Evolutionary Significance of Interspecific Differences in Gastrin-Like Immunoreactivity in the Pylorus of Phyllostomid Bats

Abstract

Gastrin is a peptide hormone synthesized and secreted by G-cells located in the antrum, or pylorus, of the mammalian stomach and thought to stimulate gastric acid secretion in response to feeding. Immunohistochemical techniques using antisera to gastrin 17-1 and cho-lecystokinin 10–20 were used to demonstrate for the first time the presence of gastrin-like im-munoreactivity in cells in the pylorus in four genera of phyllostomid bats, Glossophaga soricina, Artibeus jamaicensis, Ariteus flavescens, and Erophylla sezekorni. Significant (P ≥ 0.05) interspecific differences in gastrin cell density among these bats are the first such data for any family of mammals and correlate with interspecific histological differences in the pylorus and with interspecific differences in parietal cell abundance and activity in the fundus. Differences in density of gastrin-producing cells in bats could help explain the evolution of interspecific differences in pyloric histology because gastrin might function as a trophic hormone. An ultrastructural study of the pylorus revealed the presence of cells matching gastrin-producing G-cells described from domestic and laboratory species of mammals, suggesting that the morphology of these cells is conservative in mammals.