METABOLISM OF H-3 RETINOL BY LAKE TROUT (SALVELINUS-NAMAYCUSH) PREEXPOSED TO 3,3',4,4',5-PENTACHLOROBIPHENYL (PCB-126)

To provide insight into retinoid metabolism in fish exposed to polychl orinated biphenyl (PCB), juvenile lake trout were orally exposed to 0, 3, 10 or 30 mu g 3,3',4,3',5-pentachlorobiphenyl (PCB 126) kg(-1) bod y weight for 12 weeks. Phase I (MFO) enzyme activity was induced by 60 , 177 and 450 fold, while glucuronyltransferase enzyme activity was 2. 3, 2.5 and 5 fold higher in the 3, 10 and 30 mu g PCB kg(-1) dose grou ps, respectively, compared with untreated fish. After IZ weeks, cannul ae were inserted into the dorsal aorta. Two days later, H-3-retinol wa s injected as a bolus in charcoal stripped plasma through the cannula. Blood samples were obtained 15 and 30 min and 1, 3, 6, 15, 30, 50 and 75 h after the injection. The radioactivity recovered from plasma was compared for each PCB dose group and was not significantly different for any of the treatments at ally of the sample times. However, greate r radioactivity recovered from bile after 75 h indicates accelerated m etabolism of H-3-retinol with increasing PCB dose. Tissue distribution s of aqueous and lipophilic soluble radioactivity indicates that direc t metabolism of retinol by MFO and conjugation enzymes is probably res ponsible for the depletion of retinoids in PCB 126 exposed lake trout. (C) 1997 Elsevier Science B.V.