Extracts of Drynariae Rhizoma Promote Bone Formation in OVX Rats through Modulating the Gut Microbiota

Drynariae Rhizoma (DR) has been commonly used as a preventive and therapeutic agent for bone diseases. However, its pharmacological mechanisms have not been fully elucidated. Here, we aimed to investigate the effects of DR in a bilateral ovariectomized (OVX) rat model and explore the correlation with the gut microbiome. We established an OVX rat model and treated with different doses of DR (DR-L, 0.27 g/kg/day; DR-M, 0.81 g/kg/day; DR-H, 2.43 g/kg/day) through intragastric administration for 12 weeks. Results showed that DR alleviated body weight, moderated bone microstructure, and promoted the expression of bone formation related factors in OVX rats, in which DR-H behaved the most significant effects among the three doses. Furthermore, the effects of DR on promoting bone formation were correlated to the changes in microbial richness and the restorations of several genera, among which Ruminiclostridium and Ruminococcaceae_UCG_007 were positively correlated with the bone formation related factors, and both of them enriched in DR-H group as biomarker. Moreover, CMP-legionaminate biosynthesis I might be a crucial pathway of DR regulates gut microbiota, and the content of serum short-chain fatty acids in OVX rats were regulated by DR. Our results demonstrated that DR promoted bone formation in OVX rats, and it was related to the regulation of the gut microbiota structure.