ToxSci Advance Access published online on June 22, 2009
Toxicological Sciences, doi:10.1093/toxsci/kfp133
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Acrylonitrile-induced Oxidative Stress and Oxidative DNA Damage in Male Sprague-Dawley Rats
Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202
1 Corresponding author: James E. Klaunig, Ph.D., Robert B. Forney Professor of Toxicology, Director, Center for Environmental Health, Associate Director IU Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, R3-C132, Indianapolis, IN 46202, 317 274 7824 (voice), 317 274 7787 (fax), jklauni{at}iupui.edu
Received February 2, 2009; revision received June 12, 2009; accepted June 16, 2009
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Abstract |
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Studies have demonstrated that the induction of oxidative stress may be involved in brain tumor induction in rats by acrylonitrile. The present study examined whether acrylonitrile induces oxidative stress and DNA damage in rats, and whether blood can serve as a valid surrogate for the biomonitoring of oxidative stress induced by acrylonitrile in the exposed population. Male Sprague-Dawley rats were treated with 0, 3, 30, 100, and 200 ppm acrylonitrile in drinking water for 28 days. One group of rats were also coadministered N-acetyl cysteine (0.3% in diet) with acrylonitrile (200ppm in drinking water) to examine whether antioxidant supplementation was protective against acrylonitrile-induced oxidative stress. Direct DNA strand breakage in white blood cells (WBC) and brain was measured using the alkaline Comet assay. Oxidative DNA damage in WBC and brain was evaluated using formamidopyrimidine (fpg)-modified Comet assay and with HPLC-electrochemical detection. No significant increase in direct DNA strand breaks was observed in brain and WBC from acrylonitrile treated rats. However, oxidative DNA damage (fpg-Comet and OH8dG) in brain and WBC was increased in a dose-dependent manner. In addition, plasma levels of reactive oxygen species (ROS) increased in rats administered acrylonitrile. Dietary supplementation with N-acetyl cysteine prevented acrylonitrile-induced oxidative DNA damage in brain and WBC. A slight, but significant, decrease in the GSH/GSSG ratio was seen in brain at acrylonitrile doses > 30 ppm. These results provide additional support that the mode of action for acrylonitrile-induced astrocytomas involves the induction of oxidative stress and damage. Significant associations were seen between oxidative DNA damage in white blood cells and brain, ROS formation in plasma and the reported tumor incidences. Since oxidative DNA damage in brain correlated with oxidative damage in WBC, these results suggest that monitoring WBC DNA damage maybe a useful tool to assess acrylonitrile-induced oxidative stress in humans.
Key Words: acrylonitrile; Comet assay; oxidative DNA damage; brain; white blood cells.