Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Histol Histopathol. 2011 Dec;26(12):1545-53. doi: 10.14670/HH-26.1545.
Fifteen-week-old rats were subjected to unloading induced by hindlimb suspension for 3 weeks. The peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and forkhead box-containing protein O1 (FOXO1) mRNA levels and fiber profiles of the soleus and plantaris muscles in rats subjected to unloading (unloaded group) were determined and compared with those of age-matched control rats (control group). The body weight and both the soleus and plantaris muscle weights were lower in the unloaded group than in the control group. The PGC-1α mRNA was downregulated in the soleus, but not in the plantaris muscle of the unloaded group. The FOXO1 mRNA was upregulated in both the soleus and plantaris muscles of the unloaded group. The oxidative enzyme activity was reduced in the soleus, but not in the plantaris muscle of the unloaded group. The percentage of type I fibers was decreased and the percentages of type IIA and IIC fibers were increased in the soleus muscle of the unloaded group, whereas there was no change in fiber type distribution in the plantaris muscle of the unloaded group. Atrophy of all types of fibers was observed in both the soleus and plantaris muscles of the unloaded group. We conclude that decreased oxidative capacity and fiber atrophy in unloaded skeletal muscles are associated with decreased PGC-1α and increased FOXO1 mRNA levels.
15 周龄大鼠接受 3 周后肢悬吊致去负荷处理。测定去负荷（去负荷组）大鼠比目鱼肌和跖肌中过氧化物酶体增殖物激活受体γ共激活因子 1α（PGC-1α）和叉头框 O1（FOXO1）mRNA 水平和纤维形态，并与同龄对照组大鼠（对照组）进行比较。与对照组相比，去负荷组大鼠体重及比目鱼肌和跖肌重量均降低。PGC-1αmRNA 在比目鱼肌中下调，但在跖肌中未下调。FOXO1mRNA 在比目鱼肌和跖肌中均上调。去负荷组大鼠比目鱼肌氧化酶活性降低，但跖肌中无变化。去负荷组大鼠比目鱼肌Ⅰ型纤维比例降低，ⅡA 型和ⅡC 型纤维比例增加，而跖肌纤维类型分布无变化。去负荷组大鼠比目鱼肌和跖肌的所有类型纤维均发生萎缩。我们的结论是，去负荷骨骼肌的氧化能力降低和纤维萎缩与 PGC-1α 降低和 FOXO1mRNA 水平升高有关。
