Induction of 7-ethoxyresorufin-o-deethylase activity by planar chlorinatedhydrocarbons and polycyclic aromatic hydrocarbons in cell lines from the rainbow trout pituitary

The induction of 7-ethoxyresorufin-o-deethylase (EROD) activity was examine d in three rainbow trout pituitary cell lines: RTP-91E, RTP-91F and RTP-2. RTP-91E and RTP-91F were developed from the pituitary of a male and have ep ithelial-like and fibroblast-Like morphologies, respectively. RTP-2, which was described previously, was developed from the pituitary of a female and has an epithelial-like shape. In all cell lines EROD activity was induced b y 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Immunoblotting with the polyc lonal antibody, anti-trout CYP1A1(277-294)/KLH, confirmed induction of a 58 -kDa polypeptide, Potential inhibitors of the aryl hydrocarbon receptor, ge ldanamycin and alpha -naphthoflavone, inhibited EROD induction by TCDD. Oth er compounds inducing EROD activity were 1,2,3,7,8-pentachlorodibenzo-p-dio xin (PCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 3,3',4,4',5-pentachloro biphenyl (PCB 126), and 3-methylcholanthrene (3MC). When judged by the conc entration eliciting 50% of the maximal response (EC50)induction was similar in RTP-2 and RTP-91E, and Less effective in RTP-91F. Regardless of the cel l Line, the rank order from most to least potent inducer on the basis of EC 50 value was TCDD greater than or equal to PCDD > TCDF > PCB 126 much great er than 3MC, When induction potencies were expressed relative to TCDD, the values obtained with the pituitary cell lines were similar to previously pu blished values derived with a rainbow trout liver cell line, (C) 2001 Elsev ier Science Inc. All rights reserved.