title: An amino acid mixture improves glucose tolerance and insulin signaling in Sprague-Dawley rats.
abstract: The aims of this investigation were to evaluate the effect of an amino acid supplement on the glucose response to an oral glucose challenge (experiment 1) and to evaluate whether differences in blood glucose response were associated with increased skeletal muscle glucose uptake (experimental 2). Experiment 1 rats were gavaged with either glucose (CHO), glucose plus an amino acid mixture (CHO-AA-1), glucose plus an amino acid mixture with increased leucine concentration (CHO-AA-2), or water (PLA). CHO-AA-1 and CHO-AA-2 had reduced blood glucose responses compared with CHO, with no difference in insulin among these treatments. Experiment 2 rats were gavaged with either CHO or CHO-AA-1. Fifteen minutes after gavage, a bolus containing 2-[(3)H]deoxyglucose and [U-(14)C]mannitol was infused via a tail vein. Blood glucose was significantly lower in CHO-AA-1 than in CHO, whereas insulin responses were similar. Muscle glucose uptake was higher in CHO-AA-1 compared with CHO in both fast-twitch red (8.36 ± 1.3 vs. 5.27 ± 0.7 μmol·g(-1)·h(-1)) and white muscle (1.85 ± 0.3 vs. 1.11 ± 0.2 μmol·g(-1)·h(-1)). There was no difference in Akt/PKB phosphorylation between treatment groups; however, the amino acid treatment resulted in increased AS160 phosphorylation in both muscle fiber types. Glycogen synthase phosphorylation was reduced in fast-twitch red muscle of CHO-AA-1 compared with CHO, whereas mTOR phosphorylation was increased. These differences were not noted in fast-twitch white muscle. These findings suggest that amino acid supplementation can improve glucose tolerance by increasing skeletal muscle glucose uptake and intracellular disposal through enhanced intracellular signaling.
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, 78712-0360, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Bernard
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Liao
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hara
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: Chung-Yu
authors.initials: CY
authors.lastname: Chen
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Nelson
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000596:Amino Acids / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D018149:Glucose Intolerance / Q000178:diet therapy* / Q000378:metabolism; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D004044:Dietary Proteins; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D011494:Protein Kinases; D005947:Glucose