Simvastatin Partially Prevents Bone Loss in Tail-suspended Rat:Bone Mineral Density and Histomorphometry Analysis

Background: Skeletal unloading induces osteopenia in the loaded bones. Simvastatin, as one of the HMG-CoA reductase inhibitors for lowering lipids, has been demonstrated its potential benefit in bone formation, while no study reported whether simvastatin could prevent the bone loss in unloaded bone. Objective: We performed this study to assess the effect of simvastatin on bone mass and bone formation in tail-suspension rat. Methods: Tail- suspension rats were treated with or without simvastatin for 3 weeks, The right femurs were removed for the measurement of bone histomorphometry after bone mineral density(BMD) assessment by dual-energy X-ray absorptiometry. Results: The total bone mineral density(tBMD) and distal bone mineral density(dBMD) of tail- suspended rats were significantly lower than that of normal rat, while proximal bone mineral density(pBMD) of normal rats was significantly higher than tail-suspended rat, but no statistical difference was observed between normal and simvastatin-treatment rats. Similar to the BMD results, histomorphometric assessment for the trabeculae bone of distal femurs showed markedly higher BV/TV and lower trabecular Tb. Sp in normal rats compared to those of tail- suspended rats, while both the bone formation and bone resorption parameters were markedly increased in tail-suspended rats with or without simvastatin treatment, simvastatin showed stimulation on osteoid formation comparing to normal and tail-suspended rats. Conclusion: simvastatin treatment could partially prevent tail- suspention-induced osteoporosis in unloaded limb. Index Terms - Tail-suspension, Simvastatin, Bone histomorphometry, Bone mineral density, Bone formation