New animal model of glandular stomach carcinogenesis in Mongolian gerbils infected with Helicobacter pylori and treated with a chemical carcinogen.

In 1994 WHO/IARC concluded that "Helicobacter pylori is a definite carcinogen" based on epidemiological studies, but there have been few reports demonstrating a relation between H. pylori and stomach cancer in animal models. We have succeeded in producing adenocarcinomas in the glandular stomachs of Mongolian gerbils with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or N-methyl-N-nitrosourea as carcinogens and hope to establish an experimental stomach carcinogenesis model using H. pylori. Male Mongolian gerbils, 7 weeks old, were infected with H. pylori followed by MNNG administration at a concentration of 100ppm administration or treated with MNNG at a concentration of 300ppm in their drinking water followed by inoculation with H. pylori. They were then killed sequentially, and their excised stomachs underwent microbiological and histopathological examinations. H. pylori were detected in all infected gerbils. Hyperplastic change of pyloric mucosa was observed with high 5-bromo-2'-deoxyuridine incorporation in affected animals. H. pylori infection persists on administration of MMNG and enhances glandular stomach proliferation in Mongolian gerbils. Whether long-term colonization promotes carcinogenesis in the glandular stomach of Mongolian gerbils is a matter of great interest.