A POSSIBLE MEDIUM-TERM ASSAY FOR DETECTING THE EFFECTS OF LIVER AND COLON CARCINOGENS IN RATS

The aim of the present study was to verify whether the tumorigenic eff ect of a rat liver carcinogen, 2-acetylaminofluorene (AAF), and of a p romoter of rat colon carcinogenesis, chenodeoxycholic acid (CDCA), cou ld be detected with a single medium-term assay using as markers gamma- glutamyltranspeptidase (GGT)-positive foci in the liver and aberrant c rypt foci (ACF) in colon mucosa In rats given in the first 2 weeks of treatment both N-nitrosodiethylamine (NDEA), as initiator of liver car cinogenesis, and azoxymethane (AOM), as initiator of colon carcinogene sis, the subsequent 6-week feeding on a diet containing AAF (0.01%) pr oduced a significant marked increase of the number and area of GGT-pos itive foci which is consistent with the results of long term assays. W hen rats initiated with both NDEA and AOM were fed for 6 weeks on a di et containing CDCA (0.1%) a significant increase of large ACF as well as of crypt multiplicity was observed, consistently with the promoting effect of CDCA in colon carcinogenesis. The results obtained in this preliminary study suggest that this medium-term assay might be able to screen both liver and colon carcinogens in rats.