Agouti-related peptide (AgRP) is a neuropeptide produced in the brain by the AgRP/NPY neuron. It is only synthesized in NPY containing cell bodies located in the ventromedial part of the arcuate nucleus in the hypothalamus. The appetite-stimulating effects of AgRP are inhibited by the hormone leptin and activated by the hormone ghrelin. Adipocytes secrete leptin in response to food intake. This hormone acts in the arcuate nucleus and inhibits the AgRP/NPY neuron from releasing orexigenic peptides.

Ghrelin has receptors on NPY/AgRP neurons that stimulate the secretion of NPY and AgRP to increase appetite. AgRP is stored in intracellular secretory granules and is secreted via a regulated pathway. The transcriptional and secretory action of AgRP is regulated by inflammatory signals. Levels of AgRP are increased during periods of fasting. It has been found that AgRP stimulates the hypothalamic-pituitary-adrenocortical axis to release ACTH, cortisol, and prolactin. It also enhances the ACTH response to IL-1-beta, suggesting it may play a role in the modulation of the neuroendocrine response to inflammation [3].