Praomys (Mastomys) natalensis: animal model for study of histamine-induced duodenal ulcers.

Praomys (Mastomys) natalensis, an African rodent ranging in size between a mouse and a rat, is more susceptible to the induction of duodenal ulcers by constant infusion of exogenous histamine through an osmotic minipump implanted subcutaneously than other rodent species tested such as mouse, rat, or guinea-pig. By increasing the doses of infused histamine, there were increases in the incidence, intensity, and perforation rate of duodenal ulcers in Mastomys. The induction of duodenal ulcers in Mastomys by tetra- and pentagastrins was unsuccessful, probably because of the limited releasing capacity of the present minipump for use of these two peptides which were sparingly soluble in water. More soluble human synthetic gastrin I was approximately three to four times as potent as histamine for inducing duodenal ulcers in Mastomys. The susceptibility of Mastomys to the induction of duodenal ulcer by cysteamine appears to be comparable to that of rat. The complete suppression of histamine-induced duodenal ulcers of Mastomys was possible by repeated subcutaneous injections of cimetidine.