Effects of central and peripheral administration of dopamine on pattern of intestinal motility in dogs

The central vs peripheral effects of dopamine on the motility pattern of the small intestine were investigated by electromyography in four conscious dogs, chronically fitted with transparietal duodenal and jejunal electrodes. In the fasted dog intracerebroventricular administration of dopamine (10 micrograms/kg) increased the duration of the interval between two consecutive migrating myoelectric complexes (MMC) while the intravenous administration at a 10-fold higher dose induced in 37.5% of trials a phase of regular spiking activity propagated over the duodenum and the jejunum. When dopamine was centrally administered 1 hr before a daily meal, the duration of the postprandial disruption of the MMC pattern was significantly (P less than 0.01) reduced from 9.4 +/- 1.8 to 3.2 +/- 1.3 hr at the level of the duodenum. Peripheral administration of dopamine did not modify the duration of the postprandial disruption. All of the central and peripheral effects persisted after vagotomy. It is concluded that in the dog dopamine acts centrally to modify the food-induced disruption of the MMC pattern and the frequency of the interdigestive myoelectric complexes.