Musculoskeletal Alterations of Hindlimb During Simulated Microgravity and Reloading in Rats: Compared by Gender

Although several researches have reported potential gender differences in adaptations during microgravity, the musculoskeletal alterations of different genders are still under debate. Besides, there were few researches which involved recovery phase after reloading. In the present study, we investigated the musculoskeletal alterations of rats hindlimb via tail-suspension in both genders, and analyzed the serum sex hormone at the same time. Thirty-two Sprague Dawley rats were equally divided by gender into four groups randomly: control of male (CONM), tail-suspension of male (TSM), control of female (CONF) and tail-suspension of female (TSF). The experiment consisted two phases, which were 21 days of tail suspension phase and 21 days’ reloading phase, and parameters of bone, muscle and serum were tested at the end point of each phase. The results indicated that during tail suspension phase, male rats showed a greater and earlier bone loss and microstructure deterioration compared with females, but they could maintain muscle strength much better. In addition, during reloading phase, male rats showed a slower bone recovery and some parameters could not recover until the end, while loss in muscle mass and strength in both genders could recover to control level.