Serotonin distribution in the canine gastric mucosa: acute response to feeding and pouch preparation.

The gastric mucosa of anesthetized dogs was examined for serotonin (5-HT) in all major stomach regions. In animals examined immediately after anesthesia induction, the proximal corpus or antrum had substantially more 5-HT than the pyloric canal. Histological studies in 4 animals reveal a general pattern of declining enterochromaffin cell populations, from proximal corpus to pyloric canal. Either antral distention or digestive activity was induced in different groups of dogs, and only the latter produced a demonstrable, albeit transient, change in 5-HT. In 6 animals prepared with gastric fistulas, a uniform distribution of 5-HT was found throughout the stomach, after secreting 0.4 ml/h for 4 h neutral gastric juice. Their 5-HT concentrations in most regions of the stomach were substantailly greater than in any other animals in this study.