Ghrelin is the ligand for growth hormone secretagogue receptor type 1 (GHSR). Induces the release of growth hormone from the pituitary. Has an appetite-stimulating effect, induces adiposity and stimulates gastric acid secretion. Involved in growth regulation. Obestatin may be the ligand for GPR39. May have an appetite-reducing effect resulting in decreased food intake. May reduce gastric emptying activity and jejunal motility. Ghrelin is broadly expressed with higher expression in the stomach. Very low levels are detected in the hypothalamus, heart, lung, pancreas, intestine and adipose tissue. Obestatin is most highly expressed in jejunum, and also found in duodenum, stomach, pituitary, ileum, liver, hypothalamus and heart. Expressed in low levels in pancreas, cerebellum, cerebrum, kidney, testis, ovary colon and lung. O-octanoylated by GOAT/MBOAT4 (By similarity). O-octanoylation is essential for ghrelin activity. The replacement of Ser-26 by aromatic tryptophan preserves ghrelin activity (PubMed:10604470, PubMed:10801861). Amidation of Leu-98 is essential for obestatin activity. The measured range is 24-51. The measured range is 24-50. Belongs to the motilin family. PubMed:16284174 reports obestatin as ligand of GPR39. However, PubMed:17289961 and others are unable to reproduce these results. It also seems to be unclear whether obestatin has opposite effects on food intake compared with ghrelin. Gut feelings - Issue 66 of January 2006