Recent Advances in Motilin Research: Its Physiological and Clinical Significance

Since 1975, when motilin was synthesized in Japan1,2, we concentrated our efforts on various aspects of motilin in man and dog. We have found that: 1.) motilin induces the cyclic recurring episodes of caudad-moving bands of strong contractions that move from the lower esophageal sphincter (LES) to the terminal ileum, 2.) motilin has no significant influence upon the gastrointestinal contractile activity during the digestive state, and 3.) the naturally-occurring and motilin-induced gastric contractions are completely abolished by the ingestion of food or the i.v. infusion of pentagastrin3,4. These actions of motilin are all related to the interdigestive function of the gut and, therefore, we have proposed the name “interdigestive hormone” for motilin5. Recently, we have developed a RIA for motilin and this then enabled us to measure changes in plasma motilin concentration. Moreover, we synthesized fragments and an analogue of motilin, the biological activity of which was also investigated.