Site-specific attenuation of food intake but not the latency to eat after hypothalamic injections of neuropeptide Y in dehydrated-anorexic rats

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2009-12, Vol.297 (6), p.R1813-R1821
• Main Authors: Salter-Venzon, Dawna, Watts, Alan G
• Format: Article
• Language: English
• Subjects: Animals; Anorexia; Anorexia - etiology; Anorexia - metabolism; Anorexia - psychology; Brain; Dehydration; Dehydration - complications; Dehydration - metabolism; Dehydration - psychology; Disease Models, Animal; Drinking; Drinking Behavior; Eating; Effects; Feeding Behavior; Hypothalamic Area, Lateral - metabolism; Injections; Male; Neurons; Neuropeptide Y - administration & dosage; Neuropeptide Y - metabolism; Paraventricular Hypothalamic Nucleus - metabolism; Peptides; Rats; Rats, Sprague-Dawley; Reaction Time; Rodents; Satiety Response; Time Factors
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00116.2009

The Neuroscience Graduate Program and Department of Biological Sciences, University of Southern California College, University of Southern California, Los Angeles, California Submitted February 20, 2009 ; accepted in final form September 8, 2009 Anorexia that accompanies cellular dehydration in rats (DE-anorexia) offers a relatively simple model for investigating the functional organization of neural mechanisms that can suppress feeding during dehydration. Previous studies strongly suggest that the inputs that drive ingestive behavior control neurons in the paraventricular nucleus of the hypothalamus (PVH) and lateral hypothalamic area (LHA) remain active during DE-anorexia. Here we examine whether these two regions retain their sensitivity to neuropeptide Y (NPY). NPY is an important component in two major feeding-related inputs from the arcuate nucleus and the hindbrain. We found that intake responses to NPY injections in the LHA and PVH were suppressed in DE-anorexia, but the PVH remained less sensitive to the effects of NPY than the LHA in DE-anorexic animals. Indeed the higher dose of NPY (238 pmol) completely overcame shorter periods of DE-anorexia when injected into the LHA but not the PVH. However, the latency to eat after NPY injections remained unchanged from control animals, regardless of NPY dose, injection location, or intensity of anorexia. Furthermore, the onset and size of the strong and rapidly induced compensatory feeding that follows the return of water to DE-anorexic animals was also unaffected by any NPY injections. These data support the hypothesis that DE-anorexia develops as a consequence of the premature termination of regularly initiated meals, which perhaps involves processes that alter the sensitivity of satiety mechanisms downstream to the PVH and LHA. paraventricular nucleus of the hypothalamus; lateral hypothalamic area; satiety; ingestive behavior Address for reprint requests and other correspondence: A. G. Watts, D. Phil Hedco Neuroscience Bldg., MC 2520, Univ. of Southern California, Los Angeles, CA 90089-2520 (e-mail: watts{at}usc.edu ).