Research For The Nervous System And Cardiovascular System Toxicity Of Nano-titanium Dioxide

Nanomaterials are widely used in almost every areas because of its unique properties, and then the safety of the nanotechnology have received the widespread attention. Epidemiologic studies indicated that the cardiovascular effects of the nanoparticles have been the focus of public recently, however, little is currently known about the neurotoxicity and cardiovascular toxicity after expose the skin under nano-TiO₂ for a long time. This project uses the methods of in vivo and in vitro studies, we preliminary evaluated the neurotoxicity and cardiovascular toxicity of nano-TiO₂.In this vivo study,6 weeks old female BALB/c mice were exposed to 0,4,20,100, 500 mg/kg/d nano-TiO₂ by skin exposure, the pathological sections of brains were observed, the indexes including oxidative stress in brain tissues （reactive oxygen species, ROS; glutathione, GSH; malonaldehyde, MDA）, and inflammatory indexes （interleukin-4, IL-4 and Interferon-y, IFN-y） were detected to evaluate the toxic effect on the nervous system. And the indexes in the mice serum （ROS; Immunoglobulin-E, IgE; Thrombomodulin, TM; soluble adhesion molecules 1, sICAM-1; D-Dimer, D2D） were detected to explore the toxic effect on the cardiovascular system. In the vitro study, the Human umbilical vein endothelial cells （HUVECs） were exposed to 0.45,2.25,11.25, 56.25 μg/mL nano-TiO₂. The cell viability was determined as well as the indexes including ROS, Interleukin-4 （IL-8）, hypersensitive C-reactive protein （hsCRP）, zonula occludens-1 （ZO-1）,8-hydroxylation deoxy guanosine （8-OHdG） and cysteinyl aspartate specific proteinase-3 （caspase-3） were detected to evaluate the toxic effect on HUVECs. In this study, Vitamin E （VE） as a protective agent was used to explore the protective effect on the damage of nervous system and cardiovascular system and its possible protection mechanisms.The results of this study revealed, no significant difference between the groups of brain tissue slices, the contents of ROS, MDA and IL-4 in brain tissues increased with the increase of exposure level, but the contents of GSH and IFN-y decreased with the increase of exposure level. Compared with the control group, ROS, MDA and IL-4 increased and there was a highly significant difference at the exposure dose of 20 mg/kg, 500 mg/kg and 100 mg/kg in sequence. GSH decreased and there was a highly significant difference at the exposure dose of 500 mg/kg. IFN-y decreased and there was a significant difference at the exposure dose of 500 mg/kg.The contents of ROS, D2D, Ig-E, sICAM-1 and TM in mice serum increased with the increase of exposure level. Compared with the control group, ROS, D2D, Ig-E, sICAM-1 and TM increased and there were highly significant difference at the exposure dose of 100 mg/kg,100 mg/kg,20 mg/kg,20 mg/kg and 20 mg/kg in sequence.The results of this vitro study showed that HUVECs activity and the contents of IL-8 decreased with the increase of exposure level, The contents of ROS, hs-CRP, ZO-1, 8-OHdG and caspase-3 in HUVECs increased with the increase of exposure level. Compared with the control group, cell activity decreased and there was a highly significant difference at the exposure dose of 56.25 μg/mL, IL-8 decreased and there was a significant difference at the exposure dose of 56.25 μg/mL, ROS, hs-CRP, ZO-1 and 8-OHdG increased and there were highly significant differences at the exposure dose of 11.25 μg/mL,11.25 μg/mL,2.25 μg/mL and 2.25 μg/mL in sequence, caspase-3 increased and there was a significant difference at the exposure dose of 56.25 μg/mL.At the same time to add 100 mg/kg VE to the exposure dose of 100 mg/kg and 500 mg/kg in vivo study and add 11.25 μg/mL VE to the exposure dose of 11.25 μg/mL and 56.25 μg/mL in vitro study as protection groups, compared with groups merely exposured to nano-TiO₂, the degree of cerebral and serous function damages relieved obviously and that the level of oxidative stress and inflammatory decreased significantly, the cell viability increased and the level of oxidative stress, inflammatory, DNA damage and apoptosis decreased.The conclusion of this thesis, nano-TiO₂ shows a weak neurotoxicity and cardiovascular toxicity in low dose groups, only the higher dosage of the nano-TiO₂ group could cause the toxic effect of nervous system and cardiovascular system, oxidative stress and inflammation were possible mechanisms which caused the damage of nervous system and cardiovascular system, nano-TiO₂ has the remarkable cytotoxicity. In this study 4 mg/kg nano-TiO₂ would be the safe dose for mice and 0.45 μg/mL nano-TiO₂ would be the safe dose for HUVECs. VE can reduce the damage degree of function of nervous system and cardiovascular system.