＜シンポジウム（3）―10―1＞宇宙医学と神経内科
筋萎縮
埜中 征哉
国立精神・神経医療研究センター病院〔〒187―8551 小平市小川東町4―1―1〕
Muscle fibers have been classified into two major forms of red (slow twitch) and white (fast twitch) muscles. The red muscle utilizes lipid as energy source through mitochondrial metabolism and function to sustain the position against gravity (sometimes called as antigravity muscle). Under microgravity the red muscle is selectively involved. In our unloading study by hindlimb suspension experiment on rats, the one of the representative red muscle of soleus muscle underwent rapid atrophy; they reduced their weights about 50% after 2 week-unloading. In addition, myofibrils were occasionally markedly disorganized with selective thin filament loss. Mitochondria in the degenerated area were decreased in number. The white muscle fibers in the soleus muscle had mostly transformed to the red ones. It took about 1 month to recover morphologically. The satellite cell playing a major role in muscle regeneration was not activated. There still remained unsolved what are the mechanosensors to keep muscle function under normal gravity. Dr Nikawa's group proposed that one of ubiquitin ligases, Cbl-b is activated under microgravity and induces muscle fiber degeneration. There might be many factors to induce muscle atrophy and degeneration under microgravity. Further study is necessary to explore the pathomechanism of muscle atrophy in disused and under immobility conditions.
Full Text of this Article in Japanese PDF (631K)
(臨床神経, 52：1315−1317, 2012)
key words：微小重力，筋萎縮，赤筋，宇宙医学
（受付日：2012年5月25日）
