<P> The receptor for ghrelin, the ghrelin / growth hormone secretagogue receptor (GHS - R), is found on the same cells in the brain as the receptor for leptin, the satiety hormone that has opposite effects from ghrelin . Ghrelin also plays an important role in regulating reward perception in dopamine neurons that link the ventral tegmental area to the nucleus accumbens (a site that plays a role in processing sexual desire, reward, and reinforcement, and in developing addictions) through its colocalized receptors and interaction with dopamine and acetylcholine . Ghrelin is encoded by the GHRL gene and is presumably produced from the cleavage of the prepropeptide ghrelin / obestatin . Full - length preproghrelin is homologous to promotilin and both are members of the motilin family . </P> <P> Unlike the case of many other endogenous peptides, ghrelin is able to cross the blood - brain - barrier, giving exogenously - administered ghrelin unique clinical potential . </P> <P> Ghrelin was discovered after the ghrelin receptor (called growth hormone secretagogue type 1A receptor or GHS - R) was discovered in 1996 and was reported in 1999 . The hormone name is based on its role as a growth hormone - releasing peptide, with reference to the Proto - Indo - European root ghre -, meaning "to grow". </P> <P> The GHRL gene produces mRNA which has four exons . Five products arise: the first is the 117 - amino acid preproghrelin . (It is homologous to promotilin; both are members of the motilin family). It is cleaved to produce proghrelin which is cleaved to produce a 28 - amino acid ghrelin (unacylated) and C - ghrelin (acylated). Obestatin is presumed to be cleaved from C - ghrelin . </P>

Ghrelin is a hormone produced in the stomach that acts much like leptin