In vitro and in vivo comparisons of fish-specific CYP1A induction relative potency factors for selected polycyclic aromatic hydrocarbons

Induction of cytochrome P450 (CYP1A), as measured by liver ethoxyresorufin-O-deethylase (EROD) activity in juvenile rainbow trout (Oncorhynchus mykiss), was used to derive relative potency factors (RPFs) for several polycyclic aromatic hydrocarbons (PAHs), chosen for their induction potency in a rai...

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Bibliographic Details
Published in:Ecotoxicology and environmental safety 2004-11, Vol.59 (3), p.292-299
Main Authors: Billiard, S.M., Bols, N.C., Hodson, P.V.
Format: Article
Language:English
Subjects:
Animal, plant and microbial ecology
Animals
Applied ecology
Biological and medical sciences
Cell Line
CYP1A
Cytochrome P-450 CYP1A1 - biosynthesis
Ecotoxicology, biological effects of pollution
Enzyme Induction
Fundamental and applied biological sciences. Psychology
General aspects
Juvenile trout
Liver - cytology
Liver - enzymology
Oncorhynchus mykiss
Oncorhynchus mykiss - physiology
Polycyclic aromatic hydrocarbons
Polycyclic Aromatic Hydrocarbons - toxicity
RPFs
RTL-W1
TCDD
TEFs
Water Pollutants, Chemical - toxicity
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Summary:Induction of cytochrome P450 (CYP1A), as measured by liver ethoxyresorufin-O-deethylase (EROD) activity in juvenile rainbow trout (Oncorhynchus mykiss), was used to derive relative potency factors (RPFs) for several polycyclic aromatic hydrocarbons (PAHs), chosen for their induction potency in a rainbow trout liver cell line (RTL-W1). Potency for causing induction was estimated as the median effective concentration (EC50) from exposure–response curves. With the exception of phenanthrene, all PAHs tested induced EROD activity in juvenile trout, ranked as: benzo[k]fluoranthene>benzo[b]fluoranthene>benzo[b]fluorene>β-napthoflavone>retene (7-isopropyl-1-methylphenanthrene). When induction potency was expressed relative to benzo[k]fluoranthene, RPFs ranged from 0.02 to 1, and the rank order in vivo was identical to the rank order with RTL-W1-derived values. The additivity of PAHs in mixtures in RTL-W1 cells was compared to whole-fish results from a previous study. EROD induction showed additive interactions for PAHs with exposure–response curves of similar slopes. This study demonstrates that assays of CYP1A induction using rainbow trout liver cells in culture would be a convenient substitute for assays with whole fish as part of testing programs for risk assessment of PAHs.
ISSN:0147-6513
1090-2414
DOI:10.1016/j.ecoenv.2004.06.009