Opposite effects of gastrin on cell proliferation in the antrum and other parts of the upper-gastrointestinal tract in the rat.

The effect of gastrin on DNA synthesis and mitotic activity in the mucosa of the upper-gastrointestinal tract was explored in unanesthetized rats with a gastric fistula. Animals were killed at 4-hr intervals, after starting a 3-hr intravenous infusion with the lowest dose of gastrin provoking a maximal acid output. Tritiated thymidine was injected 1 hr before killing. Autoradiography was used, and labeling and mitotic indices were estimated in the fundic, antral, duodenal, and jejunal mucosa. The proliferative activity in the fundic, duodenal, and jejunal glands was significantly increased 16 hr after the administration of gastrin. In the antral glands, however, a significant decrease in both labeling and mitotic indices was observed. Rhythmic variations in proliferative activity were observed in the antral, duodenal, and jejunal mucosa in control animals. They were different from those in the gastrin-treated animals. Our data confirm the trophic action of gastrin in the fundic, duodenal, and jejunal mucosa. They also indicate an inhibitory effect of this hormone on cell proliferation in the antral mucosa.