Abstract: Objective: Through the establishment of abortion model caused by embryo implantation difficulties, exploring the role of Yun Kang oral liquid in protecting embryos.Methods: The pregnant rats were divided into 6 groups:normal control group (NC), model group (MG), dydrogesterone group (DT), and three dose groups of low, medium and high levels of Yun Kang oral liquid (YK-L, YK-M, YK-H), 11 in each group.From the first day of pregnancy, daily intragastric administration, the dose of DT group was 3.02 mg/kg, and the doses of Yun Kang oral liquid were 4, 6, and 9 ml/kg, respectively.The rats in NC and MG were treated with an equal volume of purified water for 10 days.On the third day of pregnancy, except for the NC group, the other groups were injected with mifepristone subcutaneously at the back of the neck at a dose of 5 mg/kg to cause an embryo implantation barrier model.On the 10th day of pregnancy, blood was collected from the abdominal aorta in each group.Serum follicle stimulating hormone (FSH), interferon-γ (IFN-γ) and interleukin (IL-4) were measured by enzyme-linked immunosorbent assay.The number of embryo implantation was observed in the uterus, and the pathological changes of the uterus were observed by HE staining.Results: Compared with the NC group, the number of embryo implantation and the serum levels of FSH and IL-4 in the MG group were decreased significantly (P< 0.05, 0.01), and pathological changes such as uterine glandular epithelial hyperplasia and inflammatory cell infiltration in the glandular cavity were observed.Compared with MG group, the number of embryo implantation and serum FSH and IL-4 levels of rats in YK-M and YK-H groups were increased significantly (P<0.05, 0.01).The pathological changes such as uterine glandular epithelial hyperplasia and inflammatory cell infiltration in the gland were also improved.There was no significant difference in serum IFN-γ levels between the groups.Conclusion: Yun Kang oral liquid may improve the endometrial pathological changes and increase the number of embryo implantation by increasing the levels of serum sex hormone FSH and immune cytokine IL-4 in embryo implantation impediment rats.

Key words: Yun Kang oral liquid, embryo implantation disorder, tocolysis, FSH, IL-4, rats