Treadmill exercise ameliorates social isolation-induced memory impairment by enhancing silent information regulator-1 expression in rats

The effect of treadmill exercise on the social isolation-induced memory impairment in relation with the silent information regulator-1 (SIRT-1) was investigated. The rats in the control groups lived four in the stan-dard cages for 8 weeks. The rats in the social isolation groups lived alone in the small cages for 8 weeks. The rats in the treadmill exercise groups were subjected to run on a treadmill for 30 min once a day for 8 weeks. We used step-through avoidance test for short-term memory and Morris water maze task for spatial working memory. Immunohisto-chemistry for SIRT-1 and western blot analysis for Bax, Bcl-2, cleaved caspase-3, brain-derived neurotrophic factor (BDNF), and tropomyosin receptor kinase B (TrkB) were performed. The rats in the social isolation group showed a decrease in short-term memory and spatial working memory. Treadmill exercise alleviated short-term memory and spatial working memory in the social isolation rats. SIRT-1 expression in the hippocampus was decreased in the rats of social isolation group. Treadmill exercise increased SIRT-1 expression in the social isolation rats. Bax expression was increased, Bcl-2 expression was decreased, and cleaved caspase-3 expression in the hippocampus was increased in the rats of social isolation group. Treadmill exercise decreased Bax expression, increased Bcl-2 expression, and decreased cleaved caspase-3 expression in the social isolation rats. Hippocampal BDNF and TrkB expression was decreased in the rats of social isolation group. Treadmill exercise increased BDNF and TrkB expression in the social isolation rats.