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Leucine contents of isonitrogenous protein sources predict post prandial skeletal muscle protein synthesis in rats fed a complete meal
Author(s) -
Norton Layne Eiseman,
Wilson Gabriel J,
Rupassara Indu,
Garlick Peter J,
Layman Donald K
Publication year - 2009
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.23.1_supplement.227.4
Subject(s) - leucine , meal , medicine , amino acid , phosphorylation , lysine , food science , p70 s6 kinase 1 , insulin , soy protein , methionine , endocrinology , biology , chemistry , biochemistry , protein kinase b
Leucine (leu) is recognized as a nutrient signal for regulation of muscle protein synthesis (MPS), however previous research has been limited primarily to acute studies with free amino acids (J. Nutr. 133:1553S‐6S, 2005). It is unclear if isonitrogenous protein sources containing different levels of leu will produce differential MPS responses in animals adapted to meal feeding. This study examined 4 different protein sources: wheat (supplemented with lysine), soy, egg, and whey, (containing 6.8, 8.0, 8.8, and 10.9% leu respectively) on the potential to activate initiation factors and MPS. Male rats (250g) were trained for 14d to eat 3 meals/d consisting of 16/54/30% of energy from protein, carbohydrates and fats. Rats were sacrificed after 13hr fast or 90min after consuming their normal breakfast. Measurements included plasma insulin, glucose and amino acids, MPS via D5‐Phe incorporation, and phosphorylation of initiation factors 4E‐BP1 and S6K. Wheat and soy did not stimulate MPS above fasted levels whereas egg and whey significantly increased MPS with whey greater than egg. MPS responses were closely related with changes in plasma leu and phosphorylation of 4E‐BP1 and S6K. These findings suggest that leu content of protein sources is a critical factor in determining protein quality as it relates to changes in post prandial MPS responses. Supported by National Dairy Council, Egg Nutrition Center, Illinois CFAR. Grant Funding Source Egg Nutrition Center and National Dairy Council