Implications of Dietary Leucine on Muscle mTOR Gene Expression and Redox Status in Rats Following High Intensity Effort

Leucine supplementation exerts a positive effect on mTOR pathway that is involved in the synthesis of skeletal muscle protein. In the present study, the capability of a 15-day dietary leucine supplementation (310 mg/kg) to improve the performance in acute high intensity effort and the inductive capacity on skeletal muscle protein anabolism in rats submitted to swimming exercise with a 10% bodyweight load attached to the tail, were studied. A 1.83-fold increase in mTOR gene expression in the treated group was found, while no changes in muscle protein content and rats body weight were observed. An increase in protein oxidation and a significant decrease in catalase were found in treated rats, while no changes in DNA damage, GSH and SOD levels were reported. We found an increase of superoxide anion and hydrogen peroxide/myeloperoxidase system in polymorphonuclear neutrophils obtained by treated group. These outcomes suggest slight enhancement in basal inflammation due to exercise activity via mTOR activation during treatment, without serious impairment of the antioxidant system and cell status. In conclusion, the 15-day leucine supplementation at the given dose, enhanced mTOR gene expression in the presence of acute effort which was also well tolerated by skeletal muscle, but probably too short to improve its anabolic activity.