The effect of dioscin increasing the OPG/ RANKL mRNA ratio was dependent on Lrp5. (A) Reduced Lrp5 expression by RNA interference against Lrp5. MC3T3-E1 cells grown in regular medium were transfected with Lrp5-siRNA construct and control vector. Total RNA was extracted and analyzed by RT-PCR. (B) The effect of dioscin-increased Lrp5 expression level in MC3T3-E1 cells which were transfected with Lrp5-siRNA was abolished. (C, D, E) Dioscin increased OPG/RANKL ratio was dependent on Lrp5 pathway. Cells were treated with vehicle and dioscin (1.0 μg/ml) for 72 h, and then the expression of Lrp5, OPG and RANKL mRNA were examined by RT-PCR. Results were obtained from three independent experiments and were expressed as mean ± SD. **P < 0.01 vs Control; ##P < 0.01 vs Dio group.