Protein and amino acid supplementation does not alter proteolytic gene expression following immobilization

• Type of Material: Article
• Authors: Jennifer A. Bunn, Baylor University; Thomas W. Buford, University of Florida College of Medicine; Monica Serra, Emory University; Richard B. Kreider, Texas A & M University; Darryn S. Willoughby, Baylor University
• Language: English
• Date: 2011-12-01
• Publisher: Hindawi Publishing Corporation
• Publication Version: Final Published Version
• Copyright Statement: © 2011 Jennifer A. Bunn et al.
• License: Creative Commons Attribution 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1155/2011/539690
• Title of Journal or Parent Work: Journal of Nutrition and Metabolism
• ISSN: 2090-0724
• Volume: 2011
• Start Page: 539690
• End Page: 539690
• Grant/Funding Information: This work was funded by the Baylor Exercise and Biochemical Nutrition Lab, by the Baylor Exercise and Sport Nutrition Lab, and by a student research award from the Texas Regional Chapter of the American College of Sports Medicine.
• Research Categories: Health Sciences, General; Health Sciences, Medicine and Surgery

Abstract

Objective. To determine if supplementation of protein and amino acids (PAA) decreases skeletal muscle expression of atrophy-related genes, muscle mass, and strength during immobilization in humans. Methods. Twenty males wore a lower-limb immobilization boot for 28 days and consumed either a PAA supplement (28 g protein) or carbohydrate placebo (28 g maltodextrose), while consuming their normal daily diet. Testing sessions included dietary analysis, lower-leg girth and body composition measurements, strength testing, and gastrocnemius muscle biopsies. Muscle was analyzed for mRNA expression of markers in the ubiquitin and calpain systems, myostatin, TNF- and NF-B. Results. All genes of interest increased over time (P < .05), but there was no difference between groups. Lower-leg girth decreased over time (P = 0.02); however, there were no significant changes in body composition or strength. Conclusion. Short-term lower-limb disuse, despite the absence of significant muscle atrophy, is associated with increases in skeletal muscle gene expression of several proteolysis-related genes. These changes do not appear to be altered by oral PAA supplementation.