Potential mechanisms for redistribution of polychlorinated biphenyls during pregnancy and lactation.
Female mice treated with 14C-2,4,5,2',4',5'-hexachlorobiphenyl (6-CB) two weeks prior to mating eliminated virtually their entire body burden of the compound through milk during one lactation cycle. 6-CB was shown to distribute among rat and human plasma lipoproteins and protein in vitro. It was readily transferred among plasma constituents and its distribution was related to the triacylglycerol:protein ratio in plasma. At one hour following its intravenous administration to virgin rats, 6-CB was primarily distributed to LDL. With the hypertriglyceridemia of late pregnancy, more than 70% of circulating 6-CB was associated with VLDL. VLDL is a major substrate for mammary gland lipoprotein lipase which is elevated during lactation. When 6-CB was complexed with human VLDL and injected i.v. into late pregnant mice, mammary gland concentrations of 6-CB exceeded those of adipose tissue at all sacrifice times between 5 min and 6 h. No differences between adipose tissue and mammary gland concentrations of 6-CB were observed with Emulphor:ethanol:saline as vehicle until 6 h. Isolated hepatocytes were capable of secreting protein and triacylglycerol in the form of VLDL into serum-free media. Eighty percent of 6-CB released from hepatocytes was in association with VLDL, with the remainder in association with protein. Adipocytes isolated from epididymal fat pads of male rats which were pretreated with 6-CB released progressively less radioactivity to incubation media with time after treatment even though PCB content of these cells increased. 6-CB may not be evenly distributed among adipocyte lipids.
D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D005260:Female; D007700:Kinetics; D007774:Lactation / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008099:Liver / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014280:Triglycerides / Q000097:blood
D001798:Blood Proteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D011078:Polychlorinated Biphenyls; C014024:2,4,5,2',4',5'-hexachlorobiphenyl