| Objective To investigate the effect of ursolic acid (XGS) on bone mass loss in ovariectomized rats and to explore the possible mechanism. Methods The osteoporotic rat model was established by bilateral ovariectomy. Then the rats were randomly divided into sham operation group (n=10), ovariectomized group (OVX), and XGS group (n=10). The rats in XGS group received XGS (100 mg/kg) for 12 weeks. Bone mass, bone mineral density (BMD), bone mineral content (BMC), bone metabolic index, and the expression of BMP-2, Smad4, Wnt-1, and β-catenin were measured. Results After 12 weeks of treatment, the results of micro-CT and dual energy X-ray showed that the trabecular microscopic parameters, BMD, and BMC in XGS group were significantly improved compared to those in OVX group. BMD, BMC, TV/BV, Tb.N, Tb.Th, and Tb.Sp in XGS group were significantly better than those in OVX group. The results of serum test and biomechanical test showed that the maximum load and elastic modulus in XGS group were higher than those in OVX group (P<0.05). The levels of serum ALP, OPD, and OCN in XGS group were significantly lower than those in OVX group. Western blotting detection showed that the expression levels of BMP-2, Smad4, Wnt-1, and β-catenin in XGS group were significantly higher than those in OVX group. Conclusion XGS mediates the protective effect on bone mass loss in ovariectomized rats through BMP-2/Smad4/Wnt/ β-catenin signal pathway. |