| Objective To observe the effect of tocotrienol on bone mass in glucocorticoid-induced osteoporosis (GIOP) rats and to explore the possible mechanisms. Methods Thirty12-week-old male Sprague-Dawley rats were randomly divided into three groups: the control group (n=10), the dexamethasone group (DEX, n=10), and the dexamethasone plus tocotrienol group (DEX+TTS, n=10). DEX and DEX+TTS were administered accordingly. The bilateral femurs were collected after 12 weeks to perform micro-CT and bone biomechanical examinations. Meanwhile, tartrate-resistant acid phosphatase (TRACP), cross-linked carboxy-terminal telopeptide of type I collagen (CTX-I), alkaline phosphatase (ALP), and osteocalcin (OC) were tested. Western blotting (WB) was used to detect the changes of BMP-2, OPG, and RANKL protein expressions in each group. Results Bone mineral density (BMD), bone microstructure, and bone biomechanical indexes in the DEX group were significantly lower than those in the control group (P<0.05). Bone resorption indicators (TRACP and CTX-I) increased and bone formation markers (ALP and OC) decreased. BMD, bone microstructure, and bone biomechanical parameters were significantly improved after TTS treatment. Compared with those in the DEX group, TRACP and CTX-I in the DEX+TTS group were significantly reduced, and ALP and OC were significantly increased. WB results showed that BMP-2 and OPG were significantly decreased, while RANKL levels were significantly increased in the DEX group. BMP-2 and OPG were significantly increased, while RANKL levels were significantly decreased after TTS treatment. Conclusion TTS increases BMD, bone microstructure, and bone strength in GIOP rats by reducing bone resorption and promoting bone formation and activating Wnt/β-catenin signaling. |