[Genetic factors in gastric carcinogenesis]

Genetic control of susceptibility of rats to gastro-carcinogenesis by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was studied in susceptible ACI strain rats, resistant Buffalo strain rats, and their F1 and F2 offsprings. Rats were given MNNG at a concentration of 83 micrograms/ml in drinking water for 32 weeks and sacrificed on week 72. The incidence of gastric adenocarcinomas in F1 was as low as that in Buffalo rats. The results showed that susceptibility to MNNG was controlled genetically and that the resistance of Buffalo strain rats was autosomal dominant. To clarify the mechanisms which determine susceptibility to MNNG, some biochemical parameters such as pH of gastric juice, glutathione content in the gastric mucosa and the binding of MNNG to DNA, were analysed. No difference was observed between ACI and Buffalo strains in regard to the events leading to the binding of MNNG to DNA.