Bushen Huoxue recipe regulates endometrial epithelial ion channels to promote embryo implantation in controlled ovarian hyperstimulation mice

BACKGROUND: Controlled ovarian hyperstimulation (COH) is commonly used to obtain large numbers of high-quality oocytes. However, elevated estrogen levels due to COH can disrupt uterine fluid metabolism and impair embryonic implantation. We investigated the effects and mechanisms of Bushen Huoxue recipe (BSHX) on COH-induced impairment of endometrial receptivity. METHODS: Female mice were randomly divided into the following five groups: control, model, BSHX-L, BSHX-M, and BSHX-H. In addition to the control group, the COH model was established by injecting mice in the other groups with 0.4 IU/g pregnant mare serum gonadotropin and 1 IU/g human chorionic gonadotropin. After successful mating, mice in the BSHX-L, BSHX-M, and BSHX-H groups were treated with 5.5, 11.0, and 22.0 g/kg, respectively. Mice in the control and model groups were administered distilled water (10 mL/kg) daily via gavage. Embryo numbers were examined on embryo day 10 (D10). Serum estradiol and progesterone levels were measured using an enzyme-linked immunosorbent assay on D4. Endometrial morphology was analyzed using hematoxylin-eosin staining. The protein and gene expression of leukemia inhibitory factor (LIF), cystic fibrosis transmembrane regulator (CFTR), and epithelial sodium channel (ENaC) subunits were assessed using immunohistochemistry, western blotting, and quantitative real-time polymerase chain reaction. RESULTS: BSHX treatment reduced superphysiological serum estradiol and progesterone levels, improved endometrial morphology during the implantation window, upregulated LIF, α-, β-, and γ-ENaC expression, and downregulated CFTR expression, thereby enhancing embryo implantation. CONCLUSION: BSHX may improve assisted reproductive technology pregnancy rates by regulating sex hormones and uterine fluid balance to prevent COH-induced endometrial damage.