Swimming exercise ameliorates multiple sclerosis-induced impairment of short-term memory by suppressing apoptosis in the hippocampus of rats

Multiple sclerosis is one of the autoimmune diseases in the central nervous system. Multiple sclerosis occurs through multiple mechanisms, and it is also mediated in part by an apoptotic mechanism. Swimming exercise has been recommended for the prevention and treatment of chronic diseases. In the present study, we investigated the effects of swimming exercise on short-term memory in relation with apoptotic neuronal cell death in the hippocampus following induction of multiple sclerosis. For this study, step-down avoidance task, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, immunohistochemistry for caspase-3 were performed. The animal model of multiple sclerosis was made by bilateral intracerebral ventricle injection of ethidium bromide. The rats in the swimming exercise groups were forced to swim for 30 min once daily for 14 consecutive days, starting 3 days after induction of multiple sclerosis. In the present results, short-term memory was deteriorated in the multiple sclerosis-induced rats. The number of TUNEL-positive and caspase-3-positive cells in the hippocampal dentate gyrus was increased in the multiple sclerosis-induced rats. Swimming exercise alleviated multiple sclerosis-induced short-term memory impairment by suppressing apoptotic neuronal cell death in the hippocampus. These effects of swimming exercise may aid symptom relief in the incurable neurodegenerative diseases.