Effect of 1,25(OH)2D3 on the expression of RANKL and osteoprotegerin mRNA in primary rat osteoblasts

Objective To observe the effect of 1,25(OH)2D3on the expression of RANKL and osteoprotegerin(OPG) mRNA in primary rat osteoblasts.Methods Primary osteoblastic cells were obtained from the calvaria of newborn SD rats by digestion with 0.1% collagenase and cultured in PRMI 1640 medium supplemented with 15% fetal bovine serum.Cells were treated with 1,25(OH)2D3 according to the experimental design.Total cellular RNA was isolated with Trizol.Semiquantitative reverse transcription RCR method was used to screen the level of RANKL and OPG mRNA.Results RANKL mRNA expression in the calvarial osteoblasts was elevated dose-dependently following 1,25(OH)2D3 treatment and reached its peak level at a concentration of 10-8mol·L-1(P0.01).1,25(OH)2D3 inhibited OPG mRNA levels by 60% at a concentration 10-7mol·L-1 after 48h(P0.01).1,25(OH)2D3(10-7mol·L-1)time-dependently resulted in a upregulation of RANKL mRNA levels and a downregulation of OPG mRNA peaking both at 48h(P0.01).Conclusions 1,25(OH)2D3enhanced RANKL and inhibited OPG mRNA expression of primary rat osteoblasts in a time-and dose-dependent fashion.By altering the relative expression of OPG and RANKL mRNA,1,25(OH)2D3 might stimulate the osteoclastic bone resorption.