Treadmill running and swimming increase cell proliferation in the hippocampal dentate gyrus of rats

The effects of treadmill exercise and swimming on cell proliferation in the dentate gyrus and the involvement of opioid receptors were investigated via 5-bromo-2'-deoxyuridine (BrdU) immunohistochemistry. Sprague-Dawley rats of the running groups were made to run on treadmill for 30 min each day, while those of the swimming groups were made to swim for 5 min each day over 3 consecutive days. In addition, intensity-dependency of the effects of running and swimming on cell proliferation was investigated. The present results demonstrate that both treadmill running and swimming increase the number of BrdU-labeled cells in the dentate gyrus and these increasing effects are more potent in light intensity and 5 min swimming groups. Treatment with naloxone increases cell proliferation in the dentate gyrus in all groups, although this increase is statistically insignificant. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.