Iron oxide nanoparticles (IONPs) have come into focus for their use in medical applications although possible health risks for humans, especially in terms of brain functions, have not yet been fully clarified. The present study investigates the effects of IONPs on neurobehavioural functions in rats. For this purpose, we infused dimercaptosuccinic acid-coated IONPs into the medial prefrontal cortex (mPFC) and caudate putamen (CPu). Saline (VEH) and ferric ammonium citrate (FAC) were administered as controls. One- and 4-week post-surgery mPFC-infused animals were tested for their working memory performance in the delayed alternation T-maze task and in the open field (OF) for motor activity, and CPu-infused rats were tested for their motor activity in the OF. After completion of the experiments, the brains were examined histologically and immunohistochemically. We did not observe any behavioural or structural abnormalities in the rats after administration of IONPs in the mPFC and the CPu. In contrast, administration of FAC into the CPu resulted in decreased motor activity and increased the number of microglia in the mPFC. Perls’ Prussian blue staining revealed that FAC- and IONP-treated rats had more iron-containing ramified cells than VEH-treated rats, indicating iron uptake by microglia. Our results demonstrate that local infusions of IONPs into selected brain regions have no adverse impact on locomotor behaviour and working memory.

氧化铁纳米粒子（IONP）因其在医疗应用中的应用而受到关注，尽管其对人类可能存在的健康风险，特别是在大脑功能方面的风险尚未完全明确。本研究调查了 IONP 对大鼠神经行为功能的影响。为此，我们将二巯基丁二酸涂层的 IONP 注入内侧前额叶皮层 (mPFC) 和尾壳核 (CPu)。施用盐水（VEH）和柠檬酸铁铵（FAC）作为对照。术后 1 周和 4 周，输注 mPFC 的动物在延迟交替 T 迷宫任务中测试其工作记忆表现，并在开放场 (OF) 中测试运动活动，并测试输注 CPU 的大鼠的运动能力OF 中的活动。实验完成后，对大脑进行组织学和免疫组织化学检查。在mPFC和CPu中给予IONP后，我们没有观察到大鼠有任何行为或结构异常。相反，将 FAC 注入 CPu 会导致运动活动减少，并增加 mPFC 中的小胶质细胞数量。Perls 的普鲁士蓝染色显示，FAC 和 IONP 处理的大鼠比 VEH 处理的大鼠具有更多的含铁分支细胞，表明小胶质细胞对铁的吸收。我们的结果表明，将 IONP 局部输注到选定的大脑区域对运动行为和工作记忆没有不利影响。