Experimental model of gastric carcinogenesis with N-methyl-N-nitrosourea for F344 rats and C3H mices is valid for Wistar rats?BACKGROUND: The N-methyl-N-nitrosourea (MNU) is a direct acting carcinogen, inducing tumors in several species in a variety of organs, including stomach of rats. Treatment of MNU in the drinking water for 25-42 weeks selectively induced glandular gastric carcinoma in F344 rats and C3H mice. AIM: To establish an experimental model for selective MNU induction of glandular stomach cancer in Wistar rats. METHODS: A total of 48 males eight-week-old Wistar rats were used in the present study. MNU (Sigma-Aldrich) was dissolved in DMSO and provided as the drinking water ad libitum for a period ranging from 16 to 70 weeks. After 16 weeks, four rats were randomly selected and killed. After every six weeks four animals were killed until 70 weeks. RESULTS: Survival rate was higher than 90%. It had the induction of two adenocarcinomas, one squamous cell carcinoma and one sarcoma. The incidence of gastric adenocarcinoma was 4.5% (0.5 to 15). CONCLUSIONS: The experimental model of gastric carcinogenesis in Wistar rats, using MNU dissolved in water, showed not practice viability in this study due to the low rate of gastric adenocarcinoma.
