Effects of exercise intensity on lymphocyte apoptosis induced by oxidative stress in men

Exercise is linked with intensity-dependent immune response. Intracellular redox status is important in programmed cell death. This study, by closely examining 18 sedentary men who exercised moderately and severely (ie. 60% and 80% VO_2max, respectively) for 40 min, investigated how exercise intensities influence intracellular redox status and oxidative stress-induced apoptosis in lymphocyte. Intracellular superoxide and reduced glutathione (GSH) levels, lipid peroxidation, mitochondrial transmembrane potential (MTP), active caspases contents, phosphotidyl serine (PS) exposure, and DNA fragmentation in lymphocytes were determined. Moreover, sublethal oxidative stress was administered by treating the lymphocyte with H₂O₂, to closely approximate in vivo pro-oxidative conditions. Immediately or 24 h after severe exercise, (1) lymphocyte GSH level and MTP had diminished while active caspase-8, -9, and -3 contents and DNA fragmentation had risen; and (2) H₂O₂ induced- lymphocyte PS exposure and DNA fragmentation were enhanced. In contrast, lymphocyte MTP, caspases activation, PS exposure, and DNA fragmentation were unaltered immediately following moderate exercise, whereas GSH level rose, lipid peroxidation diminished, and H₂O₂ induced- PS exposure and cell damage reduced 24 h after this exercise. These results suggest that heavy exercise diminishes lymphocyte GSH content and subsequently enhances the oxidative stress-induced apoptosis. However, moderate exercise attenuates lymphocyte apoptosis induced by oxidative stress, possibly by improving intracellular anti-oxidative capacity.