Bushen Zhuyun Decoction Enhances Endometrial Receptivity via the IL-6/STAT3 Signaling Pathway in Rats

Background: Reproductive endocrine disorder can impair endometrial receptivity, preventing embryo implantation and increasing miscarriage risk. Impaired endometrial receptivity contributes significantly to female infertility. Inflammatory signaling pathways including the IL-6/STAT3 pathway help embryos implant. Therefore, it is crucial to explore the relationship between the IL-6/STAT3 signaling pathway and endometrial receptivity. Objective: To investigate the mechanism by which Bushen Zhuyun decoction (BSZY) enhances endometrial receptivity in rats through the IL-6/STAT3 signaling pathway. Methods: Mifepristone-induced poor endometrial receptivity models of female SD rats were established, followed by histopathological observation. ELISA was used to measure serum sex hormones and VEGF. Western blotting or IHC was used to measure steroid receptors, IGFBP1, and IL-6/STAT3 pathway activation in the uterus during each estrus cycle and early gestation of normal rats. The Treg/Th17 balance was assessed using flow cytometry. Results: Significant differences were found in the protein expressions of steroid receptors, IL6, STAT3, and p-STAT3 during each estrus cycle and early gestation of normal rats. The protein expressions of STAT3 and PR were strongly correlated with each other. BSZY notably improved uterine morphology increased the expression of implantation markers and raised the serum concentrations of sex hormones and VEGF. BSZY enhanced the expressions of IL-6 and its receptors and restored the expressions of STAT3 and p-STAT3 in the uterus of pregnant rats. In addition, BSZY effectively restored the Treg/Th17 balance in the peripheral blood of pregnant rats. Conclusion: BSZY enhances endometrial receptivity and promotes decidualization in SD rats via the IL-6/STAT3 signaling pathway.