Effect of Ischemic Pre-Postconditioning on the Expression of Heat Shock Protein 70 and the Injury of Global Cerebral Ischemia-Reperfusion in Rats

Objective: To observe the effect of postconditioning,preconditioning and pre-and post-conditioning on the expression of heat shock protein 70(HSP70) and ultrastructure of brain and injury of global cerebral ischemia reperfusion in rats,and to explore the mechanisms.Methods: The SD rats were randomly divided into five groups: group A(sham operation group),group B(global cerebral ischemia reperfusion group),group C(preconditioning group),group D(postconditioning group),and group E(pre-and post-conditioning group).The model of global ischemia and reperfusion was established in group B,C,D,and E by improved Pulsinelli's method.The rats were sacrificed at 6,8,or 24 hours after ischemia-reperfusion.The expression of HSP70 in brain tissue was examined by immunohistochemistry,and the ultrastructure of cortex was observed by electron microscope.Results: The expression of HSP70 in brain tissue of rats after cerebral ischemia-reperfusion injury increased reactively at the 6th hour,reached the peak at the 8th hour,and decreased at the 24th hour in group E,which was significant different from that in group B,C,and D,respectively.In group B,the ultrastructure image presented fragmental destruction of neuronal membrane,swelling mitochondria,aggregation of chromatin,or neuron apoptosis,while in other groups,especially in group E,the above ultrastructural damages were ameliorated markedly.Conclusion: The expression of HSP70 is induced in the brain of rats after cerebral ischemia-reperfusion,and through which,pre-and post-conditioning contributes to the protection of brain neurotrophic cells after ischemia-reperfusion.