ToxSci Advance Access originally published online on May 24, 2004
Toxicological Sciences 2004 81(1):103-111; doi:10.1093/toxsci/kfh173
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Toxicological Sciences vol. 81 no. 1 © Society of Toxicology 2004; all rights reserved.
Genotoxicity of Motorcycle Exhaust Particles In Vivo and In Vitro



,1
* School of Pharmacy, Taipei Medical University, Taipei, Taiwan, and
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
Received March 2, 2004; accepted May 7, 2004
We studied the genotoxic potency of motorcycle exhaust particles (MEP) by using a bacterial reversion assay and chromosome aberration and micronucleus tests. In the bacterial reversion assay (Ames test), MEP concentration-dependently increased TA98, TA100, and TA102 revertants in the presence of metabolic-activating enzymes. In the chromosome aberration test, MEP concentration-dependently increased abnormal structural chromosomes in CHO-K1 cells both with and without S9. Pretreatment with antioxidants (
-tocopherol, ascorbate, catalase, and NAC) showed varying degrees of inhibitory effect on the MEP-induced mutagenic effect and chromosome structural abnormalities. In the in vivo micronucleus test, MEP dose-dependently induced micronucleus formation in peripheral red blood cells after 24 and 48 h of treatment. The increase of micronucleated reticulocytes induced by MEP was inhibited by pretreatment with
-tocopherol and ascorbate. The fluorescence intensity of DCFH-DAloaded CHO-K1 cells was increased upon the addition of MEP. Our data suggest that MEP can induce genotoxicity through a reactive oxygen species(ROS-) dependent pathway, which can be augmented by metabolic activation. Alpha-tocopherol, ascorbate, catalase, and NAC can inhibit MEP-induced genotoxicity, indicating that ROS might be involved in this effect.
Key Words: motorcycle exhaust particles; Ames test; reactive oxygen species; chromosome aberration; micronucleus; genotoxicity.