Effect of mild hypothermia at the focal side on expressions of survivin and caspase-3 in rats after focal cerebral ischemia and reperfusion

Objective To explore the therapeutic effect of local mild hypothermia on expressions of survivin and caspase-3,and study the relation of apoptosis inhibiting protein survivin in rats after focal cerebral ischemia and reperfusion injury.Methods The focal cerebral ischemia and reperfusion model of rats was achieved by intraluminal middle cerebral artery occlusion(MCAO).The adult rats were randomly divided into the sham-operation group,the normothermia ischemia and reperfusion group and the hypothermia ischemia and reperfusion group.The ischemic groups maintained ischemia for 2h,3h,6h and 8h,and then all were reperfused for 4h,24h,72h,1w and 2w,n=4 per time point.Brain mild hypothermia was achieved 30min after ischemia and reperfusion for 4h.Expressions of survivin and caspase-3 were determined by immunohistochemistry.Results Compared with the normothermia group,mild focal hypothermia greatly increased expression of survivin and obviously decreased expression of caspase-3 in the penumbra(P0.05,P0.01). Conclusion Focal mild hypothermia performed 30 minutes after ischemia and maintained to the reperfusion period can reduce the infarct area and accelerate recovery of neurological outcomes.The neuroprotection of mild hypothermia may be related to inhibiting activation of Caspase-3 and enhancing expression of survivin in the penumbra.