Agouti Related Protein (AGRP, or AGRT), is an endogenous antagonist of the melanocortin receptors MC3R and MC4R found in the hypothalamus and exhibits potent orexigenic activity. AGRP can act as a competitive antagonist to proopiomelanocortin (POMC)-derived peptides at the melanocortin-4 receptor (MC4R), and that this homeostatic mechanism is important as a means of coordinating appetite with perceived metabolic requirement. AGRP is upregulated by fasting while intracerebroventricular injections of synthetic AGRP lead to increased appetite and food intake. Thus, AGRP is a powerful orexigenic peptide that increases food intake when ubiquitously overexpressed or when administered centrally.
