The impact of duration of one bout treadmill exercise on cell proliferation and central fatigue in rats

The purpose of this study was to investigate the impact of the duration-dependence of the one bout treadmill exercise on cell proliferation, stress, and central fatigue in rats. The animals were randomly divided into five groups: the non-exercise group, 1-h exercise group, 2-h exercise group, 4-h exercise group, and 6-h exercise group. The exercise load consisted of running at speed of 13 meters/min with the 0° inclination. Cell proliferation in the hippocampal dentate gyrus was increased in response to one bout moderate treadmill exercise in all exercise groups. But there was no statistical significance between the exercise duration and cell proliferation. The optical density of glucocorticoid (GR)-positive cells in the hippocampal dentate gyrus was not changed by treadmill exercise at any exercise duration. Expressions of serotonin (5-hydroxytryptamine, 5-HT) and tryptophan hyroxylase (TPH) were increased by treadmill exercise only at 6 h duration. It seemed like that there was no additional benefits on cell proliferation over 2 h exercise due to stressful factors with over exercise dose, and there was no change of GR expression due to early assessment point of time. It can be suggested that the one-bout of moderate treadmill exercise increased cell proliferation, but treadmill exercise prolonged to 6 h induced central fatigue in rats.