title: Hepatotoxicity of agents that enhance formation of focal hepatocellular proliferative lesions (putative preneoplastic foci) in a rapid rat liver bioassay.
abstract: The histopathology of hepatic toxicity for 58 chemicals previously tested in a rapid rat liver bioassay for demonstrating potential hepatocellular carcinogens and/or tumor promoters was reviewed. Rats received the test diet for 1 week prior to partial hepatectomy and for an additional 5 weeks thereafter at doses near the estimated maximally tolerated dose. These rats served as controls for others receiving initiation by N-nitrosodiethylamine (DEN) and the test diets. Twenty-two of these chemicals were previously found to enhance the formation of glutathione S-transferase, placental form (GST-P)-positive putative preneoplastic hepatocellular foci (promoters) following DEN initiation in this rapid bioassay, whereas 36 chemicals did not. Of the agents that promoted GST-P-positive foci, 14/22 (63.6%) produced toxic hepatocyte lesions while only 4/36 (11.1%) of the nonpromoters did so at the doses used. Biliary toxicity was found for 7/22 (31.8%) of the promoters and 6/36 (16.7%) of the nonpromoters. Only 2/13 (15%) chemicals that inhibited GST-P-positive foci produced hepatic toxicity. Thus, agents that were presumed hepatic tumor promoters characteristically were hepatotoxins while nonpromoters of carcinogenesis were not hepatotoxins in this rapid rat liver bioassay.
authors.affiliation: Division of Cancer Etiology, National Cancer Institute, Frederick, Maryland 21701-1013.
authors.forename: J M
authors.initials: JM
authors.lastname: Ward
authors.forename: H
authors.initials: H
authors.lastname: Tsuda
authors.forename: M
authors.initials: M
authors.lastname: Tatematsu
authors.forename: A
authors.initials: A
authors.lastname: Hagiwara
authors.forename: N
authors.initials: N
authors.lastname: Ito
mesh_terms: D000818:Animals; D001681:Biological Assay; D002273:Carcinogens; D056486:Chemical and Drug Induced Liver Injury / Q000473:pathology*; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D008297:Male; D011230:Precancerous Conditions / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002273:Carcinogens