Norepinephrine and the control of food intake

The focus of the present review is to reconsider the role of endogenous nor epinephrine (NE) in brain, specifically within the hypothalamic paraventric ular nucleus (PVN), with regard to its potential role in eliciting eating o r satiety. The PVN is innervated by NE fibers and is a site at which infusi on of exogenous NE elicits eating at low doses. Two subtypes of alpha -adre nergic receptors within the PVN exert antagonistic actions on eating in the rat:activation of PVN alpha (2)-adrenoceptors increases eating, whereas ac tivation of PVN alpha (1)-adrenoceptors suppresses eating. Pharmacologic ma nipulations that elevate NE can increase or decrease food intake; depending on the site and type of NE manipulation. Certain antiobesity drugs may act to reduce eating via release of NE and subsequent activation of alpha (1)- adrenoceptors. The PVN exhibits a reliable rhythm in the secretion of endog enous NE over the dark-and-light cycle, and this rhythm may interact with c hanges in numbers of PVN alpha (1)- and alpha (2)-adrenoceptors to modulate eating during the dark-and-light cycle. Push-and-pull and microdialysis st udies indicate that NE secretion is strongly associated with eating, partic ularly at the start of the dark phase. The present review considers potenti al interactions of NE with substances such as leptin and neuropeptide Y tha t alter eating. Nutrition 2000; 16:837-842. (C) Elsevier Science Inc. 2000.