Light aerobic physical exercise in combination with leucine and/or glutamine-rich diet can improve the body composition
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ORIGINAL PAPER
Light aerobic physical exercise in combination with leucine and/or glutamine-rich diet can improve the body composition and muscle protein metabolism in young tumor-bearing rats Emilianne Miguel Salomão & Maria Cristina Cintra Gomes-Marcondes
Received: 25 October 2011 / Accepted: 13 March 2012 / Published online: 30 March 2012 # University of Navarra 2012
Abstract Nutritional supplementation with some amino acids may influence host’s responses and also certain mechanism involved in tumor progression. It is known that exercise influences body weight and muscle composition. Previous findings from our group have shown that leucine has beneficial effects on protein composition in cachectic rat model as the Walker 256 tumor. The main purpose of this study was to analyze the effects of light exercise and leucine and/or glutamine-rich diet in body composition and skeletal muscle protein synthesis and degradation in young tumor-bearing rats. Walker tumorbearing rats were subjected to light aerobic exercise (swimming 30 min/day) and fed a leucine-rich (3%) and/or glutamine-rich (4%) diet for 10 days and compared to healthy young rats. The carcasses were analyzed as total water and fat body content and lean body mass. The gastrocnemious muscles were isolated and used for determination of total protein synthesis and degradation. The chemical body composition changed with tumor growth, increasing body water and reducing body fat content and total body nitrogen. After tumor growth, the muscle
E. M. Salomão : M. C. C. Gomes-Marcondes (*) Department of Structural and Functional Biology, Biology Institute, State University of Campinas, UNICAMP, 13083-970 Campinas, São Paulo, Brazil e-mail: [email protected]
protein metabolism was impaired, showing that the muscle protein synthesis was also reduced and the protein degradation process was increased in the gastrocnemius muscle of exercised rats. Although short-term exercise (10 days) alone did not produce beneficial effects that would reduce tumor damage, host protein metabolism was improved when exercise was combined with a leucine-rich diet. Only total carcass nitrogen and protein were recovered by a glutamine-rich diet. Exercise, in combination with an amino acid-rich diet, in particular, leucine, had effects beyond reducing tumoral weight such as improving protein turnover and carcass nitrogen content in the tumorbearing host. Keywords Leucine-rich diet . Glutamine-rich diet . Walker 256 tumour . Protein metabolism . Body composition
Introduction Cachexia is characterised by involuntary weight loss in patients that results in reduced survival [42]. The lean body mass loss occurs primarily in the skeletal muscle tissue and is directly proportional to the effects of tumor evolution. This results in a reduction in the patient’s physical performance and response to chemotherapy [43]. A decrease in protein synthesis and an increase in protein
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degradation, which alters total protein turnover balance, are major factors in tumor development [23, 43]. Such chan
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