Acute exposure to zinc oxide nanoparticles does not affect the cognitive capacity and neurotransmitters levels in adult rats

With the industrialization and increasing public exposure, nano-sized materials have received much more concerns. However, the impact of zinc oxide nanoparticles (ZnO-NPs) on the human body, especially on the central nervous system is extremely limited. The aim of this study is to investigate the effects of ZnO-NPs on the behavioral performances and the brain contents of some monoamines neurotransmitters. Male Wistar rats were treated with a single intravenous injection of a suspension of ZnO-NPs (25 mg/kg body weight). Subsequently, 14 days after nanoparticles injection, the rats were sacrificed. During that period, Morris water maze and open-field tests were performed, respectively, for the spatial working memory and the analysis of locomotor activity of the rats. The data showed that plasma and brain zinc concentrations increased after administration of ZnO-NPs. However, brain content of neurotransmitters such as norepinephrine, epinephrine, dopamine and serotonin remained unchanged in ZnO-NPs-treated rats compared with control group. The results showed also that the working memory, locomotor activity and exploratory behavior were not impaired in ZnO-NPs exposed groups. These data revealed that acute intravenous injection of ZnO-NPs does not affect neurotransmitter contents, locomotor activity and spatial working memory in adult rats. Thus, the effect of nanoparticles on the behavioral performances is still a new topic that requires more attention.