Leĭnsoo T A, Turtikova O V, Shenkman B S
Ross Fiziol Zh Im I M Sechenova. 2010 Mar;96(3):226-36.
Hindlimb unloading produces atrophy and suppresses proliferative processes in postural muscles. Muscle stretch applied simultaneously with hindlimb suspension is known to prevent soleus muscle atrophy. In the rat experiments, we assessed the number of M-cadherin (satellite cell marker molecule)-labeled cells per one myofiber cross-section. After 2-week hindlimb suspension the number of labeled cells decreases by 33% as compared to the control group. The amount of labeled cells was 2.5-fold greater in passive stretch group in comparison with the hindlimb suspended animals and 1.7-fold greater as compared to the control group. We suppose that that proliferation of satellite cells with subsequent incorporation of their nuclei in myofiber is sufficient for increasing the protein synthesis. The insulin-like growth factor (IGF-I) is involved in regulation of protein turnover and exerts potent mitogenic and differentiating effects. We investigated the level of IGF-I expression in soleus muscle tissue after 14 day hindlimb suspension with stretch and observed no changes as compared to the control or 14 day hindlimb suspended group. We conclude that the muscle IGF-I and satellite cells incorporation do not make essential contribution to passive stretch preventive action under the conditions of simulated weightlessness.
后肢卸载会导致姿势肌萎缩并抑制其增殖过程。已知与后肢悬吊同时施加肌肉拉伸可预防比目鱼肌萎缩。在大鼠实验中，我们评估了每个肌纤维横截面中M-钙黏蛋白（卫星细胞标记分子）标记的细胞数量。与对照组相比，后肢悬吊2周后，标记细胞的数量减少了33%。与后肢悬吊动物相比，被动拉伸组的标记细胞数量增加了2.5倍，与对照组相比增加了1.7倍。我们推测卫星细胞增殖并随后将其细胞核纳入肌纤维足以增加蛋白质合成。胰岛素样生长因子（IGF-I）参与蛋白质周转的调节，并发挥强大的促有丝分裂和分化作用。我们研究了后肢悬吊14天并进行拉伸后比目鱼肌组织中IGF-I的表达水平，与对照组或后肢悬吊14天组相比，未观察到变化。我们得出结论，在模拟失重条件下，肌肉IGF-I和卫星细胞的纳入对被动拉伸的预防作用没有重要贡献。
