Promoting Effect of Bile Acids on Colon Carcinogenesis After Intrarectal Instillation of N -Methyl- N ′ nitro- N -nitrosoguanidine in Rats 2

The effect of 2 bile acids in colon carcinogenesis was studied in rats. A single dose of N-methyl-N′nitro- N-nitrosoguanidine (MNNG) was instilled intrarectally. Subsequently, repeated intrarectal doses of lithocholic or taurodeoxycholic acid were administered. Both bile acids increased the frequency of MNNG-induced colorectal neoplasms. Neither bile acid induced tumors when used alone. The lesions were like those induced by MNNG alone and included adenomas and adenocarcinomas. The bile acids acted as promoters of carcinogenesis.