Efeitos da suplementação de leucina e do treinamento de força sobre a miopatia diabética em modelo experimental de diabetes mellitus induzido por estreptozotocina

MARTINS, CEC. Effects of leucine supplementation and resistance training on diabetic myopathy in experimental diabetes mellitus induced by streptozotocin. 2016. Dissertation (Masters) Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, 2016. In this study, we evaluated the effects of chronic supplementation with leucine and resistance training on diabetic myopathy. 40 Wistar Hannover rats were divided into 5 groups: control, non-diabetic (C), untreated diabetic (D), trained diabetic (DT), diabetic supplemented with leucine and trained (DLT). The beginning of the interventions occurred in the 4th week of life of the animals, and lasted for 8 weeks. Were evaluated: body weight, food and water intake, blood concentrations of glucose, insulin and lipid profile; voluntary muscle functional capacity through grip strength and ambulation test; intracellular content of proteins related to the anabolic mTOR and p70S6K pathway, total and phosphorylated in the extensor digitorum longus muscle. Diabetics untreated mice (group D) had hyperglycemia and moderate hypoinsulinemia, lower body mass, food and water intake, reduced absolute weights of the muscles of the long extensor digitorum, and gastrocnemius, the lower grip strength, lower ambulation capacity and lower activity of mTOR and p70S6K protein compared the C group, featuring diabetic myopathy. The relative weight of the gastrocnemius muscle (absolute weight / 100g of body weight) was greater in DT and DLT groups compared with group D, and higher in the DLT group compared to the DL group (P < 0.05). No statistical difference between the DL and D groups on the relative weights of the muscles, that is, chronic supplementation of leucine did not affect this parameter in diabetic rats. Interestingly, there was statistical difference between the DL and D groups on muscle strength (P < 0.05), with no difference between groups DL and C on the blood glucose; that is, the diet supplemented with leucine was able to control glycemia and avoid loss of muscle strength of diabetic animals. Resistance training also controlled glycemia, recovered muscle strength and improved the capacity of ambulation of diabetic animals and the regulation of the mTOR-p70S6K pathway. The phosphorylation of mTOR-p70S6K pathway was higher only in the DT and DLT groups compared with the D group (P < 0.05), and no difference between the DT and C groups, suggesting that the training recovered muscle mass in diabetic animals. Total cholesterol was greater in Group D compared to the group C; and trained diabetic groups (DLT and DT), this parameter was lower than that of the D group (P < 0.05). In addition, HDL-C increased in trained groups (DT and DLT) as compared to group D, but had no effect the group that received only leucine supplementation (DL group). Therefore, in this study, chronic supplementation of leucine alone normalized glucose and improved muscle strength of diabetic animals. In addition, resistance training was responsible for the largest increase in strength and muscle mass, as well as the normalization of glucose, elevated concentrations of HDL-C and reduction in total cholesterol of animals diabetics and both were able to recover mTORp70S6K pathway.