The effect of single hind-limb immobilization on the contralateral limb in the rat: a morphometric and biochemical study.

Disuse atrophy has been the subject of research studies that make the use of an animal model in which single-limb immobilization induces atrophic changes in the immobilized limb. The effect upon the nonimmobilized contralateral limb is, however, still unclear, and findings in the literature are inconclusive. We therefore performed a multidisciplinary study to clear this issue. The experimental population was 70 young male Sprague-Dawley rats. In one group of 35 rats, the left hind limb was immobilized for 3 weeks. Another group of 35 rats served as controls. limb and tibial bone weights (both "dry" and "ash") were found to be reduced in both hind limbs. Bone alkaline phosphatase (ALP) activity was likewise reduced in both limbs. We conclude that the contralateral hind limb in the rat is clearly subjected to atrophic changes that are similar in magnitude or severity to those experienced by the immobilized limb. We further discuss these findings in view of previous knowledge regarding the atrophic process.