γ-1-MSH, amide acetate (72629-65-3 free base), a putative hormone in the N-terminal region of the ACTH/beta- endorphin (beta-EP) precursor protein, was studied by RIA with an antiserum against gamma 3-MSH in ACTH-producing mouse pituitary tumor cells, AtT-20/D16v.

γ-Melanocyte Stimulating Hormone (γ-MSH) regulates a multitude of metabolic functions including energy homeostasis, food intake, sodium (Na+) balance, and blood pressure regulation. γ-MSH is processed from the precursor hormone pro-opio-melanocortin (POMC) in the pituitary gland, where component peptides are released into the cerebral spinal fluid and systemic circulation. The natural receptor for γ-MSH is the melanocortin receptor 3 (MC3-R), a G-protein-coupled receptor that activates adenylate cyclase and is expressed in brain (hypothalamus, cortex, and thalamus), gut, placenta, and kidney. γ-MSH regulates Na+ balance by inducing urinary Na+ excretion (natriuresis) under conditions of high dietary salt intake[1].