Exploration on Effect of Yinhuotang on Depression-like Behavior in Mice with Bilateral Ovariectomy Induced by Chronic Stress Based on E2/ERβ Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

Objective:To observe the effect of Yinhuotang （YHT） on the depression-like behavior of mice with bilateral ovariectomy （OVX） induced by chronic stress and explore its action mechanism based on estradiol （E₂）-estrogen receptor <italic>β </italic>（ER<italic>β</italic>） pathway. Method:The experiment was divided into two parts. In the first part， mice were randomly divided into the sham operation （Sham） group， model （OVX） group， positive drug （E₂， 0.13 mg·kg^-1） group， and YHT （23.4 g·kg^-1） group. The OVX model was reproduced by OVX combined with chronic unpredictable mild stress （CUMS）. On the 8th day after OVX， the mice in each group were exposed to CUMS and treated with drugs. The changes in immobility time， horizontal movement score， and vertical movement score of mice in each group were observed in forced swimming test （FST）， tail suspension test （TST） and open-field test （OFT）， respectively. Serum and brain E₂ levels were detected by enzyme-linked immunosorbent assay （ELISA）， the aromatizing enzyme （Cyp19） mRNA expression by real-time fluorescence polymerase chain reaction （Real-time PCR）， the expression of ER<italic>α</italic> and ER<italic>β</italic> in dentate gyrus of hippocampus by immunohistochemistry （IHC）， and the total ER<italic>α</italic> and ER<italic>β</italic> levels in the brain by Western blotting. In the second part， the mice were divided into the Sham group， OVX group， YHT group， and blocker （Y+B， 23.4 g·kg^-1+100 μg·kg^-1） group. Mice in the Y+B group were first treated with intragastric administration of YHT and then with intraperitoneal injection of ER<italic>β</italic> blocker （PHTPP） on the next day. The changes in immobility time， horizontal motor score， and vertical motor score were observed in the three behavioral tests. Result:Compared with the Sham group， the OVX group displayed significantly increased immobility time， decreased horizontal and vertical movement scores （<italic>P</italic><0.01）， down-regulated serum and brain E₂levels （<italic>P</italic><0.01） and Cyp19 mRNA expression in the brain （<italic>P</italic><0.01）， and up-regulated total ER<italic>β</italic> in dentate gyrus and brain （<italic>P</italic><0.01）. However， there was no significant change in total ER<italic>α</italic> expression in the dentate gyrus or brain. As revealed by comparison with the OVX group， the immobility time of the E₂ group was decreased significantly， while the horizontal and vertical movement scores were increased significantly （<italic>P</italic><0.01）. The E₂ levels in the serum was significantly elevated （<italic>P</italic><0.01）. The Cyp19 mRNA expression in the brain and the total ER<italic>α</italic> expression in the dentate gyrus and brain were not significantly changed， while the expression levels of total ER<italic>β</italic> in dentate gyrus and brain were significantly increased （<italic>P</italic><0.01）. In the YHT group， the immobility time declined significantly， and the horizontal and vertical movement scores rose significantly （<italic>P</italic><0.01）. The serum E₂ did not increase， whereas the brain E₂ increased significantly （<italic>P</italic><0.01）. The expression of Cyp19 gene in the brain was significantly increased （<italic>P</italic><0.05，<italic>P</italic><0.01）. There was no significant change in the total ER<italic>α</italic> of dentate gyrus and brain， but the expression levels of total ER<italic>β</italic> in dentate gyrus and brain were significantly increased （<italic>P</italic><0.05，<italic>P</italic><0.01）. PHTPP reversed the effects of YHT on OVX mice in FST， TST and OFT. Conclusion:YHT promotes the synthesis and release of endogenous estrogen in brain and improves the depression-like behavior of OVX mice induced by chronic stress， which is possibly related to the activation of E₂/ER<italic>β</italic> pathway.