Increased expression of receptors for orexigenic factors in nodose ganglion of diet-induced obese rats

1 Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, 2 United States Department of Agriculture/Agricultural Research Service Western Human Nutrition Research Center, and 3 Department of Nutrition, University of California, Davis, California Submitted 26 September 2008 ; accepted in final form 30 January 2009 The vagal afferent pathway is important in short-term regulation of food intake, and decreased activation of this neural pathway with long-term ingestion of a high-fat diet may contribute to hyperphagic weight gain. We tested the hypothesis that expression of genes encoding receptors for orexigenic factors in vagal afferent neurons are increased by long-term ingestion of a high-fat diet, thus supporting orexigenic signals from the gut. Obesity-prone (DIO-P) rats fed a high-fat diet showed increased body weight and hyperleptinemia compared with low-fat diet-fed controls and high-fat diet-induced obesity-resistant (DIO-R) rats. Expression of the type I cannabinoid receptor and growth hormone secretagogue receptor 1a in the nodose ganglia was increased in DIO-P compared with low-fat diet-fed controls or DIO-R rats. Shifts in the balance between orexigenic and anorexigenic signals within the vagal afferent pathway may influence food intake and body weight gain induced by high fat diets. cholecystokinin; diet-induced obesity; ghrelin Address for reprint requests and other correspondence: H. E. Raybould, 1321 Haring Hall, Vet Med: APC, Univ. of California, Davis, 1 Shields Ave., Davis, CA 95616 (e-mail: heraybould{at}ucdavis.edu )