MSH (melanocyte-stimulating hormone), produced by the pituitary gland, regulates the pigmentation of the skin by increasing melanin production in melanocytes. Gamma-1 MSH corresponds to aa 77-87 of corticotropin precursor (pro-opiomelanocortin, POMC). Gamma-MSH peptides contain a core 7-amino-acid residue sequence similar to ACTH(4-10). Gamma-1 MSH is an endogenous melanocortin MC3 receptor agonist (pKi=7.46) that displays a 40-fold selectivity over MC4. It increases the release of extracellular dopamine, which induces grooming and vertical activity (rearing) in rats. It also exhibits hypertensive, tachycardic and short-term analgesic activity in vivo. Gamma-1 MSH facilitates learning and memory. It can also affect inflammatory, immune response and peripheral nerve regeneration.