Making rats rise to erect bipedal stance for feeding partially prevented orchidectomy-induced bone loss and added bone to intact rats

The objectives of this study were to investigate the different effects on m uscle mass and cancellous (proximal tibial metaphysis [PTM]) and cortical ( tibial shaft [TX]) bone mass of sham-operated and orchidectomized (ORX) mal e rats by making rats rise to erect bipedal stance for feeding. Specially d esigned raised cages (RC) were used so that the rats had to rise to erect b ipedal stance to eat and drink for 12 weeks, Dual-energy X-ray absorptiomet ry (DEXA) and peripheral quantitative computerized tomography (pQCT) were u sed to estimate the lean leg mass and bone mineral. Static and dynamic hist omorphometry were performed on the triple-labeled undecalcified sections. W e found that making the intact rats rise to erect bipedal stance for feedin g increased muscle mass, cortical bone volume, and periosteal bone formatio n, Orchidectomy increased net losses of bone next to the marrow by increasi ng bone turnover. Making the ORX rats rise to erect bipedal stance increase d muscle mass, partially prevented cancellous bone loss in the PTM, and pre vented net cortical bone loss in TX induced by OILY by depressing cancellou s and endocortical high bone turnover and stimulating periosteal bone forma tion. The bone-anabolic effects were achieved mainly in the first 4 weeks i n the PTM and by 8 weeks in the TX. These findings suggested that making th e rats rise to erect bipedal stance for feeding helped to increase muscle m ass and cortical bone mass in the tibias of intact rats, increase muscle ma ss, and partially prevented cancellous and net cortical bone loss in ORX ra ts.