Trophic effect of some regulatory peptides on gastric exocrine and endocrine cells of the rat.

The effects of somatostatin and bombesin on gastric cells of the rat were demonstrated by measurement of epithelial cell proliferation after injection of tritiated thymidine and by quantification of cell populations. An 8 h-infusion of somatostatin transiently reduced labelling and mitotic indices in fundic and antral mucosae of normal rats and inhibited the growth stimulating effect of gastrin for a longer period of time. Three weeks administration of long-acting somatostatin preparation in combination with gastrin to normal rats, or alone to rats with chronic endogenous hypergastrinaemia, significantly antagonized the trophic effect of gastrin on the parietal cell population. An 8 day administration of bombesin by subcutaneous injection significantly increased the labelling index of antral gastrin cells compared to controls but did not change the labelling index of antral somatostatin cells. Quantification of the total antral gastrin cell population in bombesin-treated rats demonstrated a significant gastrin cell hyperplasia, which was correlated to the increase in gastrin content found in antral tissue. We conclude that cell kinetic and morphometric methods are complementary tools for the study of in vivo trophic effects of hormones.