[Promotion of adenocarcinomas at the preternatural anus by bile acids in rats (author's transl)].

Wistar rats spontaneously develop adenomatous polyps with cell dysplasia (Figs. 2 and 3) and finally, adenocarcinomas (Fig. 1) at the preternatural anus 120-200 days after the formation of a double loop colostomy. With respect to the potential significance of bile acid metabolites in the pathogenesis of colonic cancer, the effect of continuous oral administration of chenodeoxycholic acid (CDCA) on the rate of carcinomas at the preternatural anus was examined. This animal model gained special interest because until now the possible cocarcinogenic rule of bile metabolites was generally demonstrated only after additional administration of chemical carcinogens like dimethylhydracin or nitrosoguanidin. Of ten rats in the CDCA-treated group, three already showed a malignant transformatin to adenocarcinomas at the preternatural anus 60 days after a colostomy (Fig. 4). Apparently the alteration of natural ecologic conditions diminishes the resistance against external and internal carcinogenic or coarcinogenic agents. The role of bile acid metabolites is discussed under these circumstances.