GLP-1 mechanisms for appetite effects. (A) Local GLP-1 release causes an increase in concentration in the hepatic portal vein to reach area postrema. (B) GLP-1 receptors on vagus nerve afferent fibers modulate the sensation of gastric distension. (C) Chemosensitive vagal afferents stimulated by GLP-1 terminate in NTS. (D) GLP-1 receptors are found in key appetite regulating areas of the brain. Arc, arcuate nucleus; AP, area postrema; NTS, nucleus of the solitary tract; PBN, parabrachial nucleus; PVN, paraventricular nucleus of the hypothalamus.