Altered Expression of Bax in Hippocampus after Global Ischemia-Reperfusion and Protective Effect of EGb 761

Objective To observe the altered expression of Bax protein and ultrastucture in CA1 region of hippocampus after global ischemia-reperfusion in rats,and to investigate the protective effect of Ginkgo biloba extract(EGb 761).Methods An global cerebral ischemia-reperfusion model of SD rats was established in Pulsinelli way.Healthy SD rats was divided into three groups at random:①Sham operated group(SAM),which is surgically exposed both cervicalarteries only.②Ischemia-reperfusion group(IR):global cerebral ischemia for 20min and reperfusion for 24h,48h and 72h respectively.③EGb 761-treated group(EGb):pretreated (7 days) with oral administration of EGb 761(100mg/kg·d -1 ).Immunohistochemistry staining(SP method) was used to detect Bax protein and TEM to morphologically observe the ultrastructure of injured neurons in CA1 region.Results A significant increase in Bax-positive expression was detected after reperfusion 24h,with much lower value at 72h after ischemia than SAM group.While Bax-positive expression in EGb group was obviously lower than that in IR group.In addition,ultrastructure of injured neurons in EGb group was markedly improved in comparison with IR group.Conclusion Bax protein played a very important role in the delayed neuronal death(DND) after global cerebral ischemia in hippocampus,and EGb 761 has highly protective effects against it, whose protective mechanism might be related to reducing the expression of Bax protein.