Aerobic exercise alleviates ischemia-induced memory impairment by enhancing cell proliferation and suppressing neuronal apoptosis in hippocampus

Abstract

Purpose: Neurogenic lower urinary tract dysfunction (NLUTD) is a possible consequence of several neurological disorders. NLUTD may produce debilitating symptoms and serious complications, such as chronic renal failure, and recurrent urinary tract infections. Many animal studies of NLUTD symptoms have focused on animal models of cerebral ischemia. In the present study, we investigated the effects of treadmill exercise on memory function and its relation to cell proliferation and apoptosis in the hippocampus, following transient global ischemia in gerbils. Methods: To induce transient global ischemia in gerbil, both common carotid arteries were occluded for 5 minutes. Gerbils in the exercise groups were forced to run on a treadmill exercise for 30 minutes once a day for 2 weeks. Step-down avoidance task and Y maze task were performed. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)- staining, immunohistochemistry for 5-bromo-2′-deoxyridine, doublecortin, caspase-3, and Western blot for brain-derived neurotrophic factor (BDNF), Bax, Bcl-2, cytochrome c, caspase-3 were conducted. Results: Ischemia caused memory impairment with an increase of cell proliferation, BDNF expression, and apoptosis in the hippocampus. Treadmill exercise improved memory function with further increase of cell proliferation and BDNF expression and a decrease of apoptosis. Conclusions: The animal model that we have developed and our assessment of the relation between exercise and brain function can be useful tools for future investigations of NLUTD symptoms associated with stroke, particularly ischemic stroke. The present study suggests that treadmill exercise promoted the recovery of brain function after cerebral ischemia.