Effect of genistein on learning and memory in ovariectomized rats.

Objective:To evaluate the effect of genistein on learning and memory in ovariectomized(OVX) Sprague Dawley(SD) rats and their mechanism of action.Methods:Forty female SD rats were randomized into mimic sham operation group(Sham),ovariectomized group(OVX),OVX + high-dose Genistein group(G-h),OVX + low-dose Genistein group(G-l) and 17β-estradiol group(L).These rats were intragastric administrated(ig) with drugs or distilled water for six weeks respectively.Learning and memory were tested by Morris water maze.The hyperphosphorylation of tau protein was detected by immunohistochemical staining and the results compared.AchE,ChaT,SOD activity and MDA contents were assayed in frontal cortex.The ultrastructural changes of the hippocampus was observed by electron microscope.Results:Six weeks after Ovariectomy(OVX) resulted in the decrease on learning and memory in female rats tested by Morris water maze.The hyperphosphorylate tau protein positive cell in hippocampus saw more expression.The SOD,ChaT activities in frontal cortex were found decrease while the MDA content,AchE activity were found increased.After treatment of low-dose-Genistein and 17β-estradiol,learning and memory was improved markedly.Conclusion:Low dose and 17β-estradiol can ameliorate the reduction of learning and memory in ovariectomized rats,which may correlate with the decrease of the AchE activity,the increase of the ChaT activity,the enhancement of anti-oxidation ability and the inhibition of abnormal phosphorylation of tau in the hippocampus.