title: Induction of rat hepatic cytochromes P-450 by environmental nitropolycyclic aromatic hydrocarbons.
abstract: Nitrated polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that result from various incomplete combustion processes. We have examined the activity of hepatic microsomal enzymes in rats pretreated with a series of environmentally occurring nitrated PAHs including: 1- and 4-nitropyrene, 1,3-, 1,6- and 1,8-dinitropyrene, 6-nitrochrysene, 7-nitrobenz[a]anthracene, 3-nitrofluoranthene, and 1-, 3-, and 6-nitrobenzo[a]pyrene. None of the compounds increased the cytochrome P-450 content more than 2-fold. 1,8-Dinitropyrene, 6-nitrochrysene, and 1- and 3-nitrobenzo[a]pyrene significantly increased arylhydrocarbon hydroxylase activity 2- to 8-fold higher than solvent-treated controls. The induction of 7-ethoxycoumarin O-deethylase activity paralleled that found with arylhydrocarbon hydroxylase. The maximum induction of aminopyrine N-demethylase was only 1.5-fold, and none of the nitrated PAHs caused significant increases in epoxide hydrase or NADPH-cytochrome c reductase. 1-Nitropyrene reductase activity was induced by each of the compounds with the exception of 6-nitrobenzo[a]pyrene. The greatest increase was caused by 1-nitrobenzo[a]pyrene followed by 1,3-dinitropyrene, 3-nitrobenzo[a]pyrene and 6-nitrochrysene. These data suggest that nitrated PAHs may potentiate the effects of subsequent exposures to various chemical carcinogens.
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase; D000393:Air Pollutants / Q000494:pharmacology*; D000633:Aminopyrine N-Demethylase / Q000096:biosynthesis; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis; D001551:Benz(a)Anthracenes / Q000494:pharmacology; D001580:Benzopyrenes / Q000494:pharmacology; D002911:Chrysenes / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction; D004851:Epoxide Hydrolases / Q000096:biosynthesis; D005449:Fluorenes / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000096:biosynthesis; D009574:Nitro Compounds / Q000494:pharmacology*; D010105:Oxygenases / Q000096:biosynthesis; D011083:Polycyclic Compounds / Q000494:pharmacology*; D011721:Pyrenes / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000393:Air Pollutants; D001551:Benz(a)Anthracenes; D001580:Benzopyrenes; D002911:Chrysenes; D005449:Fluorenes; D007527:Isoenzymes; D009574:Nitro Compounds; D011083:Polycyclic Compounds; D011721:Pyrenes; C038954:7-nitrobenzanthracene; C042055:3-nitrobenzo(a)pyrene; C040217:1-nitrobenzo(a)pyrene; C035986:6-nitrochrysene; D003577:Cytochrome P-450 Enzyme System; C037413:1,3-dinitropyrene; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D001189:Aryl Hydrocarbon Hydroxylases; D000633:Aminopyrine N-Demethylase; D009251:NADPH-Ferrihemoprotein Reductase; D004851:Epoxide Hydrolases; C033643:3-nitrofluoranthene; C032668:1-nitropyrene