纳米银的脑神经毒性效应研究进展

Research progress on neurotoxic effects of silver nanoparticles

纳米银指粒径为1~100 nm之间的银单质颗粒,被广泛应用于抗菌、超导、催化、光学材料等多个领域。人体可经消化道、呼吸道、皮肤等途径接触到纳米银。脑是中枢神经系统的重要器官,也是纳米银作用的靶器官之一。当前研究表明纳米银可经3条途径--穿越血脑屏障、沿嗅神经到达嗅球和经三叉神经感觉末梢入脑。进入脑内的纳米银通过释放Ag+、引起氧化应激、炎症反应和Ca2+内流等机制造成脑神经毒性损伤。本文总结了纳米银进入脑的具体途径,归纳有关纳米银的体内、体外脑神经毒性效应的研究,并分析纳米银的脑神经毒性作用机制。目前关于纳米银的脑神经毒性研究资料较少,尤其是纳米银对脑各个结构及功能分区的毒性研究很不充分,建议在该方面加大研究力度。体外实验研究纳米银对脑神经细胞的毒性时不应局限于常见的永生化细胞株,应着重于对原代神经细胞毒性的研究,使实验代表性更好。纳米银的脑神经毒性作用机制研究中,纳米银释放Ag+的定量仍是一个难题,对于多个毒性机制之间的相互联系需进一步明确。

Silver nanoparticles(AgNPs), 1-100 nm in diameter, have been wildly used in anti-bacterial agents, superconductors, catalyzers, optical materials, etc. Human exposure pathways of AgNPs include digestive tract, respiratory tract, and skin contract. As the important organ of central nervous system, brain is one of the target organs of AgNPs. Available studies have revealed three pathways of AgNPs entering the brain: crossing the blood-brain barrier, translocating into the olfactory bulb along the olfactory nerve, and passing through the trigeminal sensory terminals. Then AgNPs induce brain neurotoxic effects by releasing Ag+ and causing oxidative stress, inflammation, and Ca2+ influx. Therefore, the specific ways of AgNPs entering the brain,in vivo and in vitro studies on AgNPs neurotoxicity, and related neurotoxic mechanisms were summarized in this paper. Considering that there are few studies evaluating the neurotoxicity of AgNPs, especially the toxicity to brain structures and functional areas, it calls for more efforts in this field. In vitro studies on AgNPs neurotoxicity should focus on primary nerve cells more than common immortalized cell lines to improve experiment representativeness. To quantify the release of Ag+ from AgNPs is still a difficult problem in studying the mechanism of brain neurotoxicity;moreover, the relationship among different toxic mechanisms needs to be clarified.