Physical training associated to tumor growth and nutritional suplementation in Walker 256 tumor-bearing rats / Atividade fisica associada ao crescimento tumoral e suplementação nutricional : estudo experimental em ratos jovens portadores do carcinossarcoma de Walker 256

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The intense nutrients mobilisation of the host carcass tissue, in function of the neoplastic growth, leads to the host cachexia. Present in most of the patients with cancer, the cachexia is the state characterized by the involuntary weight loss that overtakes the protein muscle depletion increasing the degradation and/or decreasing the protein synthesis process in the muscle. In these cases, there is reduction of the quality and the life expectancy. On the other hand, some studies have shown that the development of the cancer is more aggressive and severe in younger patients. The branched-chain amino acids (BCAA), especially leucine, actively participate on cell signalling, stimulating the synthesis as well as inhibiting the protein degradation. The glutamine, a non essential amino acid, indirectly activates the muscle protein synthesis, as well as inhibits the protein catabolism. Additionally, the physical exercise stimulates the protein synthesis. Knowing these facts, our main interests, were to minimize the metabolic alterations in tumor-bearing host. The nutritional supplementation of leucine and/or glutamine and moderate aerobic exercise associated to the Walker 256 tumor growth could avoid the muscular depletion, preserve the protein body mass and the energetic source, possibly preventing the cachetic state of the animal. For this purpose, we evaluated the body chemical composition, the protein metabolism, measuring the muscle protein synthesis and catabolism, as well as the oxidative stress and biochemical blood profile in young tumor-bearing rats. The results showed reduced body weight and food intake in tumorbearing rats. The tumor effects changed the chemical body composition, showing high body water content, reduced total body fat and low carcass nitrogen in Walker tumor bearing rats. Protein synthesis was reduced and proteolysis was increased in young tumor-bearing rats. Additionally, the malondyhaldeide content increased in skeletal and cardiac muscle suggesting high oxidative stress associated to the tumor development. We observed low blood protein, albumin, globulin, glucose and cholesterol in tumor-bearing rats. The improvement of the cachexia was less pronounced in tumor-bearing animal which received supplemented diet associated to physical exercise. In these groups, we verified that food efficiency was slightly increased in comparison to the non-exercised tumour-bearing group. The carcass protein was maintained as well as the phenylalanine incorporation in muscle and less tyrosine was released from skeletal muscle when tumour-bearing groups were fed leucine rich diet. In these groups, the total blood protein, glycemia, total blood cholesterol and reduced blood lactate were preserved, mainly in exercised group. Those data suggest that the beneficial effect of the association among amino acids rich diet, exercise and tumor growth was not so expressive, probably due to the exponential tumor growth overcame the physical training program

ASSUNTO(S)

aminoacidos caquexia amino acids cachexia cancer protein metabolism exercise proteinas - metabolismo exercicios fisicos cancer

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