D-17 Thematic Poster - Sex Hormones and Musculoskeletal Effects

Abstract

Physical detraining (PD) is associated with increased fat mass, body weight gain and changes in protein metabolism. One of the nutritional strategies used to minimize the increase in adipose mass is caloric restriction (CR). This strategy may potentiate the loss of muscle mass, as observed in PD. The supplementation with essential amino acids, particularly leucine, can be used to mitigate these changes. PURPOSE:Evaluate the effect of leucine supplementation on the expression of myofibrillar proteins, particularly slow myosin heavy chain (MyHC-7), in detrained rats undergoing CR. METHODS:40 adult male Sprague-Dawley rats were assigned to 2 groups: Sedentary (SED, n = 8) and Trained (TRAIN, n = 32); the animals of the latter group underwent training on a treadmill for 8 weeks. TRAIN animals were then re-distributed into four groups: Trained (TRAIN, n = 8): animals who continued following the physical training protocol; Detrained (DT, n = 8): animals who stopped training and had free access to food; Detrained + CR (CR + DT): animals who stopped training and consumed 70% of DT caloric intake; Detrained + Leucine + CR (CR + DT + LEU): animals who stopped training and consumed 70% of DT caloric intake, and received 5% leucine supplementation. Body weight and food consumption were measured weekly. After 14 weeks the animals were euthanized, body composition was assessed using carcass chemical analysis, and the soleum tissue was used to assess the expression of MyHC-7 through imunoblotting. ANOVA was used for group comparison, along with Tukey test, considering a 5% significance level. RESULTS:Statistically significant difference was observed in body fat in CR+DT (16.08±6.98g) and CR+DT+LEU (15.98±7.74g) groups compared to DT (56.16±18.01g). No statistical difference was observed in fat-free mass (%) and relative protein (%) in the leucine-supplemented group. Additionally, a statistically significant difference was seen in the expression of MyHC-7 between TRAIN and SED groups (TRAIN 1.29±0.39, SED .44±0.12; p < 0.05), there was no difference when comparing groups DT, CR + DT and CR + DT + LEU. CONCLUSION:Leucine supplementation was not effective to minimize the loss of lean body mass and specifically to mitigate the decreased expression of MyHC-7 in detrained animals under CR. Acknowledgements to FAPESP