RESUMO
Objective To investigate the molecular mechanism of the glucocorticoid?induced osteoblasts apoptosis,and to develop the effective intervention measures. Methods The MC3T3?E1 cells were treated with different concentrations of dexamethasone for 24 hours,then the apoptosis rate was detected with TUNEL analysis,the intracellular expression of Bim and Bax were determined by Westen blot. In addition,MC3T3?E1 cells were randomly divided into Bim?siRNA group,negative control siRNA group and control group. Twenty?four hours after transfection,10-4mmol/L dexamethasone was added to each group of cells for another 24 hours administration. The apoptosis rate was analyzed using the TUNEL,the mito?chondrial transmembrane electric potential was detected by flow cytometry after JC?1 staining,the expression of Bax,Bcl?2 in mitochondrial and Cyt?C,AIF in cytosolic were determined by Western blot. Results The rate of osteoblast apoptosis and Bim expression in cells were both significantly in?creased with the dosage of dexamethasone,there was no significant difference between the groups in the expression of Bax;the rate of osteoblast apop?tosis after the expression of silence Bim was significantly lower than the negative control siRNA group and control group,the expression of Bax and Cyt?C,AIF in cytosolic were significantly reduced,and the mitochondrial transmembrane electric potential was increased. Conclusion Bim is the key molecules in hormone?induced apoptosis of osteoblasts ,the expression of silence Bim can inhibit dexamethasone induced osteoblasts apoptosis through the mitochondrial pathway.