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영어

Diabetes is metabolic disorder, and this disease is a major risk factor for Alzheimer’s disease (AD). In the present study, we investigated the preventive effect of treadmill exercise on the incidence of AD using streptozotocin-induced diabetic rats. To evaluate this purpose, we investigated the expressions of GSK-3β and tau protein in the PI3K/Akt pathway. Male Sprague-Dawley rats were used for this study. The animals were divided into four groups (n = 10 in each group): control group, exercise group, DM-induction group, DM-induction and exercise group. DM was induced by intraperitoneal injection of streptozotocin (50 mg/kg dissolved in 0.05 M citrate buffer, pH 4.5). The rats in the exercise groups were made to run on the treadmill for 30 min, five times a week for 12 weeks. For this study, step-down avoidance task, immunohistochemistry for GSK-3β and tau, and western blot for p-PI3K/PI3K and p-Akt/Akt were performed. The present results showed that short- and long-term latencies in the step-down avoidance task were lower in the diabetic rats, but treadmill exercise increased both latencies in the diabetic rats. The ratio of p-PI3K/PI3K and p-Akt/Akt in the hippocampus were lower in the diabetic rats, whereas treadmill exercise increased the ratio of p-PI3K/PI3K and p-Akt/Akt in the diabetic rats. The levels of GSK-3β and tau-positive cells in the hippocampus were increased by induction of DM, in contrast, treadmill exercise suppressed the expression of GSK-3β and tau. These results suggest that treadmill exercise may ameliorate memory impairment and decrease risk factors of AD by inhibiting expressions of GSK-3β and tau in the PI3K/Akt pathway.