Motilin

Abstract

Motilin is likely to be accepted as a member of the established gut hormone club in the near future. It will require further research to determine whether the role of motilin in the alimentary tract is limited to its motor activity or other functions such as secretory function. Moreover, the effort will be made to determine whether, indeed, motilin limits its role to the motor activity in the interdigestive state only or if it acts in the postprandial state as well. In order to investigate these aspects, investigators will have to improve the sensitivity of radioimmunoassay methodology to be able to determine motilin levels that cannot be detected by the currently available method. Physiological stimuli for endogenous release of motilin will have to be determined and the mechanism for release of motilin will have to be investigated. The lack of elevation of plasma motilin in response to nutrients except for fats or intravenous amino acids makes us wonder whether the paracrine or neurocrine functions of this peptide may be more predominant than its endocrine function. If motilin acts predominantly as a paracrine hormone, the investigation into its physiological actions on a local tissue or organ will require a new approach, different from the traditional endocrine research. As its physiological roles become defined, disordered physiology of motilin in diseased states will undoubtedly emerge.