Agouti-related peptide (AgRP) is a neuropeptide produced in the brain in the arcuate nucleus of the hypothalamus. It is an endogenous antagonist of melanocortin receptors (MC3-R and MC4-R) which plays a critical role in energy balance. AgRP plays a regulatory role in energy metabolism. AgRP not only increases food intake, but also decreases energy expenditure. AgRP increases fat mass, suppresses uncoupling protein I (UCP-1) in brown adipose tissue (BAT) and decreases plasma thyroid-stimulating hormone (TSH) concentrations in rats.