Abstract. The present study investigated the effect of exogenous estrogen on post-stroke depression. Rats were exposed to chronic mild stress following middle cerebral artery occlusion. The occurrence of post-stroke depression was evaluated according to the changes in preference for sucrose and performance in a forced swimming test. Estrogen therapy significantly improved these neurological symptoms, indicating that estrogen is effective in treating post-stroke depression. Increased brain-derived neurotrophic factor (BDNF) expression was reported in the hippocampus of rats that had been treated with estrogen for two weeks, suggesting that BDNF expression may be an important contributor to the improvement of post-stroke depression that is observed following estrogen therapy. IntroductionDepression is a common complication of stroke, occurring in ~33% of patients (1,2); the clinical symptoms of this include feelings of guilt, low self-esteem, reduction in food intake, sleep disorders and fatigue. There are between 1.6-2.0 million new stroke patients in China every year and post-stroke depression (PSD) is closely associated with the increased risk of mortality following a stroke (3). PSD negatively impacts upon subsequent rehabilitation; in a previous study by Sinyor et al, PSD patients demonstrated greater functional impairment than patients without depression, also scoring lower on behavioral action and functional status (4). The severity of depression is closely associated with health-associated quality of life and functional recovery in stroke survivors (5). PSD patients demonstrate a negative mood during rehabilitation and achieve poorer outcomes during functional recovery therapy. These patients also have greater difficulty in restoring social activities (6). Several studies have described a higher mortality rate in stroke patients with depression (7), and certain studies have reported that PSD patients using antidepressant drugs demonstrate improved ability to function than those without antidepressant therapy. The treatment of depression has been demonstrated to aid functional recovery (8), meaning that the early diagnosis and effective treatment of PSD are crucial to recovery from a stroke.Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family, which regulates neurogenesis (9), apoptosis (10), the expression level of monoamine transmitters (11), and the function and plasticity of synapses (12). Neurotrophins may be key in the development of depression (13); BDNF, for instance, can activate intracellular mitogen-activated protein kinase/extracellular signal-regulated kinase cascade signaling pathways (14), affecting synaptic plasticity (12) and alleviating the symptoms of depression (15), and BDNF may thus be important in the maintenance of emotional stability. Deletion of the BDNF receptor induces a reduction in neurogenesis and increases anxious behavior (16). Additionally, BDNF expression is associated with 5-hydroxytryptamine receptor expression in the brain, particularly the hi...

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 E2-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 E2 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.

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