Transient increase of rat gastric amylin in the neonatal period and in experimental ulcers

Background. Amylin (islet amyloid polypeptide; IAPP)-containing cells are present in the gastric mucosa and duodenum, but little is known about their regulation. In the present study, we investigated rat gastric mucosa in the neonatal period and in an experimental model of gastric ulcer. Methods. Gastric mucosa was fixed in Bouin's solution and cut into 5-mum sections, which were examined for amylin-containing cells by light microscopic morphometry, using specific antisera and the peroxidase-antiperoxidase (PAP) method. Results. In the neonatal period (days 1, 7, 18, 28, and 45: five animals at each time point), small numbers of amylin-positive cells were consistently found in the basal cell layer of the mucosa, from birth throughout the study. A marked, transient increase in amylin-positive cells was noted in all animals examined on day 18, the day after the introduction of pellet feed. In the second set of experiments, acetic acid-induced gastric ulcers were examined. Necroticulcer lesions were observed on day 4 after the acetic acid injection, associated with increases in amylin-positive cells in the vicinity of the ulcer margins. Amylin positivity peaked on day 6 and had returned to the control level by day 28. Conclusions. The results indicate that gastric amylin increases in response to mucosal stimuli and may suggest a role of amylin in mucosal growth and repair.