title: Effects of motorcycle exhaust inhalation exposure on cytochrome P-450 2B1, antioxidant enzymes, and lipid peroxidation in rat liver and lung.
abstract: The effects of motorcycle exhaust (ME) on metabolic and antioxidant enzymes and lipid peroxidation were determined using male rats exposed to 1:10 diluted ME by inhalation 2 h daily for 4 wk. For microsomal cytochrome P-450 enzymes, ME resulted in threefold increases of 7-ethoxyresorufin and pentoxyresorufin O-deethylase activities in liver and a sixfold increase of 7-ethoxyresorufin O-deethylase activity and an 80% decrease of pentoxyresorufin O-dealkylase activity in lung. The results of immunoblot analysis of microsomal proteins revealed that ME increased liver and lung cytochrome P-450 1A1 with minimal effects on cytochrome P-450 2E1. ME increased cytochrome P-450 2B1/2 proteins in liver but decreased cytochrome P-450 2B1 in lung. ME did not change microsomal cytochrome P-450 enzyme activity or protein level in kidney. For phase II enzymes, ME resulted in 53% and twofold increases of cytosolic NAD(P)H:quinone oxidoreductase activities in liver and lung, respectively, and no effect on microsomal UDP-glucuronosyltransferase activities. For antioxidant enzymes, ME produced 23% and 35% decreases of superoxide dismutase, 9% and 27% decreases of catalase, and no changes of glutathione peroxidase activities in liver and lung cytosols, respectively. For lipid peroxidation, the results of thiobarbituric acid assay showed that ME resulted in a twofold increase of formation of malondialdehyde by liver microsomes incubated with FeCl(3) -ADP. ME produced a threefold increase of malondialdehyde formation by lung microsomes. The present study demonstrates that ME inhalation exposure differentially modulates cytochrome P-450 2B1 and antioxidant enzymes and increases susceptibility to lipid peroxidation in rat liver and lung.
authors.affiliation: Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China. thueng@ha.mc.ntu.edu.tw
authors.forename: Tzuu-Huei
authors.initials: TH
authors.lastname: Ueng
authors.forename: Hui-Wu
authors.initials: HW
authors.lastname: Wang
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Hung
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Chang
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000187:drug effects* / Q000378:metabolism; D019363:Cytochrome P-450 CYP1A1 / Q000187:drug effects / Q000378:metabolism; D019362:Cytochrome P-450 CYP2B1 / Q000187:drug effects / Q000378:metabolism; D019392:Cytochrome P-450 CYP2E1 / Q000187:drug effects / Q000378:metabolism; D015151:Immunoblotting; D019570:Inhalation Exposure; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D015227:Lipid Peroxidation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008168:Lung / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D009049:Motorcycles; D051381:Rats; D017208:Rats, Wistar; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D001335:Vehicle Emissions; D019392:Cytochrome P-450 CYP2E1; D001189:Aryl Hydrocarbon Hydroxylases; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1