| Objective To investigate the mechanism of Zuogui Pill in treating postmenopausal osteoporosis (PMOP). Methods In vitro experiments were conducted by preparing low, medium, and high-dose serum of Zuogui Pill for drug intervention of cultured MC3T3-E1 cells. The cells were divided into the blank control group, osteogenic induction group (OGI group), and OGI + Zuogui Pill low, medium, and high-concentration groups. After transfection with FNDC5, the cells were divided into the control group, OGI+ transfection group, and OGI + transfection + Zuogui Pill low, medium, and high-concentration groups for osteogenic induction. ALP activity and staining were performed on the above cell culture supernatants. In the in vivo experiments, wild-type mice were randomly divided into wild-type control group, wild-type ovariectomy (OVX) group, and wild-type treatment group, and FNDC5 gene knockout (KO) mice were randomly divided into KO control group, KO-OVX group, and KO treatment group. OVX was used to establish the PMOP model, and the treatment group mice were orally administered with Zuogui Pill for 12 weeks. After 12 weeks of gavage, BMD of the femur was measured, H&E staining was performed on femoral sections, ELISA was used to detect serum E2, PINP, and Irisin levels, and real-time fluorescent quantitative PCR was used to detect mRNA expression of FNDC5, Runx2, OPN, OCN, and OSX, and Western Blot was used to detect protein expression of FNDC5, Wnt3a, and β-catenin. Results Serum containing Zuogui Pill could increase ALP expression in MC3T3-E1 cells, and ALP expression decreased after FNDC5 transfection. Zuogui Pill could significantly improve the decrease in BMD and damage to femoral trabeculae caused by OVX in wild-type mice and alleviate the decrease in E2, PINP, and Irisin expression, but showed no significant difference in KO mice. Zuogui Pill could inhibit OPN expression, alleviate the decrease in E2, and increase mRNA expression of osteogenic differentiation-related genes such as Runx2, OSX, and OCN. There was no significant difference in OPN, Runx2, OSX, and OCN expression between the KO-OVX group and the KO treatment group. Zuogui Pill could upregulate the expression of Wnt3a and β-catenin, and this upregulation effect was significantly inhibited when FNDC5 was knocked out. Conclusion Zuogui Pill may treat PMOP through the FNDC5/Wnt3a/β-catenin pathway. |