Treadmill Exercise Ameliorates Short-term Memory Impairment by Suppressing Hippocampal Neuroinflammation in Poloxamer-407-Induced Hyperlipidemia Rats

PURPOSE: Poloxamer-407 (P-407) is used to induce hyperlipidemia. Exercise is effective in improving arteriosclerosis and cognitive impairment. In this research, the effect of treadmill running on short-term memory in the P-407-treated hyperlipidemia rats was studied focusing on neuroinflammation. METHODS: Rats were classified in normal group, normal and treadmill exercise group, P-407-treated group, and P-407-treated and treadmill exercise group. Hyperlipidemia rats were made by single intraperitoneal injection with P-407 (500 mg/kg). Treadmill exercise was conducted for 30 minutes once a day, 5 days per week during 28 days. Step-down avoidance task was done to measure short-term memory. Glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 were assessed by immunohistochemistry. Expression of adhesion molecules and proinflammatory cytokines was determined by western blot analysis. RESULTS: Treadmill exercise alleviated lipid profiles in the P-407-induced hyperlipidemia rats. Treadmill exercise improved short-term memory, inhibited reactive astrogliosis and microglia activation, and suppressed expression of adhesion molecules and proinflammatory cytokines in the hyperlipidemic rats. CONCLUSIONS: Treadmill exercise exerts alleviating effect on memory deficits by inhibiting hippocampal neuroinflammation in the hyperlipidemia. The current results suggest that treadmill running serves as the treatment strategy for the cognitive dysfunction caused by hyperlipidemia.