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

Han D, Tian Y, Zhang T, Ren G, Yang Z - Int J Nanomedicine (2011)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, China.

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.

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Comparison of escape latency of reacquision phase between nano-ZnOtreated group and control group.Notes: Data are expressed as mean ± standard error of the mean; *P < 0.05 compared with control group; **P < 0.01 compared with control group.Abbreviation: nano-ZnO, zinc oxide nanoparticles.
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f4-ijn-6-1453: Comparison of escape latency of reacquision phase between nano-ZnOtreated group and control group.Notes: Data are expressed as mean ± standard error of the mean; *P < 0.05 compared with control group; **P < 0.01 compared with control group.Abbreviation: nano-ZnO, zinc oxide nanoparticles.

Mentions: The reacquisition phase was applied 24 hours after retention. The hidden platform was placed into the middle of the SW quadrant to assess an animal’s ability to reacquire the learned strategy. During the reacquisition phase, significantly shorter escape latencies were obtained on the training trial (P < 0.05, repeated-measures ANOVA), at the second trial (control, 6.51 ± 1.50 seconds; nano-ZnOtreated group, 24.56 ± 5.93 seconds, P < 0.01), the third trial (control, 4.86 ± 0.77 seconds; nano-ZnO-treated group, 8.94 ± 1.90 seconds, P < 0.05), and the fourth trial (control, 1.61 ± 0.23 seconds; nano-ZnO-treated group, 5.04 ± 1.03 seconds, P < 0.05) (Figure 4). Interestingly, at the same time, in temporal distribution of the quadrants, rats of the nano-ZnO-treated group spent a dramatically longer time in the SW quadrant (original location quadrant) in which the hidden platform had been located in the acquisition phase (control, 8.91% ± 2.07%; nano-ZnO-treated group, 14.82% ± 2.85%, P < 0.05, repeated-measures ANOVA), and shorter time in the NE quadrant (novel location quadrant), in which the hidden platform was relocated in the reacquisition phase (control, 61.10% ± 4.06%; nano-ZnO-treated group, 42.75% ± 3.59%, P < 0.01, repeated-measures ANOVA) than the control group (Figure 5). There was no significant difference between the two groups in the NW quadrant (control, 13.72% ± 1.92%; nano-ZnO-treated group, 19.87% ± 1.97%, P > 0.05, repeated-measures ANOVA) and SE quadrant (control, 15.19% ± 2.36%; nano-ZnO-treated group, 20.05% ± 2.59%, P > 0.05, repeated-measures ANOVA). Therefore, reacquisition of spatial information was slowed down in rats of the nano-ZnO group due to much more time spent on exploration in the original location quadrant.


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

Han D, Tian Y, Zhang T, Ren G, Yang Z - Int J Nanomedicine (2011)

Comparison of escape latency of reacquision phase between nano-ZnOtreated group and control group.Notes: Data are expressed as mean ± standard error of the mean; *P < 0.05 compared with control group; **P < 0.01 compared with control group.Abbreviation: nano-ZnO, zinc oxide nanoparticles.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3141872&req=5

f4-ijn-6-1453: Comparison of escape latency of reacquision phase between nano-ZnOtreated group and control group.Notes: Data are expressed as mean ± standard error of the mean; *P < 0.05 compared with control group; **P < 0.01 compared with control group.Abbreviation: nano-ZnO, zinc oxide nanoparticles.
Mentions: The reacquisition phase was applied 24 hours after retention. The hidden platform was placed into the middle of the SW quadrant to assess an animal’s ability to reacquire the learned strategy. During the reacquisition phase, significantly shorter escape latencies were obtained on the training trial (P < 0.05, repeated-measures ANOVA), at the second trial (control, 6.51 ± 1.50 seconds; nano-ZnOtreated group, 24.56 ± 5.93 seconds, P < 0.01), the third trial (control, 4.86 ± 0.77 seconds; nano-ZnO-treated group, 8.94 ± 1.90 seconds, P < 0.05), and the fourth trial (control, 1.61 ± 0.23 seconds; nano-ZnO-treated group, 5.04 ± 1.03 seconds, P < 0.05) (Figure 4). Interestingly, at the same time, in temporal distribution of the quadrants, rats of the nano-ZnO-treated group spent a dramatically longer time in the SW quadrant (original location quadrant) in which the hidden platform had been located in the acquisition phase (control, 8.91% ± 2.07%; nano-ZnO-treated group, 14.82% ± 2.85%, P < 0.05, repeated-measures ANOVA), and shorter time in the NE quadrant (novel location quadrant), in which the hidden platform was relocated in the reacquisition phase (control, 61.10% ± 4.06%; nano-ZnO-treated group, 42.75% ± 3.59%, P < 0.01, repeated-measures ANOVA) than the control group (Figure 5). There was no significant difference between the two groups in the NW quadrant (control, 13.72% ± 1.92%; nano-ZnO-treated group, 19.87% ± 1.97%, P > 0.05, repeated-measures ANOVA) and SE quadrant (control, 15.19% ± 2.36%; nano-ZnO-treated group, 20.05% ± 2.59%, P > 0.05, repeated-measures ANOVA). Therefore, reacquisition of spatial information was slowed down in rats of the nano-ZnO group due to much more time spent on exploration in the original location quadrant.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, China.

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.

Show MeSH