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

Abstract

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.

Stress-Induced Depression Is Alleviated by Aerobic Exercise Through Up-Regulation of 5-Hydroxytryptamine 1A Receptors in Rats

“…TPH regulates 5-HT activity, and is used as an indicator of serotonin synthesis [ 24 ]. Increase in 5-HT synthesis and TPH expression caused by treadmill exercise is well documented [ 11 , 20 ]. Increment of serotonin synthesis and activity might be involved in the antidepressant effect of exercise in the elderly [ 25 ].…”

“…To visualize 5-HT and TPH expressions, immunohistochemistry for 5-HT and TPH in the dorsal raphe was performed, according to a previously described method [ 11 ]. The dorsal raphe spanning 7.20 to 8.00 mm from the Bregma was obtained from each brain.…”

“…5-HT is closely associated with depression [ 9 ], and decrement in 5-HT metabolism was ascertained in the brains of a subgroup of patients with depression [ 10 ]. Tryptophan hydroxylase (TPH), the rate-limiting enzyme in 5-HT synthesis, regulates 5-HT activity in the brain [ 11 ].…”

Aerobic Exercise Alleviates Ischemia-Induced Memory Impairment by Enhancing Cell Proliferation and Suppressing Neuronal Apoptosis in Hippocampus

“…To detect newly generated cells in the hippocampal dentate gyrus, BrdU-specific immunohistochemistry was performed according to a previously described method [ 6 , 20 ]. The sections were first permeabilized by incubation in 0.5% Triton X-100 in PBS for 20 minutes, then pretreated in 50% formamide-2X standard saline citrate at 65℃ for 2 hours, denatured in 2N HCl at 37℃ for 30 minutes, and rinsed twice in 100 mM sodium borate (pH 8.5).…”

“…The hippocampus is a primary site of neurogenesis: a four-stage process where neuronal progenitors that originate from neural stem cells undergo proliferation, migration, survival, and differentiation into new neurons. For the detection of newly formed cells, 5-bromo-2'-deoxyuridine (BrdU) and Ki-67 immunohistochemistry have been previously used [ 5 , 6 , 7 ]. A decrease in the number of cells labeled with these markers represents a reduction in cell proliferation, while an increase in the number of labeled cells correlates with new cell formation [ 7 , 8 ].…”