Abnormal protein turnover and anabolic resistance to exercise in sarcopenic obesity.
Anabolic resistance is the inability to increase protein synthesis in response to an anabolic stimulus, such as growth factors, amino acids, or contractile activity. Anabolic resistance may lead to muscle wasting (i.e. sarcopenia). In healthy people, sarcopenia occurs during aging. In obese people however, sarcopenia may occur in adulthood as well. The authors suggested in an earlier study that sarcopenic obesity may be due to the fact that the anabolic response to exercise is absent. This current study tried to improve understanding of the underlying reasons for a desensitization to anabolic stimuli in obesity.
This study used a novel tracer method to assess 24-h biosynthesis of proteins in skeletal muscle of genetically obese rats under free-living conditions. Basal protein synthesis rates (without an anabolic stimulus) were significantly elevated in obese rats compared with lean rats. This suggests that there is an obesity-induced increase in net protein turnover favoring protein degradation. However, in response to exercise, the increase in protein synthesis that was observed in lean rats, was absent in obese rats. The authors suggested that the lack of this anabolic response in the obese state may be due to an already diminished expression of an important protein involved in the regulation of the rate of protein synthesis (DEPTOR). > From: Nilsson et al., FASEB J (2013) (Epub ahead of print). All rights reserved to The FASEB Journal.
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