RÉSUMÉ
Objective To study the effect of estrogen on proliferation of astrocytes in hippocampus of mice following middle cerebral artery occlusion(MCAO).Methods One hundred and eight Kunming mice were randomly divided into estrogen group(n=54)and saline group(n=54).The animals in two groups underwent right MCAO with tissue samples taken at 3,6,12,24,48and 72h after MCAO.The ischemic site was detected and the ischemic size was measured with TTC staining,the damage of neurons in hippocampus was assayed with HE staining,the expression of GFAP in hippocampal astrocytes was detected with immunohistochemical staining.Results The cerebral infarction size was significantly smaller in estrogen group than in saline group at different time points after MCAO(P＜0.05,P＜0.01)especially at 12hafter MCAO(31.50％±3.36％vs 54.50％±5.68％,P=0.019).The damage of hippocampal neurons aggregated with the prolonged ischemia time in two groups and was milder in estrogen group than in saline group at the same time points.The expression level of GFAP positive cells in bilateral hippocampal areas was higher when the ischemia time was prolonged and was significantly higher in ischemic hippocampus of estrogen group than in that of control group except at 6hin CA3ischemic area(P＜0.05).Conclusion Estrogen can protect mice against focal cerebral ischemia,stimulate the genesis of astrocyte synapses,alleviate neuronal damage after ischemia,and can thus reduce the size of cerebral infarction.