[Comparative study of the effect on oxidative damage in rats inhaled by nano-sized and micro-sized silicon dioxide].

Objective: To compare the changes of oxidative damage in rats inhaled by nano-sized and micro-sized silicon dioxide.

Methods: 36 male rats were randomly divided into two control groups and four experimental groups which was inhaled by nano-sized and micro-sized silicon dioxide respectively at the concentration of 300 mg/m3 for 2 hours and the activities of SOD, CAT and GSH-Px and the contents of H2O2, GSH and MDA of the liver, kidney, brain were determinated 24h and 48h after inhalation.

Results: The contents of H2O2 in all organs in nano-sized groups increased significantly while increased in micro-size groups only in liver and kidney at 24h and in brain at 48h. On the contrary, the activities of CAT in nano-sized group were lower than those in micro-sized group. Superoxide anion contents increased only in the brain of nano-sized group. The activities of SOD decreased significantly in nano-sized groups in kidney at 24h and brain but not in micro-sized groups. The content of GSH decreased only in liver at 24h. The activities of GSH-PX decreased significantly in nano-sized compared with control group and were lower significantly in brain than those in micro-sized group. The contents of MDA increased in all nano-sized groups but only in liver and brain in micro-sized group. The total anti-oxygen activities decreased in all nano-sized groups, but only in kidney at 24h and brain in micro-sized group, especially more significantly in brain at 48h in nano-sized than micro-sized group. While the activity in kidney in nano-sized group increased at 48h comparing to at 24h.

Conclusion: Nano-sized silicon dioxide could induce oxidative damage more easily than micro-sized silicon dioxide. Through comparing different interval, it was found that the degree of oxidative damage at 48h after inhalation inferior to that at 24h after inhalation, which could be associated with the repair of the body against the oxidative damage.