Intranasal instillation of iron oxide nanoparticles induces inflammation and perturbation of trace elements and neurotransmitters, but not behavioral impairment in rats

Over the last decades, engineered nanomaterials have been widely used in various applications due to their interesting properties. Among them, iron oxide nanoparticles (IONPs) are used as theranostic agents for cancer, and also as contrast agents in magnetic resonance imaging. With the increasing production and use of these IONPs, there is an evident raise of IONP exposure and subsequently a higher risk of adverse outcome for humans and the environment. In this work, we aimed to investigate the effects of sub-acute IONP exposure on Wistar rat, particularly (i) on the emotional and learning/memory behavior, (ii) on the hematological and biochemical parameters, (iii) on the neurotransmitter content, and (vi) on the trace element homeostasis. Rats were treated during seven consecutive days by intranasal instillations at a dose of 10 mg/kg body weight. The mean body weight increased significantly in IONP-exposed rats. Moreover, several hematological parameters were normal in treated rats except the platelet count which was increased. The biochemical study revealed that phosphatase alkaline level decreased in IONP-exposed rats, but no changes were observed for the other hepatic enzymes (ALT and AST) levels. The trace element homeostasis was slightly modulated by IONP exposure. Sub-acute intranasal exposure to IONPs increased dopamine and norepinephrine levels in rat brain; however, it did not affect the emotional behavior, the anxiety index, and the learning/memory capacities of rats.