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Leucine contents of isonitrogenous protein sources predict changes in body composition and muscle mass in rats
Author(s) -
Norton Layne Eiseman,
Layman Donald K,
Wilson Gabriel J,
Moulton Chris,
Rupassara S. Indu,
Garlick Peter J
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.97.5
Subject(s) - leucine , composition (language) , skeletal muscle , phosphorylation , p70 s6 kinase 1 , food science , chemistry , meal , medicine , intracellular , endocrinology , biochemistry , biology , amino acid , protein kinase b , philosophy , linguistics
Increases in intracellular leucine (leu) concentrations stimulate mTOR phosphorylation regulation of skeletal muscle protein synthesis (MPS) and leu content of isonitrogenous complete meals predict MPS potential of individual proteins (J Nutr 139:1103–9, 2009). While the molecular mechanism is established, direct effect of leu on long‐term changes in muscle weight or body composition are unknown. This study evaluated 4 isonitrogenous, isoenergtic diets containing wheat (supplemented with lys), soy, egg, or whey with 6.8, 8.0, 8.8, and 10.9% leu respectively, to determine meal effects of leu on signaling and MPS and long‐term impact on body composition. Male rats (275g) were fed 3 meals/d for 76d consisting of 16/54/30% of energy from protein, carbohydrates and fats. Blood and tissue were taken before or 90min after the breakfast meal at wk 2 and 11. Measurements included muscle weights, body composition by DXA, MPS by D5‐Phe incorporation, and phosphorylation of initiation factors 4E‐BP1 and S6K. Leu content of the meals increased muscle weights and was inversely correlated with bodyfat and these outcomes were associated with greater phosphorylation of 4E‐BP1 and S6K and MPS in animals fed egg and whey. These findings establish that leu content is a crucial factor defining the quality of proteins influencing muscle mass and body composition in adults. Supported by National Dairy Council and Egg Nutrition Center. Grant Funding Source : National Dairy and Egg Nutrition Center