Supplementation with dietary leucine to a protein-deficient diet suppresses myofibrillar protein degradation in rats
Supplementation with dietary leucine to a protein-deficient diet suppresses myofibrillar protein degradation in rats
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DOI：
10.3177/jnsv.53.552
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发表时间：
2007-12-01
影响因子：
1.6
通讯作者：
Nagasawa, Takashi
中科院分区：
文献类型：
--
作者：
Sugawara, Takayuki;Ito, Yoshiaki;Nagasawa, Takashi
肌肉质量由肌肉蛋白质的合成和降解调节，而肌肉蛋白质的合成和降解又受到衰老、几种分解代谢疾病和营养不良的影响。个氨基酸特别是亮氨酸，已知刺激肌肉蛋白质合成并抑制肌肉蛋白质降解，尽管它们的长期作用尚不清楚。我们的研究目的是阐明是否长期喂食无蛋白或低蛋白饮食补充亮氨酸抑制肌原纤维蛋白降解。肌原纤维蛋白降解速率通过从离体趾长伸肌（EDL）释放3-甲基组氨酸（MeHis）的速率来测量。腓肠肌的重量下降，在大鼠喂食无蛋白质饮食7天，然而，亮氨酸补充（1.5%）的饮食往往会抑制这种下降。从EDL肌肉的释放MeHis增加的无蛋白质饮食和减少喂养的饮食补充亮氨酸的水平的2无酪蛋白饮食。当大鼠喂食5%酪蛋白饮食时，腓肠肌重量降低，并且与喂食20%酪蛋白饮食的大鼠相比，从EDL肌肉释放的MeHis增加。然而.饲喂补充有亮氨酸（1.15%）的5%酪蛋白饮食减少了肌肉重量损失和MeHis释放。这些结果表明，长期喂食亮氨酸抑制了蛋白质缺乏饮食的大鼠的肌原纤维蛋白降解和肌肉重量减轻的速率。
Muscle mass is regulated by the synthesis and degradation of muscle protein, which in turn are affected by aging, several catabolic diseases, and malnutrition. Amino acids. particularly leucine, are known to stimulate muscle protein synthesis and suppress muscle protein degradation, although their long-term effects are unclear. The objective of our research was to elucidate whether long-term feeding of a protein-free or low-protein diet supplemented with leucine suppresses myofibrillar protein degradation. The rate of myofibrillar protein degradation was measured by the rate of release of 3-methylhistidine (MeHis) from isolated extensor digitorum longus (EDL) muscle. The weight of gastrocnemius muscle decreased in rats fed a protein-free diet for 7 d; however, a leucine-supplemented (1.5%) diet tended to suppress this decrease. The release of MeHis from EDL muscle was increased by the protein-free diet and decreased by the feeding of a diet supplemented with leucine to the level of a 2 No casein diet. When rats were fed a 5% casein diet, the gastrocnemius muscle weight decreased and MeHis release from EDL muscle increased compared to those fed a 20% casein diet. However. feeding of a 5% casein diet supplemented with leucine (1.15%) reduced muscle weight loss and MeHis release. These results suggest that long-term feeding of leucine suppresses the rate of myofibrillar protein degradation and muscle weight loss in rats fed a protein-deficient diet.