title: Ethoxyresorufin O-deethylase induction by TCDD, PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes: Time-dependent effects on concentration-response curves.
abstract: Ethoxyresorufin O-deethylase (EROD) activity was measured in primary cultures of ring-necked pheasant (Phasianuscolchicus) and Japanese quail (Coturnix japonica) embryonic hepatocytes exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) for 12, 24, 36 and 48 h. In ring-necked pheasant hepatocytes there was a significant time-dependent increase in the EROD-inducing potency of TCDD, PeCDF and TCDF (i.e. decrease of the EC50). In Japanese quail hepatocytes there was no time-dependent change in the EROD-inducing potency of TCDD, PeCDF and TCDF. There was no time-dependent change in the relative potency of PeCDF and TCDF (i.e. compared to the potency of TCDD) in ring-necked pheasant hepatocytes and of PeCDF in Japanese quail hepatocytes. The results indicate that the relative potencies of these compounds at 24h are representative of their relative potencies between 12 and 48 h. However, in Japanese quail hepatocytes, the relative potency of TCDF decreased in a time-dependent manner (up to 3.6-fold difference). These results suggest that the effect of time on the EROD-inducing potency of TCDD, PeCDF and TCDF in ring-necked pheasant and Japanese quail hepatocytes is compound- and species-specific, but experimental conditions could also be involved in the differences observed.
authors.affiliation: Department of Biology, Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Hervé
authors.forename: Doug
authors.initials: D
authors.lastname: Crump
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Zwiernik
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Bursian
authors.forename: Sean W
authors.initials: SW
authors.lastname: Kennedy
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000633:toxicity*; D002478:Cells, Cultured; D003370:Coturnix; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D046094:Galliformes; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*
chemical_list: D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; D019363:Cytochrome P-450 CYP1A1; C038890:2,3,4,7,8-pentachlorodibenzofuran; C014211:2,3,7,8-tetrachlorodibenzofuran