Motilin is a gastrointestinal regulatory polypeptide produced by motilin cells in the duodenal epithelium. It is released into the general circulation at about 100-min intervals during the inter-digestive state and is the most important factor in controlling the inter-digestive migrating contractions. Motilin also stimulates endogenous release of the endocrine pancreas [1]. This family also includes ghrelin, a growth hormone secretagogue synthesised by endocrine cells in the stomach. Ghrelin stimulates growth hormone secretagogue receptors in the pituitary. These receptors are distinct from the growth hormone-releasing hormone receptors, and thus provide a means of controlling pituitary growth hormone release by the gastrointestinal system [2].

1: Motilin and clinical application. Itoh Z; Peptides 1997;18:593-608. PMID:9210180

2: Ghrelin: discovery of the natural endogenous ligand for the growth hormone secretagogue receptor. Kojima M, Hosoda H, Matsuo H, Kangawa K; Trends Endocrinol Metab 2001;12:118-122. PMID:11306336