Comparison of the effect of iron oxide nanoparticles and bulk on the memory and associated alterations in dopamine and serotonin levels in the hippocampus of adult male rats

Introduction: With the increasing development of nanotechnology, nanomaterials are used instead of conventional compounds. One of these nanomaterials that have many applications in the biomedical field, is iron oxide (Fe2O3) nanoparticles and there is not much research on its effects on the physiological features. So in this research, effect of iron oxide nanoparticles on short and long-term passive avoidance memory and levels of serotonin and dopamine in hippocampus was evaluated in comparison to the bulk type. Methods: In this study, 80 male adult Wistar rats (220±30grams) were used and divided into 10 groups, and the study was performed in two parts in order to measure the behavioral changes and neurotransmitters levels. In the first part, animals received intraperitoneal injections of iron oxide nanoparticles and bulk at different doses (0.2, 1, 5 mg/kg( before training. Then, 90 minutes and 24 hours after training their memory was tested by a step–through instrument. In the second part of the study, right and left hippocampi of every group were extracted after receiving the effective dose (5 mg/kg) of iron oxide nanoparticles and bulk, and neurotransmitters levels were measured by an ELISA kit. Results: Iron oxide nanoparticles caused a disruption in passive avoidance memory in a dose-dependent manner, while bulk iron oxide showed a non significant partial effect. Also both type of iron oxide reduced dopamine levels and increased serotonin levels significantly or relatively in both hippocampi. Conclusion: It seems that iron oxide nanoparticles induce a disruption of memory, which is in part related to the alterations of neurotransmitters levels in hypocampus and the other is associated to its physicochemical properties.