Role of temperature and enzyme induction in the biotransformation of polychlorinated biphenyls and bioformation of hydroxylated polychlorinated biphenyls by rainbow trout (Oncorhynchus mykiss).
Hydroxylated PCBs (OH-PCBs) are metabolites of polychlorinated biphenyls (PCBs) that have recently been found in the plasma of Great Lakes fish. Studies have shown that the ability of laboratory-held rainbow trout (Oncorhynchus mykiss) to bioform OH-PCBs from dietary mixtures of PCB congeners is complex and may be attributed to factors such as temperature and/or enzyme induction. Past studies have also suggested that CYP1A- and 2B-like enzymes are the likely mechanism for forming OH-PCBs, but this has not been directly studied in a controlled setting. To address these issues, we exposed rainbow trout (-80 g) to dietary concentrations of a mixture of three Aroclors (1248, 1254, and 1260), at three water temperatures (8, 12, and 16 oC), as well as additional PCBs known to induce CYP1A- and CYP2B-like isoforms in mammals. PCB half-lives in trout were inversely related to water temperature, but biotransformation of PCBs was positively related to water temperature. Thirty-one OH-PCBs were observed in trout plasma after 30 days of dietary exposure to the Aroclor mixtures, although approximately 40% of the sigmaOH-PCBs concentrations were OH-PCB for which no standards were available. Concentration of OH-PCBs in the trout plasma increased with increasing temperature and with the addition of CYP2B-like inducing congeners but not with the addition of CYP1A-inducing congeners to food. The results of this study provide the first in vivo evidence that rainbow trout are responsive to CYP2B-like induction by PCBs and that this enzyme system can influence PCB concentrations and OH-PCB formation in fish.
Buckman
Andrea H
AH
Department of Environmental Biology, University of Guelph, Guelph, ON, Canada N1G 2W1.
Brown
Scott B
SB
Small
Jeff
J
Muir
Derek C G
DC
Parrott
Joanne
J
Solomon
Keith R
KR
Fisk
Aaron T
AT
D000818:Animals; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004789:Enzyme Activation; D006207:Half-Life; D006900:Hydroxylation; D008099:Liver / Q000033:anatomy & histology; D017686:Oncorhynchus mykiss / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism*; D009929:Organ Size; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D018508:Water Purification
D003577:Cytochrome P-450 Enzyme System; D011078:Polychlorinated Biphenyls