Ovariectomy results in bone loss caused by increased bone resorption. RANKL is an essential mediator of bone resorption. The purpose of a recent study [1] was to examine whether the RANKL inhibitor osteoprotegerin (OPG) would preserve bone volume, density, and strength in ovariectomized rats. Rats were ovariectomized or sham-operated at 3 mo of age. Sham controls were treated for 6 wk with vehicle. Ovariectomized rats were treated with vehicle or human OPG-Fc (10 mg/kg, 2/wk). Serum RANKL and TRACP5b, an osteoclast marker, was measured by ELISA. BMD of lumbar vertebrae (L1–L5) and distal femur was measured by DXA. Right distal femurs were processed for bone histomorphometry. Left femurs and the fifth lumbar vertebra (L5) were analyzed by µCT and biomechanical testing, and L6 was analyzed for ash weight.

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