Effects of osthole on expressions of OPG and RANKL in rat osteoblasts

Objective To study the effects of osthole(OST) on expression of OPG and RANKL mRNA in rat osteoblasts. Methods Calvariae were obtained from Sprague-Dawley rats(24h after birth), bones samples were processed by collagenase/trypsin digestion, and the osteoblasts were cultured in vitro. 48h and 7 days after addition of osthole (0, 10-7,10-6,10-5 mol·L-1) to the culture medium of osteoblasts, total mRNA was prepared from osteoblasts, and mRNA expression of OPG and RANKL were deleted by RT-PCR. Results 48h after treatment with OST, the genes of OPG and RANKL were both expressed. Compared with the controls, OST increased the expression of OPG mRNA but had no effect on the expression of RANKL mRNA, the OPG/RANKL ratio being increased markedly in the treatment group. The mRNA expressions of OPG and RANKL were both increased 7 days after treatment with OST. OST at 10-5 mol·L-1 increased the expression of OPG mRNA, but deceased the expression of RANKL, the OPG/RANKL ratio in the treatment group was also increased, compared with the control. Conclusions Osthol stimulates the OPG mRNA expression of osteoblasts and decreases RANKL mRNA level. And osthol has no effect on the expresion of RANKL mRNA at the early stage of the experiment.