title: Relative tumour promoting activity of three polychlorinated biphenyls in rat liver.
abstract: The relative tumour promoting activity of three structurally and toxicologically diverse polychlorinated biphenyls (3,4,5,3',4'-penta- 2,3,4,3',4'-penta- and 2,4,5,2',4',5'-hexachlorobiphenyl) was measured in an initiation/promotion assay in nitrosodiethylamine-initiated female Sprague-Dawley rats. The congeners under study were administered by once-weekly subcutaneous injections for 20 weeks. Evaluation of the development of gamma-glutamyl transpeptidase (GGT)- and glutation transferase P (GST-P)-positive hepatic foci showed that all congeners promoted altered hepatic foci, although 3,4,5,3',4'-pentachlorobiphenyl was far more potent. The volume fraction of the liver occupied by GGT-positive tissue in the 3,4,5,3',4'-pentachlorobiphenyl-treated animals (100 micrograms/kg per week) was 23%, while the volume fractions of altered liver tissue in the rats treated with 2,3,4,3',4'-pentachlorobiphenyl (5000 micrograms/kg per week) and 2,4,5,2',4',5'-hexaCB (20,000 micrograms/kg per week) were 1.2 and 2.3, respectively. The enhancement of GGT- and GST-P-positive foci was accompanied by an increased incidence of histological changes in the livers.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Hemming
authors.forename: S
authors.initials: S
authors.lastname: Flodström
authors.forename: L
authors.initials: L
authors.lastname: Wärngård
authors.forename: A
authors.initials: A
authors.lastname: Bergman
authors.forename: T
authors.initials: T
authors.lastname: Kronevi
authors.forename: I
authors.initials: I
authors.lastname: Nordgren
authors.forename: U G
authors.initials: UG
authors.lastname: Ahlborg
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000378:metabolism / Q000633:toxicity*; D005260:Female; D005982:Glutathione Transferase / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced*; D011078:Polychlorinated Biphenyls / Q000378:metabolism / Q000633:toxicity*; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D005723:gamma-Glutamyltransferase / Q000378:metabolism
chemical_list: D002273:Carcinogens; D000072317:Polychlorinated Dibenzodioxins; D011078:Polychlorinated Biphenyls; D005723:gamma-Glutamyltransferase; D005982:Glutathione Transferase; C023035:3,4,5,3',4'-pentachlorobiphenyl; C014024:2,4,5,2',4',5'-hexachlorobiphenyl