Department of Internal Medicine, Faculty of Medicine, Universidad de La Frontera, Temuco 4780000, Chile.
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
Nutrients. 2017 Oct 6;9(10):1100. doi: 10.3390/nu9101100.
The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.
在均衡饮食喂养的 Fat-1 转基因和 C57BL/6 野生型小鼠中，研究了两周后肢悬吊（HS）对骨骼肌萎缩的影响。测量了身体成分和比目鱼肌脂肪酸组成。评估了比目鱼肌的骨骼肌力量、横截面积（CSA）以及与蛋白质合成（蛋白激酶 B、Akt；核糖体蛋白 S6、S6、真核翻译起始因子 4E 结合蛋白 1、4EBP1；糖原合酶激酶 3-β、GSK3-β；细胞外信号调节激酶 1/2、ERK 1/2）和蛋白质降解（萎缩基因-1/肌肉萎缩 F 盒，atrogin-1/MAFbx 和肌肉 RING 指蛋白 1、MuRF1）相关的信号通路。HS 降低了比目鱼肌的湿重和干重（分别减少了 43%和 26%）、肌肉等张和强直力量（分别减少了 29%和 18%）、比目鱼肌 CSA（减少了 36%）和比目鱼肌纤维（减少了 45%）。与 C57BL/6 野生型小鼠相比，Fat-1 转基因小鼠的 ω-6/ω-3 多不饱和脂肪酸（PUFAs）比例下降了 56%（0.001）。与 C57BL/6 野生型小鼠相比，HS 后 Fat-1 小鼠的比目鱼肌干重丢失减少了 10%（10%），绝对等张力量保留了 17%（17%），比目鱼肌 CSA 保留了 28%（28%）。HS 后 Fat-1 小鼠比目鱼肌的 p-GSK3B/GSK3B 比值增加了 70%（70%），MuRF-1 含量减少了 50%（50%）。在废用状态下，均衡饮食喂养的 Fat-1 小鼠能够部分保留比目鱼肌的质量、绝对等张力量和 CSA。
