Nano-zinc oxide damages spatial cognition capability via over-enhanced long-term potentiation in hippocamus of Wistar rats

Abstract

This study focused on the effects of zinc oxide nanoparticles (nano-ZnO) on spatial learning and memory and synaptic plasticity in the hippocampus of young rats, and tried to interpret the underlying mechanism. Rats were randomly divided into four groups. Nano-ZnO and phosphate-buffered saline were administered in 4-week-old rats for 8 weeks. Subsequently, performance in Morris water maze (MWM) was determined, and then long-term potentiation (LTP) and depotentiation were measured in the perforant pathway to dentate gyrus (DG) in anesthetized rats. The data showed that, (1) in MWM, the escape latency was prolonged in the nano-ZnO group and, (2) LTP was significantly enhanced in the nano-ZnO group, while depotentiation was barely influenced in the DG region of the nano-ZnO group. This bidirectional effect on long-term synaptic plasticity broke the balance between stability and flexibility of cognition. The spatial learning and memory ability was attenuated by the alteration of synaptic plasticity in nano-ZnO-treated rats.

Comparative Evaluation of Prosopis cineraria (L.) Druce and Its ZnO Nanoparticles on Scopolamine Induced Amnesia

“…But it was observed that ZnOPC treatment was not able to significantly reverse the scopolamine induced memory deficit. This is in well agreement with past study, which revealed chemically synthesized ZnONP damages the spatial learning and memory capability in rats through disruptive effect at the homeostasis of synaptic Zn concentration leading to direct hyperactive long-term potentiation and insufficient depotentiation in hippocampus ( Han et al, 2011 ). In contrast to these results, it has also been reported that no steady difference was observed in emotional behavior of ZnOPC treated rats via EPM as compared to control group ( Xie et al, 2012 ).…”

Neurotoxicity induced by zinc oxide nanoparticles: age-related differences and interaction

“…However, no significant changes in locomotor activity or exploratory behavior were identified. ZnO NPs have been demonstrated to damage spatial cognition capability via over-enhanced long-term potentiation in the hippocampus of Wistar rats 15 . However, Xie et al reported that ZnO NPs ameliorated behavioral and cognitive impairments in Swiss male mice with depressive-like behaviors induced by LPS 50 .…”

“…In recent years, more and more researches have provided evidence that NPs can reach the brain via blood-brain barrier (BBB) penetration or translocation along the olfactory nerve pathway and subsequently cause damage by the induction of oxidative stress, inflammatory responses, and cytotoxicity 12 . It has also been found that ZnO NPs could reach the brain after oral and inhalatrory administration in animals 13 14 , induce the changes in the spatial learning and memory ability of rats by altering the synaptic plasticity 15 , and interact diversely with plasma and brain proteins during inducing their toxic effects in the blood and brain 16 . In vitro studies, ZnO NPs showed the strongest toxicity for mice brain tumor cell lines (Neuro-2a) when compared with similar sized particles of Al 2 O 3 , TiO 2 , Fe 3 O 4 and CrO 3 17 , decreased the activity of mice neural stem cells and human SHSY5Y neuronal cells by inducing DNA damage and cell apoptosis 18 19 , and induced apoptosis in primary cultured astrocytes through JNK signaling pathway 20 .…”

Exposure to Zinc Oxide Nanoparticles Induces Neurotoxicity and Proinflammatory Response: Amelioration by Hesperidin

“…Recently, there have been reports that NPs can reach the brain via blood-brain barrier (BBB) penetration and subsequently cause damage by the induction of oxidative stress, inflammatory responses, and cytotoxicity [1][2][3][4]. It has also been found that ZnONPs could reach the brain after oral administration in animals or translocation along the olfactory nerve pathway [5,6] and may induce the changes in the spatial learning and memory ability of rats by altering the synaptic plasticity [7], and induce toxic effects in the blood and brain [8]. Earlier, ZnONPs have shown toxicity in mice brain tumor cell lines (Neuro-2a) when compared with similar sized particles of Al 2 O 3 , TiO 2 , Fe 3 O 4 , and CrO 3 [9].…”