Influence of Different Sizes of Titanium Dioxide Nanoparticles on Hepatic and Renal Functions in Rats with Correlation to Oxidative Stress

As titanium dioxide (TiO2) nanoparticles are widely used commercially, the potential effects of TiO2 nanoparticles on humans are a concern. To evaluate the effects of TiO2 nanoparticles on hepatic and renal functions and correlate changes to oxidative stress, Sprague-Dawley rats were treated with TiO2 particles of two different specific surface areas (TiO2-S50: 50 m2/g, and TiO2-S210: 210 m2/g) at 0.5, 5, or 50 mg/kg body weight by intratracheal instillation. After 7 d, TiO2 nanoparticles produced no obvious acute toxicity on hepatic and renal functions. However, superoxide dismutase (SOD) activity of plasma and glutathione peroxidase (GSH-PX) activity of kidney in the low-dose TiO2-S210 group were significantly decreased. After TiO2-S210 exposure, malondialdehyde (MDA) levels of liver and kidney in intermediate and high-dose groups were significantly increased. This change only appeared in liver after TiO2-S50 exposure. Furthermore, SOD activity in liver and kidney and GSH-PX activity in kidney with low TiO2-S210 exposure group were significantly less than with low TiO2-S50. No apparent pathological changes in liver and kidney were observed. Intratracheal exposure to TiO2 nanoparticles may induce oxidative stress in liver and kidney, but does not influence hepatic or renal functions. There was no apparent evidence that TiO2-S210 was more toxic than TiO2-S50. In general, intratracheal exposure to TiO2 did not markedly affect extrapulmonary tissue functions.