Behavioral and neuroendocrine effects of repeated gastric distension in the rat: A model for bulimia nervosa?
Abstract
Bulimia nervosa (BN) is an eating disorder characterized by a pattern of uncontrolled ingestion (binging) and expulsion (purging) of food. Bulimics have increased gastric capacity, delayed gastric emptying, blunted post-meal ghrelin and insulin responses, disproportionately low leptin levels, resistance to alpha melanocyte stimulating hormone (α-MSH), and significantly increased neuropeptide tyrosine (NPY) expression. Binge eating induces gastric distension, and the stimulation of gastric mechanoreceptors, to a greater degree than experienced by non-binging individuals. In contrast to non-purging binge eaters, the amount of food entering the small intestines in bulimics is less than the amount ingested, suggesting that the signal from mechanical sensation is larger than that from chemical sensation. To test the effects of repeated gastric distesnsion (RGD) without nutrient absorption on the neuroendocrine factors associated with BN, a permanent intra-gastric balloon was implanted in rats, and inflated daily for 4 weeks. Though body weights and daily food intakes remained equivalent in RGD and control rats, a significant delay in the onset of feeding was present during the first and second, but not the third and fourth weeks of inflations. Leptin levels were decreased after RGD (p < .05); insulin and ghrelin were unaffected. Expression of proopiomelanocortin, the precursor to α-MSH, was unaffected by RGD. These animals tended to have increased fasting arcuate NPY levels (p = .0835), which dropped to a greater degree than control animals following food intake (control and RGD decreases from baseline were 184.95% and 257.42%, respectively). Expression of NPY in the nucleus of the solitary tract followed a similar pattern, but of a lower magnitude. These data suggest a role for RGD in multiple factors associated with BN.
Degree
M.S.
Advisors
Kinzig, Purdue University.
Subject Area
Neurosciences|Psychobiology|Behavioral psychology
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