Geraniol improved memory impairment and neurotoxicity induced by zinc oxide nanoparticles in male wistar rats through its antioxidant effect

Aims: Zinc oxide nanoparticles (ZnO-NPs) are currently applied in food and pharmaceutical industries whose neurotoxic effect on the central nervous system (CNS) is a major concern. Considering the pharmacological properties (antioxidant, anti-inflammatory) of the geraniol (GE), we aimed to investigate the efficacy of geraniol on ZnO-NPs neurotoxicity. Materials and methods: We used 32 male Wistar rats, randomly assigned to four groups (n = 8): Control, GE (daily received 100 mg/kg of GE by gavage), ZnO-NPs (received intraperitoneal injection of 75 mg/kg of ZnO-NPs twice a week), and ZnO-NPs + GE (received both GE and ZnO-NPs at same doses above during 4 weeks). Morris water maze (MWM) and Y-maze tasks were done to evaluate learning and memory function. Biochemical assays were done to measure total antioxidant capacity (TAC), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX) and ZnO-NPs bioaccumulation. Nissl and H&E staining were performed for histological evaluations. Key findings: The results of behavioral study revealed that GE improved learning and memory impairment induced by ZnO-NPs. Moreover, neuroprotective effect of GE significantly decreased pathological parameters such as necrosis and gliosis, and consequently increased the number of nerve cells in the cortex and different hippocampal areas. Furthermore, biochemical studies demonstrated that GE significantly increased antioxidant indices (namely, TAC, SOD, and GPX) and reduced oxidative stress marker (MDA) and Zn bioaccumulation in ZnO-NPs treated animals. Significance: Our results provide experimental evidence to further investigate the precise mechanisms underlying the geraniol as a promising therapeutic approach for improvement of cognitive function and neurotoxicity induce by ZnO-NPs.