Oxidative stress and DNA damage responses in rat and mouse lung to inhaled carbon nanoparticles

We have investigated whether short-term nose-only inhalation exposure to electric spark discharge-generated carbon nanoparticles (similar to 60 nm) causes oxidative stress and DNA damage responses in the lungs of rats (152 mu g/m(3); 4 h) and mice (142 mu g/m(3); 4 h, or three times 4 h). In both species, no pulmonary inflammation and toxicity were detected by bronchoalveolar lavage or mRNA expression analyses. Oxidative DNA damage (measured by fpg-comet assay), was also not increased in mouse whole lung tissue or isolated lung epithelial cells from rat. In addition, the mRNA expressions of the DNA base excision repair genes OGG1, DNA Pol beta and XRCC1 were not altered. However, in the lung epithelial cells isolated from the nanoparticle-exposed rats a small but significant increase in APE-1 mRNA expression was measured. Thus, short-term inhalation of carbon nanoparticles under the applied exposure regimen, does not cause oxidative stress and DNA damage in the lungs of healthy mice and rats.