BONE RESPONSE TO EXERCISE DURING RECOVERY BETWEEN UNLOADING BOUTS IN ADULT MALE RATS

摘要

Mechanical unloading has deleterious effects on the musculoskeletal system, and exercise offers a way to reduce or reverse these effects. Studies of crew members from the International Space Station have documented bone losses that do not fully recover even years after returning to Earth [1,2], and this raises concerns with repeated missions. We have used the adult hindlimb unloaded (HU) rat model [3] to simulate repeated exposure to microgravity, and to study densitometric and mechanical properties at multiple bone sites. This study focuses on mixed bone sites including proximal tibia metaphysis (PTM), and femoral neck (FN) region which also has a significant clinical relevance. Surprisingly, losses for the 2nd HU were milder than those for the 1st HU for bone mineral content (BMC) and volumetric bone mineral density (vBMD), suggesting a possible protective effect of the 1st HU [4].