Development of Toxic Equivalency Factors for PCB Congeners and the Assessment of TCDD and PCB Mixtures in Rainbow Trout

Newsted, John L.; Giesy, John P.; Ankley, Gerald T.; Tillitt, Donald E.; Crawford, Robert; Gooch, Jay W.; Jones, Paul D.; Denison, Michael S.

doi:10.1897/1552-8618(1995)14[861:doteff]2.0.co;2

Cited by 28 publications

(37 citation statements)

References 17 publications

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“…In this study ( Fig. 4, Table 2) as in several others [15,[46][47][48], EROD was found to be more sensitive than CYP1A protein as an index of induction. Moreover, EROD activity can be measured easily and rapidly.…”

Section: Measurement Of Cyp1a Proteinsupporting

confidence: 75%

“…Chem. 15,1996 M.E. Hahn et al The PLHC-1 cells were treated with the indicated inducers, and EROD and CYP1A were measured as described in the legends to Figures 4 and 5.…”

Section: Discussionmentioning

confidence: 99%

“…Evidence from several studies shows that I-SAR may differ between classes of vertebrate animals [12][13][14][15]. Thus, as noted previously [16][17][18][19], the relative potencies established in mammalian cells may not apply to other animal groups, indicating the need for taxon-specific model systems that can be used to define such differences.…”

Section: Introductionmentioning

confidence: 95%

“…Toxicol. Chem 15,. 1996 587 Immunochemical detection of CYP1A protein induced by TCDD or planar PCB congeners.…”

mentioning

confidence: 99%

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Rapid Assessment of Induced Cytochrome P4501a Protein and Catalytic Activity in Fish Hepatoma Cells Grown in Multiwell Plates: Response to Tcdd, Tcdf, and Two Planar PCBS

Hahn¹,

Woodward²,

Stegeman³

et al. 1996

Environ Toxicol Chem

102

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Abstract-Induction of cytochrome P450 1A1 (CYP1A1) in cultured cells can be used to determine taxon-specific relative potencies of Ah receptor agonists. This report describes optimized methods for growth and treatment of PLHC-1 fish hepatoma cells in multiwell plates, in situ analysis of ethoxyresorufin O-deethylase (EROD) activity, and measurement of CYP1A protein by immunoblotting of cell lysates. EROD activity was undetectable (Ͻ1 pmol min Ϫ1 mg Ϫ1) in untreated or dimethyl sulfoxide-treated cells, but was highly induced (up to 150 pmol min Ϫ1 mg Ϫ1) in cells exposed to Ah receptor agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), or planar chlorobiphenyls (CB). Addition of exogenous NADPH was not required for measurement of EROD activity in PLHC-1 cells. As inducers of EROD activity, TCDD, TCDF, 3,3Ј,4,4Ј,5-pentachlorobiphenyl (CB-126), and 3,3Ј,4,4Ј-tetrachlorobiphenyl (CB-77) differed both in potency and in apparent efficacy (maximal level of induced activity). In each case, EROD induction was biphasic, with stronger induction at lower concentrations and an attenuated response at higher concentrations. In contrast, the content of immunodetectable CYP1A protein increased monotonically with dose of CB, and the maximum level achieved was similar for all inducers. The discrepancy in results obtained for EROD activity versus CYP1A protein may result from inhibition or inactivation of catalytic function at high concentrations of inducer. By reducing peak EROD values, this inhibition leads to lower apparent EC50 values and thus the overestimation of relative potencies or toxic equivalency factors (TEFs) for many inducers. These studies demonstrate the necessity of measuring both EROD activity and immunodetectable CYP1A protein for the accurate assessment of CYP1A induction and relative potencies in cultured cells.

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Section: Measurement Of Cyp1a Proteinsupporting

confidence: 75%

“…Chem. 15,1996 M.E. Hahn et al The PLHC-1 cells were treated with the indicated inducers, and EROD and CYP1A were measured as described in the legends to Figures 4 and 5.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

“…Toxicol. Chem 15,. 1996 587 Immunochemical detection of CYP1A protein induced by TCDD or planar PCB congeners.…”

mentioning

confidence: 99%

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Rapid Assessment of Induced Cytochrome P4501a Protein and Catalytic Activity in Fish Hepatoma Cells Grown in Multiwell Plates: Response to Tcdd, Tcdf, and Two Planar PCBS

Hahn¹,

Woodward²,

Stegeman³

et al. 1996

Environ Toxicol Chem

102

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“…Thus, it is likely that higher doses of 3,4,5-HCB would have been required to demonstrate antiestrogenic effects in trout. Our results are consistent with the work of Monosson et al [22,23], who reported that similar doses of 3,4-TCB (a congener with a CYP1A induction po-tential comparable to that of 3,4,5-HCB [38]) did not suppress Vg synthesis in sexually mature striped bass and white perch.…”

Section: Discussionsupporting

confidence: 93%

Effects of 3,3′,4,4′,5,5′‐hexachlorobiphenyl on cytochrome P4501A and estrogen‐induced vitellogenesis in rainbow trout (Oncorhynchus mykiss)

Donohoe

Wang-Buhler

Buhler

et al. 1999

Enviro Toxic and Chemistry

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Abstract-Estrogen-regulated synthesis of vitellogenin (Vg), a yolk-protein precursor required for reproduction, was monitored to explore the potential antiestrogenic effects of the coplanar polychlorinated biphenyl (PCB), 3,3Ј,4,4Ј,5,4,, in juvenile rainbow trout (Oncorhynchus mykiss). The effects of 17␤-estradiol on 3,4,5-HCB induction of cytochrome P4501A (CYP1A) were also examined. Trout were injected with 3,4,5-HCB (0.25, 2.5, 25, 50, or 100 mg/kg) or a vehicle control, and after 10 weeks, they were sampled or injected with 17␤-estradiol (0.1 mg/kg). Markers of vitellogenesis, such as liver somatic index, hepatic estrogen-binding sites, and plasma Vg concentrations, in 17␤-estradiol-treated fish were not affected by 3,4,5-HCB. Maximal induction of CYP1A protein and mRNA occurred at doses above 2.5 mg/kg, and 17␤-estradiol reduced CYP1A protein content at a single dose (0.25 mg 3,4,5-HCB/kg). Ethoxyresorufin-O-deethylase (EROD) activity was induced by 3,4,5-HCB doses of between 0.25 and 2.5 mg/kg, but induction was reduced at higher doses, indicating that 3,4,5-HCB suppressed CYP1A catalytic activity. In 3,4,5-HCB/17␤-estradiol-treated fish, plasma estradiol was significantly reduced at 100 mg 3,4,5-HCB/kg, but the depression was not associated with CYP1A induction or with other antiestrogenic effects. Although CYP1A was induced, 3,4,5-HCB did not interfere with vitellogenesis, which suggests that the PCB congener is not a potent antiestrogen in rainbow trout.

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MFO Induction of three Australian fish species

Smith

Gagnon

2000

Environ. Toxicol.

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The use of mixed function oxygenase MFO enzymes as a biomarker of pollution in Port ( ) Phillip Bay was investigated in three indigenous fish species, sand flathead Plathycephalus bassensis , ( ) ( ) bluethroat wrasse Notalabrus tetricus , and sixspine leatherjacket Meuschenia freycineti . Investigation of the relative MFO induction potential was performed by intraperitoneally injecting each experimental X X ( ) fish species with 100 g / kg of 3,3 ,4,4 ,5-pentachlorobiphenyl PCB 126 using corn oil as a carrier. Hepatic induction was fluorimetrically measured by the activity of 7-ethoxyresorufin O-deethylase ( ) EROD activity 10 days post-injection. Of the three species tested, the sand flathead was selected as the most suitable indicator species for its high MFO induction potential and desirable characteristics related to its population biology. Bluethroat wrasse appeared relatively uninducible by PCB 126, while sixspine leatherjacket demonstrated a medium induction potential but was unsuitable as a biomonitoring tool because of its scarcity and distribution limited to reef beds.

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Development of Toxic Equivalency Factors for PCB Congeners and the Assessment of TCDD and PCB Mixtures in Rainbow Trout

Cited by 28 publications

References 17 publications

Rapid Assessment of Induced Cytochrome P4501a Protein and Catalytic Activity in Fish Hepatoma Cells Grown in Multiwell Plates: Response to Tcdd, Tcdf, and Two Planar PCBS

Rapid Assessment of Induced Cytochrome P4501a Protein and Catalytic Activity in Fish Hepatoma Cells Grown in Multiwell Plates: Response to Tcdd, Tcdf, and Two Planar PCBS

Effects of 3,3′,4,4′,5,5′‐hexachlorobiphenyl on cytochrome P4501A and estrogen‐induced vitellogenesis in rainbow trout (Oncorhynchus mykiss)

MFO Induction of three Australian fish species

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