Abstract
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 γ coactivator-1α) 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.
Highlights
Exercise is known to induce physiological adaptations, especially in mitochondria, and many underlying mechanisms and signaling molecules have been identified, including lactate [1,2,3,4].PGC1-alpha is the master regulator of mitochondrial biogenesis [5,6]
L-lactate caused a significant increase in PGC1-alpha expression in the myotubes
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)
Summary
Exercise is known to induce physiological adaptations, especially in mitochondria, and many underlying mechanisms and signaling molecules have been identified, including lactate [1,2,3,4]. PGC1-alpha (peroxisome proliferator-activated receptor γ coactivator-1α) is the master regulator of mitochondrial biogenesis [5,6]. It is up-regulated following exercise and is dependent on the exercise intensity [7]. Lactate is known to increase PGC1-alpha expression. In L6 myoblasts cultured with 20 mM of sodium lactate for six hours, PGC1-alpha expression was increased around 30% [8]. It was shown that 20 mM of sodium lactate increased reactive oxygen species (ROS) activity. The temporal effect of lactate exposure in myotubes was explored
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