Introduction: According to the expand application of zinc oxide nanoparticles in medicine, industry and etc., human constantly are exposing to this compound. Zinc ions after transfer from the environment to the blood circulation potentially lead to toxicity in various organs, including the brain. Stimulation of hippocampal nicotinic receptors differently, affects the structure and function of memory and learning. In the present study, the role of dorsal hippocampal nicotinic receptors in the effects of zinc oxide nanoparticles on long-term investigated. Materials and methods: In this experimental study, adult male Wistar rats were divided into control groups (saline 1 ml/kg), zinc oxide nanoparticles (0.5 and 1 mg/kg) and nicotine (0.3 and 0.4 µg/rat). In all groups, bilaterary cannulated was performed in CA1 region. Intracerebral injection of saline or nicotine immediately after training and intraperitoneal injection of saline or zinc oxide nanoparticles 5 minutes after the first injection was performed. Passive avoidance test, 1 and 3 days after training to assess memory was used. Results: Injection Post-training of zinc oxide nanoparticles in a dose-dependently, lead to reduced memory compared with control group (p<0.01). Injection of nicotine dose-dependently, was able the amnesia effect of injection of zinc oxide nanoparticles (1 mg/kg) to eliminated (p<0.01). Compared with control group, injection of zinc oxide nanoparticles and nicotine alone had not effect on long-term memory (p>0.05). Conclusion: Injections of zinc oxide nanoparticles in a dose-dependently leads to amnesia. Stimulation of nicotinic receptors in the CA1 region of the hippocampus, can prevent from amnesia due to these nanoparticles.
