The agouti-related protein (AgRP) consists of 132 amino acids and belongs to the group of neuropeptides. It occurs in the brain only in the nucleus arcuatus (hypothalamus) and there in neurons along with NPY and GABA.
AgRP has a strong appetite stimulating effect and significantly increases food intake and fat formation.
A signal outflow from the nucleus arcuatus to the nucleus parabrachialis inhibits certain parabrachialis neurons which, if "unleashed", trigger anorexic (self-starvation) behavior. If the AgRP neuron in the nucleus arcuatus is destroyed in mice, the animal stops eating and starves to death within a week.
Bäckberg M, Madjid N, Ögren SO, Meister B (2004). Down-regulated expression of agouti-related protein (AGRP) mRNA in the hypothalamic arcuate nucleus of hyperphagic and obese tub/tub mice. Brain Res. Mol. Brain Res. 125 : 129–39.
Wu, Q., Clark, M.S. and Palmiter, R.D. (2012) Deciphering a neuronal circuit that mediates appetite. Nature. 483 : 594 - 597.