title: Sequential study on the synergistic effects of 2,2',4,4',5,5'-hexabromobiphenyl and 3,3',4,4',5,5'-hexabromobiphenyl on hepatic tumor promotion.
abstract: A sequential study was completed to determine the effect of polybrominated biphenyl (PBB) congeners on the enhancement of gamma-glutamyl transpeptidase (GGT)-positive altered hepatic foci (AHF) and the development of hepatic nodules (HN) and carcinomas. Female Sprague-Dawley rats were given a single dose of N-nitrosodiethylamine (NDEA) 24 h following a 70% partial hepatectomy. Thirty days later, rats were randomly assigned to groups and fed a basal diet or the basal diet containing 10 p.p.m. 2,2',4,4',5,5'-hexabromobiphenyl (245-HBB), 0.1 p.p.m. 3,3',4,4',5,5'-hexabromobiphenyl (345-HBB) or 10 p.p.m. 245-HBB plus 0.1 p.p.m. 345-HBB for 140 days followed by a basal diet for up to another 310 days. Rats from each group were killed 170, 240 or 480 days after partial hepatectomy. Dietary exposure to 245-HBB and 245-HBB plus 345-HBB enhanced the development of AHF and HN whereas 345-HBB alone did not. The combination of 245-HBB and 345-HBB caused a synergistic effect on the development of AHF and HN. The number of hepatocellular carcinomas was low and evenly distributed among the groups of rats fed diets containing PBB.
mesh_terms: D000818:Animals; D004052:Diethylnitrosamine; D005260:Female; D008099:Liver / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced*; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D011230:Precancerous Conditions / Q000139:chemically induced*; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000032:analysis
chemical_list: D011075:Polybrominated Biphenyls; D004052:Diethylnitrosamine; C018566:2,4,5,2',4',5'-hexabromobiphenyl; D005723:gamma-Glutamyltransferase; C032790:3,3',4,4',5,5'-hexabromobiphenyl