UBC Theses and Dissertations
The effects of short term voluntary exercise in isolated animals Webber, Alina Jane
Voluntary exercise has been shown to consistently increase proliferation and neurogenesis in the dentate gyrus. Recently it was reported that social isolation can counteract the effects of voluntary exercise on cell proliferation and neurogenesis in the dentate gyrus of the hippocampus. We examined the effects of social isolation on animals engaging in voluntary exercise, looking at adult male C57BL/6J mice. Animals in this study were isolated for 1 week and then placed in their respective housing conditions. Exercise wheels were quasi-randomly assigned to cages, and animals were left in this environment for 11 days. On the 12th day, 5-bromo-2-deoxyuridine (BrdU) was injected as a marker of dividing cells. Animals were sacrificed 2 hours later to measure cell proliferation. We found no significant effects of social isolation on cell proliferation. In contrast, voluntary exercise nearly doubled the number of BrdU labeled cells regardless of the animals housing situation. The number of cells positive for doublecortin, (DCX), a protein found specifically in immature neurons, also significantly increased in response to voluntary exercise. Social isolation did not have a significant effect on this measure, and voluntary exercise, rather than social housing was also found to increase the complexity of the processes of immature neurons labeled by DCX. In addition, a pilot study in aged mice indicated that even aged animals that have been isolated for more prolonged periods of time have a greater survival of BrdU labeled cells in response to voluntary exercise, although this was a non significant trend.
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