Oxidative eustress is associated with AMPK and AKT activation, GLUT4 translocation and glucose uptake in skeletal muscle cells and fibres

Objectives: Reactive oxygen and nitrogen species (RONS) act as signalling molecules under physiological conditions; however, how oxidative eustress regulates glucose uptake in skeletal muscle remains poorly defined. We investigated the role of moderate oxidation in skeletal muscle glucose uptake, focusing on AKT/AMPK phosphorylation, GLUT4 translocation and functional glucose uptake. Methods: AKT and AMPK phosphorylation were analysed in C2C12 myoblasts/myotubes exposed to insulin and redox-modulating stimuli associated with oxidative eustress, including hydrogen peroxide, nitric oxide donors and angiotensin II. GLUT4 translocation was assessed by quantitative immunocytochemistry and confocal fluorescence microscopy in cells expressing a GLUT4 reporter. Glucose uptake was evaluated in isolated skeletal muscle fibres using 6-NBDG. Results: Oxidative eustress was associated with increased AKT and AMPK phosphorylation and enhanced GLUT4 translocation to the plasma membrane. Hydrogen peroxide, nitric oxide donors and angiotensin II increased GLUT4 presence at the plasma membrane and enhanced glucose uptake, with hydrogen peroxide showing a dose-dependent effect. Increased glucose uptake was consistent with GLUT4 translocation. Discussion: These findings support oxidative eustress as a physiological redox mechanism linking AKT/AMPK activation, GLUT4 translocation and glucose uptake in skeletal muscle. Redox signalling may therefore contribute to skeletal muscle glucose metabolism.