SYMPATHETIC B ANTAGONIST PREVENTS BONE MINERAL DENSITY DECREASE INDUCED BY LABYRINTHECTOMY
We previously showed that bilateral vestibular lesion in rats induces a bone loss in weight bearing bones [5]. To determine whether this effect is mediated by the sympathetic nervous system (SNS), bone mineral density (BMD) was measured in 4 groups of 10 female Wistar rats: bilateral labyrinthectomy (Bilab), Bilab with propranolol treatment, sham operated with or without propranolol. In untreated rats, 30 days after lesion Bilab animals showed a reduced BMD in distal femoral metaphysis comparatively to intact rats (p < 0.001). In treated rats, there was no difference in BMD 30 days after lesion. This protective effect of propranolol against bone loss suggests that the vestibular system influence on bone remodeling is mediated by SNS. If this hypothesis is correct, this could have important consequences in devising countermeasures to spaceflight induced bone loss.