Effects of estrogen on congnitive function and the expression of insulin like growth factor-1,choline acetyltransferase in hippocampus CA1 region in rats with vascular dementia

Objective To explore the effects of estrogen on cognitive function and the expression of insulin like growth factor-1(IGF-1),choline acetyltransferase(ChAT) in hippocampus CA1 region in rats with vascular dementia(VD).Methods Thirty male SD rats were randomly divided into sham-operated group,VD group and estrogen group,10 rats in each group.VD models were made with permanent bilateral common carotid arteries occlusion(2VO).The 17-β estradiol(1 mg/kg,dissolution in peanut oil) was injected in intraperitoneal in estrogen group;while,same-dose peanut oil was injected in intraperitoneal in the sham-operated group and VD group.The injection in the 3 groups was once every other day,total 30 times.After 60 d,the escape latency and number of crossing original platform were examined by Morris water maze test.Neurons morphologic change in hippocampus CA1 region was observed by HE stain;the quantity of IGF-1 and ChAT positive cells were detected by immunohistochemistry.Results In hippocampus CA1 region,no pathologic change was found out in sham-operated group;the quantity and layer of neurons were significantly decreased in VD group;the small local malacosis could be found in estrogen group,but the quantity and form of neurocyte were like as sham-operated group.Compared to sham-operated group,in VD group and estrogen group,the escape latencies were significantly delay,the number of crossing original platform were significantly decreased;the expression of IGF-1 were increased and ChAT was decreased in hippocampus CA1 region(all P0.05).Compared with VD group,the escape latency was significantly shorter,the number of crossing original platform was significantly increased;the expression of IGF-1 and ChAT in hippocampus CA1 region were significantly increased obviously in estrogen group(all P0.05).Conclusion By up regular the expression of endogenous IGF-1,estrogen can reduce the damage of hippocampal neurons,and increase the expression of ChAT,and improver cognitive function in VD rats.