title: Chronic gastric ulcers are not predisposed to tumor formation when exposed to a low dose of carcinogen.
abstract: The purpose of this experiment was to determine whether chronic gastric ulcers in the rat are predisposed to tumor formation when exposed to a usually noncarcinogenic dose of the carcinogen, N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG). Two groups of rats were prepared; one subjected to a standard ulcer-producing operation, the other as control. Both groups were given oral MNNG (100 mg/liter as drinking water) for 12 weeks, the carcinogen was then stopped and replaced with tap water, and the experiment terminated at 52 weeks. Results showed that a low dose of carcinogen (200 mg) did not induce tumor formation in any of the normal rats. In the presence of a chronic gastric ulcer, only intestinal metaplasia and hyperplastic glandular nodules were observed, but there were no gastric tumors. It is concluded that the presence of a chronic gastric ulcer did not increase the likelihood of gastric tumor formation in rats treated with a noncarcinogenic dose of the carcinogen MNNG.
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000494:pharmacology*; D005260:Female; D005744:Gastric Acid / Q000378:metabolism; D005755:Gastrins / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013270:Stomach / Q000187:drug effects / Q000473:pathology; D013274:Stomach Neoplasms / Q000209:etiology*; D013276:Stomach Ulcer / Q000150:complications* / Q000473:pathology
chemical_list: D002273:Carcinogens; D005755:Gastrins; D008769:Methylnitronitrosoguanidine