Age-dependent differences of treadmill exercise on spatial learning ability between young- and adult-age rats.

The effect of exercise, which increases hippocampal neurogenesis and improves memory function, is well documented, however, differences in the effect of exercise on young children and adults are not yet known. In the present study, age-dependent differences of treadmill exercise on spatial learning ability between young- and adult-age rats were investigated. The rats in the exercise groups were forced to run on a motorized treadmill for 30 min once a day for 6 weeks. Radial 8-arm maze test was conducted for the determination of spatial learning ability. Cell proliferation in the hippocampal dentate gyrus was determined by 5-bromo-2'-deoxyuridine immunohistochemistry. Western blot for brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) was performed. In the present study, the number of errors in the young-age rats was effectively decreased by treadmill exercise. Hippocampal neurogenesis was more active in the young-age rats than in the adult-age rats. BDNF and TrkB expression in the hippocampus was greater in the adult-age rats than in the young-age rats. The results of this study showed that adults have excellent spatial learning abilities than children, but the improvement of exercise-induced spatial learning ability through neurogenesis is better in children.