Baicalein Ameliorates Chronic Stress-Mediated Ovarian Dysfunction by Upregulating the Expression of Gamma-Aminobutyric Acid B2 Receptor

Background:The aim of this study is to assess the effect of baicalein on chronic stress-mediated ovarian dysfunction in a mouse model.Methods:Forty female C57BL/6 mice were randomly divided into four groups as follows:the normal saline group(control,n=10),the daily stress group(daily stress,n=10),the baicalein group(baicalein,n=10),and the daily stress+baicalein group(daily stress+baicalein,n=10).For the daily stress model,we used a restricted stress model.Baicalein(10 mg/kg)was administered by gavage every day,and control mice received normal saline equivalently.Biopsy specimens were harvested after 4 weeks.Measurement of norepinephrine(NE)in serum was performed to assess the psychological stress level of the mice.In addition,histological changes of the uterus and ovaries and the levels of anti-Müllerian hormone(AMH)in serum were assessed to evaluate changes in ovarian function.To detect the underlying mechanisms of the amelioration of baicalein in chronic stress-mediated ovarian dysfunction,immunohistochemical methods,and quantitative real-time polymerase chain reaction were applied to determine the expression of gamma-aminobutyric acid(GABA)receptors.Results:Compared with values in the control group,serum NE concentrations were significantly increased(P<0.001),AMH concentrations were markedly decreased(P<0.01),the thickness of the endometrium was clearly reduced,and the percentage of atretic follicles was significantly increased in the daily stress group(P<0.001),indicating that the chronic stress model was successfully established.In contrast,compared with values in the daily stress group,serum NE concentrations were significantly reduced(P<0.001),AMH concentrations were significantly enhanced(P<0.05),the thickness of the endometrium was clearly increased,and the percentage of atretic follicles was significantly reduced(P<0.001)in the daily stress+baicalein group,indicating that baicalein clearly attenuated the ovarian dysfunction mediated by chronic stress.Moreover,the expression of the GABAB2 receptor in the daily stress group was significantly reduced(P<0.01).In contrast,treatment with baicalein resulted in increased expression of the GABAB2 receptor(P<0.01).Conclusions:Treatment with baicalein ameliorates the enhancing effect of chronic stress on ovarian dysfunction,and the mechanism can be attributed,in part,to the increased expression of the GABAB2 receptor.