title: Colon carcinogenesis with azoxymethane and dimethylhydrazine in germ-free rats.
abstract: The effect of intestinal microflora on the sensitivity of the colon to the carcinogenic effect of azoxymethane and a large dose of 1,2-dimethylhydrazine was studied using germ-free and conventional female Fischer rats. Injection s. c. of 1,2-dimethylhydrazine-induced tumors of the ear duct, kidney, and small intestine of conventional rats but none in germ-free animals. Only 20% germ-free rats showed 1,2-dimethylhydrazine-induced colonic tumors, whereas 93% of conventional rats developed multiple colonic tumors. Intrarectal instillation of azoxymethane appreciably increased the multiplicity of colonic tumors in germ-free rats and in gnotobiotic rats contaminated with Clostridium perfringens, as compared to conventional controls. None of the germ-free rats showed ear duct tumors. The incidence of kidney tumors was lower in germ-free rats than in other groups. It is concluded than the intestinal microbial populations alter the effect of carcinogens in the large intestine.
mesh_terms: D000230:Adenocarcinoma / Q000139:chemically induced*; D000818:Animals; D001391:Azo Compounds; D002273:Carcinogens; D003015:Clostridium Infections / Q000150:complications; D003016:Clostridium perfringens; D003110:Colonic Neoplasms / Q000139:chemically induced*; D004428:Ear Neoplasms / Q000139:chemically induced; D005260:Female; D005856:Germ-Free Life; D006834:Hydrazines; D007267:Injections; D007414:Intestinal Neoplasms / Q000139:chemically induced; D007680:Kidney Neoplasms / Q000139:chemically induced; D009002:Monomethylhydrazine; D009374:Neoplasms, Experimental / Q000139:chemically induced; D051381:Rats; D012007:Rectum
chemical_list: D001391:Azo Compounds; D002273:Carcinogens; D006834:Hydrazines; D009002:Monomethylhydrazine