On the mechanism of action of bombesin on gastric and pancreatic secretion of the chicken.

The present experiments have been carried out in order to establish whether the stimulatory effect of bombesin on the chicken gastric acid secretion is a direct effect or is mediated by the release of hormones, such as the Avian Pancreatic Petide and/or Gastrin. removal of the pancreas, which is known to be the site of starage of the Avian Pancreatic Polypeptide, does not produce any decrease of the stimulant effect of bombesin on gastric secretion. Removal of the zone between the gizzard and duodenum, which shows histological features similar to those of the mammalian antrum and in which gastrin cells have been described, sharply decreases the basal values of gastric secretion as well as the stimulant effect of bombesin, while the effectiveness of caerulein, a gastrin-like peptide directly acting on oxintopeptic cells, is maintained. In chickens deprived of the duodenum-gizzard zone, bombesin shows a stimulant effect on pancreatic secretion indistinguishable from that observed in intact animals. It is concluded that the gastric but not pancreatic, action of bomtesin is mediated through the release of a factor(gastrin) from the gizzard-duodenum junction. Release of Avian Pancreatic Polypeptide from the pancreas is not involved in the mechanism of the action of bombesin on gastric secretion of the chicken.