2007 Fiscal Year Final Research Report Summary
Different response of amino acids on muscle protein synthesis and degradation under nutritional stresses
| Project/Area Number |
18580110
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Food science
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| Research Institution | Iwate University |
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Principal Investigator |
NAGASAWA Takashi Iwate University, Faculty of Agriculture, Professor (80189117)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Yoshiaki Iwate University, Faculty of Agriculture, Associate Professor (50312517)
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| Project Period (FY) |
2006 – 2007
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| Keywords | muscle / amino acids / leucine / protein synthesis / protein degradation |
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| Research Abstract |
1. The function of leucine under low nutritional conditions Skeletal muscle weight decreased in feeding of one week protein free diet, however the weight loss was suppressed in 1.5% leucine supplementation. Muscle protein degradation evaluated by A-V difference of 3-methylhistidine concentration was also suppressed by leucine supplemented diet. The rate of muscle protein synthesis was not changed. Although ubiquitin-proteasome expression and calpain activity were not reduced in feeding of leucine supplemented diet, LC-3II expression was decreased. These results suggested that leucine enhances muscle protein degradation rather synthesis and the degradation might be regulated by autophagy in low nutritional conditions.
2. Effects of repeated leucine consumption on muscle protein synthesis and degrdation Six hours interval leucine administration to rats decreased myofibrillar protein degradation evaluated by 3-methylhistidine release from the isolated muscle. However, synthesis evaluated by phosphrylation of S6K1 did not, suggesting that repeated leucine supplementation is beneficial for muscle atrophy.
3. Effects of leucine on muscle atrophy in disuse model Immobilization of hind limb increased muscle protein degradation and then resulted muscle atrophy. In this model, leucine supplemented diet attenuated muscle atrophy due to muscle protein degradation especially ubiquitin-proteasome.
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