Impact of 1 alpha, 25-dihydroxy vitamin D_3 on osteoblastic proliferation and differentiation and the expressionof OPG mRNA / RNAKL mRNA.

Objective To research the influence of 1α, 25-(OH)2 D3 on osteoblastic proliferation, differentiation, the expression of Nuclear factor kappa ligand and osteoprotegerin mRNA in vitro cultured osteoblasts of SD rats(OB). Methods The OB were isolated from neonatal SD rat calvaria in 24 h by trypsin and collagenase digestion method. Set up 0 nmol/L, 1 nmol/L, 10 nmol/L, 100 nmol/L, 1α, 25-(OH)2 D3 as blank control, low, middle and high intervention group. Use MTT assay to detect the proliferation rate of OB. PNPP method was used to determine the activity of alkaline phosphatase(ALP). The RT-PCR method was applied to detect the expression of OPG mRNA/RNAKL mRNA after intervening for 24 h, 48 h and 72 h. Results The A value of osteoblasts of the 1 nmol/L group was(0.335±0.080),(0.451±0.086),(0.545±0.085) after the intervention of 24 h, 48 h, 72 h; the ALP activity of osteoblasts of the 100 nmol/L group were increased to(6.274±1.561),(5.021±1.703),(6.854±1.468) respectively; the mRNA expression of osteoblastic proliferation(OPG) were respectively decreased to(0.365 ± 0.068),(0.340 ± 0.046),(0.381 ± 0.051); while the mRNA expression of RANKL were increased to(0.622±0.089),(0.550±0.064),(0.468±0.062); the ratio of RANKL and OPG increased by 138.53%, 153.45%, 157.71% respectively, compared with 0 nmol/L group, the statistical differences were significant(P0.05). Conclusion High concentration of 1α, 25-(OH)2 D3 can inhibit OB proliferation and the OPG mRNA expression, promote the differentiation and mineralization of OB, enhance the gene expression of the ratio of RANKL and OPG-thus promoting osteoclast-mediated bone resorption and enhancing bone update.