The Role of Indole in Incidence of 2-Acetylaminofluorene-Induced Bladder Cancer in Rats.

Abstract

Fischer line 344 female rats were fed 0.06% 2-acetylaminofluorene in synthetic diets containing 25% casein and supplements of 1.4% DL-tryptophan; 1.0% indole acetic acid; 0.8% indole and 1.6% indole. Liver cancers developed in 91% of the rats of the first group and in 83% of the rats of the other 3 groups. Cancers of the urinary bladder were observed in 75% of the rats that received DL-tryptophan; 58% of the rats that received indole acetic acid and in 83% of the rats of the 2 groups that received indole. The bladder cancers were papillary or squamous cell carcinoma and previously had been observed in Fischer rats on synthetic diets that contained added DL-tryptophan. From this study it appears that indole is as effective as dietary tryptophan in the initiation of these neoplasms.