Toxicity of nano-TiO₂ in rat kidney under oxidative stress

Objective: To investigate the adverse effects of nano-titanium dioxide (TiO₂) on kidney tissues in healthy rats and rats with oxidative stress (OS). Methods: Thirty-six healthy male SD rats were randomly divided into control group, alloxan-treated group, nano-TiO₂ treated (NM) group, and alloxan and nano-TiO₂ dual treatment (OS-NM) group. Nano-TiO₂ of three concentrations (0.5, 5 and 50 mg/kg body weight) was injected intraperitoneally. The level of OS biochemical factors and blood urea nitrogen (BUN) and pathological changes of kidney were determined. Results: Compared with those in NM and OS groups, the levels of O₂^-· and superoxide dismutase (SOD) in OS-NM group were significantly increased after exposure to nano-TiO₂ of 5 mg/kg body weight (P<0.05). Nano-TiO₂ of 50 mg/kg body weight led to significant changes of O₂^-·, SOD, and glutathione (GSH) levels in OS-NM group in comparison with OS and NM groups (P<0.01). The levels of O₂^-· and GSH between OS group and NM group changed significantly (P<0.05). Compared with healthy rats, OS rats showed significant increased BUN level (P<0.01), cell number and edema of renal tubular epithelial cells after nano-TiO₂ exposure. A synergic effect between OS condition and nano-TiO₂ level was shown on the increased level of O₂^-·. Conclusion: Nano-TiO₂ induced more adverse effects on the kidney in OS rats, suggesting a synergistic effect between nano-TiO₂ and OS. This result provides experimental evidence for patients' safe use of nano-TiO₂.