Paper of the week: Zinc oxide nanoparticles reverse symptoms of depression
Xie, Y., Wang, Y., Zhang, T., Ren, G., & Yang, Z. (2012). Effects of nanoparticle zinc oxide on spatial cognition and synaptic plasticity in mice with depressive-like behaviors. Journal of biomedical science, 19(1), 14. doi:10.1186/1423-0127-19-14
Zinc oxide nanoparticles (ZnO) are used in a variety of products – in sunscreens, powders, creams, food packaging, cigarette filters, breakfast cereals, coatings for metals and plastics, and so on. ZnO nanoparticles also have biological effects that are central in the development of novel anti-cancer and drug delivery technologies. However, little is known about the effects of ZnO nanoparticles on brain function.
Researchers at Nankai University in China hypothesized that they may be involved in priming key brain circuits involved in learning and emotion by regulating synaptic transmission. To test these ideas, mice were treated with 20-80 nm sized ZnO particles (5.6 mg/kg) for 16 days. A second group were treated with lipopolysaccharides (100 µg/kg) to induce symptoms of depression. A third group was given both compounds, and a fourth group served as control.
Mice treated with lipopolysaccharides showed signs of depression in behavioral assays designed to reveal “despair” – spending more time immobile in water (‘forced swim test’) and while suspended in air (‘tail suspension test’). Notably, mice receiving ZnO treatment showed immobility times similar to control mice, indicating antidepressant-like properties of ZnO. ZnO also reversed the negative effects of lipopolysaccharides on spatial memory performance.
Electrophysiological recordings using a PowerLab revealed a potential mechanism to explain these effects: ZnO treatment boosted EPSP slopes (‘synaptic enhancement’) in brain circuits involved in memory and emotion in the hippocampus.
Neural effects of ZnO nanoparticles clearly warrant further investigation. As this study shows, they may hold significant potential in treating a range of brain disorders.
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10 February 2012
