Preadministration of incadronate disodium can prevent bone loss in rat proximal tibial metaphysis when induced by hindlimb immobilization by bandage

The purpose of this study is to determine whether short-term preadministration of bisphosphonates prevents bone loss in rat proximal tibial metaphysis when induced by hindlimb immobilization by bandage. Six-month-old female Sprague Dawley rats were injected with incadronate disodium (YM-175, 10 μg/kg) or vehicle, three times per week for 2 weeks (YM or V groups). Then, the left hindlimb was fixed to the abdomen with a bandage (V-B, YM-B groups), or only the abdomen was bandaged as control (V-SHM, YM-SHM groups), for 4 weeks. The animals were subsequently killed and left proximal tibiae were processed undecalcified for quantitative histomorphometric evaluation. Immobilization-induced cancellous bone loss resulted not only from increased percent eroded surface area but also from decreased percent labeling surface and bone formation rate in V-B compared with V-SHM animals. In contrast, preadministration of YM-175 decreased percent eroded surface significantly and prevented the loss of cancellous bone mass in YM-B compared with V-B animals. Cancellous bone mass was neither increased nor decreased by preadministration of YM-175 in YM-SHM animals. Our results suggest that preadministration of bisphosphonates is effective in prevention of bone loss at the tibial metaphysis when induced by hindlimb immobilization in rats.