Premium
Abnormal protein turnover and anabolic resistance to exercise in sarcopenic obesity
Author(s) -
Nilsson Mats I.,
Dobson Justin P.,
Greene Nicholas P.,
Wiggs Michael P.,
Shimkus Kevin L.,
Wudeck Elyse V.,
Davis Amanda R.,
Laureano Marissa L.,
Fluckey James D.
Publication year - 2013
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/fj.12-224006
Subject(s) - anabolism , endocrinology , medicine , lean body mass , myofibril , protein turnover , sarcopenia , protein degradation , wasting , insulin resistance , chemistry , obesity , protein biosynthesis , body weight , biochemistry
Obesity may impair protein synthesis rates and cause anabolic resistance to growth factors, hormones, and exercise, ultimately affecting skeletal muscle mass and function. To better understand muscle wasting and anabolic resistance with obesity, we assessed protein 24‐h fractional synthesis rates (24‐h FSRs) in selected hind‐limb muscles of sedentary and resistance‐exercised lean and obese Zucker rats. Despite atrophied hind‐limb muscles (–28% vs. lean rats), 24‐h FSRs of mixed proteins were significantly higher in quadriceps (+18%) and red or white gastrocnemius (+22 or +38%, respectively) of obese animals when compared to lean littermates. Basal synthesis rates of myofibrillar (+8%) and mitochondrial proteins (–1%) in quadriceps were not different between phenotypes, while manufacture of cytosolic proteins (+12%) was moderately elevated in obese cohorts. Western blot analyses revealed a robust activation of p70S6k (+178%) and a lower expression of the endogenous mTOR inhibitor DEPTOR (–28%) in obese rats, collectively suggesting that there is an obesity‐induced increase in net protein turnover favoring degradation. Lastly, the protein synthetic response to exercise of mixed (–7%), myofibrillar (+6%), and cytosolic (+7%) quadriceps subfractions was blunted compared to the lean phenotype (+34, +40, and +17%, respectively), indicating a muscle‐ and subfraction‐specific desensitization to the anabolic stimulus of exercise in obese animals.—Nilsson, M. I., Dobson, J. P., Greene, N. P., Wiggs, M. P., Shimkus, K. L., Wudeck, E. V., Davis, A. R., Laureano, M. L., Fluckey, J. D., Abnormal protein turnover and anabolic resistance to exercise in sarcopenic obesity. FASEB J. 27, 3905–3916 (2013). www.fasebj.org