Skeletal muscle autophagy and protein breakdown following resistance exercise are similar in younger and older adults

Christopher S. Fry, Micah J. Drummond, Erin L. Glynn, Jared M. Dickinson, David M. Gundermann, Kyle L. Timmerman, Dillon K. Walker, Elena Volpi, Blake B. Rasmussen

Research output: Contribution to journalArticlepeer-review

128 Scopus citations

Abstract

Background.The loss of skeletal muscle mass and strength during aging, sarcopenia, increases the risk for falls and dependency. Resistance exercise (RE) training is effective at improving muscle mass and strength in older adults; however, aging is associated with reduced training-induced hypertrophy. Recent research has illustrated an impaired muscle protein synthetic response following an acute bout of RE in older adults but much less is known regarding the effect of acute RE on muscle protein breakdown (MPB). We hypothesize that the ubiquitin proteasome system and the autophagosomal-lysosomal system may regulate the overall rate of MPB during postexercise recovery.Methods.Muscle biopsies of the vastus lateralis were sampled from 16 older (age = 70±2 years) and 16 younger (age = 27±2 years) participants at baseline and at 3, 6, and 24 hours following an acute bout of RE. In conjunction with stable isotopic techniques to measure MPB, we utilized immunoblotting and RT-PCR to examine protein and mRNA expression for key signaling molecules in both the ubiquitin proteasome system and the autophagosomal-lysosomal system.Results.MuRF1 mRNA expression increased, whereas GABARAP mRNA decreased after RE in both younger and older adults (p <. 05). The LC3B-II/LC3B-I protein ratio decreased in both groups after RE (p <. 05), but MPB was not different 24 hour post-RE in either group (p >. 05).Conclusions.Aging does not influence skeletal MPB, autophagy, or the ubiquitin proteasome system following an acute bout of RE. Therefore, targeting the muscle protein synthesis response to exercise may hold more promise in the prevention of sarcopenia.

Original languageEnglish
Pages (from-to)599-607
Number of pages9
JournalJournals of Gerontology - Series A Biological Sciences and Medical Sciences
Volume68
Issue number5
DOIs
StatePublished - May 2013

Bibliographical note

Funding Information:
Funding This study was supported by grants from the National Institutes of health AR049877 (P30-AG024832 and T32-hD07539). In addition, this study was conducted with the support of the Institute for Translational Sciences at the University of Texas Medical Branch, supported in part by a Clinical and Translational Science Award (UL1TR000071) from the National Center for Advancing Translational Sciences, National Institutes of health.

ASJC Scopus subject areas

  • Medicine (all)

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