Treadmill running overcomes diabetes-induced suppression of cell proliferation and neuropeptide Y expression in the dentate gyrus of rats

Aim. We attempted to determine the effects of treadmill exercise on cell proliferation and neuropeptide Y expression in the dentate gyrus of streptozotocin-induced diabetic rats. Methods. Experimental design: Comparative investigation was performed over 10 days. Setting: Experimental animal laboratory. Participants: Twenty-four male Sprague-Dawley rats, each weighing 300±20 g (8 weeks of age). The animals were assigned into four groups: the control group, the streptozotocin-induced diabetes group, the streptozotocin-induced diabetes and running group, and the streptozotocin- induced diabetes and insulin injection group. Interventions: Diabetes mellitus was induced by a single injection of streptozotocin. Beginning on the second day after injection of streptozotocin, 5-bromo-2′-deoxyuridine was administrated to all animals once daily for 10 days. The rats in the running group were forced to run on a treadmill for 30 min once a day for 10 days. Measures: Cell proliferation and neuropeptide Y expression in the dentate gyrus was measured by immunohistochemistry for 5-bromo-2′-deoxyuridine and neuropeptide Y. Results. Streptozotocin-induced diabetes increased blood glucose level and induced significant weight loss compared to the control group, while treadmill running exerted no significant effects on blood glucose level and enhanced weight loss. Cell proliferation and neuropeptide Y expression in the dentate gyrus were suppressed in the streptozotocin-induced diabetic rats, however they were enhanced by both treadmill exercise and insulin treatment. Conclusion. The present study indicates that treadmill exercise may facilitate recovery from the central nervous system complications associated with diabetes mellitus by enhancing cell proliferation via augmentation of neuropeptide Y expression in the dentate gyrus.