The effect of differential concentration of dexamethasone on the expression of osteocalcin mRNA and proliferation of osteoblast

Objective: To study the effect of differential concentration of dexamethasone on the expression of osteocalcin mRNA and the proliferation of osteoblast. Method: The osteoblasts were collected from newborn SD rats' skull and cultured, and then were randomly divided into 4 groups (8 samples for each group): In Group A, the cells were treated with dexamethasone of 1×10-7mol/L, in Group B, the cells were treated with dexamethasone of 5×10-8mol/L, in Group C, the cells were treated with dexamethasone of 1×10-8mol/L ; in Group D, were cultured without medicine. Result: The expression of osteocalcin mRNA in group A,B,C,D was 0.359±0.026, 0.386±0.017, 0.447±0.024, 0.414±0.013. There were significant differences of the expression of osteocalcin mRNA between group A, group B, group C and group D. In group A it was much lower than that of group D(P0.01), Group B was decreased remarkably than that of group D(P0.01), Group C was much higher than that of group D(P0.01). The level of osteocalcin in the culture medium in group A,B,C,D was2.635±0.218, 2.860±0.093, 3.447±0.024, 3.168±0.335 ng/ml. There were significant differences of the level of osteocalcin between group A, group B , group C and group D, Group A was much lower than that of group D(P0.01), Group B was decreased remarkably than that of group D(P0.01), Group C was much higher than that of group D(P0.01). The ratio of osteoblast proliferation in group A,B,C,D was 0.2644±0.0081, 0.2773±0.0114, 0.2961±0.0085, 0.2850±0.0116. There were significant differences of the ratio of osteoblast proliferation between the four group. Conclusion: It demonstrates that dexamethasone of 1×10-8mol/L increases significantly the expression of osteocalcin mRNA and proliferation of osteoblast, dexamethasone of 1×10-7mol/L and 5×10-8mol/L declines significantly the expression of osteocalcin mRNA and the proliferation.