Hippocampal cell proliferation is involved in exercise-derived beneficial effect on stressed animal model

Abstract

It has been speculated that regular physical exercise could be a non-pharmacological form of treatment for depressive disorders. Although exercise is associated with continual elevations of stress hormones, its beneficial effect to cell proliferation in the dentate gyrus and neuro-cognitive functions such as spatial learning of adult rats have been documented. Paradoxically, elevated glucocorticoid has proven to suppress cell proliferation in the hippocampal region. It remains unverified if exercise could reverse this negative effect of glucocorticoid and hence help promote spatial memory as observed. In this study, SD rats were subjected to corticosterone treatment for two weeks. They were randomly assigned to the exercise (voluntary wheel running) or the non-exercise (without voluntary wheel running) groups. All corticosterone treated rats in the non-exercise group showed longer escape latencies compared to that of the rats with vehicle treatment. Improved spatial learning was observed in the exercise rats. However, this beneficial effect was evidenced only in rats treated with vehicle and 20mg/kg to 40mg/kg corticosteorne, but not in the rats treated with 50mg/kg corticosterone. Relative to the non-exercise rats, increase in hippocampal cell proliferation and reduction in depression-like behaviors were observed among the exercise rats. Our findings provide important biochemical evidence of the beneficial effect of exercise, in terms of alleviating the negative impact of glucocorticoid to the brain.