Effects of icariin on the expressions of osteoprotegerin and RANKL in rat osteoblasts

Objective To investigate the effects of icariin on the expressions of osteoprotegerin(OPG)and receptor activator of nuclear factor-kB ligand(RANKL)mRNA in rat osteoblasts cultured in vitro.Methods Calvarial osteoblasts were obtained from newborn SD rats aged＜24 h by trypsin-collagenase digestion method. After treatment with different concentrations of icariin(10~(-10)-10~(-4) mol/L)for 48 h,total RNA was isolated from osteoblasts.Expressions of OPG and RANKL mRNA were detected by semiquantitative RT-PCR.Results Icariin remarkably increased OPG mRNA levels and decreased RANKL mRNA levels in calvarial osteoblasts in a dose- dependent fasion with a maximum effect at a concentration of 10~(-7)mol/L(P＜0.05).Osteoblasts pre-treated with icariin prevented the inhibitory effect of dexamethasone on OPG mRNA(0.570±0.093 vs 1.083±0.081)and the stimulative effect on RANKL mRNA(1.079±0.050 vs 0.718±0.082)(both P＜0.05).Conclusion Icariin upregulates OPG expression and downregulates RANKL expression in osteoblasts,which may explain the beneficial role of icariin in preventing and treating osteoporosis.