Effect of central administration of motilin on migrating complexes in the dog

The effects of intravenous, intrathecal, and intracerebroventricular injection of motilin on the interdigestive myoelectric (MMC) activity of the stomach and small intestine were examined in conscious dogs. To monitor electrical activity, electrodes were implanted on the stomach and small bowel. To inject motilin into the central nervous system, catheters were chronically positioned in the intrathecal space at the lumbar level and in one of the lateral cerebral ventricles. In all dogs, intravenous injection of motilin caused a transient increase in the plasma concentration of motilin and initiated gastric MMCs, which propagated aborally to the ileum. Intrathecal and intracerebroventricular injections of motilin did not affect plasma motilin levels and did not induce MMCs. These data suggest that initiation of MMCs after intravenous injections of motilin occurs through receptors for motilin possibly located outside the central nervous system. These data also suggest the hypothesis that initiation of naturally occurring MMCs in the dog may not be dependent on endogenous release of motilin from the central nervous system.