Effects of Estradiol on Spontaneous Depressive-like Behaviors and Brain-derived Neurotrophic Expression after Focal Ischemia in Rat

Aim: To determine the effects of estradiol on endogenous depressive-like behaviors and BDNF expression in the penumbra region after focal ischemia in rat.Methods: Focal ischemia was generated by transient occlusion of middle cerebral artery(MCA).Rats were randomly divided into control group,stroke group and estradiol treatment group.Forced swimming test were performed to assess endogenous depression-like behavior after focal ischemia and estradiol treatment.Brain-derived neurotrophic factor(BDNF) expression in the penumbra regions was examined by immunohistochemistry.Results: Ischemic rats were found to develop significantly depressive-like behavioral 3 weeks after MCAO,compared with the sham-operated control rats.Ischemia-induced depressive-like behaviors were significantly improved after estradiol administration for 14 days.A significant regulation of BDNF protein levels in the penumbra regions of striatum were also observed in MCAO animals treated with estradiol,compared with the ischemic rats treated with vehicle.Conclusion: The findings of this study provided the evidence that spontaneous post-stroke depression(PSD) can be found in rat after focal ischemia.Estradiol can improve endogenous depressive-like behaviors in ischemic rats,and these therapeutic effects of estradiol may be related to the increasing expression of BDNF in the penumbra regions after MCAO.