17 β-estradiol attenuates poststroke depression and increases neurogenesis in female ovariectomized rats

Studies have linked neurogenesis to the beneficial actions of specific antidepressants. However, whether 17β-estradiol (E₂), an antidepressant, can ameliorate poststroke depression (PSD) and whether E ₂-mediated improvement of PSD is associated with neurogenesis are largely unexplored. In the present study, we found that depressive-like behaviors were observed at the first week after focal ischemic stroke in female ovariectomized (OVX) rats, as measured by sucrose preference and open field test, suggesting that focal cerebral ischemia could induce PSD. Three weeks after middle cerebral artery occlusion (MCAO), rats were treated with E ₂ for consecutive 14 days. We found that E₂-treated rats had significantly improving ischemia-induced depression-like behaviors in the forced-swimming test and sucrose preference test, compared to vehicle-treated group. In addition, we also found that BrdU- and doublecortin (DCX)-positive cells in the dentate gyrus of the hippocampus and the subventricular zone (SVZ) were significantly increased in ischemic rats after E₂ treatment, compared to vehicle-treated group. Our data suggest that focal cerebral ischemia can induce PSD, and E₂ can ameliorate PSD. In addition, newborn neurons in the hippocampus may play an important role in E₂-mediated antidepressant like effect after ischemic stroke.