Brain stem melanocortinergic modulation of meal size and identification of hypothalamic POMC projections

• DOI: 10.1152/ajpregu.00869.2004
• Publication Date: 2005-03-04T01:34:14Z
• Authors: Huiyuan Zheng; Laurel M. Patterson; Curtis B. Phifer; Hans-Rudolf Berthoud
• Keywords: Dorsal motor nucleus

Metabolic, cognitive, and environmental factors processed in the forebrain modulate food intake by changing potency of direct controls meal ingestion brain stem. Here, we behaviorally anatomically test role hypothalamic proopiomelanocortin (POMC) system mediating some these descending, indirect controls. Melanotan II (MTII), a stable melanocortin 4 receptor (MC4R) 3 (MC3R) agonist injected into fourth ventricle near dorsal vagal complex, potently inhibited 14-h decreasing size but not frequency; SHU9119, an antagonist, increased selectively increasing size. Furthermore, MTII SHU9119 tended to decrease heart rate body temperature measured telemetrically freely moving rats. Numerous alpha-melanocyte-stimulating hormone-immunoreactive axons were close anatomical apposition nucleus tractus solitarius neurons showing c-Fos response gastric distension, expressing neurochemical phenotypes implicated ingestive control, projecting brown adipose tissue. In retrograde tracing experiments, small percentage arcuate POMC was found project complex. Thus signaling stem is sufficient alter via satiety signals sympathetic outflow. Although findings support involvement hypothalamomedullary projections part signal, they do rule out signal.