title: Roles for Orexin/Hypocretin in the Control of Energy Balance and Metabolism.
abstract: The neuropeptide hypocretin is also commonly referred to as orexin, since its orexigenic action was recognized early. Orexin/hypocretin (OX) neurons project widely throughout the brain and the physiologic and behavioral functions of OX are much more complex than initially conceived based upon the stimulation of feeding. OX most notably controls functions relevant to attention, alertness, and motivation. OX also plays multiple crucial roles in the control of food intake, metabolism, and overall energy balance in mammals. OX signaling not only promotes food-seeking behavior upon short-term fasting to increase food intake and defend body weight, but, conversely, OX signaling also supports energy expenditure to protect against obesity. Furthermore, OX modulates the autonomic nervous system to control glucose metabolism, including during the response to hypoglycemia. Consistently, a variety of nutritional cues (including the hormones leptin and ghrelin) and metabolites (e.g., glucose, amino acids) control OX neurons. In this chapter, we review the control of OX neurons by nutritional/metabolic cues, along with our current understanding of the mechanisms by which OX and OX neurons contribute to the control of energy balance and metabolism.
authors.affiliation: Department of Pharmacology, University of Michigan, 1000 Wall St, 5131 Brehm Tower, Ann Arbor, MI, 48105, USA.
authors.forename: Paulette B
authors.initials: PB
authors.lastname: Goforth
authors.affiliation: Departments of Internal Medicine, and Molecular and Integrative Physiology, University of Michigan, 1000 Wall St, 6317 Brehm Tower, Ann Arbor, MI, 48105, USA. mgmyers@umich.edu.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Myers
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D000068797:Orexins / Q000378:metabolism*
chemical_list: D000068797:Orexins
keywords: Energy expenditure; Food intake; Glucose homeostasis; Orexin/hypocretin