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[Effects of titanium dioxide nanoparticles and lipopolysaccharide on antioxidant function of liver tissues in mice].

OBJECTIVE
To compare the effects of different sized titanium dioxide (titanium dioxide, TiO2) on the antioxidant function of liver tissues in mice, and study the effect of TiO2 nanoparticles on the susceptibility of lipopolysaccharide (LPS) on liver tissues.


METHODS
Ninety 4-week-old clean-grade male ICR mice were divided into 18 groups, in which the mice were fed for different feed involving ordinary feed, nanometer TiO2 feed which meant the feed including 1% (mass fraction) TiO2 nanoparticles, and submicron TiO2 feed which meant the feed including 1% (mass fraction) TiO2 submicron particles. Respectively, they were fed for 1 month, 3 months and 6 months. On the second day after the feeding, respectively, 0 and 10 mg/kg LPS were given by gavage. The mice were harvested after 4 h and the body weight and liver weight for calculating the liver coefficient were recorded. Then the liver tissue homogenates were prepared for determining the antioxidant indexes including the total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA).


RESULTS
The change of body weight in mice was only discovered in group fed for 1 month, which showed significant decrease of body weight in treatment groups compared with control group. And there was no significant change of the liver coefficient in each group. Compared with control groups, nanometer TiO2 groups and submicron TiO2 group, the activity of T-AOC, T-SOD and MDA of nanometer TiO2+LPS group and submicron TiO2+LPS group in which the mice were fed for 1 month and 6 months increased in different degree. And another result was also existing. The MDA activity of liver in different sized treatment groups fed for 3 months decreased. Neither significant difference between the results of different sized TiO2 treatment groups, nor significant difference among different sized TiO2 groups and the control groups were observed.


CONCLUSION
Longterm peroral TiO2 nanoparticles and TiO2 submicron particles are more likely to cause damage to the liver in the growing mice, and the damage may be either reductive or oxidative. In addition, small sized TiO2 can increase the susceptibility of mice liver to LPS and the susceptibility will increase with the increase of exposure time.