The effect of estradiol benzoate on the association of 2,4,5,2',4',5'-hexachlorobiphenyl with rainbow trout plasma lipoproteins.

The mechanism by which persistent polychlorinated biphenyls (PCBs) are redistributed from maternal storage depots to developing oocytes during estrogen-dependent vitellogenesis in rainbow trout is unknown. Since PCBs have been shown to be associated with mammalian plasma lipoproteins, and since estrogens alter lipoprotein profiles in fish, the in vitro interaction of 14C-2,4,5,2',4',5'-hexachlorobiphenyl (6-CB) with lipoproteins was assessed in corn oil- and estradiol benzoate (EB)-pretreated sexually immature rainbow trout. Serum was collected and pooled, and aliquots were incubated with 0.04 nmoles 6-CB for 48 hours at 12 degrees C. Lipoproteins were separated by density flotation. Radioactivity, as well as, triacylglycerol, cholesterol, phospholipid phosphorus and protein content were assessed in each fraction. 6-CB was found to be associated with all lipoprotein classes, as well as the protein-rich bottom fraction. EB administration resulted in dose-dependent alterations in lipoprotein profiles and a shift in 6-CB association from protein and lipoproteins of higher density to those of lower density. A significant positive correlation was observed between the triacylglycerol or cholesterol content of the fractions and the percentage of 6-CB which was distributed in that fraction.