Exendin-4 reduces glycemia by increasing liver glucokinase activity: an insulin independent effect

Exendin-4 is a stable peptide agonist of GLP-1 receptor that exhibits insulinotropic actions. Some in vivo studies indicated insulin-independent glucoregulatory actions of exendin-4. That finding prompted us to evaluate effects of exendin-4 on liver glucose metabolism. Acute and chronic treatment of exendin-4 resulted in increased hepatic glucokinase activity in db/db mice but not in lean C57 mice. The stimulatory effect of exendin-4 on glucokinase activity was abrogated by exendin 9-39, a GLP-1 antagonist. Exposure of hepatocytes isolated from db/db mice to exendin-4 elicited a rapid increase in cAMP, which was synergized by IBMX, an inhibitor of cAMP degradation. The GLP-1 antagonist, exendin 9-39, has abolished the cAMP generating effects of exendin-4 as well. Furthermore, chronic treatment of exendin-4 in streptozotocin-treated C57 mice resulted in restoration of hepatic glycogen, an indicator of improved glucose metabolism, without apparent changes in serum insulin levels. In conclusion, exendin-4 increased glucokinase enzyme protein and activity in liver via a mechanism parallel to and independent of insulin. Exendin-4-induced increase in hepatic glucokinase activity is more pronounced in the presence of hepatic insulin resistance. This beneficial effect of exendin-4 on liver glucokinase activity may be mediated by GLP-1 receptor.     

Neuroprotective effects of leonurine on ischemia/reperfusion-induced mitochondrial dysfunctions in rat cerebral cortex

Ischemic brain is particularly susceptible to free radicals mediated secondary neuronal damage, especially mitochondrial dysfunctions. Chinese Herbal Medicine with antioxidant properties is believed to have potential therapeutic effect. Leonurine, an alkaloid present in Herba Leonuri (HL), has shown biological effects such as antioxidant, anticoagulant, anti-apoptosis and protection against ischemic heart disease. In this study, neuroprotective effects of leonurine against cerebral ischemia/reperfusion-induced mitochondrial dysfunctions in cortex were evaluated. We used transient rat middle cerebral artery occlusion (MCAO) model of brain ischemia. The rats were treated with their respective treatments for 1 week prior to the MCAO. We found that leonurine significantly improved neurological outcome and reduced ischemia/reperfusion (I/R)-induced cerebral infarction 24 h after MCAO. Leonurine decreased reactive oxygen species (ROS) level in mitochondria isolated from ischemic cortex, which was increased by MCAO. Terminal deoxyuridine triphosphate (dUTP) Nick-End Labeling (TUNEL) staining showed anti-apoptotic effect of leonurine on ischemic cortex. Western blot analysis showed a marked decrease in the expression of Bax and an increase of Bcl-2 as a result of leonurine treatment. The attenuation of mitochondrial membrane swelling, restore of mitochondrial membrane potential and content of cytochrome c (Cyt-C) in mitochondria isolated from ischemic cortex could also be observed in leonurine treated group. The findings of this study suggest that leonurine has promising therapeutic effect for ischemic stroke treatment through antioxidant and anti-apoptotic mechanisms.     

左旋氨氯地平对局灶性脑缺血小鼠模型脑梗死体积的影响

目的研究左旋氨氯地平对局灶性脑缺血小鼠模型脑梗死体积的影响,探讨左旋氨氯地平对缺血性脑梗死的神经保护作用。方法制备小鼠大脑中动脉脑缺血再灌模型,根据是否使用左旋氨氯地平随机分为3组：左旋氨氯地平缺血前处理组,缺血生理盐水处理组,假手术对照组;多普勒超声血流仪监测梗死侧脑区的脑血流量;TYC染色检测脑梗死体积。结果与缺血生理盐水处理组相比较,左旋氨氯地平缺血前处理组梗死侧脑区的脑血流量没有明显变化,而脑梗死体积较小,差异有统计学意义（P〈0．05）。结论使用左旋氨氯地平可能有助于减少缺血性脑梗死体积。     

Intranasal ginsenoside Rb1 targets the brain and ameliorates cerebral ischemia/reperfusion injury in rats

Ginsenoside Rb1 (GRb1) has been shown to benefit many central nervous system (CNS) disorders, including stroke. However, its bioavailability is low after oral administration due to poor absorption. Intranasal administration has been considered as an effective method for central nervous system drug delivery for its brain-targeting effect. Here, whether intranasal GRb1 could ameliorate cerebral ischemia/reperfusion injury was investigated. First, the concentration of GRb1 in brain tissues and plasma after intranasal and intravenous delivery was calculated using HPLC-MS/MS methods in male Sprague-Dawley rats (250±10 g). Intranasal GRb1 was considered brain-targeting if the value of the drug targeting index (DTI) was greater than 1. Rats were subjected to 1.5 h middle cerebral artery occlusion (MCAO) and were killed 24 h after reperfusion. The neuroprotective effects were measured using 2,3,5-triphenyltetrazolium chloride (TTC) staining and Nissl staining. Immunoblotting of LC3 and Beclin 1, crucial autophagy-related proteins, was used to monitor the state of autophagy. With a local bioavailability of 10.28-32.48% and DTI of 7.35-23.22 in different brain regions, intranasal GRb1 was determined to be brain-targeting. Less infarct volume and more intact neuronal structure were observed in the GRb1 group. GRb1 also restored the elevation of LC3 and Beclin 1. Our work suggests that intranasal GRb1 exerts brain-targeting effects and that a single dose of intranasal GRb1 immediately after MCAO ameliorates ischemia/reperfusion insult. Autophagy is involved in these beneficial effects.     

Neuroprotection of total steroid saponins from Dioscorea zingiberensis C.H.Wright against transient focal cerebral ischemia-reperfusion injury in rats via its anti-inflammatory and anti-apoptotic effects

OBJECTIVE The total steroid saponins(TSSN) isolated from Dioscorea zingiberensis C. H. Wright(D.zingiberensis) has shown a variety of beneficial bioactivities. However, there are no reports about the neuroprotective effects of the TSSN until now. Therefore, we explored the neuroprotective effects of TSSN on rats against transient focal cerebral ischemia-reperfusion(I/R) and the underlying mechanisms. METHODS The healthy adult Sprague-Dawley rats were randomly assigned into six groups. After pre-treatment with the TSSN intragastrically for six days, the rats were subjected to the ischemia injury by the surgery of middle cerebral artery occlusion(MCAO) for 90 min. Some indexes were evaluated and detected. RESULTS As compared to the I/R group, TSSN group of rats, especial y given the 30 mg·kg~(-1) of TSSN, not only marked reduction in the neurological deficit scores, cerebral infarct volume, and brain edema, but also an increase in neuron survival(Nissl bodies) in the hippocampal cornuammons 1(CA1) and cortex hemisphere of the ipsilateral ischemia. At the same time, the inflammatory cytokines in serum induced by MCAO were significantly alleviated by the TSSN pre-administration. What′s more, the increase of caspase-3 was evidently reduced in the CA1 and cortex of the hemisphere injured brain. Final y, the down-regulating anti-apoptotic Bcl-2 and up-regulating pro-apoptotic Bax proteins were obviously suppressed. CONCLUSION TSSN plays a potential neuroprotective role against a severe injury induced by transient focal cerebral ischemic reperfusion in a rat experimental model, and this role may be mediated by its antiinflammatory and anti-apoptotic actions.     

Montelukast, a cysteinyl leukotriene receptor-1 antagonist, dose- and time-dependently protects against focal cerebral ischemia in mice

Our previous studies showed that cysteinyl leukotriene receptor-1 (CysLT1) antagonist pranlukast has a neuroprotective effect on cerebral ischemia in rats and mice. However, whether the neuroprotective effect of pranlukast is its special action or a common action of CysLT1 receptor antagonists remains to be clarified. This study was performed to determine whether montelukast, another CysLT1 receptor antagonist, has the neuroprotective effect on focal cerebral ischemia in mice, and to observe its dose- and time-dependent properties. Permanent focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). Montelukast was injected intraperitoneally either as multiple doses (once a day for 3 days and 30 min before MCAO) or as a single dose (at 30 min before, 30 min after, or 1 h after MCAO), respectively, and pranlukast and edaravone were used as controls. The neurological deficits, infarct volumes, brain edema, neuron density, and Evans blue extravasation in the brain were determined 24 h after MCAO. Pretreatments with multiple doses or a single dose of montelukast (0.1 and 1.0 mg/kg) before MCAO significantly attenuated all the ischemic insults. Post-treatment with a single dose of montelukast (0.1 and 1.0 mg/kg) at 30 min after MCAO also significantly decreased brain edema and infarct volume, but not neurological deficits. However, post-treatment with a single dose of montelukast at 1 h after MCAO had no significant effect. Pranlukast showed the same effects as montelukast, but edaravone attenuated the ischemic insults only with multiple doses before MCAO. Thus, montelukast has a dose- and time-dependent neuroprotective effect on permanent focal cerebral ischemia in mice, with an effective dose range of 0.1-1.0 mg/kg and a therapeutic window of 30 min. These findings further support the therapeutic potential of CysLT1 receptor antagonists in the treatment of cerebral ischemia at earlier phases.     

DPP4 deficiency preserves cardiac function via GLP-1 signaling in rats subjected to myocardial ischemia/reperfusion

Dipeptidyl peptidase-4 (DPP4) enzyme inhibition has been reported to increase plasma glucagon-like peptide-1 (GLP-1) level for controlling postprandial glucose concentration. Both DPP4 inhibitors and GLP-1 analog have been approved for antihyperglycemic agents. In addition to the insulinotropic effect, GLP-1 signaling was reported to modulate cardiac function. DPP4 inhibition was shown to improve survival rate after myocardial infarction in mice, but the precise mechanism remains unknown. We aimed to compare the cardiovascular responses of ischemia/reperfusion (I/R) between wild-type and DPP4-deficient rats and investigate the underlying mechanism. Rats were subjected to 45 min of coronary artery occlusion, followed by reperfusion for 2 h. Cardiac function was characterized by analyzing pressure–volume loops. As compared to wild-type rats, after I/R, DPP4-deficient rats had better cardiac performance in association with less infarct size and cardiac injury markers (LDH, ANP, and BNP), which could be attenuated by exendin-(9–39), a GLP-1 receptor antagonist. Exendin-(9–39) could diminish the increased phosphorylation levels of myocardial AKT and GSK-3β as well as the higher expression of GLUT4 in post-infarcted DPP4-deficient rats. However, exendin-(9–39) could not completely abrogate the less infarct size in DPP4-deficient rats as compared with that in wild-type rats, implicating the involvement of GLP-1 receptor-independent pathway. In summary, this study demonstrated that the benefit of cardiac protective action against I/R injury was demonstrated in DPP4-deficient rats, which is mediated through both GLP-1 receptor-dependent and receptor-independent mechanisms.     

The neuroprotection of Sinomenine against ischemic stroke in mice by suppressing NLRP3 inflammasome via AMPK signaling

Neuroinflammation remains the primary cause of morbidity and mortality in stroke-induced secondary brain injury. The NOD-like receptor pyrin 3 (NLRP3) inflammasome is involved in diverse inflammatory diseases, including cerebral ischemia, and is thus considered an effective therapeutic target. In the present study, we investigated the neuroprotection of Sinomenine (SINO), a potent natural anti-apoptotic and anti-inflammatory molecule, against cerebral ischemia in a mouse model of middle cerebral artery occlusion (MCAO) in vivo and in an oxygen glucose deprivation (OGD)-treated astrocytes/microglia model in vitro. SINO administration intraperitoneally alleviated the cerebral infarction, brain edema, neuronal apoptosis, and neurological deficiency after MCAO induction. SINO also attenuated astrocytic and microglial activation in the ischemic hemisphere. NLRP3 inflammasome activation after MCAO and OGD induction, with the up-regulation of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), cleaved caspase-1 and pro-inflammatory cytokines, was significantly inhibited by SINO treatment both in vivo and in vitro. In addition, SINO reversed the OGD-induced inhibition of AMPK phosphorylation in vitro. Further, the suppressive effect of SINO on NLRP3 inflammasomes was blocked by an AMPK inhibitor, Compound C. Our findings demonstrate that SINO exerts a neuroprotective effect in ischemic stroke by inhibiting NLRP3 inflammasomes via the AMPK pathway, which also provides evidence of a novel treatment for clinical stroke therapy.     

艾塞那肽促进葛根素改善高脂饮食糖尿病模型小鼠糖代谢作用的研究

前期研究发现葛根素通过上调胰岛β细胞GLP-1R(GLP-1 receptor)的表达保护β细胞,但葛根素综合降糖作用是否受到GLP-1R激活调控,尚未验证。本文采用GLP-1R激动剂艾塞那肽(exendin-4,Ex4)与GLP-1R拮抗剂毒蜥外泌肽9-39(exendin 9-39,Ex9-39),以高脂饮食(high-fat diet,HFD)诱导小鼠糖尿病模型,实验分为对照组、高脂组、高脂/葛根素组(300 mg·kg^-1·d^-1)、高脂/葛根素/Ex9-39组(Ex9-39:10 nmol·kg^-1·d^-1)、高脂/葛根素/Ex4组(Ex4:10 nmol·kg^-1·d^-1)。动物实验已获得南京中医药大学附属中西医结合医院动物伦理委员会批准(AEWC-025)。葛根素灌胃给药,Ex9-39与Ex4腹腔注射给药。给药10天,考察小鼠空腹血糖及口服葡萄糖耐量(oral glucose toler‐ance test,OGTT),测定血清胰岛素等指标,...     

缺血再灌注时间对小鼠大脑中动脉闭塞模型的影响

目的:探讨不同缺血时间对小鼠大脑中动脉闭塞(MCAO)所致脑缺血-再灌注损伤的影响。方法:以雄性C57BL/6J小鼠为研究对象,线栓法致小鼠局灶性脑缺血,分别在缺血0.5,1和2 h后进行再灌注。再灌注24 h后,进行神经行为学评分,计算存活率、脑梗死率及脑水含量。结果:缺血后各组小鼠均出现不同程度的缺血损伤。缺血1 h再灌注24 h组小鼠出现明显的神经行为缺陷,脑梗死体积和脑水含量与假手术组相比有显著性差异,且变异系数最小,显示其最稳定。结论:缺血1 h再灌24 h可引起小鼠大脑中动脉供血区域梗死大小适宜,稳定性好,可作为研究脑缺血生理病理和药效学评价的动物模型。     

西洛他唑对小鼠慢性缺血性脑损伤的保护作用及机制

目的：观察西洛他唑对小鼠慢性缺血性脑损伤的保护作用,探讨其与促血管生成的关系。方法：以大脑中动脉栓塞方法诱导小鼠局灶性脑缺血,缺血后1、4、7h和术后1～14d腹腔注射西洛他唑（10mg／kg）,每天一次,观察缺血后35d西洛他唑对神经症状评分、斜板角度、脑梗死体积、神经元密度和缺血侧血管内皮生长因子（VEGF）、血管内皮生长因子受体2（Flk-1）表达的作用。结果：西洛他唑能降低缺血后神经症状评分,提高斜板角度,减少脑梗死体积,增加存活神经元密度和VEGF、Flk-1表达的数目。结论：西洛他唑对小鼠慢性局灶性脑缺血具有保护作用,其作用机制可能与诱导缺血侧VEGF、Flk-1表达,促进血管生成有关。     

Phthalide derivative CD21 ameliorates ischemic brain injury in a mouse model of global cerebral ischemia: involvement of inhibition of NLRP3

The activation of NLRP3 inflammasome is closely related to ischemic brain injury and inhibition of NLRP3 inflammasome activation may be a new therapeutic strategy for ischemic stroke. Our previous studies showed that ligustilide (LIG) had a dose-dependent neuroprotective effect on various models of cerebral ischemia and dementia in vivo and in vitro. CD21, a kind of phthalide derivative, was modified from LIG. In this study, we established a global cerebral ischemia–reperfusion model in mice by bilateral common carotid artery ligation (2VO), and explored the neuroprotective effect of CD21 and its anti-inflammatory mechanism on cerebral ischemia mice. CD21 significantly improved weight loss, neurobehavioral deficits and neurons loss in hippocampal CA1 and caudate putamen (CPu) subregions, which were induced by 2VO in mice. CD21 significantly inhibited the overactivation of astrocyte and microglia, and decreased the mRNA level of IL-6, TNF-α and IL-1β. Moreover, CD21 significantly inhibited the activation of TLR4/NF-κB signaling pathway mediated by HMGB1 and NLRP3/ASC/Caspase-1 signaling pathway mediated by Cathepsin B, thus inhibiting the activation of NLRP3 inflammasome. Our results demonstrated that CD21 may exert a neuroprotection by inhibiting NLRP3 inflammasome activation after cerebral ischemia. These findings provide a new strategy for the treatment of ischemic stroke.     

Combination of omeprazole with GLP-1 agonist therapy improves insulin sensitivity and antioxidant activity in liver in type 1 diabetic mice

BackgroundCombination with suitable pharmacological agents can improve the antiobesity and antidiabetic actions of glucagon like peptide-1 (GLP-1) based therapies. GLP-1 agonist exendin-4 may have insulin-independent effects on amelioration of insulin resistance and hepatic steatosis by virtue of its action on hepatic GLP-1 receptors, and these effects can be improved by combination with proton pump inhibitors. However, it was not assessed whether omeprazole can improve the peripheral actions of exendin-4 in the state of insulin deficiency.MethodsWe investigated the effects of combination of omeprazole with GLP-1 agonist exendin-4 in multiple low-dose streptozotocin(STZ)-induced diabetes in C57BL/KsJ mice, a model of type 1 diabetes. Male diabetic mice were treated with exendin-4 and/or omeprazole for a period of 4 weeks.ResultsOmeprazole treatment had no significant effect on lowering the blood glucose levels of diabetic mice, when compared to control, although it improved the antihyperglycemic actions of exendin-4. Similarly, serum triglycerides and total cholesterols levels were significantly lower in the combination treated mice compared to either exendin-4 and omeprazole alone. In addition, the combination treatment significantly ameliorated lipid peroxidation and hepatic triglycerides in diabetic mice compared to either exendin-4 and omeprazole alone. The improvement in hepatic insulin sensitivity, as indicated by insulin tolerance test (ITT) and pyruvate tolerance test (IPPTT), was correlated with the expression of nuclear factor erythroid-related factor 2 (Nrf2) and insulin receptor substrate-1 (IRS-1) and the combination treatment significantly improved the insulin sensitivity in comparison to vehicle control.ConclusionWe conclude that combination with omeprazole improves the insulin sensitizing actions of GLP-1 therapy and these effects are partially mediated through the decrease in hepatic steatosis and improvement in antioxidant status in the liver.     

The role of nausea in food intake and body weight suppression by peripheral GLP-1 receptor agonists, exendin-4 and liraglutide

The FDA-approved glucagon-like-peptide-1 receptor (GLP-1R) agonists exendin-4 and liraglutide reduce food intake and body weight. Nausea is the most common adverse side effect reported with these GLP-1R agonists. Whether food intake suppression by exendin-4 and liraglutide occurs independently of nausea is unknown. Further, the neurophysiological mechanisms mediating the nausea associated with peripheral GLP-1R agonist use are poorly understood. Using two established rodent models of nausea [conditioned taste avoidance (CTA) and pica (ingestion of nonnutritive substances)], results show that all peripheral doses of exendin-4 that suppress food intake also produce CTA, whereas one dose of liraglutide suppresses intake without producing CTA. Chronic (12 days) daily peripheral administration of exendin-4 produces a progressive increase in pica coupled with stable, sustained food intake and body weight suppression, whereas the pica response and food intake reduction by daily liraglutide are more transient. Results demonstrate that the nausea response accompanying peripheral exendin-4 occurs via a vagal-independent pathway involving GLP-1R activation in the brain as the exendin-4-induced pica response is attenuated with CNS co-administration of the GLP-1R antagonist exendin-(9-39), but not by vagotomy. Direct administration of exendin-4 to the medial subnucleus of the nucleus tractus solitarius (mNTS), but not to the central nucleus of the amygdala, reduced food intake and produced a pica response, establishing the mNTS as a potential GLP-1R-expressing site mediating nausea responses associated with GLP-1R agonists.     

Neuroprotective effect of dioscin on cerebral ischemia/reperfusion mice by reducing glial cell activation and maintaining the levels of SODs

In the present study, we aimed to explore the neuroprotective effect of dioscin, a natural steroid saponin, on transient focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO) in mice and its related mechanism. We observed that dioscin (1.5 mg/kg, intracerebroventricular injection 30 min before MCAO) dramatically reduced the cerebral infarct volume, leading to improved neurological symptoms and reduced death of neuron, astrocytes and microglia in the infarct region. The gliosis and the reduced expressions of SOD1 and SOD2 by MCAO in the hippocampal CA1 region were significantly elevated by 1.5 mg/kg dioscin administration. These findings suggested that pretreatment of dioscin had a neuroprotective effect on mice transient focal cerebral ischemia via inhibiting the gliosis and elevating the SOD levels.     

Matrix Metalloproteinase Inhibitors Attenuate Neuroinflammation Following Focal Cerebral Ischemia in Mice

The aim of this study was to investigate whether matrix metalloproteinase (MMP) inhibitors attenuate neuroinflammation in an ischemic brain following photothrombotic cortical ischemia in mice. Male C57BL/6 mice were anesthetized, and Rose Bengal was systemically administered. Permanent focal ischemia was induced in the medial frontal and somatosensory cortices by irradiating the skull with cold white light. MMP inhibitors, such as doxycycline, minocycline, and batimastat, significantly reduced the cerebral infarct size, and the expressions of monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and indoleamine 2,3-dioxygenase (IDO). However, they had no effect on the expressions of heme oxygenase-1 and neuroglobin in the ischemic cortex. These results suggest that MMP inhibitors attenuate ischemic brain injury by decreasing the expression levels of MCP-1, TNF-α, and IDO, thereby providing a therapeutic benefit against cerebral ischemia.     

Exendin-4与神经退行性疾病的关系

Exendin-4是一种糖尿病新药,也是胰高血糖素样肽-1(GLP-1)类似物,能激活GLP-l受体,上调cAMP发挥生理活性。GLP-1受体与神经元可塑性及存活密切联系。Exendin-4还能激活多条信号通路,调节胞内钙离子(Ca2+)稳态,减轻兴奋性毒性,抑制细胞凋亡,促进神经元增生、分化,对神经退行性疾病有治疗作用。该文旨在阐明exendin-4的神经保护机制,为神经退行性疾病的预防与治疗提供新思路。     

Honokiol suppresses the development of post-ischemic glucose intolerance and neuronal damage in mice

Honokiol, a constituent of Magnolia obovata, has various pharmacological effects, including protection against cerebral ischemia. However, few studies have been conducted to evaluate the possible neuroprotective effects of honokiol against cerebral ischemia. We recently reported that cerebral ischemic neuronal damage could be triggered by glucose intolerance that develops after the onset of ischemic stress (i.e., post-ischemic glucose intolerance). In addition, suppression of post-ischemic glucose intolerance significantly ameliorated ischemic neuronal damage. Here, we investigated the effects of honokiol on the development of post-ischemic glucose intolerance and neuronal damage. Mice were subjected to middle cerebral artery occlusion (MCAO) for 2?h. The development of post-ischemic glucose intolerance on day 1 and neuronal damage on day 3 after MCAO were significantly reduced by intraperitoneal administration of honokiol (10?mg/kg) compared with the vehicle-treated group. Honokiol did not affect serum insulin or adiponectin levels. However, honokiol significantly decreased the expression of phosphoenolpyruvate carboxykinase and increased the expression of 5'-AMP-activated protein kinase (AMPK) on day 1 after MCAO, compared with the vehicle-treated MCAO group. The results of this study suggest that honokiol could prevent post-ischemic glucose intolerance in an AMPK-dependent manner, which may be involved in the neuroprotective effects of honokiol against cerebral ischemia.     

Neuroprotection by Valproic Acid in Mouse Models of Permanent and Transient Focal Cerebral Ischemia

Valproic acid (VPA) is a well-known anti-epileptic and mood stabilizing drug. A growing number of reports demonstrate that VPA is neuroprotective against various insults. Despite intensive efforts to develop new therapeutics for stroke over the past two decades, all treatments have thus far failed to show clinical effect because of treatment-limiting side effects of the drugs. Therefore, a safety-validated drug like VPA would be an attractive candidate if it has neuroprotective effects against ischemic insults. The present study was undertaken to examine whether pre- and post-insult treatments with VPA protect against brain infarct and neurological deficits in mouse transient (tMCAO) and permanent middle cerebral artery occlusion (pMCAO) models. In the tMCAO (2 hr MCAO and 22 hr reperfusion) model, intraperitoneal injection of VPA (300 mg/kg, i.p.) 30 min prior to MCAO significantly reduced the infarct size and the neurological deficit. VPA treatment immediately after reperfusion significantly reduced the infarct size. The administration of VPA at 4 hr after reperfusion failed to reduce the infarct size and the neurological deficit. In the pMCAO model, treatment with VPA (300 mg/kg, i.p.) 30 min prior to MCAO significantly attenuated the infarct size, but did not affect the neurological deficit. Western blot analysis of acetylated H3 and H4 protein levels in extracts from the ischemic cortical area showed that treatment with VPA increased the expression of acetylated H3 and H4 at 2 hrs after MCAO. These results demonstrated that treatment with VPA prior to ischemia attenuated ischemic brain damage in both mice tMCAO and pMCAO models and treatment with VPA immediately after reperfusion reduced the infarct area in the tMCAO model. VPA could therefore be evaluated for clinical use in stroke patients.