Relative tumour promoting activity of three polychlorinated biphenyls in rat liver.
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.
Hemming
H
H
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Flodström
S
S
Wärngård
L
L
Bergman
A
A
Kronevi
T
T
Nordgren
I
I
Ahlborg
U G
UG
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
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