Stimulating effect of bombesin on the growth of gastrointestinal tract and pancreas in suckling rats

Comparative development of gastrin and somatostatin cell populations in the pancreas, stomach, and duodenum of the rat during the perinatal period

The comparative growth patterns of endocrine gastrin and somatostatin cell populations were examined in the rat, during the perinatal period, to investigate possible relationships between their development and that of gastric acid secretion, gastrin and somatostatin hormones being implicated in the regulation of acid secretion. Total cell populations were estimated daily in the pancreas, stomach, and duodenum, by using a quantitative morphological method, from 19 days postcoitum to 8 days postpartum. In the pancreas, both cell types were present at 19 days postcoitum. After increasing, gastrin cells abruptly dropped from 4 days postpartum, while somatostatin cells continued to increase. In the stomach, gastrin cells seemed to appear at 19 days postcoitum, increasing with age. Somatostatin cells appeared only after birth and could be precisely quantified from 4 days postpartum. In the duodenum, the two cell types were present in similar numbers at 19 days postcoitum and increased similarly with age. Comparison of gastrin and somatostatin cell developmental behavior with previous data on the ontogeny of acid secretion shows a parallelism between the appearance of basal H+ fluxes at 20-21 days postcoitum and the high daily multiplication of the gastrin cell number in the three organs. Additionally, the marked decrease of pancreatic gastrin cell population at 4 days postpartum and the simultaneous development of the gastric somatostatin cell population might explain, among other mechanisms, the diminution of gastric acid secretion noted after birth.

Peptides and epithelial growth regulation

There is now considerable evidence implicating several peptides in the control of gastrointestinal epithelial cell proliferation and cell renewal. While some of these may act directly, many may be involved in regulating the powerful trophic effects of the intake and digestion of food on the gut epithelium. Several peptides have been associated with the regulation of intestinal cell proliferation. There is little doubt that gastrin is trophic to the stomach, but, its role in the rest of the gastrointestinal tract is debatable. Enteroglucagon has often been associated with increased intestinal epithelial proliferation, but at the moment all the evidence for this is circumstantial. The effects of peptide YY and bombesin warrant further study. The availability of recombinant epidermal growth factor (EGF) has recently enabled us to demonstrate a powerful trophic response to infused EGF throughout the gastrointestinal tract. The increasing availability of peptides will eventually allow the rigorous in vivo evaluation of the trophic role of these potentially very important peptides.