ABSTRACT
BACKGROUND: Bisphosphonates are a novel inhibitor of bone resorption that can inhibit the activity and function of osteoclasts. OBJECTIVE: To observe the effects of sodium ibandronate on the expression of dentin matrix protein 1, Caspace3, Bcl-2 and Bax in condylar cartilage in osteoporosis rats. METHODS: Thirty-six female rats were randomly divided into sham group, osteoporosis group and sodium ibandronate group, twelve in each group. The sham group did not excise ovaries during surgery. Bilateral ovaries of rats were removed in the osteoporosis and sodium ibandronate groups. On the 7th day after operation, rats in the sodium ibandronate group were intraperitoneally given sodium ibandronate 10 µg/kg, once every 7 days. After 90 days, the rat ovaries were taken. Bone mineral density was measured in each group. The changes of condylar cartilage were observed by toluidine blue staining and TUNEL staining. The expression of dentin matrix protein 1 protein was detected by immunohistochemistry. The levels of Caspase3, Bcl-2 and Bax were detected by western blot assay. The study protocol was approved by the Animal Ethics Committee of Nanhua Hospital in China with the approval No. SLXD_201804010. RESULTS AND CONCLUSION: Compared with the sham group or sodium ibandronate group, the bone mineral density in the osteoporosis group was significantly decreased (P < 0.05). The results of toluidine blue staining showed that the hypertrophic layer of condylar cartilage in the sodium ibandronate group was significantly thicker than that in the osteoporosis group. Compared with the sham group or sodium ibandronate group, the number of apoptotic cells in condylar cartilage and subchondral bone increased significantly in the osteoporosis group (P < 0.05). The expression of dentin matrix protein 1 protein was significantly lower in the osteoporosis group than the sham group, but it increased after treatment with sodium ibandronate (P < 0.05). Compared with the sham group, the expression of Caspase 3 and Bax in the osteoporosis group increased significantly, and the expression of Bcl-2 decreased. However, treatment with sodium ibandronate decreased the expression of Caspase 3 and Bax and increased the expression of Bcl-2 significantly. Overall, our findings reveal that sodium ibandronate can inhibit the apoptosis of condylar chondrocytes and the number of osteoclasts in osteoporotic state, which may be related to the regulation of Caspase 3, Bcl-2, Bax and dentin matrix protein 1 expression.