Osteoking downregulates Mgp in an osteoporotic fracture rat model

OBJECTIVE: To investigate the effectiveness of osteoking, a Traditional Chinese Medicine originating from Yi nationality, against osteoporosis(OP) and osteoporotic fracture(OPF), and to elucidate its mechanism of action.METHODS: An osteoporotic fracture rat model was established; animals were divided into three treatment groups: parathyroid hormone, osteoking and0.9%NaCl. After 4, 8 and 12 weeks of treatment, serum and bone tissues were collected. Enzyme-linked immuno sorbent assay, x-ray, histopathological evaluation and proteomics were used.Proteomics and GO annotation were performed based on identified peptides. The relative network was obtained from the STRING database and verified by polymerase chain reaction and Western blotting.RESULTS: After osteoking treatment, the bone mineral density(BMD) increased with time in the osteoking group. At week 12, the BMD and bone mineral salt content of the osteoking group were 4.5%and 20.6% higher than those of the negative control group, respectively. Furthermore, the body weight followed the order of positive control group > osteoking group > negative control group,with significant differences among the groups(P <0.05). Micro-CT analysis of femur sections revealed that the bone surface/volume ratio was significantly higher in the osteoking group than that in the negative control group. X-ray images demonstrated that the osteoking group showed clear callus.Moreover, high-voltage micro-CT demonstrated a massive cortical bone accumulation in the osteoking group. The gray values of callus in the osteoking group were higher than those in the negative group. From week 4 to 12, the serum bone alkaline phosphatase level increased by 49.6% in the osteoking group and the serum propeptide of type procollagen level decreased by 80.6%. Alizarin reⅠd staining demonstrated that the calcium deposition in the osteoking group was higher than that in the negative control group. Notably, the expression of Mgp, a key osteogenesis inhibitor, was lower in the osteoking group compared with the negative control group. Moreover, Sparc, bone morphogenetic protein-2 and Bglap expression was higher in the osteoking group through activation of the transforming growth factor-receptor activator of nuclear factor κB Ligand pathway.CONCLUSION: Osteoking treatment increased bone quality and promoted calcium deposition.The results suggest that osteoking inhibits Mgp through the TGF-β/RANKL pathway to improve OP/OPF.