The diverse effects of brain GLP-1 receptors on ingestive behavior.

Glucagon-like peptide 1 (GLP-1) is well known as a gut hormone, but also acts as a neuropeptide, produced in a discrete population of caudal brainstem neurons that project widely throughout the brain. GLP-1R receptors (GLP-1Rs) are expressed in many brain areas of relevance to energy balance, and stimulation of GLP-1Rs at many of these sites potently suppresses food intake. This review surveys the current evidence for GLP-1R effects on feeding behavior at a wide array of brain sites, and discusses behavioral and neurophysiological mechanisms for these effects identified thus far. Taken together, it is clear that GLP-1R activity in the brain can impact feeding by diverse means, including mediation of gastrointestinal satiation and/or satiety signaling, suppression of motivation for food reward, induction of nausea, and mediation of restraint stress-induced hypophagia, but many questions about the organization of this system remain.