Influence of long-term 16,16-dimethyl prostaglandin E2 treatment on the rat gastrointestinal mucosa.

We performed acid secretory and histomorphometric studies in rats treated intragastrically with a regimen of 100 micrograms/kg or 5 micrograms/kg of 16,16-dimethyl prostaglandin E2, or of saline every 8 h for 21 days. All animals given the high-dose treatment developed a macroscopically visible enlargement of the ridge at the corpus-forestomach border, due to an increase in connective tissue and epithelial cell layer. Mucosal thickness was significantly increased in all parts of the stomach, the duodenum, and the proximal colon, but most markedly in the gastric antrum (+115%), where it was accompanied by a higher mitotic rate and hyperplasia of surface and foveolar mucous cells. Within the oxyntic area (corpus), high-dose prostaglandin treatment led to an increase in the number of surface and foveolar mucous cells and chief cells. In contrast, both the number of parietal cells and maximal acid output were not influenced. It is unlikely that the hyperplasia of gastric mucosa is mediated by gastrin since gastrin has no trophic effects on the rat antrum and disproportionally increases the parietal cell number of the oxyntic gastric glands.