The Neuroprotection Role Of Resveratrol On Recurrent Stroke Recurrent Ischemic Rat

Background and Purpose-Recurrent stroke following a transient ischemic attack or minor stroke provides an opportunity for treatment with neuroprotective agents after the initial insult. Polyphenol resveratrol (RSV) is considered an effective neuroprotective compound in ischemic stroke. Mechanisms of protective effects of RSV are still poorly understood. RSV has been associated with SIRT1(silent information regulatorTl, SIRT1) and AMPK(AMP-activated protein kinase, AMPK) metabolic stress sensors and probably responses to the intracellular energy status. This study investigates the neuroprotective effects of RSV on regulating the SIRT1and AMPK signalling in recurrent ischemia models to provide a potential therapy to recurrent stroke patients.Methodology: Elderly male Wistar rats at the age of18to20months were received RSV (25mg/kg/day) or vehicle (juice) orally for certain days and then received a single mild(n=14) or a combination of two mild transient Middle Cerebral Artery Occlusion (MCAO)(n=16). MCAO was produced by placing an aneurysm microclip on middle cerebral artery of the rat. Other rats(sham-operatted) were used to determine plasma, liver and brain concentrations of resveratrol in treated (n=5) and control animals (n=3). Infarct volumes and behavioral deficits were evaluated by horizontal ladder task and cylinder task test. Primary cortical neurons were isolated from embryonic day18Wistar rat fetuses obtained from pregnant females Primary cultured cortical neuronal cells subjected to combined oxygen—glucose deprivation (OGD) were used as in vitro recurrent ischemic model.A double OGD treatment was to establish recurrent stroke models in vitro., and cortical neurons were pre-treated with50u M resveratrol or vehicle for3hours berofre next OGD treatment. SIRT1activity, AMPK activity and ATP level were tested respectively by Western blot, SIRT1activity kit, phosphor-AMPK assay and Bioluminescence ATP Detection Kit. SIRT1and AMPK inhibitors were used to test the direct correlation of SIRT1and AMPK to resveratrol regulated t neuroprotection.Principal Findings: RSV administration significantly reduced infarct volumes (P<0.01) in single mild ischemic stroke model, especially reduced infarct volumes dramatically (P<0.001) in recurrent ischemic stroke models in vivo. RSV treatments significantly protected neuronal cells from cell death induced by OGD in in vitro recurrent ischemia models(P<0.001). Treatments of RSV for three hours increased SIRTl expression in cultured neuronal cells (P<0.05) but no significant difference was observed in brain tissue (P<0.05) after RSV administrated for three days. Interestingly, RSV treatments increased SITR1activity both in brain tissues and cultured neuronal cells(P=0.0014%WP=0.002).RSV administration also increased AMPK activities both in brain tissues and cultured neuronal cells (P<0.01). RSV treatments decreased energy assumption and restored cell energy ATP level in vivo and in vitro (P<0.001).SIRTl and AMPK specific inhibitors were used to test the direct correlation of SIRTl and AMPK to resveratrol regulated t neuroprotection.Conclusions-A dietary polyphenol resveratrol acts to provide neuroprotection not only in single ischemic stroke models but also in recurrent ischemic stroke models in vivo and in vitro. The neuroprotective effects of RSV related by up-regulating SIRTl and AMPK activities thereby reducing energy requirements during ischemia.