in Agtr2(+) -MSC-injected mice. After 48 hours of ischemia-reperfusion injury, brain infarct size was reduced in Agtr2(+) -MSC-injected mice, but not in Agtr2(-) -MSC-injected mice. Moreover, brain edema was significantly ameliorated in Agtr2(+)- MSC-treated mice but not in Agtr2(-) -MSC-treated mice. Furthermore, the increase in mRNA expression of tumor necrosis factor-alpha and monocyte chemoattractant protein-1 in the ischemic brain was less in Agtr2(+) -MSC-treated mice in the ipsilateral site, but was similar in the contralateral hemisphere. Tumor necrosis factor-alpha level was increased in both the contralateral hemisphere and ipsilateral hemisphere of Agtr2(-) -MSC-treated mice. In contrast, monocyte chemoattractant protein-1 levels tended to increase Agtr2(-) MSC-treated mice without a significant difference. Treatment of MSC with an AT(1) receptor blocker, valsartan, significantly improved survival rates in Agtr2(-) -MSC-injected mice.
Conclusions-These results suggest that AT(2) receptor signaling in MSC attenuated brain damage and neurological deficit (deleted).

DOI： 10.1161/STROKEAHA.107.513275

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Background and Purpose - We investigated the effect of temporary treatment with a nonhypotensive dose of valsartan on ischemic brain damage in C57BL/6 mice.
Methods - We separated the mice into 3 groups of valsartan treatment before middle cerebral artery (MCA) occlusion: (1) for 4 weeks: Val (2W, 2W); (2) for 2 weeks followed by its cessation for 2 weeks: Val (2W, -); and (3) no treatment for 4 weeks: Val (-, -).
Results - Ischemic volume, DNA damage, superoxide production, and mRNA levels of monocyte chemoattractant protein-1 and tumor necrosis factor-alpha on the ipsilateral side after 24 hours of MCA occlusion were significantly reduced in both Val (2W, 2W) and Val (2W, -) mice compared with those in Val (-, -) mice, whereas these parameters were larger in Val (2W, -) mice than in Val (2W, 2W) mice. Moreover, mice in both the Val (2W, 2W) and Val (2W, -) groups exhibited an increase in cerebral blood flow in the peripheral territory of the MCA 1 hour after MCA occlusion, with increases in endothelial nitric oxide synthase activation and nitric oxide production. Before MCA occlusion, treatment with valsartan did not influence superoxide production or mRNA levels of monocyte chemoattractant protein-1 and tumor necrosis factor-alpha in the brain. However, the capillary density in the brain in both Val (2W, 2W) and Val (2W, -) mice was increased before MCA occlusion.
Conclusions - Our results suggest that temporary valsartan treatment could protect against ischemic brain damage even after its cessation, at least in part due to an increase in capillary density.

DOI： 10.1161/STROKEAHA.107.503458

Web of Science

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Vascular senescence is closely associated with age-related vascular disorders and is enhanced by angiotensin (Ang) II type 1 receptor stimulation. However, the role of Ang II type 2 receptor activation in vascular senescence is still an enigma. Ang II stimulation significantly increased senescence-associated beta-galactosidase activity and the level of 8-hydroxy-2'-deoxyguanosine, with enhancement of oxidative stress and expression of Ki-ras2A, p53, and p21 in vascular smooth muscle cells (VSMCs) from wild-type (Agtr2(+)) mice, whereas these effects of Ang II were enhanced in VSMCs from Ang II type 2 receptor null (Agtr2(-)) mice. Administration of an Ang II type 1 receptor blocker, valsartan, attenuated these parameters, with less effect in Agtr2(-) VSMCs. Ang II stimulation increased methyl methanesulfonate sensitive 2 (MMS2) expression in Agtr2(-) VSMCs but not in Agtr2(-) VSMCs. MMS2 small-interfering RNA treatment enhanced Ang II-induced senescence-associated beta-galactosidase activity and 8-hydroxy-2'-deoxyguanosine level with no significant changes in oxidative stress markers and the expression of Ki-ras2A, p53, and p21. Moreover, exposure of Agtr2(+) VSMCs to hydrogen peroxide and ultraviolet irradiation induced marked increases in senescence-associated beta-galactosidase activity and 8-hydroxy-2'-deoxyguanosine level, which were further enhanced in Agtr2(-) and MMS2 small-interfering RNA-treated Agtr2(+) VSMCs. Agtr2(+) mice exposed to x-ray irradiation showed increases in senescence-associated beta-galactosidase activity and 8-hydroxy-2'-deoxyguanosine level in the aorta, which were further exaggerated in the aorta of Agtr2(-) mice with a lower MMS2 level. These findings suggest that Ang II type 2 receptor signaling attenuates DNA damage and consequent vascular senescence at least in part through MMS2 transactivation and propose the beneficial effects of Ang II type 2 receptor stimulation with Ang II type 1 receptor blockers in age-related vascular disorders.

DOI： 10.1161/HYPERTENSIONAHA.107.105692

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Nifedipine, a calcium channel blocker, has been reported to exert pleiotropic effects on atherosclerosis, mainly through its antioxidative properties. However, the effect of the calcium channel blocker on cognitive impairment associated with type 2 diabetes mellitus is not well known. Here, we examined the possibility that a calcium channel blocker could improve cognitive function in a type 2 diabetic mouse model, KK-A(y). KK-A(y) mice subjected to 20 trials of a passive avoidance task every week from 7 weeks of age exhibited impairment of the increase in avoidance rate and, moreover, exaggeration of its age-dependent decline, especially after 12 weeks of age. Oral administration of nifedipine at a nonhypotensive dose (0.001% in laboratory chow) to KK-A(y) mice from 10 weeks of age improved cognitive function. Nifedipine treatment decreased serum insulin level to one fifth of that in KK-A(y) mice without nifedipine. Moreover, nifedipine treatment significantly reduced superoxide anion production in the brain. Furthermore, treatment with nifedipine markedly reduced the mRNA level of Id-1, inhibitor of neural differentiation, in the brain hippocampus. We also observed the increase in blood flow in the brain in KK-A(y) mice with nifedipine treatment compared with nontreated mice. Taken together, our findings suggest that nifedipine ameliorates impaired cognitive function in type 2 diabetic mice, at least because of attenuation of hyperinsulinemia and superoxide production in the brain and possible upregulation of the neural differentiation-controlling gene, Id-1.

DOI： 10.1161/HYPERTENSIONAHA.107.101634

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The metabolic syndrome is closely related to dietary habits and seems to be associated with impairment of cognitive function in humans. Angiotensin receptor blockers are widely used with the expectation of preventing cardiovascular events and stroke and potential amelioration of the metabolic syndrome. We examined the diet-induced changes of cognitive function in mice treated with a high-salt and high-cholesterol diet. C57BL/6J mice were fed a high-salt (2% NaCl in drinking water) and high-cholesterol (1.25% cholesterol, 10% coconut oil) diet (HSCD) or a normal diet (ND), and subjected to 20 trials of a passive avoidance task every week from 8 weeks of age. An age-dependent decline of the avoidance rate starting from 10 weeks of age was observed in HSCD mice, whereas the avoidance rate gradually increased in the ND group. Oral administration of an angiotensin receptor blocker, olmesartan, at a dose of 3 mg/kg per day in drinking water from 8 weeks of age prevents this decline of avoidance rate in HSCD mice (49% vs. 82% at 12 weeks of age). Treatment with olmesartan significantly decreased serum glucose and cholesterol levels in HSCD mice, with a slight decrease in blood pressure. Administration of olmesartan in HSCD-fed mice showed a 1.6-fold increase in mRNA expression of a neuroprotective factor, MMS2, compared to HSCD-fed mice without olmesartan. Olmesartan attenuated the increase in superoxide anion production detected by dihydroethidium staining in the brain of HSCD mice. Our results suggest that olmesartan could be therapeutically effective in preventing the impairment of quality of life in persons on a high-fat and high-salt diet. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.neuropharm.2007.08.020

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Angiotensin II type-1 receptor blockers are widely used with the expectation of prevention of stroke, potential effects to ameliorate of type-2 diabetes, which seems to be closely associated with the impairment of cognitive function in humans. Recently, we have reported that an angiotensin II type-1 receptor blocker prevented cognitive impairment in mice after focal cerebral ischemia, at least partly through an angiotensin II type-2 receptor-mediated increase in a neuroprotective factor, methyl methanesulfonate sensitive- 2. Here, we examined the possibility that an angiotensin II type-1 receptor blocker could improve cognitive function in a type- 2 diabetic mouse model, KK-A(y). KK-A(y) mice subjected to 20 trials of a passive avoidance task every week from 8 weeks exhibited a significantly impaired avoidance rate, and moreover, its age- dependent decline, especially after 14 weeks of age, compared with age-matched C57BL6 mice. Oral administration of candesartan at a nonhypotensive dose (0.005% in laboratory chow) in KK-A(y) mice improved cognitive function and inhibited the impairment of cognitive decline. Methyl methanesulfonate sensitive-2 expression in the brain was lower in KK-A(y) mice than in C57BL6 mice. Treatment with candesartan markedly increased mRNA expression of angiotensin II type-2 receptor and methyl methanesulfonate sensitive-2 in the brain in KK-A(y) mice, determined by quantitative RT-PCR. In KK-A(y) mice treated with candesartan, age-dependent increases in blood glucose and insulin were significantly suppressed. Our results suggest that candesartan ameliorates the impaired cognitive function in type-2 diabetes mice, at least because of an increased expression of methyl methanesulfonate sensitive-2, a neuroprotective factor, in addition to improvement of glucose intolerance. (Hypertension. 2007; 50: 1099- 1105.).

DOI： 10.1161/HYPERTENSIONAHA.107.099374

Web of Science

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Objective: Our aim was to examine the possible cross-talk of angiotensin II (Ang II) and aldosterone (Aldo) in the regulation of vascular cell senescence in cultured vascular smooth muscle cells (VSMC).
Methods: VSMC were prepared from thoracic aorta of adult male Sprague-Dawley rats. Cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-beta-gal) staining and expression of p21, p53, p16, and p27. Oxidative stress was determined by measuring NADPH oxidase activity and superoxide production. Signal transduction was examined by immunoblot analysis with or without RNA interference methods.
Results: Persistent Ang II (100 nM) stimulation increased SA-beta-gal-stained VSMC and enhanced expression of p21, p53, p16, p27 and Ki-ras2A. These effects of Ang II were markedly inhibited by treatment with a selective AT I receptor blocker, valsartan, but partially attenuated by a mineralocorticoid receptor antagonist, spironolactone. The culture medium of VSMC treated with Ang II (100 nM) showed a time-dependent increase in Aldo concentration, which increased senescent VSMC. Antioxidant, N-acetyl-L-cysteine or superoxide dismutase attenuated Ang II- or Aldo-induced VSMC senescence and Ki-ras2A expression. A lower dose combination of Ang II (100 pM) and Aldo (1 pM) significantly enhanced SA-p-gal-stained VSMC with increases in expression of p21, p53, p 16, p27 and Ki-ras2A, oxidative stress, and activity of transcription factors such as NF-kappa B, AP-1, whereas Ang II or Aldo alone at these doses did not affect these parameters. Ki-ras2A-siRNA treatment attenuated senescent VSMC, expression of p21, p53, p16 and p27, oxidative stress induced by Ang II or a lower dose combination of Ang II and Aldo.
Conclusion: These results suggest that Ang II and Aldo exert cross-talk in VSMC senescence with involvement of oxidative stress and Ki-ras2A, and could provide a therapeutic benefit for age-related vascular disorders by blockade of both Ang II and Aldo. (c) 2007 European Society of Cardiology. Published by Elsevier B.V.. All rights reserved.

DOI： 10.1016/j.cardiores.2007.07.008

Web of Science

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis   Publisher：ELSEVIER SCIENCE BV  

Eplerenone, a mineralocorticoid receptor antagonist, is reported to be effective to prevent end-stage cardiovascular damage induced by aldosterone. However, the effect of eplerenone on brain damage is not fully understood. Here, we investigated whether pretreatment with eplerenone attenuates stroke size in mice subjected to middle cerebral artery occlusion. Middle cerebral artery occlusion with a microfilament technique induced focal ischemia, to approximately 25% of the total area in a coronal section of the brain. Treatment with eplerenone at a dose of 1.67 mg/g chow significantly reduced the ischemic area, ischemic volume, and neurological deficit, without a blood pressure-lowering effect. Laser-Doppler flowmetry analysis showed a decrease in surface cerebral blood flow in the peripheral region after I h of middle cerebral artery occlusion. This decrease was smaller in mice treated with eplerenone. Superoxide production evaluated by staining with dihydroethidium was attenuated in the ischemic area of the brain in eplerenone-treated mice. Taken together, our findings suggest that eplerenone has a protective effect on ischemic brain damage, at least partly due to improvement of cerebral blood flow in the penumbra and reduction of oxidative stress. (c) 2007 Elsevier B.V All rights reserved.

DOI： 10.1016/j.ejphar.2007.03.043

Web of Science

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis   Publisher：OXFORD UNIV PRESS INC  

Angiotensin II (Ang II) type 2 (AT(2)) receptors are abundantly expressed not only in the fetal brain where they probably contribute to brain development, but also in pathological conditions to protect the brain against stroke; however, the detailed mechanisms are unclear. Here, we demonstrated that AT 2 receptor signaling induced neural differentiation via an increase in MMS2, one of the ubiquitin-conjugating enzyme variants. The AT(2) receptor, MMS2, Src homology 2 domain-containing protein-tyrosine phosphatase 1 (SHP-1), and newly cloned AT(2) receptor-interacting protein ( ATIP) were highly expressed in fetal rat neurons and declined after birth. Ang II induced MMS2 expression in a dose-dependent manner, reaching a peak after 4 h of stimulation, and this effect was enhanced with AT(1) receptor blocker, valsartan, but inhibited by AT(2) receptor blocker PD123319. Moreover, we observed that an AT 2 receptor agonist, CGP42112A, alone enhanced MMS2 expression. Neurons treated with small interfering RNA of MMS2 failed to exhibit neurite outgrowth and synapse formation. Moreover, the increase in AT(2) receptor-induced MMS2 mRNA expression was enhanced by overexpression of ATIP but inhibited by small interfering RNA of SHP-1 and overexpression of catalytically dominant-negative SHP-1 or a tyrosine phosphatase inhibitor, sodium orthovanadate. After AT(2) receptor stimulation, ATIP and SHP-1 were translocated into the nucleus after formation of their complex. Furthermore, increased MMS2 expression mediates the inhibitor of DNA binding 1 proteolysis and promotes DNA repair. These results provide a new insight into the contribution of AT 2 receptor stimulation to neural differentiation via transactivation of MMS2 expression involving the association of ATIP and SHP-1.

DOI： 10.1210/me.2006-0005

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The potential combined effect and mechanism of calcium channel blockers (CCB) and angiotensin II type 1 receptor blockers (ARB) to improve insulin resistance were investigated in type 2 diabetic KK-Ay mice, focusing on their antioxidative action. Treatment of KK-Ay mice with a CCB, azelnidipine (3 mg/kg/day), or with an ARB, olmesartan (3 mg/kg/day), for 2 weeks lowered the plasma concentrations of glucose and insulin in the fed state, attenuated the increase in plasma glucose in the oral glucose tolerance test (OGTT), and increased 2-[(3)H]deoxy-d-glucose (2-[(3)H]DG) uptake into skeletal muscle with the increase in translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Both blockers also decreased the in situ superoxide production in skeletal muscle. The decrease in plasma concentrations of glucose and insulin in the fed state and superoxide production in skeletal muscle, as well as GLUT4 translocation to the plasma membrane, after azelnidipine administration was not significantly affected by coadministration of an antioxidant, 2,2,6,6-tetramethyl-1-piperidinyloxy (tempol). However, those changes caused by olmesartan were further improved by tempol. Moreover, olmesartan enhanced the insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 induced in skeletal muscle, whereas azelnidipine did not change it. Coadministration of azelnidipine and olmesartan further decreased the plasma concentrations of glucose and insulin, improved OGTT, and increased 2-[(3)H]DG uptake in skeletal muscle. These results suggest that azelnidipine improved glucose intolerance mainly through inhibition of oxidative stress and enhanced the inhibitory effects of olmesartan on glucose intolerance, as well as the clinical possibility that the combination of CCB and ARB could be more effective than monotherapy in the treatment of insulin resistance.

PubMed

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

The molecular mechanisms of the contribution of angiotensin II type-1 receptor blockers to neuronal protection are still unclear. Here, we investigated the effect of angiotensin II type-2 (AT2) receptor stimulation on neurons and cognitive function involving a new neuroprotective factor, methyl methanesulfonate sensitive 2 (MMS2). Angiotensin II treatment of neurospheres enhanced their differentiation and increased MMS2 expression. Knockdown of the MMS2 gene by small interference RNA (siRNA) significantly reduced the number of neurospheres, with loss of sphere formation. An angiotensin II type-1 receptor blocker, valsartan, enhanced such neurosphere differentiation and MMS2 induction, whereas an AT2 receptor antagonist, PD123319, inhibited them. After mice underwent permanent middle cerebral artery occlusion, AT2 receptor mRNA expression was significantly increased in the ischemic side of the brain. Passive avoidance rate to evaluate cognitive function was significantly impaired in AT2 receptor null (Agtr2-) mice compared with wild-type mice. Treatment with valsartan prevented the cognitive decline in wild-type mice, but this effect was weaker in Agtr2- mice. In ischemic brain regions, MMS2 was increased in wild-type mice, but not in Agtr2- mice. Valsartan also enhanced MMS2 expression to a greater degree in wild-type mice. Finally, intracerebroventricular administration of MMS2 siRNA showed more impaired avoidance rate after middle cerebral artery occlusion compared with that in control siRNA-transfected mice. These findings experimentally support the clinical evidence and indicate a unique mechanism of the AT(2) receptor in brain protection.

DOI： 10.1161/01.HYP.0000229648.67883.f9

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The role of angiotensin II (Ang II) type 2 (AT2) receptor in atherosclerosis was explored with the use of AT2 receptor/apolipoprotein E (ApoE)-double-knockout (AT2/ApoE-DKO) mice, with a focus on oxidative stress. METHODS AND RESULTS: After treatment with a high-cholesterol diet (1.25% cholesterol) for 10 weeks, ApoE-knockout (KO) mice developed atherosclerotic lesions in the aorta. In AT2/ApoE-DKO mice receiving a high-cholesterol diet, the atherosclerotic changes were further exaggerated, without significant changes in plasma cholesterol level and blood pressure. In the atherosclerotic lesion, an increase in superoxide production, NADPH oxidase activity, and expression of p47phox was observed. These changes were also greater in AT2/ApoE-DKO mice. An Ang II type 1 (AT1) receptor blocker, valsartan, inhibited atherosclerotic lesion formation, superoxide production, NADPH oxidase activity, and p47phox expression; these inhibitory effects were significantly weaker in AT2/ApoE-KO mice. We further examined the signaling mechanism of the AT2 receptor-mediated antioxidative effect in cultured fetal vascular smooth muscle cells. NADPH oxidase activity and phosphorylation and translocation of p47phox induced by Ang II were inhibited by valsartan but enhanced by an AT2 receptor blocker, PD123319. CONCLUSIONS: These results suggest that AT2 receptor stimulation attenuates atherosclerosis through inhibition of oxidative stress and that the antiatherosclerotic effect of valsartan could be at least partly due to AT2 receptor stimulation by unbound Ang II.

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Doctoral thesis  

Interaction between aldosterone (Aldo) and angiotensin II (Ang II) in the cardiovascular system has been highlighted; however, its detailed signaling mechanism is poorly understood. Here, we examined the cross-talk of growth-promoting signaling between Aldo and Ang II in vascular smooth muscle cells (VSMC). Treatment with a lower dose of Aldo (10(-12) mol/L) and with a lower dose of Ang II (10(-10) mol/L) significantly enhanced DNA synthesis, whereas Aldo or Ang II alone at these doses did not affect VSMC proliferation. This effect of a combination of Aldo and Ang II was markedly inhibited by a selective AT1 receptor blocker, olmesartan, a mineralocorticoid receptor antagonist, spironolactone, an MEK inhibitor, PD98059, or an EGF receptor tyrosine kinase inhibitor, AG1478. Treatment with Aldo together with Ang II, even at noneffective doses, respectively, synergistically increased extracellular signal-regulated kinase (ERK) activation, reaching 2 peaks at 10 to 15 minutes and 2 to 4 hours. The early ERK peak was effectively blocked by olmesartan or an EGF receptor kinase inhibitor, AG1478, but not by spironolactone, whereas the late ERK peak was completely inhibited by not only olmesartan, but also spironolactone. Combined treatment with Aldo and Ang II attenuated mitogen-activated protein kinase phosphatase-1 (MKP-1) expression and increased Ki-ras2A expression. The late ERK peak was not observed in VSMC treated with Ki-ras2A-siRNA. Interestingly, the decrease in MKP-1 expression and the increase in Ki-ras2A expression were restored by PD98059 or AG1478. These results suggest that Aldo exerts a synergistic mitogenic effect with Ang II and support the notion that blockade of both Aldo and Ang II could be more effective to prevent vascular remodeling.

DOI： 10.1161/01.RES.0000180753.63183.95.

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: Angiotensin II type 1 receptor blockers (ARB) are widely recognized to have a vasculoprotective effect. Accumulating data have revealed that calcium antagonists also retard atherosclerosis. We examined the possibility that combination therapy of ARB and calcium antagonists could more effectively prevent atherosclerosis than monotherapy. METHODS AND RESULTS: We observed a marked increase in the atherosclerotic area, associated with the exaggerated expression of nicotinamide adenine dinucleotide (phosphate), reduced form [NAD(P)H] oxidase subunits (p22 and p47) and superoxide anion production, in the aorta of apolipoprotein E-deficient mice maintained on a 1.25% high-cholesterol diet for 10 weeks. A calcium antagonist, azelnidipine, at a dose of 1 mg/kg a day or an ARB, olmesartan, at a dose of 3 mg/kg a day, significantly inhibited these parameters, with no change in systolic blood pressure and the blood cholesterol level. Moreover, the co-administration of lower doses of azelnidipine (0.1 mg/kg a day) and olmesartan (1 mg/kg a day) significantly inhibited the atherosclerotic area and oxidative stress, whereas azelnidipine or olmesartan alone at these doses did not affect these parameters. Furthermore, we observed similar inhibitory effects of azelnidipine or olmesartan on angiotensin II-induced NADPH oxidase activity and Akt activity in cultured vascular smooth muscle cells. CONCLUSION: These results suggest that the co-administration of calcium antagonists and ARB synergistically blunts oxidative stress at least partly through the inhibition of Akt activity and enhances the beneficial effects of these drugs on atherosclerosis compared with monotherapy.

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The detailed mechanism of the effects of extracellular Ca2+ entry blockade on angiotensin II (Ang II) type 1 (AT1) receptor-mediated growth-promoting signals in vascular smooth muscle cells (VSMCs) is not fully understood. Ang II stimulation caused biphasic activation of growth-promoting signals, reaching a peak at 5 to 10 min followed by a decrease and a second peak at around 2 to 4 h. Addition of PD98059 (2'-amino-3'-methoxyflavone), a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor, or AG490 [alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide], a Janus-activated kinase 2 (Jak2) inhibitor, even 4 h after Ang II treatment inhibited [3H]thymidine incorporation. The calcium channel blocker azelnidipine attenuated the later peaks of extracellular signal-regulated kinase (ERK), tyrosine kinase 2, Jak2 activation, and phosphorylation of signal transducer and activator of transcription (STAT)1 and STAT3. Interestingly, azelnidipine increased rather than decreased the later ERK peaks in cells treated with small interfering RNA against mitogen-activated protein kinase phosphatase-1. Ang II-mediated [3H]thymidine incorporation was inhibited dose dependently by azelnidipine and also by azelnidipine, plus olmesartan, whereas olmesartan or azelnidipine alone at such lower doses did not affect [3H]thymidine incorporation. These data provide new insight into the manner in which calcium channels exert an essential action in the AT1 receptor-mediated growth-promoting actions in VSMCs.

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis  

The present study explored the possibility that estrogen enhances the inhibitory effect of an angiotensin II type-1 (AT1) receptor blocker (ARB), olmesartan, on atherosclerosis, focusing on oxidative stress using apolipoprotein E knockout mice (ApoEKO). After 6 weeks on a high-cholesterol diet, marked atherosclerotic lesion formation with an increase in oxidative stress, such as superoxide production, NAD(P)H oxidase activity and expression of p47phox mRNA and rac-1 mRNA, were observed in the proximal aorta in both male and female ApoEKO mice, whereas these changes were less marked in female mice. Ovariectomy enhanced these parameters, the changes of which were reversed by 17beta-estradiol (80 microg/kg per day) replacement. Treatment with olmesartan (3 mg/kg per day) significantly inhibited oxidative stress and atherosclerosis, whereas its inhibitory effects were more marked in female than in male or ovariectomized mice. Smaller doses of olmesartan (0.5 mg/kg per day) or 17beta-estradiol (20 microg/kg per day) did not influence atherosclerosis and oxidative stress in ovariectomized mice, whereas co-administration of olmesartan and 17beta-estradiol at these doses attenuated these parameters. An angiotensin-converting enzyme (ACE) inhibitor, temocapril, also inhibited atherosclerotic changes similarly to olmesartan. Moreover, angiotensin II-mediated activation of NAD(P)H oxidase in cultured vascular smooth muscle cells was attenuated by 17beta-estradiol. These results indicate that estrogen and an ARB synergistically attenuate atherosclerosis at least partly via inhibition of oxidative stress.

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis  

Angiotensin II has been shown to contribute to the pathogenesis of insulin resistance; however, the mechanism is not well understood. The present study was undertaken to investigate the potential effect of an angiotensin II type-1 (AT1) receptor blocker, valsartan, to improve insulin resistance and to explore the signaling basis of cross-talk of the AT1 receptor- and insulin-mediated signaling in type 2 diabetic KK-Ay mice. Treatment of KK-Ay mice with valsartan at a dose of 1 mg/kg per day, which did not influence systolic blood pressure, significantly increased insulin-mediated 2-[3H]deoxy-d-glucose (2-[3H]DG) uptake into skeletal muscle and attenuated the increase in plasma glucose concentration after a glucose load and plasma concentrations of glucose and insulin. In contrast, insulin-mediated 2-[3H]DG uptake into skeletal muscle was not influenced in AT2 receptor null mice, and an AT2 receptor blocker, PD123319, did not affect 2-[3H]DG uptake and superoxide production in skeletal muscle of KK-Ay mice. Moreover, we observed that valsartan treatment exaggerated the insulin-induced phosphorylation of IRS-1, the association of IRS-1 with the p85 regulatory subunit of phosphoinositide 3 kinase (PI 3-K), PI 3-K activity, and translocation of GLUT4 to the plasma membrane. It also reduced tumor necrosis factor-alpha (TNF-alpha) expression and superoxide production in skeletal muscle of KK-Ay mice. Specific AT1 receptor blockade increases insulin sensitivity and glucose uptake in skeletal muscle of KK-Ay mice via stimulating the insulin signaling cascade and consequent enhancement of GLUT4 translocation to the plasma membrane.

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

In the present study we examined the effects of angiotensin II (Ang II) type 2 (AT(2)) receptor stimulation on AT(1) receptor-mediated monocyte chemoattractant protein-1 (MCP-1) expression and the possible mechanisms of AT(2) receptor-mediated signaling in cultured rat fetal vascular smooth muscle cells, which express both AT(1) and AT(2) receptors. Ang II stimulation induced MCP-1 mRNA expression as well as an increase in nuclear factor-kappaB (NF-kappaB) binding to the corresponding cis DNA element of the MCP-1 promoter region and a decrease in the cytosolic inhibitory protein-kappaB (IkappaB) protein level via AT(1) receptor stimulation, whereas stimulation of the AT(2) receptor decreased Ang II-induced MCP-1 expression, NF-kappaB DNA binding, and IkappaB degradation, suggesting that activation of the AT(2) receptor attenuated AT(1) receptor-mediated MCP-1 expression via a decrease in NF-kappaB DNA binding and an increase in IkappaB stability. Moreover, we demonstrated that AT(2) receptor stimulation attenuated TNFalpha-mediated NF-kappaB activation and MCP-1 expression. A tyrosine phosphatase inhibitor, orthovanadate, attenuated the AT(2) receptor-mediated increase in IkappaB protein. Moreover, we observed that two IkappaB subunits (IkappaBalpha and IkappaBbeta) were tyrosine-phosphorylated after Ang II stimulation. Transfection of a dominant-negative Src homology protein tyrosine phosphatase-1 mutant into vascular smooth muscle cells inhibited the AT(2) receptor-mediated increase in IkappaB, leading to a significant increase in AT(1) receptor-induced NF-kappaB activation and MCP-1 expression. Taken together, our results demonstrated that AT(2) receptor stimulation attenuated MCP-1 expression via IkappaB stabilization, and Src homology protein tyrosine phosphatase-1 might play a critical role in the transcriptional regulation of MCP-1 expression through the control of IkappaB protein stability.

PubMed

researchmap

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

We examined the possibility of whether angiotensin (Ang) II type 1 (AT1) and type 2 (AT2) receptor stimulation differentially regulates collagen production in mouse skin fibroblasts. Both AT1 and AT2 receptors were expressed in neonatal skin fibroblasts prepared from wild-type mice to a similar degree, and the AT1a receptor was exclusively expressed as opposed to the AT1b receptor. In wild-type fibroblasts, Ang II increased collagen synthesis accompanied by an increase in expression of tissue inhibitor of metalloproteinase (TIMP)-1, and these increases were inhibited by valsartan, an AT1 receptor blocker, but augmented by PD123319, an AT2 receptor antagonist. Ang II decreased basal and IGF-I-induced collagen production and inhibited TIMP-1 expression in neonatal skin fibroblasts prepared from AT1a knockout (KO) mice. These Ang II-mediated inhibitory effects on collagen production and TIMP-1 expression observed in AT1a KO fibroblasts were attenuated by the addition of PD123319 or a tyrosine phosphatase inhibitor, sodium orthovanadate, but not affected by a serine/threonine phosphatase inhibitor, okadaic acid. Moreover, we demonstrated that transfection of a catalytically inactive, dominant negative SHP-1 (Src homology 2-containing protein-tyrosine phosphatase-1) mutant inhibited the Ang II-mediated inhibitory effect on both collagen synthesis and TIMP-1 expression in AT1a KO fibroblasts. These results suggest that AT1a receptor stimulation increases collagen production in skin fibroblasts at least in part due to the inhibition of collagen degradation via the increase in TIMP-1 expression, whereas AT2 receptor stimulation exerts inhibitory effects on TIMP-1 expression, which is mediated at least partially by the activation of SHP-1, thereby possibly inhibiting collagen production.

DOI： 10.1210/en.2003-0673

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVE: The pathogenetic mechanism of tobacco-related cardiovascular diseases is still not well defined. We examined the potential possibility of an interaction between nicotine, a major component of cigarette smoke, and angiotensin II (Ang II), which plays an important role in the pathogenesis of cardiovascular diseases characterized by Ang II type 1 (AT1) receptor-mediated abnormal growth of vascular smooth muscle cells (VSMC) and fibroblasts. METHODS AND RESULTS: Nicotine or Ang II-stimulated [3H]thymidine incorporation and c-fos expression in adult rat aortic VSMC and adventitial fibroblast. The nicotine-induced DNA synthesis was not affected by valsartan, an AT1 receptor-specific blocker, or PD123319, an Ang II type 2 (AT2) receptor-specific antagonist. Nicotine or Ang II stimulation rapidly increased extracellular signal-regulated kinase (ERK) activation, tyrosine- and serine-phosphorylation of signal transducer and activator of transcription (STAT)1 and STAT3, and p38 mitogen-activated protein kinase (p38 MAPK), in both cell types. Interestingly, co-administration of nicotine and Ang II at lower doses, which did not affect cell growth, induced DNA synthesis and c-fos expression accompanied by enhancement of ERK, STAT, and p38MAPK activity. PD98059, a mitogen-activated protein kinase/ERK kinase inhibitor, or SB23058, a p38MAPK inhibitor, significantly attenuated the vasotrophic effect of nicotine and Ang II. CONCLUSIONS: These results suggest that nicotine exerts a growth-promoting effect on vascular cells and enhances the Ang II-induced vasotrophic effect, which is at least partly mediated by the activation of ERK, STAT, and p38MAPK.

PubMed

researchmap

Language：English   Publishing type：Doctoral thesis  

To examine the possible role of the bradykinin-NO system in the action of ACE inhibitors, we studied the effects of imidapril, an ACE inhibitor, on inflammatory vascular injury by using AT1a-receptor-deficient (AT1aKO) mice. A polyethylene cuff was placed around the femoral artery of AT1aKO mice and wild-type (WT; C57BL/6J) mice. Neointimal area in cross sections of the artery was measured 14 days after cuff placement. A low dose of imidapril (1 mg/kg per day), which did not affect blood pressure, was administered by gavage. Expression of monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-alpha was detected by immunohistochemical staining and reverse transcriptase-polymerase chain reaction (RT-PCR) 7 days after the operation. Neointimal formation, vascular smooth muscle cell proliferation, and expression of MCP-1 and TNF-alpha were attenuated in the injured artery in AT1aKO mice compared with those in WT mice. Imidapril inhibited neointimal formation, DNA synthesis of vascular smooth muscle cells, and expression of MCP-1 and TNF-alpha in AT1aKO mice as well as in WT mice. In addition, imidapril increased tissue cGMP content after cuff placement. These inhibitory effects of imidapril were significantly reduced or abolished by a bradykinin receptor antagonist, Hoechst 140, or an NO synthase inhibitor, L-NAME, both in WT and AT1aKO mice. Treatment with imidapril did not change AT2 receptor and ACE expression detected by RT-PCR in the injured artery. These results indicate that not only blockade of angiotensin II production but also activation of the bradykinin-NO system plays an important role in the beneficial effects of imidapril on vascular remodeling.

PubMed

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：English   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：日本臨床栄養学会  

乳由来ペプチドであるCH-3(bovine Casein Hydrolysate which is produced by 3 enzymes)の経口摂取による認知機能低下抑制について、脳室内アミロイドβ(Aβ)投与マウスを用いて検討した。CH-3にはメチオニン-リジン-プロリンのトリペプチド(MKP)が含まれ、アンジオテンシン変換酵素(ACE)の阻害作用を有することがこれまでに報告されている。今回の検討によって、MKPは神経および脳血管への保護的な効果により、Aβ投与によって生じる認知機能低下を抑制する作用を持つと考えられた。ただし、脳内ACEへの影響については詳しく検討しておらず、CH-3のACE阻害が認知機能に影響を及ぼしたかどうかは明確にされなかった。今後、ACE阻害作用を持つペプチドが同じように認知機能改善効果を持つかを検討する必要がある。

CiNii Books

researchmap

Other Link： http://search.jamas.or.jp/link/ui/2017356776

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(一社)日本臨床栄養協会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：English   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：English   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Authorship：Lead author   Language：Japanese  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPANESE PHARMACOLOGICAL SOC  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPANESE PHARMACOLOGICAL SOC  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPANESE PHARMACOLOGICAL SOC  

Web of Science

researchmap

Language：English   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：English   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：Japanese   Publisher：(一社)日本老年医学会  

researchmap

Language：Japanese   Publisher：(一社)日本老年医学会  

researchmap

Language：Japanese   Publisher：(一社)日本老年医学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPANESE PHARMACOLOGICAL SOC  

Web of Science

researchmap

Language：English  

Background: Limonoids are highly oxygenated triterpenoid compounds abundantly contained in citrus fruits. It has been reported that limonoids have several pharmacological activities such as anti-cancer, anti-malarial, and antimicrobial activities. Moreover, recent reports have indicated that limonoids may have a preventive effect on cardiovascular disease and metabolic disorders. However, very little information is available about the effects of limonoids on cognitive impairment due to Alzheimer disease and vascular dementia. In the present study, we investigated whether limonin, one of the major limonoids, has a preventive effect on cognitive dysfunction in a mouse vascular dementia model induced by chronic cerebral hypoperfusion. Materials and Methods: Ten-week-old C57BL/6J male mice were subjected to bilateral common carotid artery stenosis (BCAS) using external microcoils. Mice were administered limonin (10 mg/kg/day) from 8 to 16 weeks of age. Spatial working memory was evaluated by the Morris water maze test at 16 weeks of age. Blood pressure was measured by tail-cuff method. Cerebral blood flow was assessed by 2D laser speckle flowmetry. Results: Chronic cerebral hypoperfusion induced by BCAS significantly impaired cognitive function compared with that of the control group. However, administration of limonin did not ameliorate cognitive dysfunction induced by BCAS. Moreover, cerebral blood flow was reduced by BCAS, but this reduction was not improved by limonin treatment. There was no significant change in blood pressure in each mouse. Conclusion: Limonin had no apparent effect on cognitive impairment attributed to chronic cerebral hypoperfusion. © 2013 Bentham Science Publishers.

DOI： 10.2174/1871522211313020008

Scopus

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：English   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：Japanese   Publisher：(株)メディカルレビュー社  

researchmap

Language：English   Publisher：(株)メディカルレビュー社  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(一社)日本抗加齢医学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Authorship：Lead author   Language：Japanese  

researchmap

Other Link： http://search.jamas.or.jp/link/ui/2011038891

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPAN ENDOCRINE SOC  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：JAPAN ENDOCRINE SOC  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Authorship：Lead author   Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Angiotensin (Ang) II, the major effector of the rennin-angiotensin-aldosterone system (RAAS), has multiple functions in regulating cardiovascular hemodynamics and structure. Recent evidence strongly supports that Ang II promotes the onset and progression of vascular senescence, which is associated with vascular functional and structural changes, contributing to age-related vascular diseases. The vast majority of the cardiovascular actions of Ang II, including vascular senescence, are mediated by the Ang II type-1 (AT(1)) receptor. Similar to its growth-promoting process, the signaling mechanisms of AT(1) receptor-mediated vascular senescence-promoting effects involve activation of small G-protein Ras such as Ki-ras2A, mitogen-activated protein kinases (MAPK) such as extracellular signal-regulated kinase 1/2, and transcription factors including nuclear factor (NF)-kappaB and activator protein (AP)-1, and increased generation of reactive oxygen species. Moreover, AT(1) receptor stimulation has been suggested to inactivate cyclin-dependent kinase complexes by up-regulation of cell cycle regulators such as p53 and p21, resulting in cellular senescence. Furthermore, the interaction between Ang II and aldosterone (Aldo) in their contribution to cardiovascular pathophysiology has been highlighted. Aldo can interact with Ang II signaling via a genomic mechanism mediated by the mineralocorticoid receptor (MR). Aldo via MR couples with the AT(1) receptor to elicit the Ras/NF-kappaB, AP-1/p53/p21 pathway involving oxidative stress, leading to synergistic promotion of vascular senescence. Although the precise mechanisms controlling cellular senescence are currently poorly understood, this article reviews recent findings on the signaling mechanisms elicited by RAAS from the perspective of AT(1) receptor blockers and/or MR blockers in the treatment of age-related vascular diseases.

DOI： 10.1016/j.arr.2008.12.002.

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(一社)日本老年医学会  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Authorship：Lead author   Language：Japanese  

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：English   Publishing type：Research paper, summary (international conference)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Web of Science

researchmap

Language：Japanese   Publisher：(株)日本臨床社  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Language：Japanese   Publisher：(NPO)日本高血圧学会  

researchmap

Event date： 2017.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】認知障害における虚血性脳障害と脳室内Aβとの相互作用、およびアンジオテンシンII 2 型 (AT2) 受容体の抑制効果について検討した。
【方法】10～12週齢の雄性野生型マウス及び血管平滑筋細胞特異的にAT2受容体を過剰発現するマウス(SMAT2-Tg)を用い、Aβ 1-40の脳室内投与および一過性全脳虚血モデルマウスを作成し、対照マウスと比べて認知機能について検討した。
【結果】一過性全脳虚血とAβの脳室内投与が、炎症性サイトカインのMCP-1やNADPHオキシダーゼ活性を増強することで、海馬の神経細胞障害を増大させ、認知機能障害を相加的に増悪することが示唆された。一方で、この全脳虚血とAβの脳室内投与の相加効果はSMAT2-Tgにおいては認められなかった。
【考察】Aβの存在下では虚血性脳障害により認知機能がさらに悪化することが示唆されたが、AT2 受容体シグナルはそれを抑制した。

researchmap

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山   Country：Japan  

背景：脳血管障害はアミロイドβ（Aβ）のクリアランスを障害し、アルツハイマー病の病態に影響を与えることが示唆されている。一方、Aβの沈着によりアミロイドアンギオパチーが誘導され、脳虚血性の認知障害につながることが報告され、血管障害とAβの相互作用に注目が集まっている。 アンジオテンシンII 1 型（AT1）受容体の活性化は認知機能を低下させるが、2 型（AT2）受容体の刺激は認知障害を改善することが報告されてきた。 我々は認知障害における虚血性脳障害とAβ沈着との相互作用、および認知機能低下におけるAT2受容体の抑制効果について検討した。
方法：10～12週齢の雄性野生型マウス及び血管平滑筋細胞特異的にAT2受容体を過剰発現するマウス(SMAT2-Tg)を用い、Aβ投与および一過性全脳虚血（Aβ-虚血）モデルマウスを作成して検討を行った。Aβ1-40を脳室内に投与し、翌日15分の両側総頸動脈閉塞術を実施した。投与3週間後にモリス水迷路試験にて空間認知機能を評価した。リアルタイムRT-PCR法にて炎症と酸化ストレスやPPAR-γの発現等を調べた。HE染色法にて神経細胞のピクノシスを検討した。
結果：野生型マウスにおいて、Aβの投与では認知機能の低下が認められたが、SMAT2-Tgでは有意な低下を認めなかった。一過性全脳虚血の野生型マウスでは顕著な認知機能の低下は認めなったが、興味深いことに、Aβ-虚血マウスでは対照マウスと比べて、認知機能が明らかに低下した。このことから、一過性全脳虚血とAβ投与が少なくとも相加的な増大効果を有することが示唆された。脳血流の変化は各群で認めなかったが、炎症性サイトカインやNADPHオキシダーゼサブユニット発現の増加傾向がAβ-虚血群で認められた。一方、この認知障害におけるAβ投与と全脳虚血の相加効果はSMAT2-Tgにおいては認められなかった。野生型マウスにおいて、全脳虚血群やAβ投与群では神経細胞のピクノシスが増加したが、この増加はAβ-虚血群ではさらに増強した。この結果はSMAT2-Tgにおいては認められなかった。また、SMAT2-Tgにおいて、Aβ-虚血群では対照群と比べてPPAR-γレベルが有意に増加した。
結論：虚血性脳障害と脳室内Aβは相互的に認知障害を悪化させ、血管におけるAT2受容体の活性化はこの認知障害を抑制する可能性が示唆された。

researchmap

Event date： 2017.9

Language：English   Presentation type：Poster presentation  

Venue：San Francisco   Country：United States  

Objectives: Cerebrovascular damage could breakdown amyloid-β (Aβ) clearance and accelerate Aβ deposition. We examined the interaction between ischemic brain damage and Aβ deposition in cognitive function, focusing on the roles of angiotensin II type 2 (AT2) receptor in vascular smooth muscle cells (VSMC).
Methods: Male wild-type mice (WT) or the mice with VSMC-specific AT2 receptor overexpression (smAT2) were used. Mice were subjected to ICV injection of Aβ1-40. Ischemic brain injury was induced by bilateral common carotid artery occlusion (BCCAO) 24 hours after Aβ1-40 injection. Three weeks after Aβ1-40 injection, cognitive function was evaluated by the Morris water maze test. Brain samples obtained 8 days after Aβ1-40 injection were used to study the related signals.
Results: ICV injection of Aβ1-40 in WT showed impaired cognitive function (arriving time to platform at day 5: control, 26.53±4.46 sec; Aβ, 65.35±7.44 sec), whereas BCCAO alone did not decline significantly cognitive function. In contrast, BCCAO following Aβ1-40 injection exhibited more marked cognitive impairment (84.27±8.00 sec) compared to Aβ injection alone with the increase in expressions of NADPH oxidase subunits such as p22phox and p67phox in the hippocampus of mice. Aβ1-40 injection with BCCAO tended to increase the mRNA levels of inflammatory cytokines such as MCP-1 and TNF. BCCAO significantly enhanced the expression of Aβ clearance factor, RAGE (receptor for advanced glycation end product). Aβ1-40 injection did not increase the neuron pyknosis in the hippocampus, whereas the number of neuron pyknosis was increased significantly with BCCAO (control, 6.33±0.88/field; Aβ with BCCAO, 46.33±4.10/field). On the other hand, smAT2 did not show cognitive impairment, the changes of the expression for NADPH oxidase subunits and inflammatory cytokines, and neuron pyknosis, which were induced by BCCAO with/without Aβ1-40 injection in WT.
Conclusion: Ischemic brain injury could enhance Aβ-induced cognitive impairment with possible involvement of enhanced oxidative stress, neuron degeneration, and breakdown of RAGE-mediated Aβ clearance. AT2 receptor activation in VSMC could play inhibitory roles in the cognitive decline induced by ischemic brain damage and Aβ deposition.

researchmap

Event date： 2017.2

Language：English   Presentation type：Poster presentation  

Venue：Houston   Country：United States  

Background and Aim: Stroke is known to be causally related with Alzheimer’s disease pathology and amyloid-β (Aβ) deposition has been suggested to induce cerebral amyloid angiopathy resulting in stroke-associated cognitive decline. Angiotensin (Ang) type 1 (AT1) receptor activation impairs cognitive performance, whereas Ang II type 2 (AT2) receptor stimulation has been reported to improve cognitive impairment. We examined the interaction between stroke and Aβ deposition in cognitive function, and the possible antagonist effect of AT2 receptor in vascular smooth muscle cells (VSMC) on this cognitive decline.
Methods: Adult (10-12 weeks old) male wild-type (WT) mice (C57BL/6J mice) or the mice with AT2 receptor overexpression in VSMC (SMAT2) were used. Mice were subjected to intracerebroventricular (ICV) injection of Aβ1-40 following 15 minutes global brain ischemia operation. Three weeks after Aβ1-40 ICV injection, cognitive function of spatial learning memory was evaluated by the Morris water maze test. Brain samples were obtained after behavioral testing, and the expression of inflammatory cytokines and NADPH oxidase subunits were measured by real-time quantitative RT-PCR.
Results: ICV injection of Aβ1-40 in WT mice showed impaired cognitive function. On the other hand, WT mice with transient global brain ischemia did not decline significantly cognitive function. In contrast, WT mice with Aβ1-40 ICV injection with global brain ischemia exhibited more marked cognitive impairment compared with control mice. These results suggested that transient brain ischemia and amyloid-β deposition exerted at least additive effects on cognitive impairment. This cognitive decline was accompanied with increased expressions of inflammatory cytokines such as monocyte chemoattractant protein-1 and NADPH oxidase subunits including p22phox. On the other hand, SMAT2 mice did not show cognitive impairment by global brain ischemia with/without Aβ1-40 ICV injection.
Conclusion: Brain ischemia and amyloid-β deposition induced additive or synergistic effect on cognitive impairment. AT2 receptor activation in VSMC could play an inhibitory role in the cognitive decline induced by brain ischemia and amyloid-β deposition.

researchmap

Event date： 2016.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Seoul   Country：Korea, Republic of  

Objective: The activity of angiotensin (Ang) converting enzyme (ACE)/Ang II/Ang II type 1 (AT1) receptor axis which is the classical renin-angiotensin system (RAS), causes various organ damage including cognitive decline. On the other hand, the ACE2/Ang-(1-7)/Mas receptor axis has been highlighted as exerting antagonistic actions against the classical RAS axis in the cardiovascular system. However, the roles of the ACE2/Ang-(1-7)/Mas axis in cognitive function are unknown. Here, we explored possible roles of ACE2 in cognitive function.
Design and method: Male 10-week-old C57BL6 (wild-type: WT) mice and ACE2 knockout (KO) mice were used. Vascular dementia model was induced by bilateral common carotid artery stenosis (BCAS). Morris water maze task was performed 6 weeks after BCAS operation to evaluate spatial cognitive function.
Results: There were no significant differences in body weight, brain weight and systolic blood pressure between ACE2KO and WT mice. ACE2KO mice exhibited significant impairment of cognitive function, compared with that in WT mice, with no significant difference in cerebral blood flow. Mas receptor mRNA was highly expressed in the hippocampus compared with the cortex, with no significant difference between ACE2KO and WT mice. AT1 receptor mRNA in the hippocampus was higher in ACE2KO mice compared with WT mice, whereas AT2 receptor mRNA in the hippocampus did not differ between the two strains. Superoxide anion production increased in ACE2KO mice, with increased NADPH oxidase subunits mRNAs in the hippocampus. Protein level of SOD3 decreased in ACE2KO mice compared with WT mice. Brain-derived neurotrophic factor (BDNF) mRNA and protein levels were lower in the hippocampus in ACE2KO mice compared with WT mice. Administration of Ang-(1-7) (0.5 mg/kg/day) attenuated the cognitive decline in ACE2KO mice without changes in systolic blood pressure.
Conclusions: Taken together, ACE2 deficiency caused impaired cognitive function with enhancement of oxidative stress and decrease in BDNF level.

researchmap

Event date： 2016.9

Language：English   Presentation type：Poster presentation  

Venue：Seoul   Country：Korea, Republic of  

Objective: There is a large interest in the prevention of dementia including Alzheimer’s disease (AD) by natural food ingredients. Peptides derived from food proteins have been demonstrated to have hypotensive action. Increasing evidence indicated possible associations of hypertension with AD risk, and implied that angiotensin converting enzyme (ACE) inhibitors with the potential to pass blood-brain barrier may reduce the risk of AD. Here, we examined the effect of milk peptide (CH-3), which contains a tripeptide (methionine-lysine-proline, MKP) and has strong ACE inhibitory effect on cognitive function in AD model mice.
Design and method: Male 10-week-old ddY mice were used. The animal model of AD was induced by intracerebroventricular (ICV) injection of amyloid β (Aβ) (1-42). CH-3 was orally administrated at a concentration of 250 mg/kg every day starting 2 days before ICV injection. Three weeks after ICV injection, cognitive function was evaluated by Morris Water Maze Test. Brain samples were obtained after behavioral test, and subjected to real-time RT-PCR to measure inflammatory cytokine and NADPH oxidase subunit expression levels.
Results: In mice, Aβ (1-42) injected by ICV impaired cognitive function compared with vehicle-injected mice. Daily administration of CH-3 significantly attenuated Aβ-induced impairment of cognitive function. Aβ (1-42) injection enhanced mRNA expressions of inflammatory cytokines such as monocyte chemoattractant protein-1, tumor necrosis factor-alpha, interleukin-6, NADPH oxidase subunits such as p22phox and p47phox, and inducible nitric oxide synthase in hippocampus of mouse brain; whereas treatment with CH-3 tended to reduce these increases of mRNA expressions. Conclusions: Our study demonstrated that cognitive impairment could be improved by repeated oral administration of CH-3. And this ameliorated effect of CH-3 was probably due to the reduction of oxidative stress and inflammatory cytokine levels.

researchmap

Event date： 2015.10

Language：Japanese   Presentation type：Poster presentation  

Venue：松山   Country：Japan  

【目的】柑橘類には抗酸化作用などによる心血管保護作用がヒトにおける検討で期待されるが、動物モデルを用いた検討はあまりない。そこで今回、愛媛県で有名な温州みかんと特産の伊予柑の果汁をマウスに飲用投与し、血管リモデリングに与える影響について検討を行った。
【方法】8週齢の雄性野生型マウス(C57BL6)を用いて、無果汁（水）、温州みかん果汁（10％・40％）、伊予柑果汁（10％・40％）の5群に分け、それぞれを2週間投与した。2週間後、マウスの大腿動脈にポリエチレンカフを留置し血管リモデリングを誘導した。新生内膜の増生をElastica van Gieson staining (EVG) 染色により、アンジオテンシン1型受容体（AT1R）、同2型受容体（AT2R）、PPAR-gamma、IRF-1、MCP-1、CCR-2、IL-6、IL-1β、TNF-αの発現をRT-PCR法により、superoxide anion産生をdihydroethidium （DHE）染色により、細胞増殖をproliferation cell nuclear antigen (PCNA)、新生内膜でのERKの発現を免疫染色によりそれぞれ評価した。さらに外膜での炎症細胞の浸潤について、マクロファージ（F4/80）と好中球（LY-6G/6C）のマーカーによる蛍光免疫染色で評価した。
【結果】5群間で血圧、血糖値、飲水量には著明な変化を認めず、体重は果汁投与群でやや増加傾向を認めた。新生内膜面積は、温州みかん40％投与群と伊予柑10％、40％投与群において無果汁群に比べて半減したが、温州みかん10％投与群では有意な減少効果は認められなかった。無果汁群、温州ミカン・伊予柑10％投与群の3群間でメカニズムに関して検討したところ、カフ留置していない血管に比べてカフ留置血管ではAT1R、AT2Rの発現には大きな差は認めず、炎症マーカーは顕著に増加し、PPARγは減弱傾向を示したが、無果汁・果汁投与群間では特に変化は認められなかった。細胞増殖は果汁群で減弱を認めたが、伊予柑投与群では温州みかん投与群に比べて増殖細胞の抑制がより顕著に認められた。DHE染色による酸化ストレスへの影響については伊予柑10％投与群において無果汁群に比べて有意な減少が認められた。一方でERKの発現と炎症細胞の浸潤は果汁投与群で減弱していたものの、２つの柑橘間で有意な差は認められなかった。
【考察】温州みかんや伊予柑果汁摂取は細胞増殖を抑え、血管リモデリングを抑制する可能性が示唆された。その効果は温州みかんよりも伊予柑の方がより顕著であると思われた。

researchmap

Event date： 2014.6

Language：English   Presentation type：Poster presentation  

Venue：Athens   Country：Greece  

Objectives: The renin-angiotensin-system is known to play some role in the central nervous system (CNS), however, its role in senescence is not well examined. Recent evidence demonstrated that defects in astrocyte function, such as accumulation of senescent astrocytes is associated with age-related neuronal degeneration and cognitive decline. We previously reported that angiotensin II stimulated vascular smooth muscle cell (VSMC) senescence via angiotensin type 1 (AT1) receptor-mediated oxidative stress/cycling-dependent kinase inhibitor (CDKI) signaling pathway, and inhibited VSMC senescence via angiotensin II type 2 (AT2) receptor-mediated methyl methanesulfonate sensitive 2 /DNA repair signaling mechanism. Therefore, we examined the potential roles of angiotensin II receptor subtypes in regulating astrocyte senescence.
Methods: Astrocytes prepared from the neonate of wide-type (WT) mice (day 0-2 after birth) and AT2 receptor knockout (AT2KO) mice were persistently stimulated with angiotensin II (10-7 M) with medium change every day. Cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-beta-gal) activity. Signaling molecules were investigated by Western blot analysis.
Results: Persistent angiotensin II treatment increased SA--gal activity, p53 and CDKI expression, such as p21, p27 and p16 in time-dependent manner; these effects of angiotensin II were further enhanced in astrocytes prepared from AT2KO mice. Angiotensin II-induced SA--gal activity and CDKI expression were inhibited by an AT1 receptor blocker, azilsartan, whereas these inhibitory effects of azilsartan were weaker in AT2KO astrocytes than in WT astrocytes. Administration of an AT2 receptor agonist, C21, decreased SA--gal activity and CDKI expression in WT astrocytes, but not in AT2KO astrocytes. Moreover, C21 treatment further enforced the inhibitory effects of azilsartan on angiotensin II-induced SA--gal activity and CDKI expression in WT astrocytes.
Conclusion: Angiotensin II promoted astrocyte senescence via AT1 receptor-mediated signaling pathway. On the other hand, direct AT2 receptor stimulation exerted inhibitory effect on AT1 receptor-induced astrocyte senescence. AT1 receptor blockers and direct AT2 receptor stimulation might be useful for the treatment of CNS diseases associated with astrocyte senescence.

researchmap

Event date： 2014.6

Language：English   Presentation type：Poster presentation  

Country：Japan  

Objectives: We examined the potential roles of angiotensin II receptor subtypes in regulating astrocyte senescence.
Methods: Astrocytes prepared from the neonate of wide-type (WT) mice and AT2 receptor knockout (AT2KO) mice were persistently stimulated with angiotensin II (10-7 M). Cellular senescence was evaluated by senescence-associated -galactosidase (SA--gal) activity.
Results: Angiotensin II treatment increased SA--gal activity, p53 and CDKI expression; these effects of angiotensin II were further enhanced in astrocytes prepared from AT2KO mice. Angiotensin II-induced SA--gal activity and CDKI expression were inhibited by an AT1 receptor blocker, azilsartan, whereas these inhibitory effects of azilsartan were weaker in AT2KO astrocytes than in WT astrocytes. Administration of an AT2 receptor agonist, C21, decreased SA--gal activity and CDKI expression in WT astrocytes, but not in AT2KO astrocytes. Moreover, C21 treatment further enforced the inhibitory effects of azilsartan on angiotensin II-induced SA--gal activity and CDKI expression in WT astrocytes. However, changes of methyl methanesulfonate sensitive 2 (MMS2) expression were not observed in astrocytes prepared from both WT and AT2KO mice.
Conclusion: Angiotensin II promoted astrocyte senescence via AT1 receptor-mediated signaling pathway. On the other hand, direct AT2 receptor stimulation exerted inhibitory effect on AT1 receptor-induced astrocyte senescence without MMS2-dependent signaling mechanism. AT1 receptor blockers and direct AT2 receptor stimulation might be useful for the treatment of central nervous system diseases associated with astrocyte senescence.

researchmap

Event date： 2014.6

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

[目的]：これまで我々はアンジオテンシンII2型（AT2）受容体の脳保護効果をAT2受容体欠損マウスやアンジオテンシンII1型受容体ブロッカーを使うなどで報告してきたが、AT2受容体直接刺激薬であるcompound 21（C21）が開発され、治療をターゲットにしたAT2受容体刺激が行えるようになってきた。今回我々は脳梗塞モデルにおけるAT2受容体直接刺激薬の脳保護効果を検討した。
[方法]：10週齢雄性C57BL6あるいはAT2受容体欠損マウスに中大脳動脈梗塞術(MCAO)を施行し、脳梗塞巣は1.5T MRIにより検討した。C21はMCAO施行の2週間前、あるいはMCAO直後より毎日10μg/kg/dayの濃度で腹腔内投与を行った。脳血流はレーザードップラー血流計で評価し、酸化ストレスはDHE染色で、血液脳関門機能はエバンスブルーの透過性の測定にて評価した。
[結果]：C21前投与実験では、MCAO後1日目から無投薬群に比べて脳梗塞巣の縮小効果が認められたが、AT2受容体欠損マウスにC21を前投与しても脳梗塞巣への影響は認められなかった。MCAO後投与実験では、無投薬群では脳梗塞巣の大きさはMCAO後３日目でピ-クに達したが、C21の投与群では２日目をピークとして脳梗塞巣の大きさが軽減した。C21投薬群は無投与群と比較して、脳血流量の増加や酸化ストレスの減少、炎症因子（TNF-α、MCP-1）の発現の低下が認められた。また、C21投与群では、血液脳関門の破綻は軽減し、脳浮腫が減少した。
[結論]：AT２受容体をC21で刺激することにより、急性期投与でも脳血流の増加や、酸化ストレス・炎症反応の抑制、血液脳関門機能低下の抑制と脳浮腫の改善効果により、虚血性脳障害を改善する可能性が示唆された。

researchmap

Event date： 2013.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】最近アストロサイトの老化がアルツハイマー病のリスクになるとの報告があり、疫学研究では高血圧と認知症との関連が示唆されている。今回高血圧関連ホルモンであるアンジオテンシンIIがアストロサイトの老化に及ぼす影響について検討を行った。
【方法】C57BL6マウス及びアンジオテンシンII2型受容体欠損（AT2KO）マウスより調整したアストロサイトに連日アンジオテンシンIIで刺激し老化細胞の増加をSA-βgal染色にて検討した。
【結果】アンジオテンシンII刺激5日後よりSA-βgal陽性細胞の増加が認められ、サイクリン依存性キナーゼ阻害因子ｐ16の発現も増加した。こうした老化の指標はアンジオテンシン1型受容体ブロッカー（ARB）のアジルサルタン投与で抑制され、AT2KOマウス由来のアストロサイトでは促進された。
【考察】アンジオテンシンIIはアストロサイトの老化を促進し神経障害を促進する可能性がある。ARBはアストロサイトの老化を抑制する可能性がある。

researchmap

Event date： 2012.9

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋   Country：Japan  

目的： AT1受容体拮抗薬(ARB)テルミサルタンはAT1受容体ブロックに加え、PPARγの部分的活性化作用による相乗効果が期待される。脳の微小血管網である血液脳関門（BBB）の障害はサイトカインや炎症性細胞を脳内に侵入させ神経細胞を傷害し認知機能低下を誘導すると考えられ、我々は2型糖尿病マウス（KKAy）モデルにおけるBBBの障害、認知機能低下へのテルミサルタンによる改善効果の可能性をPPARγ活性化作用の関与を含め検討した。

方法： KKAyマウスは8週齢よりテルミサルタン(1 mg/kg/日）、PPARγのアンタゴニストであるGW9662 (0.35 mg/kg/日）を7週間投与した。認知機能はモリス水迷路試験、BBBの透過性はエバンスブルー（EB）とAlexa Fluro-488で標識したアルブミンおよびDyLight549で標識したIgGを尾静脈より投与し、脳内での漏出を観察することにより評価した。BBBの微細構造変化は透過型電子顕微鏡にて検討し、BBB構成タンパク等の発現をウエスタンブロット法で、酸化ストレスについてはジヒドロエチジウム染色法によりスーパーオキシドアニオンの産生を評価した。

結果：各群で血圧・血糖には有意な影響は認めなかった。15週齢のKKAyマウスは同週齢のC57BL6マウスと比較して、認知機能の著明な低下を示したが、テルミサルタン投与により、認知機能低下は有意に抑制された。GW9662同時投与にて、テルミサルタンによる認知機能低下改善作用は一部減弱された。KKAyマウスでは、BBBの透過性が増加しており、EBや蛍光標識アルブミン・IgGの漏出が顕著に認められた。テルミサルタン投与によりBBBの透過性亢進は軽減したが、GW9662の同時投与によりテルミサルタンによるBBB透過性減弱作用は抑制された。KKAyマウスでは、ZO-1、occludin、claudinsなどの発現減少や、MMPの発現増加、酸化ストレス,炎症性サイトカインの産生増強が認められ、これらの変化はテルミサルタン投与により抑制されたが、GW9662同時投与でその抑制効果は減弱した。KKAyマウスは、微小血管周囲を取り巻くアストロサイトの終足に浮腫様の微細構造変化が認められ、テルミサルタン投与ではこうした変化は殆ど認めず、GW9662の同時投与群その作用は減弱した。PPARγの活性化作用の殆どないARB、ロサルタンの投与では、テルミサルタンと比較すると、BBBの透過とアストロサイトの終足の浮腫様変化抑制作用は弱かった。

結論：テルミサルタンはBBBの透過性の亢進を防ぎ、糖尿病性認知症の低下を予防し、その作用には一部PPARγの活性化が関与していると考えられた。

researchmap

Event date： 2012.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

血管性認知症の基礎実験を考える場合、微小脳梗塞による脳神経障害の検討が重要であるが、微小脳梗塞の実験モデルの作成は難しく中大脳動脈閉塞（MCAO）モデルの解析が用いられることが多い。アンジオテンシンII2型（AT2）受容体シグナルは脳保護効果を持つことが期待されるが、AT2受容体を直接刺激による脳保護効果は検討されていなかった。今回MCAOモデルにおけるAT2受容体直接刺激薬（C21）の効果をMRIにより検討した。MCAO施行2週間前からC21を投与したマウスではDay 1より脳梗塞巣の大きさが軽減したが、この効果はAT2受容体欠損マウスでは認められなかった。C21をMCAO施行直後に腹腔内投与したマウスではDay 3より脳梗塞巣の大きさが軽減し、非投与群と比較して脳表血流の増加が認められた。以上より、AT2受容体刺激は慢性的投与だけでなく、急性期の投与によっても脳梗塞後の神経障害を軽減すると考えられ、血管性認知症に効果がある可能性が示唆される。

researchmap

Event date： 2012.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

糖尿病による認知機能障害が臨床的にも報告され、患者数の急増に伴ってその機構の解明と対策が急がれている。糖尿病性認知機能低下の原因に糖代謝異常が関与することは言うまでもないが、微小血管障害の関与も示唆される。今回糖尿病モデルマウス、KKAyを用いて血液脳関門（BBB）の機能とPPAR-γの活性化作用を持つアンジオテンシン受容体ブロッカーのテルミサルタンの効果を検討した。KKAyは認知機能の低下を認め、エバンスブルーや蛍光で標識したアルブミンやIgGなどの比較的大きな分子も脳内に漏出しており、電子顕微鏡による微細構造の検討では微小血管周囲のアストロサイトの終足が膨化し、BBBの破綻が示唆された。タイトジャンクション構成蛋白の発現は低下し、マトリックスメタロプロテアーゼの発現は増加していた。テルミサルタンを投与したKKAyでは上記のBBB破綻による影響を一部PPAR-γの活性化を介した作用で抑制し、糖尿病に起因する認知機能低下を抑制した。

researchmap

Event date： 2011.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】血管老化は加齢による心血管病の発症に深く関与する。 今回は血管平滑筋細胞（VSMC）の老化におけるAldoとAng IIの相互作用について検討した。【方法】細胞老化は、老化関連βガラクトシダーゼ (SA-β-gal) 染色とサイクリン依存性キナーゼ（CDKI）の発現の増大を指標とした。【結果】VSMCはAng II 刺激5日後に老化細胞が有意に増加した。老化細胞はAng II1型受容体ブロッカー（ARB）投与でほぼ完全に抑制されたが、ミネラルコルチコイド拮抗薬のスピロノラクトンでも部分的に抑制された。Ang II刺激によりVSMCからのAldo分泌が認められAldo単独投与でも老化が促進された。また、それぞれ単独では、細胞老化は来たさない低濃度のAng IIとAldoも併用刺激により老化細胞が増大した。【考察】Ang II とAldoは血管老化に重要な役割を果たしていることが示唆された。

researchmap

Event date： 2011.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】2型糖尿病マウス（KKAy）を用いて、糖尿病による血液脳関門（BBB）の破綻とペルオキシソーム増殖因子受容体(PPAR)-γの活性化作用を持つアンジオテンシン受容体ブロッカー、テルミサルタンの投与による効果を検討した。【方法】8週齢よりテルミサルタンとPPAR-γ アンタゴニスト(GW9662)を7週間投与し認知機能をモリス水迷路試験で BBBの透過性は色素性物質の尾静脈からの投与で評価し、電子顕微鏡でBBBの超微細構造を検討した。【結果】C57BL6マウスと比較して糖尿病マウスではBBBの透過性が増加し、膨化した星状細胞終足の膨化が認められた。こうした変化がテルミサルタン投与群で抑制されたが、GW9662同時投与群ではその抑制効果は減弱していた。【考察】糖尿病ではBBBの破綻が認められ、テルミサルタンは一部PPAR-γの活性化を介してBBBの破綻を抑制していることが示唆された。

researchmap

Event date： 2011.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】アンジオテンシ(Ang) II 1型受容体結合性タンパク、ATRAP と2型受容体関連タンパク、ATIPが血管平滑筋細胞（VSMC）の老化に及ぼす影響を検討した。【方法】ATRAP-TgとATIP-Tgマウスおよび野生型マウスからVSMCを調整し、AngIIの連日投与による血管老化を評価した。【結果】ATRAP-Tg とATIP-Tg-VSMCでは老化が有意に抑制された。ATRAP-Tg VSMCでは野生型VSMCと比べてNFAT (calcineurin/nuclear factor of activated T cells) の活性が減少しており、老化の抑制にATRAP/NFAT系の関与が示唆された。また、ATIP-Tg-VSMCではDNA損傷の修復に関与するMMS2の発現の増加が認められ、ATIP/MMS系の関与が示唆された。【考察】ATRAPやATIPはVSMCの老化を抑制する作用を有する。

researchmap

Event date： 2011.12

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪   Country：Japan  

【目的】アンジオテンシン(Ang) II2型（AT2）受容体からのシグナルが血管老化にどう影響するかを検討した。【方法】AT2受容体欠損（AT2KO）マウスから抽出した血管平滑筋細胞（VSMC）をAng IIで連日刺激したin vitro実験と、マウスに放射線照射したin vivo実験を行った。老化細胞は老化関連βガラクトシダーゼ染色により評価した。【結果】野生型に比べてAT2KOマウス及びAT2KOマウス由来のVSMCでは老化細胞数の促進が認められた。また、DNA損傷の程度が野生型に比べ、AT2KOでは増加を認め、野生型VSMCで増加するDNA修復因子、MMS2の発現がAT2KO VSMCでは増加を認めなかった。野生型VSMCにMMS2のsiRNAを投与すると老化の促進が認められた。
【考察】AT2受容体シグナルは血管老化を抑制し、そのメカニズムとして、DNA修復機構の関与が示唆された。

researchmap

Event date： 2011.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宇都宮   Country：Japan  

目的：アンジオテンシンII 1型(AT1)受容体拮抗薬、テルミサルタンはのAT1受容体ブロックに加えて、ペルオキシソーム増殖因子受容体（PPAR）-gammaを活性化することにより認知機能の低下を防止する可能性が報告されているが、詳細なメカニズムン解明が期待される。血液脳関門（BBB）の障害はサイトカインや炎症性細胞の脳内への侵入などにより認知機能低下を誘導する可能性があるが、我々は、2型糖尿病マウス（KKAy）モデルを用いて、糖尿病の認知機能障害にBBBの破綻が関与しているのかどうか、またテルミサルタンの投与によりBBBの障害を抑制することができるのか、PPAR-gammaの活性化の影響を含めて検討した。
方法： KKAyと野生型のC57BL6マウスを用い、KKAyマウスは8週齢よりテルミサルタン投与、テルミサルタン+PPAR-gamma アンタゴニスト（GW9662）投与、GW9662投与、無投与群の４群に分けて7週間薬剤投与を行った。テルミサルタンは１mg/kg/日を経口投与し、GW9662は 0.35ｍｇ/kg /日の濃度で調整した飲用水にて投与した。 認知機能はモリス水迷路試験にて評価した。 BBBの透過性はエバンスブルーとAlexa Fluro-488標識アルブミン-およびDyLight549標識のIgGを尾静脈より投与し、脳内での漏出を観察することにより評価した。
結果：テルミサルタン、GW9662投与群およびテルミサルタン+GW9662投与群において血圧に有意な影響を与えなかった。 15週齢のKKAyマウスは同週齢のC57BL6マウスと比較して、認知機能の著明な低下を示した。 テルミサルタン投与により、この認知機能の低下が有意に抑制された。しかし、GW9662とテルミサルタンを同時に投与すると、テルミサルタンによる認知機能低下改善作用は一部減弱された。KKAyマウスでは、BBBの透過性がC57BL6マウスと比較して増加しており、アルブミンとIgGの漏出が認められた。テルミサルタンの投与によりBBBの透過性の亢進が減少し、野生型マウス程度のBBBの透過性を示した。GW9662の同時投与によりテルミサルタンによるBBBの透過性の減弱作用は抑制された。また、KKAyマウスでは、tight junction蛋白であるZO-1などの発現減少が認められ、この減少はテルミサルタン投与により抑制されたが、GW9662同時投与群ではその抑制効果は減弱した。
結論：以上よりテルミサルタンはtight junction蛋白の低下を抑制し、BBBの透過性の亢進を防ぐことにより、糖尿病性認知症の低下を予防する可能性が示唆された。また、このテルミサルタンの作用には一部PPAR-の活性化が関与していることが示唆された。

researchmap

Event date： 2011.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：宇都宮   Country：Japan  

目的：アンジオテンシンII2型(AT2)受容体刺激は１型(AT1)受容体を介した血管平滑筋細胞老化促進作用に拮抗して作用するだけでなく、DNA修復因子のmethyl methanesulfonate sensitive 2 （MMS2）を直接活性化することにより、血管老化を抑制することを報告してきた。ところで、7回膜貫通Gタンパク結合型受容体の作用を調節するタンパクが注目されているが、我々は、AT２受容体のC末端尾部に特異的に結合し、AT2受容体の作用を増強するAT2 receptor interacting protein(ATIP)をクローニングし、神経細胞分化促進に関与していることを報告した。そこで、今回我々はATIPが血管細胞老化に及ぼす影響についてATIPトランスジェニック(ATIP-Tg)マウスを作製して検討を行った。
方法： ATIP-Tgマウスおよび野生型マウスの胸部大動脈から血管平滑筋細胞を調整した。In Vivo 実験はマウスに致死量（10 Gy）のX線を照射することにより大動脈に血管老化を誘導して評価した。細胞老化は老化関連βガラクトシダーゼ染色で評価し、DNA損傷の程度は8-OHdG量を ELISA法にて、シグナルについてはウエスタンブロット法などにより評価した。
結果：野生型血管平滑筋細胞においてアンジオテンシンIIの連日刺激により時間依存性に老化細胞数や総細胞数における老化細胞の割合が増強したが、ATIP-Tg血管平滑筋細胞では、アンジオテンシンII刺激による老化が有意に抑制された。同様の結果は、酸化ストレスによるDNA損傷の指標である8-OHdGの細胞内レベルでも観察された。また、ATIP-Tg血管平滑筋細胞ではSrc homology 2 domain-containing protein-tyrosine phosphatase 1(SHP-1)の活性化とともに、MMS2の発現の増加が認められた。X線照射により大動脈で誘導される老化関連βガラクトシダーゼ陽性領域や、8-OHdGレベル、MMS2の発現の増加を認めたが、この老化とDNA損傷の増加はATIP-Tgマウスの血管で有意に抑制された、MMS2の発現はATIP-Tgマウスではさらに増強していた。
結論：以上の結果より、ATIPが血管平滑筋細胞の老化を抑制する可能性が示唆された。このATIPの血管老化抑制作用に少なくともSHP-1の活性化による、MMS2の発現増加が関与していると考えられた。

researchmap

Event date： 2011.9

Language：English   Presentation type：Poster presentation  

Venue：Orlando   Country：United States  

Objectives: An angiotensin II type-1 receptor blocker, telmisartan is reported to prevent cognitive decline with the activation of peroxisome proliferators-activated receptor (PPAR)-gamma; however, detailed mechanisms remain largely unknown. Blood-brain barrier (BBB) impairment associated with alterations of tight junctions (TJ) has been suggested as a critical factor to decrease cognitive function in diabetes mellitus. We examined the possibility that telmisartan could attenuate BBB impairment in a type-2 diabetic mouse model, KKAy with PPAR-gamma activation, thereby resulting in the improvement of cognitive decline.
Methods: KKAy and C57BL6 mice were used. KKAy mice were treated with telmisartan (1 mg/kg/day by oral) and/or GW9662 (0.35 mg/kg/day in drinking water), a PPAR-gamma antagonist, for 7-weeks from 8-weeks of age. Cognitive function was evaluated by the Morris water maze test. BBB permeability was determined by measuring extravasation of Evans blue dye, and fluorescent dye albumin-Alexa Fluro-488 and IgG-DyLight549. TJ protein expressions were analyzed by western blot analysis.
Results: Administration of telmisartan and/or GW9662 had no significant effect on blood pressure. KKAy mice at 15-weeks of age showed impairment of cognitive function compared with age-matched C57BL6 mice. Treatment with telmisartan of KKAy mice markedly attenuated this cognitive decline. However, co-treatment with GW9662 significantly prevented this improvement of cognitive decline by telmisartan. Moreover, in KKAy mice, BBB permeability increased compared with C57BL6 mice. Administration of telmisartan attenuated this increase in BBB permeability. Co-administration of GW9662 partially restored this telmisartan-mediated improvement of BBB permeability. Significant decreased expressions in TJ protein ZO-1 were observed in the brain of KKAy mice compared with C57BL6 mice. Treatment with telmisartan of KKAy mice inhibited this attenuated ZO-1 expression. Co-treatment with GW9662 prevented this inhibitory effect of telmisartan on ZO-1 expression.
Conclusion: Telmisartan could ameliorate diabetes-associated cognitive decline via attenuating BBB impairment associated with induction of ZO-1 expression, partly due to PPAR-gamma activation.

researchmap

Event date： 2011.9

Language：English   Presentation type：Poster presentation  

Venue：Orlando   Country：United States  

Objectives: We reported that angiotensin II type 2 (AT2) receptor simulation antagonized the type 1 (AT1) receptor-mediated vascular senescence, and that AT2 receptor-interacting protein (ATIP), as a protein interacting with the C-terminal tail of the AT2 receptor, regulated the functions of AT2 receptor. We examined whether ATIP could regulate vascular senescence, focusing on methyl methanesulfonate sensitive 2 (MMS2) which AT2 receptor stimulation transactivates by making complex of ATIP and SHP-1.
Methods: Vascular smooth muscle cells (VSMC) were prepared from the thoracic aorta of ATIP transgenic (ATIP-Tg) and wild-type (WT) mice (10 to 12 weeks old). Some mice were irradiated with the dose of 10 Gy total-body X-ray irradiation. Cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-beta-gal) activity. DNA damage was examined by quantification of 8-hydroxy-2`-deoxyguanosine (8-OhdG) levels by ELISA. MMS2 expression was assessed by Western blot.
Results: Angiotensin II treatment (10-7 mol/L) induced significant increases in total cell number, SA--gal-positive cell number, and percentage of SA-beta-gal-positive VSMC, whereas these effects of angiotensin II were attenuated in ATIP-Tg-VSMC. Similar results were observed in the level of 8-OHdG, which is a biomarker of oxidative stress-induced DNA damage. We also observed that angiotensin II stimulation induced time-dependent increase in MMS2 protein level, whereas this angiotensin II-increased MMS2 expression was further enhanced in ATIP-Tg VSMC. Moreover, angiotensin II stimulation promoted the increases in SHP-1 activity, and this effect of angiotensin II on SHP-1 activity was further enhanced in ATIP-Tg-VSMC. We tried to address the pathophysiological relevance of the role of ATIP in vascular senescence in vivo, and observed that X-ray irradiation induced significant increases in SA-beta-gal-positive area and 8-OHdG level in the aorta, whereas these effects of X-ray irradiation were attenuated in ATIP-Tg mice with the significant increase in MMS2 expression.
Conclusion: These results suggest that ATIP could inhibit VSMC senescence at least in part due to the increase in MMS2 expression and SHP-1 activity.

researchmap

Event date： 2009.10

Language：Japanese   Presentation type：Poster presentation  

Venue：大津   Country：Japan  

目的：我々はこれまでに脳におけるレニン • アンジオテンシン系（ＲＡＳ）が神経細胞に直接影響を与え、アンジオテンシンII受容体ブロッカーが神経細胞保護効果を有する基礎検討や、神経変性疾患患者の脳脊髄液の検討から、ＲＡＳが筋萎縮性側索硬化症（ＡＬＳ）の臨床重症度と関連性をもつ臨床検討を報告してきた。アストロサイトは脊髄運動神経の細胞死を促進し、ＡＬＳなどの神経変性疾患を誘導する可能性や病態への関与が示唆されている。昨今アストロサイトにおけるＲＡＳの働きが注目されているが、アストロサイトと神経細胞のクロストークにＲＡＳがどのように影響しているかについてはこれまでほとんどわかっていなかった。そこでアストロサイトと後根神経節（ＤＲＧ）細胞の共培養系を用いて神経障害におけるＲＡＳの影響を検討した。
方法：胎生マウスのＤＲＧから神経細胞を、および新生マウスからアストロサイトを単離調整し、２つの細胞の共培養系を使用した。ＤＲＧ細胞の障害は8-OHdG量を ELISA法にて評価しDNA損傷の程度で検討した。アルドステロンの産生はELISA法で評価し、細胞死はフローサイトメータで評価した。
結果：アンジオテンシンIIによりＤＲＧ細胞では時間依存性に損傷DNA量の増加が認められた。この損傷DNA量はアストロサイト共培養下でさらに増加したが、アンジオテンシンＩＩで刺激しないアストロサイト共培養下では増加は認めなかった。AT1受容体ブロッカー（ARB）のバルサルタン投与により、アンジオテンシンIIの直接刺激によるＤＲＧ細胞のDNA損傷は抑制された。またアンジオテンシンII刺激したアストロサイトのメディウムをＤＲＧ細胞に添加するとDNA損傷が増加したが、バルサルタン投与下で刺激したアストロサイトのメディウムを添加ではDNA損傷の増加は認めなかった。一方、アンジオテンシンII刺激したアストロサイトのメディウム添加によるＤＮＡ損傷の増加はバルサルタンでは抑制できなかったが、選択的アルドステロン受容体ブロッカーのエプレレノン添加で顕著に抑制された。アンジオテンシンII添加によりアストロサイトからアルドステロンが産生されることがＥＬＩＳＡ法で確認された。またアルドステロンの直接刺激によってもＤＲＧ細胞のDNA損傷が増大した。最後にアンジオテンシンIIとアルドステロンの直接刺激により、ＤＲＧ細胞の細胞死が顕著に増加することがわかった。
結論：以上よりＤＲＧ細胞は、アンジオテンシンIIの存在下で直接刺激による障害だけでなく、アストロサイトを介してアンジオテンシンII刺激により分泌されたアルドステロンの影響も受けて、細胞障害が誘導されて細胞死に至る可能性が示唆された。こうしたことから、ＡＬＳの病態にＲＡＳを介したアストロサイトとのクロストークによる神経障害を起こすという新しい機構が関連する可能性が示唆された。

researchmap

Event date： 2009.9

Language：English   Presentation type：Poster presentation  

Venue：Chicago   Country：United States  

Objectives: Contribution of the rennin-angiotensin-aldosterone system (RAAS) to the neurodegenerative diseases and protective effects of RAAS blockers have been highlighted. Amyotrophic lateral sclerosis (ALS) is one of the progressive and intractable motor neuron diseases with neural cell death. Non-neuronal cells such as astrocytes have an important role in ALS pathogenesis. Recent studies implicated the involvement of RAAS in astrocytes; however, the role of RAAS in the pathological cross-talk between astrocytes and neurons is an enigma. Therefore, we examined the possible promoting effect of RAAS on the damage of spinal ganglion neurons (SGN) involving the correlation with astrocytes.
Methods: SGN were isolated from embryonic day 20 mouse spinal cords, and astrocytes were dissected from neonatal mice. Some SGN were co-cultured with astrocytes using transwell chamber. Cell damage was evaluated by quantification of DNA damage marker 8-hydroxy-2`-deoxyguanosine level. Cell death was determined by flowcytometry analysis. Aldosterone (Aldo) production was determined by ELISA method.
Results: Angiotensin (Ang) II stimulation significantly increased DNA damage of SGN in a time-dependent manner. This increase in DNA damage was further enhanced when co-cultured with astrocytes. However, no increase was observed in SGN co-cultured with astrocytes without Ang II stimulation. Moreover, addition of culture medium of Ang II-treated astrocytes enforced DNA damage. An Ang II type 1 receptor blocker, valsartan, inhibited Ang II-stimulated DNA damage, but not astrocyte culture medium-induced DNA damage. On the other hand, an Aldo antagonist, eplerenone, significantly inhibited DNA damage induced by culture medium of Ang II-treated astrocytes. Ang II stimulated Aldo secretion in conditioned medium of astrocytes. Furthermore, administration with Aldo alone also enhanced DNA damage in SGN. Finally, flowcytometry analysis showed that treatment with Ang II or Aldo markedly increased SGN death.
Conclusion: Ang II and Aldo induced neuronal damage and death in spinal ganglion with cross-talk of astrocytes, contributing to neurodegenerative diseases.

researchmap

Event date： 2007.11

Language：English   Presentation type：Poster presentation  

Venue：Beijing   Country：China  

Objective: Angiotensin (Ang) II type 1 (AT1) receptor stimulation has been known to promote premature senescence of vascular smooth muscle cells (VSMC); however, the roles of Ang II type 2 (AT2) receptor stimulation in VSMC senescence is an enigma. We examined the possibility that AT2 receptor stimulation could inhibit VSMC senescence in vitro and in vivo by the increase in methyl methanesulfonate sensitive 2 (MMS2), which is reported by us to be enhanced by AT2 receptor stimulation in neurons and prevent neuronal DNA damage. Design and Methods: VSMC prepared from the thoracic aorta of AT2 receptor null mice (Agtr2-) and wild-type (Agtr2+) mice were stimulated with persistent Ang II (10-7 M) and senescent VSMC were evaluated by senescence-associated -gal activity and cycline-dependent kinase inhibitor (CDKI) expression. Western blot analysis and MMS2-siRNA were employed to examine the involvement of MMS2. Evaluation of in vivo VSMC senescence was performed with X-ray irradiation. Results: The level of AT2 receptor expression in VSMC was increased time-dependently after persistent Ang II (10-7 M) stimulation. More marked acceleration of senescent VSMC in response to Ang II was observed in VSMC prepared from Agtr2- mice compared to Agtr2+ VSMC. MMS2 level was low in VSMC; however, administration of Ang II increased MMS2 expression time-dependently, and valsartan treatment (10-5 M) further exaggerated this increase in VSMC prepared from Agtr2+ mice, but not from Agtr2- mice. Moreover, MMS2-siRNA treatment showed enhancement of senescent VSMC. In MMS2-siRNA treated VSMC, damaged DNA evaluated by the detection of 8-hydroxydeoxyguanosine level was increased, whereas the increases in superoxide anion production assessed by dihydroethidium staining and Ki-ras2A expression mediated by AT1 receptor activation were not changed. In in vivo study, the 10Gy X-ray irradiated thoracic aorta showed senescent cells in Agtr2+ mice and much more senescent cell numbers in Agtr2- mice. MMS2 expression in irradiated aorta was higher in Agtr2+ mice than in Agtr2- mice. Valsartan significantly inhibited increases in senescent cells and DNA damage more markedly in Agtr2+ mice, but this effect of valsartan was attenuated in Agtr2- mice. Conclusion: AT2 receptor stimulation exerts inhibitory effect on VSMC senescence with possible enhanced DNA repair pathway by MMS2 upregulation.

researchmap

Event date： 2007.10

Language：Japanese   Presentation type：Poster presentation  

Venue：沖縄   Country：Japan  

目的：アンジオテンシンII (Ang II)は1型（AT1）受容体を介して血管平滑筋細胞（VSMC）の老化に影響を与え、動脈硬化発症に深く関与するとことが示唆されているが、2型(AT2)受容体の血管老化に及ぼす影響については詳しくわかっていない。今回、AT2受容体欠損（AT2KO）マウスから調整したVSMCを用いてAT2受容体シグナルの血管老化抑制機構について検討した。
方法：AT2KOマウスおよび野生型マウスの胸部大動脈からVSMCを調整し、Ang II（10-7 M）で連日刺激し、老化関連βガラクトシダーゼ染色により細胞老化を評価した。DNA損傷の程度は8-OHdG量を ELISA法にて、シグナルについてはウエスタンブロット法で、NADPHオキシダ－ゼの活性は発光法にて、酸化ストレスについてはジヒドロエチジウム染色にてスーパーオキシドアニオンの産生を評価した。
結果：野生型VSMCにおいてAng IIの連日刺激により時間依存性に老化細胞数やその割合、損傷DNA量や、Ki-ras2A及びサイクリン依存性キナーゼ阻害因子（CDKI）の発現が増強した。これらの指標は選択的AT1受容体ブロッカー（ARB）のバルサルタン添加によりほぼ完全に抑制された。野生型細胞においてAng IIの連日刺激によりAT2受容体発現の時間依存性の増加が認められた。AT2KO VSMCでは、Ang II刺激による老化はさらに増強し、バルサルタン添加による抑制作用は減弱した。また、AT2受容体により発現が増加するDNA修復因子として知られるMMS2の発現を検討したところ、野生型VSMCではAng II刺激により時間依存性的にMMS2の発現が増強され、バルサルタン添加によりさらに増加した。このMMS2の発現増強は、AT2KO VSMCでは認められなかった。MMS2-siRNAを用いて遺伝子をノックダウンした野生型VSMCではAng IIで誘導される老化細胞と損傷DNA量の著明な増加が認められたが、Ki-ras2A 及び CDKI の発現には影響がなかった。Ang II刺激によりスーパーオキシドアニオンの産生やNADPHオキシダ－ゼ活性の増加が認められ、この作用はバルサルタン添加により抑制されたが、AT2KO VSMCではこれらの指標がさらに増加していた。MMS2-siRNAで処置した野生型VSMCではこうした酸化ストレスの指標に変化は認められなかった。
結論：以上よりVSMCの老化においてAT2受容体シグナルの関与が示唆された。そのメカニズムとして、Ki-ras2A-CDKIシグナルや酸化ストレスなどの主にAT1受容体を介したシグナルを抑制する作用とMMS2を介したDNA傷害の抑制作用が関与していると考えられた。ARBによるAT1受容体刺激の抑制と相対的AT2受容体の活性化が加齢による血管疾患の抑制に有用であることが示唆された。

researchmap

Event date： 2006.10

Language：English  

Venue：Fukuoka   Country：Japan  

researchmap

Event date： 2005.9

Venue：旭川   Country：Japan  

researchmap

Event date： 2005

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Seoul   Country：Korea, Republic of  

researchmap

Event date： 2005

Venue：松山   Country：Japan  

researchmap

Event date： 2002.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Osaka   Country：Japan  

researchmap

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：松山   Country：Japan  

背景：近年、レニン・アンジオテンシン・アルドステロン系（RAAS）は血管の老化に影響を与え、動脈硬化の発症に深く関与するとことが示唆されている。 我々はアルドステロン（Aldo）とアンジオテンシン（Ang） IIが血管平滑筋細胞（VSMC）の増殖にKi-ras2Aを介して相乗的に関与していることを報告した。Ki-ras2Aは老化に関与するRasファミリーの一つであることから、AldoとAng IIがVSMCの老化にも影響していると推測される。

目的：VSMCの老化におけるAldoとAng IIの相互作用について検討した。

方法： Sprague-Dawleyラットの胸部大動脈より調整した血管平滑筋細胞を用い、細胞の老化は、老化関連βガラクトシダーゼ (SA--gal) 染色とp53、p21、p16、p27などのサイクリン依存性キナーゼ（CDKI）の発現の増大を指標とした。また細胞内シグナルの発現をウエスタンブロットで検討し、より詳しい検討にはsiRNAによる遺伝子ノックダウン法も用いた。酸化ストレスについてはdihydroethidiumによるスーパーオキシドアニオンの産生で評価した。

結果：VSMCはAng II (10-7 M) 刺激により細胞数は初めの5日間は増加を認めたが、その後はほとんどプラトーとなり、SA--gal染色の陽性細胞数の割合やCDKIの発現がAng II刺激5日後より増強した。これらの老化の指標は選択的AT1ブロッカー（ARB）のバルサルタン(10-5 M)によりほぼ完全に抑制されたが、ミネラルコルチコイド拮抗薬のスピロノラクトン処置 (10-5 M) でも部分的に抑制された。Ang II刺激によりVSMCからのAldo分泌が時間依存的に増加し、分泌濃度のAldo単独投与でも老化が促進された。Ang II又はAldo刺激によりKi-ras2Aの発現は時間依存的に増加し、Ki-ras2A-siRNAを用いてKi-ras2A遺伝子をノックダウンするとAng II刺激による老化の指標は有意に抑制された。また、Ang II又はAldo刺激により酸化ストレスやNADPHオキシダ－ゼ活性の増加を認めたことから、抗酸化剤であるスーパーオキシドデスムターゼ（SOD）やN-アセチルシステイン（NAC）、Rotenone、Antimycin-Aを添加したところ、老化の指標とKi-ras2Aの発現の部分的な減弱が認められた。一方、それぞれ単独では、細胞老化は来たさない低濃度のAng II （10-9 M）とAldo （10-12 M）の両者で同時に刺激することにより、老化細胞数、CDKI が相乗的に増加し、そのメカニズムとしてKi-ras2Aの発現や酸化ストレス、NADPHオキシダ－ゼ活性の相乗的な増加の影響が考えられた。

結論：以上よりRAASによるVSMCの老化促進のメカニズムには、AT1受容体を介した酸化ストレスの亢進とKi-ras2Aの発現の上昇が関与していると考えられた。またAldoも老化に関与しており、Ang IIによる分泌や低濃度でも相乗効果により老化をさらに促進していると考えられた。以上の結果よりAng IIとAldoの効果的な抑制は血管の老化の予防に重要であると考えられた。

researchmap

Language：English   Presentation type：Poster presentation  

Venue：Beijing   Country：China  

Objectives: Angiotensin (Ang) II type 1 (AT1) receptor stimulation promotes premature senescence of vascular smooth muscle cells (VSMC) related with vascular disorders, whereas the roles of Ang II type 2 (AT2) receptor stimulation in senescence is unclear. We examined the possible inhibitory effect of AT2 receptor stimulation on vascular cell senescence, and explored the signaling mechanisms with involvement of methyl methanesulfonate sensitive 2 (MMS2), which we previously reported as an inhibitor of DNA damage in neuron.
Methods: VSMC prepared from the thoracic aorta of AT2 receptor null mice (AT2KO) and wild-type (WT) mice were stimulated with persistent Ang II (10-7 M) and senescent VSMC were evaluated by senescence-associated beta-gal activity and cycline-dependent kinase inhibitor (CDKI) expression. MMS2-siRNA was employed to examine the signal involvement of MMS2. Evaluation of in vivo cellular senescence was performed with X-ray irradiation.
Results: AT2 receptor expressed at low level in VSMC and increased time-dependently after persistent Ang II stimulation. VSMC prepared from AT2KO mice exhibited an acceleration of senescent activity in response to Ang II compared with WT VSMC. Expression of MMS2 protein determined by western blot analysis was low in VSMC; however, increased MMS2 expression was observed after administration of Ang II in WT VSMC. Valsartan treatment enhanced the Ang II-increased MMS2 in VSMC prepared from WT mice but not form AT2KO mice. Moreover, WT VSMC treated with MMS2-siRNA showed significant increase in senescent activity compared with control-siRNA-treated cells. In MMS2-siRNA treated VSMC, Ang II-caused damaged DNA evaluated by the detection of 8-hydroxydeoxyguanosine level was increased, whereas the increases in superoxide anion production and CDKI, Ki-ras2A expression were not changed, which are demonstrated to be mediated by AT1 receptor activation. In animal model, the 10Gy X-ray irradiated thoracic aorta exhibited much more senescence-associated beta-gal positive senescent cell numbers in AT2KO mice than in WT mice. In contrast, MMS2 expression in irradiated aorta was higher in WT mice than in AT2KO mice. Moreover, valsartan treatment significantly blocked increases in senescent activity and damaged DNA observed in WT mice, but its effects were weaker in AT2KO mice.
Conclusion: AT2 receptor stimulation prevents vascular cell senescence through possible DNA repair mechanism mediated by MMS2, in addition to its anti-oxidative stress effects involved in the Ki-ras2A/CDKI pathway.

researchmap

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：Beijing   Country：China  

【Objectives】
The functions of the angiotensin (Ang) II type 1 receptor (AT1R) are regulated in a complex manner. AT1 receptor-associated protein (ATRAP) has been reported to reduce AT1R signaling with enhancement of AT1R internalization, and to regulate the calcineurin/nuclear factor of activated T cells (NFAT) pathway. We examined whether ATRAP could attenuate AT1R-mediated vascular senescence via inactivation with the calcineurin/NFAT pathway.
【Methods】
Vascular smooth muscle cells (VSMC) prepared from the thoracic aorta of adult ATRAP transgenic mice (ATRAP-Tg) and wild-type mice (WT) were persistently stimulated with Ang II and cellular senescence was evaluated by senescence-associated -galactosidase (SA--gal) activity. Oxidative stress was evaluated with NADPH oxidase activity and superoxide anion production by dihydroethidium staining. NFAT activity was evaluated by luciferase reporter assay.
【Results】
Ang II stimulation increased SA--gal-stained cells, oxidative stress, and expression of p53 and p21 in WT-VSMC with no significant alteration in expression of ATRAP. Moreover, Ang II stimulation enhanced NFAT transcriptional activity, which was prevented by CAML-siRNA treatment. NFAT-siRNA treatment attenuated Ang II-increased SA--gal activity, p53 and p21 expression. Treatment with a calcineurin inhibitor, cyclosporin A, reduced Ang II-induced NFAT transcriptional activity and senescent VSMC. In contrast, ATRAP-Tg-VSMC exhibited attenuation of Ang II-induced SA--gal activity, oxidative stress, and expression of p53 and p21. Moreover, both cells showed a reduction of Ang II-induced NFAT transcriptional activity with or without CAML-siRNA treatment. Furthermore, in ATRAP-Tg VSMC, NFAT activity and senescent cells induced by ultraviolet irradiation were less than WT-VSMC. Treatment with an AT1R blocker, valsartan blocked these senescent cells, but did not change NFAT activity in both cells.
【Conclusions】
These results suggest that ATRAP negatively regulates VSMC senescence. ATRAP-mediated inactivation of the calcineurin/NFAT pathway could be at least partly involved in prevention of VSMC senescence, irrespective of AT1R blockade in some conditions.

researchmap

Language：Japanese   Presentation type：Poster presentation  

Venue：金沢   Country：Japan  

【目的】乳由来ペプチド、CH-3にはメチオニン-リジン-プロリンのトリペプチド（MKP)が含まれ、アンジオテンシン変換酵素（ACE）の阻害作用を持つことがわかっている。そこでCH-3の経口摂取が認知機能低下を予防すると仮説を立て検討を行った。
【対象・方法】10週齢の雄性ddYマウスを用い、アミロイドβ（1-42フラグメント）を脳室内に投与し、3週間後にモリス水迷路試験にて空間認知機能を検討した。一部マウスではアミロイドβ投与2日前よりCH-3を250mg/kgの濃度で毎日経口投与を行った。
【結果】アミロイドβ投与マウスではコントロールマウスと比較して空間認知機能の低下が認められたが、CH-3投与群ではその低下が抑制された。脳内のTNF-αやNAD(P)Hオキシダーゼのサブユニットであるp47phox、p22phox、p67phoxのmRNAの発現はアミロイドβ投与群で増加傾向を示したが、CH-3投与群ではアミロイドβ投与群と比較して有意な低下が認められた。最後にMKPのみを投与して検討を行ったところ、アミロイドβ投与による認知機能の低下及び脳血流の減少がMKP投与群で抑制された。
【結語】乳由来のペプチドCH-3は一部MKPを介してアミロイドβの蓄積によって生じる認知障害を抑制した。この抑制効果は酸化ストレスや炎症因子の抑制が関わっていることが示唆された。

researchmap

Language：English   Presentation type：Poster presentation  

Country：Japan  

【目的】The classical renin-angiotensin system (RAS), known as the angiotensin (Ang) converting enzyme (ACE)/Ang II/Ang II type 1 (AT1) receptor axis has been suggested to induce cognitive decline. On the other hand, the ACE2/Ang-(1-7)/Mas receptor axis has been highlighted as exerting antagonistic actions against the classical RAS axis in the cardiovascular system. Here, we explored possible roles of ACE2 in cognitive function.
【対象・方法】Male 10-week-old C57BL6 (wild-type: WT) mice and ACE2 knockout (KO) mice were used. Vascular dementia model was induced by bilateral common carotid artery stenosis (BCAS). Morris water maze task was performed 6 weeks after BCAS operation to evaluate spatial cognitive function.
【結果】There were no significant differences in body weight, brain weight and systolic blood pressure between ACE2KO and WT mice. ACE2KO mice exhibited significant impairment of cognitive function, compared with that in WT mice, with no significant difference in cerebral blood flow. Mas receptor mRNA was highly expressed in the hippocampus compared with the cortex, with no significant difference between ACE2KO and WT mice. AT1 receptor mRNA in the hippocampus was higher in ACE2KO mice compared with WT mice, whereas AT2 receptor mRNA in the hippocampus did not differ between the two strains. Superoxide anion production increased in ACE2KO mice, with increased NADPH oxidase subunits mRNAs in the hippocampus. Protein level of SOD3 decreased in ACE2KO mice compared with WT mice. Brain-derived neurotrophic factor (BDNF) mRNA and protein levels were lower in the hippocampus in ACE2KO mice compared with WT mice. Administration of Ang-(1-7) (0.5 mg/kg/day) attenuated the cognitive decline in ACE2KO mice without changes in systolic blood pressure.
【結語】ACE2 deletion caused impaired cognitive function probably due to the enhancement of oxidative stress and decrease in BDNF level.

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山   Country：Japan  

【目的】脳卒中は、死因の第４位としてだけでなく、後遺症により日常生活の支障に繋がるなど、克服すべき重要な疾患の一つである。心血管疾患の治療において、アンジオテンシン受容体-ネプリライシン阻害剤、LCZ696 （LCZ:バルサルタン（VAL）とAHU-377の混合物; 1:1) の投与はVAL単独群より優れた臓器保護効果が示されている。私たちは、脳卒中におけるLCZの脳保護作用について、VALと比較しての検討を行った。
【対象・方法】10週齢の雄性C57BL/6Jマウスを用い、総頸動脈よりフィラメントを挿入し中大脳動脈閉塞術（Middle Cerebral Artery Occlusion, MCAO）により脳虚血を誘導した。マウスはMCAO 2週間前よりゼラチンミニカプセルで溶媒のみ、VAL（3 mg/kg）またはLCZ（6 mg/kg）を毎日経口投与された。収縮期血圧（SBP）、拡張期血圧（DBP）と心拍数（HR）はテレメトリー法で測定した。脳梗塞の大きさは2,3,5 -塩化トリフェニルテトラゾリウム（TTC）による染色で評価し、脳血流量はLaser-Doppler Flowmetryで、酸化ストレスはジヒドロエチジウム（DHE）染色にて、ANPやBNPの濃度はELISA方法で評価した。
【結果】今回使用したVALまたはLCZの投与濃度ではSBP、DBPおよびHRの有意的な変化が認められなかった。VALまたはLCZの投与群において、コントロール群に比べて、脳梗塞サイズの有意な減少が認められた。また、このLCZの脳梗塞への抑制効果はVALよりも強く認められた。両者のそれぞれの投与は脳梗塞周辺領域の脳血流量を有意に改善した。一方、VALまたはLCZの投与群では、コントロール群に比べて、虚血側の皮質で増大するスーパーオキシドアニオン産生を抑制した。LCZの投与は脳虚血後の脳浮腫を有意に軽減したが、VALの投与では認められなかった。また、VALまたはLCZの投与により、虚血側皮質で炎症性サイトカインであるMCP-1、IL-1βおよびTNF-αのmRNA発現の増加を抑制したが、AT1、AT2受容体mRNAの発現に影響は認められなかった。また、LCZの投与により血中ANP濃度の顕著な増加が認められた。
【結論】以上より、VALとLCZとも、脳卒中後の脳障害を抑制する効果が認められたが、LCZはVALよりも、より効果的であることが示唆された。

researchmap

Language：English   Presentation type：Poster presentation  

Venue：Guangzhou   Country：China  

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap