Neuromedin S is found in the brain of humans and other mammals. It is produced in the suprachiasmatic nucleus of the hypothalamus and is related to neuromedin U. It is thought to be involved in regulation of circadian rhythm and also has appetite suppressant effects, as well as regulating the release of several other peptide hormones including vasopressin, luteinizing hormone, and oxytocin. Neuromedin S, a novel neuropeptide of 36 amino acids, was isolated from rat brain as an endogenous ligand for the orphan G protein-coupled receptors FM-3/GPR66 and FM-4/TGR-1, identified to date as type-1 and type-2 NMU receptors, respectively. The peptide was designated neuromedin S (NMS) because it is specifically expressed in the suprachiasmatic nucleus of the hypothalamus.