N-acetyl-L-cysteine Prevents Lactate-Mediated PGC1-alpha Expression in C2C12 Myotubes.

Background: Exercise induces many physiological adaptations. Recently, it has been proposed that some of these adaptations are induced by exercise-mediated lactate production. In this study, we aimed to investigate in vitro the effect of lactate in cultured myotubes and whether antioxidants could inhibit the effect. Methods: Differentiated myotubes were cultured at different concentrations of L-lactate (0, 10, 30, 50 mM) in the absence or presence of an antioxidant, N-acetyl-L-cysteine (Nac). The temporal effect of lactate exposure in myotubes was also explored. Results: Two hours of exposure to 50 mM L-lactate and six hours of exposure to 30 or 50 mM L-lactate caused a significant increase in PGC1-alpha (peroxisome proliferator-activated receptor gamma coactivator-1 alpha) expression in the myotubes. This up-regulation was suppressed by 2 mM Nac. Intermittent and continuous lactate exposure caused similar PGC1-alpha up-regulation. These results suggest that the increase in PGC1-alpha expression is mediated by reactive oxygen species (ROS) production from lactate metabolism and that both continuous and intermittent exposure to L-lactate can cause the up-regulation.