Histamine, histamine formation capacity and gastrin in cysteamine-induced peptic ulcer.

We attempted to induce chronic peptic ulcer in the rat by injection of consecutive doses of cysteamine. We investigated the incidence of peptic ulceration and measured gastric mucosal histamine, histamine formation capacity (HFC), plasma gastrin and tissue (oesophagus, duodenum, liver and lung) histamine in rats 1, 7, 14, 21, and 28 days after injection of cysteamine-HCl (300 mg/kg s.c. and 100 mg/kg 8 h later). Saline injections were used in control rats. After 24 h all rats given cysteamine had duodenal ulcers and the ulcer incidences after 7 and 14 days were 60 and 40%, respectively. After Day 21 no ulcers were found. Microscopy revealed ulcer healing seen as epithelialized scars from Day 14 onwards. A rising incidence of gastric metaplasia of the duodenal mucosa was noted from Day 7 after cysteamine treatment, which may have pathophysiological significance. Gastric mucosal histamine was higher and plasma gastrin was lower after 24 h compared with controls and values obtained later in the study. Rats with duodenal ulceration had significantly higher gastric mucosal histamine than those without lesions and control rats. A direct relationship was found between plasma gastrin and HFC in rats given cysteamine. A small but significant increase in histamine content of the liver was also observed after 24 h. No significant changes were found in other tissue specimens. Thus, a rise in gastric histamine is associated with duodenal ulcers in this model.