title: Structure dependent induction of CYP1A by polychlorinated biphenyls in hepatocytes of male castrated pigs.
abstract: Hepatocytes cultures prepared from castrated pig hepatocytes (Great Yorkshire x Dutch Landrace), as a model for human liver, were used to study the effect of twenty polychlorinated biphenyls (PCBs) on CYP1A activity, measured as the dealkylation of either ethoxyresorufin or methoxyresorufin. The selection of the PCBs was based on their differences in physico-chemical properties. The non-ortho and mono-ortho substituted PCBs were the most potent CYP1A inducers in pig hepatocytes. In addition, several multiple-ortho substituted congeners, with five or more chlorine atoms, were inducers of CYP1A activity as well. Their relative effect potencies (REP) were proximately 10,000 times lower than the most potent congener, 3,3',4,4',5 PeCB (PCB#126). Using partial least-squares (PLS) modeling, predictions of CYP1A activity could be made for all tetra to hepta substituted congeners. Several multiple-ortho substituted PCBs, which are highly abundant in the biotic and abiotic environment, have been found to induce CYP1A activity in pig hepatocytes. Because induction of CYP1A activity is used as biomarker for Ah-receptor mediated responses, it is suggested to include these congeners in future risk assessment.
authors.affiliation: Research Institute of Toxicology, Utrecht University, The Netherlands.
authors.forename: A S
authors.initials: AS
authors.lastname: Van der Burght
authors.forename: M
authors.initials: M
authors.lastname: Tysklind
authors.forename: P L
authors.initials: PL
authors.lastname: Andersson
authors.forename: G
authors.initials: G
authors.lastname: Jean Horbach
authors.forename: M
authors.initials: M
authors.lastname: van den Berg
mesh_terms: D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D008099:Liver / Q000201:enzymology*; D008297:Male; D023421:Models, Animal; D009919:Orchiectomy; D010078:Oxazines / Q000378:metabolism; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000737:chemistry* / Q000494:pharmacology*; D021281:Quantitative Structure-Activity Relationship; D013552:Swine
chemical_list: D010078:Oxazines; C007649:ethoxyresorufin; D003577:Cytochrome P-450 Enzyme System; D011078:Polychlorinated Biphenyls; D010088:Oxidoreductases; C076307:methoxyresorufin-O-demethylase; D019363:Cytochrome P-450 CYP1A1