Carcinogenic effect of 7-methoxy-2-nitro-naphtho[2,1-b] furan (R 7000) in the forestomach of rats.
7-methoxy-2-nitro-naphtho[2,1-b] furan (R 7000), known as a very potent mutagen and a very active in vivo carcinogen was employed here to develop squamous cell carcinoma in the rat. Seventy male Wistar rats received R 7000 p.o. dissolved in deionized water with 5% ethanol for periods from 1 to 21 months, while 20 served as controls receiving either water or 5% ethanol. All the animals were killed 21 months after the beginning of the experiment. Microscopic lesions were noticed in the forestomach after only 1 month of R 7000 administration. Histologic features varied from slight dysplasia to invasive carcinoma. Their sizes and invasive character increased significantly with the amount of R 7000 administered (P less than 0.05). R 7000 can be considered as a locally acting carcinogen since its carcinogenic effects appear at a place where the compound collects after swallowing. R 7000 is a weak carcinogen at the concentration employed here, when compared to some nitrosamines used in the development of forestomach cancer in rodents. The exact mechanism of the carcinogenic effects remains to be explained.
D000818:Animals; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D009153:Mutagens; D009581:Nitrofurans / Q000378:metabolism / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013274:Stomach Neoplasms / Q000139:chemically induced* / Q000473:pathology
D002273:Carcinogens; D009153:Mutagens; D009581:Nitrofurans; C030911:2-nitro-7-methoxynaphtho(2-1b)furan