The Effects of Voluntary Exercise on a Rodent Model of Binge Eating
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Date
2015-08-13
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Johns Hopkins University
Abstract
Abstract:
Binge eating disorder (BED) is an eating disorder involving repeated, intermittent over consumptions of food in brief periods of time, usually with no compensatory behaviors. Unfortunately, there has been limited progress in the development of treatment strategies, partially due to the fact that the neurological and physiological consequences of repeated bingeing are not clearly understood and cannot readily be studied in humans. Thus, in order to investigate behavioral and neurological pathways affected by BED, rodent models mimicking BED symptoms can be used. Some models use cycles of food restriction and refeeding (R/R), while others use stress to induce bingeing. There are also different types of highly palatable foods that have been used, including vegetable shortening, sucrose, and cookies.
Due to the fact that weight issues and physical inactivity can be central issues in BED, exercise may be a useful treatment. To date, no studies have been published examining the effects of exercise on binge-eating in rats. It has been shown that running wheel activity (RWA) can decrease consumption of a daily high-fat diet (HFD), but the effects of RWA on sporadic, intermittent consumption of a HFD (e.g. bingeing) are still unknown. In the studies presented here, we hypothesized that RWA could reduce binge-eating in rats. Rats were given sporadic (3 times/wk) limited (1hr) access to a HF food (Crisco), in addition to continuously available chow. Crisco was available every Mon, Wed, and Fri for 1hr before dark onset. We designed the experiments to assess whether RWA would reduce established binge-eating, as well as assess whether prior RWA would prevent binge-eating from developing.
We found that RWA significantly decreased Crisco intake, but prior RW access did not prevent bingeing. While the appetite hormones were expressed in the appropriate directions, bingeing rats were not modifying their intake, and thus another brain pathway may be interfering. There was evidence that the brain reward pathways of both bingeing and running rats were activated, and may be overriding the appetite hormones. Overall, access to a RW and the resulting activity significantly reduced binge-eating and modulated the effects of bingeing on brain appetite and reward systems.
Thesis Adviser: Timothy H. Moran, Ph.D.
Paul R. McHugh Professor of Motivated Behaviors
Vice Chair for Research
Johns Hopkins University School of Medicine
Second Reader: Lisa A. Eckel, Ph.D.
Professor of Psychology and Neuroscience
Florida State University
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Keywords
binge eating, brain reward pathways, eating disorders, highly palatable food