Effect of nano-sized SiO 2 particles on the cognitive function and biochemical response.

Several in vitro studies have convincingly demonstrated that SiO2 NPs mediated cytotoxicity, which was dose-, time- and size-dependent. The data on in vivo toxicity of SiO2 NPs are even more contradictory. In the present study, we investigated the effects of sub-acute exposure to SiO2 -NPs on spatial learning and memory, the biochemical parameters and the histology of organs. Rats were injected intravenously with a single dose of SiO2 -NPs (20 mg/kg) during five consecutive days. The analysis of spatial memory in the Morris water maze showed that SiO2 -NPs disrupt the cognitive abilities of rats. Moreover, SiO2 -NPs could changes the blood counts. However, biochemical markers remained unchanged. Histological examination showed that SiO2 -NPs induced pathological changes in rat organs. In this finding NPs were shown to cause granuloma formation and inflammatory cells infiltration in the liver.