Document Detail

Leucine supplementation of a low-protein meal increases skeletal muscle and visceral tissue protein synthesis in neonatal pigs by stimulating mTOR-dependent translation initiation.
MedLine Citation:
PMID:  20962152     Owner:  NLM     Status:  MEDLINE    
Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with amino acids. Leucine appears to be the most effective single amino acid to trigger these effects. To examine the response to enteral leucine supplementation, overnight food-deprived 5-d-old pigs were gavage fed at 0 and 60 min a: 1) low-protein diet (LP); 2) LP supplemented with leucine (LP+L) to equal leucine in the high-protein diet (HP); or 3) HP diet. Diets were isocaloric and equal in lactose. Fractional protein synthesis rates and translation initiation control mechanisms were examined in skeletal muscles and visceral tissues 90 min after feeding. Protein synthesis rates in longissimus dorsi, gastrocnemius, and masseter muscles, heart, jejunum, kidney, and pancreas, but not liver, were greater in the LP+L group compared with the LP group and did not differ from the HP group. Feeding LP+L and HP diets compared with the LP diet increased phosphorylation of mammalian target of rapamycin (mTOR), 4E-binding protein 1, ribosomal protein S6 kinase-1, and eIF4G and formation of the active eIF4E·eIF4G complex in longissimus dorsi muscle. In all tissues except liver, activation of mTOR effectors increased in pigs fed LP+L and HP vs. LP diets. Our results suggest that leucine supplementation of a low-protein meal stimulates protein synthesis in muscle and most visceral tissues to a rate similar to that achieved by feeding a high-protein meal and this stimulation involves activation of mTOR downstream effectors.
Roberto Murgas Torrazza; Agus Suryawan; Maria C Gazzaneo; Renán A Orellana; Jason W Frank; Hanh V Nguyen; Marta L Fiorotto; Samer El-Kadi; Teresa A Davis
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-10-20
Journal Detail:
Title:  The Journal of nutrition     Volume:  140     ISSN:  1541-6100     ISO Abbreviation:  J. Nutr.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-24     Completed Date:  2010-12-30     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2145-52     Citation Subset:  IM    
USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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MeSH Terms
Amino Acids / blood
Animals, Newborn
Blood Glucose / analysis
Blotting, Western
Dietary Proteins / administration & dosage*
Electrophoresis, Polyacrylamide Gel
Insulin / blood
Leucine / administration & dosage*
Muscle Proteins / biosynthesis*
Muscle, Skeletal / metabolism*
Protein Biosynthesis / physiology*
TOR Serine-Threonine Kinases / physiology*
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Blood Glucose; 0/Dietary Proteins; 0/Insulin; 0/Muscle Proteins; 61-90-5/Leucine; EC Serine-Threonine Kinases

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