Limb ischemic preconditioning induces HSP70 expression in the hippocampus CA1 after cerebral ischemia/reperfusion in rats

Objective To determine the effect of limb ischemic preconditioning(LIP) on HSP70 expression in the hippocampus after cerebral ischemia-reperfusion.Methods Sixty-six Wistar rats with vertebral arteries permanently occluded were divided into sham operation group,cerebral ischemic group and LIP+cerebral ischemic group.The two latter groups were further divided into 1,6,24,72 and 120 h groups according to the time of reperfusion after cerebral ischemia respectively.Changes in the expression of HSP70 in the hippocampus were observed using immunohistochemistry method.Results It was found that there was no obvious HSP 70 positive expression in every subfield of hippocampus in sham operation group.In cerebral ischemic group,HSP70 expression was found in the CA3 subfield and dentate gyrus but not in the CA1 subfield.In LIP+cerebral ischemic group,no HSP70 expression was found in the hippocampus CA1 1 h after cerebral ischemia.but the HSP70 expression was increased at 6 h,and obviously enhanced 24 h after cerebral ischemia,in which the number of positive cells was significantly higher than that in sham operation group and cerebral ischemia 24 h group(P0.01).The expression became very weak 120 h after cerebral ischemia.Conclusion LIP could induce the increase in HSP70 expression in the hippocampus CA1,suggesting that HSP70 might play a role in the induction of brain ischemic tolerance induced by LIP.