EFEITO DA SUPLEMENTAÇÃO DE DIFERENTES DOSES DE WHEY PROTEINS ASSOCIADAS AO TREINAMENTO RESISTIDO POR DOZE SEMANAS SOBRE A EXPRESSÃO GÊNICA DE MTOR, MURF-1 E MAFBX EM RATOS WISTAR MACHOS.

Abstract

Objective: Verify the effect of supplementation of 2, 4 and 6g/kg/day doses of Whey proteins associated with the 12 week resistance training in gene expression in the path of synthesis and protein degradation of the skeletal muscle of male Wistar rats. Materials and Methods: A study of 60 male Wistar rats with initial age of 60 days and body mass of 250g to 350g, randomly distributed in eight groups, one being a control and three interventional sedentary, identified by the dosage value of the supplement WP (2, 4 and 6g/kg/day), a resistance training control and three more trained groups and with whey proteins at doses (2, 4 and 6g/kg/day). The protocol lasted 12 weeks with daily supplementation and resistance training three times a week. The gene expressions of MTOR, MURF-1 and MAFBX in the white portion of the gastrocnemius muscle through the Polimerase Chain Reaction Real Time method (PCR-RT), muscle strength every two weeks and gastrocnemius muscle mass and mean area of the muscle cell were evaluated. Results: Gene expression of MTOR mRNA in the gastrocnemius muscle in the TC group was greater than the W2, W4 and W6 groups but did not present a significant statistical difference between groups C, TW2, TW4 and TW6. Gene expression of MURF-1 mRNA was lower in all treatment groups compared to the control group and was not different in the comparison between doses of whey proteins and/or resistance training. The gene expression of MAFBX mRNA in all groups was lower when compared to the sedentary control group. In addition, the gene expression of MAFBX mRNA in the TW6 group was greater than the W2, W4, W6, TC, TW2 and TW4 groups. Muscle strength increased in all trained groups, but whey proteins had a potentiating effect on this result. In addition, relative muscle mass was higher in the trained group and supplemented with 6g/kg/day. Discussion: Whey protein supplementation had a positive effect on the decrease in the expression of proteins related to protein degradation, which could lead to a positive balance of protein synthesis, and resistance training provided greater activation of the synthesis pathway. The lower expression of these markers of protein degradation is an important indication for a positive balance of protein synthesis in relation to protein degradation, since the reduction of the degradation pathways itself may lead to an increase in muscle hypertrophy. Nevertheless, this condition caused an increase in the relative mass of the gastrocnemius in the TW6 group and the muscle cell area did not have significant statistical difference between the groups. Conclusion: Whey proteins at doses of 2, 4 or 6 g / kg / day in sedentary rats did not provoke an increase in MTOR mRNA expression but caused a decrease in the expression of MURF-1 mRNA and MAFBX mRNA. TR increased MTOR mRNA expression, but whey protein supplementation did not potentiate this effect. The dose of 6g / kg / day of whey proteins caused a greater increase in the relative mass of the gastrocnemius muscle in rats that underwent resistance training. In addition, whey proteins had a potentiating effect on the strength of the animals that underwent resistance training.