Anti-osteoporotic effect of raloxifene on mice with osteoprotegerin gene deficiency / 中华内分泌代谢杂志

ABSTRACT

Objective To observe the effect of raloxifene, a selective estrogen receptor modulator, on osteoporosis in the osteoprotegerin (OPG) gene knock-out female and male mice. Methods Two groups of OPG gene deficient (OPG-/-) female and male mice, 20 mice in each group, were assigned to raloxifene-treated (3 mg The effect of raloxifene was evaluated by comparing the values of bone mineral density (BMD) , bone strength,histomorphometric measurement and osteoclast number between the raloxifene treated group and placebo group.Results As compared with placebo group osteoporotic manifestations were improved in OPG-/- female mice treated with raloxifene orally. BMD was increased both in lumbar vertebrae (P<0.05) and femurs (P<0.01).Bone strength was measured in femurs by three-point bending test and vertebrae by stress test. Results showed that ultimate load, ultimate stress and Young's modulus were increased both at lumbar and femur bone, suggesting decreased risk of fracture. Tartrate-resistant acid phosphatase, a marker enzyme of osteoclasts, was detected, and the number of osteoclasts declined significantly after the treatment of raloxifene. At the same time, results of histomorphometric measurements indicated that bone trabecular volume was increased and bone formation rate decreased from(8.05±4.02)mm3·mm-2·year-1 to (5.48±1.89)mm3·mm-2· year-1(P＜0.05).These findings were found in the group of OPG-/- female mice treated with reloxifene but not in male mice. Conclusions Raloxifene is effective in treating osteoporosis in female OPG-/- mice, indicating that its action is at least in part independent of OPG gene. But it is ineffective in male OPG-/- mice.