Abstract
Several in vitro studies have convincingly demonstrated that SiO
2
NPs mediated cytotoxicity, which was dose-, time- and size-dependent. The data on in vivo toxicity of SiO
2
NPs are even more contradictory. In the present study, we investigated the effects of sub-acute exposure to SiO
2
-NPs on spatial learning and memory, the biochemical parameters and the histology of organs. Rats were injected intravenously with a single dose of SiO
2
-NPs (20 mg/kg) during five consecutive days. The analysis of spatial memory in the Morris water maze showed that SiO
2
-NPs disrupt the cognitive abilities of rats. Moreover, SiO
2
-NPs could changes the blood counts. However, biochemical markers remained unchanged. Histological examination showed that SiO
2
-NPs induced pathological changes in rat organs. In this finding NPs were shown to cause granuloma formation and inflammatory cells infiltration in the liver.