Mixed function oxidase activities in lactating rats and their offspring following dietary exposure to polybrominated biphenyls
Dent, J.G.; Mccormack, K.M.; Rickert, D.E.; Cagen, S.Z.; Melrose, P.; Gibson, J.E.
Toxicology and Applied Pharmacology 46(3): 727-735
1978
ISSN/ISBN: 0041-008X PMID: 218324 Document Number: 131097
Exposure of pregnant rats to diet containing 50 ppm polybrominated biphenyls (PBB, an environmental contaminant) from day 8 of gestation to day 15 postpartum caused significant increases in hepatic and extrahepatic microsomal mixed function oxidase activity. Hepatic arylhydrocarbon hydroxylase (AHH), epoxide hydratase (EH), hexobarbital hydroxylase (hex-OH), and the 2- and 4-hydroxylation of biphenyl (2-OHBP, 4-OHBP) were increased 10, 3, 3, 23 and 6-fold, respectively, in animals fed diet containing PBB. The hex-OH, 2-OHBP and 4-OHBP activities were not detectable in the S9 fraction from maternal mammary glands of control or PBB-fed rats; exposure to PBB increased mammary AHH 2.5-fold and decreased EH activity 45%. Renal AHH activity was increased 7-fold but renal EH activity was unaltered by feeding PBB. Pups from control and PBB-exposed mothers were crossfostered at birth to give offspring which received PBB exposure prenatally, postnatally (via mothers milk) or both pre- and postnatally. Each type of exposure produced increases in hepatic AHH and EH activities over those found in pups born to and raised by mothers which received no PBB. PBB induce hepatic and extrahepatic mixed function oxidase activity in nursing rats and the extrahepatic effects of the mixture are different from the hepatic effects. PBB were effective stimulators of hepatic enzymes in 15 day old rats when the neonates were exposed transplacentally and/or via the mothers' milk. The results suggest potential toxic interaction between PBB and other agents which are of importance to mother and young.