PLoSONE：欧食品安全局对两种新烟碱亮红灯( 二 ) 欧食品安全局|新烟碱|神经系统

在1月的评估中，EFSA认为有3种新烟碱类物质与蜜蜂的健康水平关系最密切，它们是噻虫嗪（thiamethoxam）、噻虫胺（clothianidin）和吡虫啉。尽管工作还在继续，但有关另外两种化合物——啶虫脒和噻虫啉（thiacloprid）——对蜜蜂影响的评估目前暂时被搁置。
与此同时，EFSA也在着手调查新烟碱类物质对人体的影响。这些化学物质的作用相当于昆虫烟碱型乙酰胆碱受体的激动剂，但它们对于哺乳动物的影响尚没有完全搞清。EFSA明确指出由一个来自日本东京的研究团队在去年发表的一篇论文对其结论产生了影响。
【PLoSONE：欧食品安全局对两种新烟碱亮红灯】由东京医学科学大都会研究所的Junko Kimura-Kuroda及同事在《公共科学图书馆-综合》上发表的这篇论文发现，啶虫脒和吡虫啉在培养的大鼠神经细胞中引发了与在尼古丁（烟碱）中观察到的类似的反应。研究人员指出，考虑到尼古丁有可能破坏人类的大脑发育，因此新烟碱类物质“也可能对人类健康产生不利影响，尤其是对大脑的发育” 。
在对该项研究及其他证据进行评估后，EFSA认为，各种可接受的有关这两种化学物质的暴露水平被大大降低了。尽管EFSA承认，可用的证据“有限”，并建议进行更为深入的研究，但该局强调，所有的新烟碱类物质都应该就其潜在的发育神经毒性展开评估。
新烟碱类杀虫剂的作用机制主要是通过选择性控制昆虫神经系统烟碱型乙酰胆碱酯酶受体，阻断昆虫中枢神经系统的正常传导，从而导致害虫出现麻痹进而死亡。由于该类杀虫剂具有独特的作用机制，与常规杀虫剂没有交互抗性，其不仅具有高效、广谱及良好的根部内吸性、触杀和胃毒作用，而且对哺乳动物毒性低，可有效防治同翅目、鞘翅目、双翅目和鳞翅目等害虫，对用传统杀虫剂防治产生抗药性的害虫也有良好的活性。新烟碱类杀虫剂既可用于茎叶处理、也可用于土壤、种子处理。
生物谷推荐的英文摘要

PLoS ONE DOI: 10.1371/journal.pone.0032432
Nicotine-Like Effects of the Neonicotinoid Insecticides Acetamiprid and Imidacloprid on Cerebellar Neurons from Neonatal Rats
Junko Kimura-Kuroda，Yukari Komuta， Yoichiro Kuroda， Masaharu Hayashi， Hitoshi Kawano
Background
Acetamiprid (ACE) and imidacloprid (IMI) belong to a new，widely used class of pesticide，the neonicotinoids. With similar chemical structures to nicotine，neonicotinoids also share agonist activity at nicotinic acetylcholine receptors (nAChRs). Although their toxicities against insects are well established，their precise effects on mammalian nAChRs remain to be elucidated. Because of the importance of nAChRs for mammalian brain function，especially brain development，detailed investigation of the neonicotinoids is needed to protect the health of human children. We aimed to determine the effects of neonicotinoids on the nAChRs of developing mammalian neurons and compare their effects with nicotine，a neurotoxin of brain development.
Methodology/Principal Findings
Primary cultures of cerebellar neurons from neonatal rats allow for examinations of the developmental neurotoxicity of chemicals because the various stages of neurodevelopment—including proliferation，migration，differentiation，and morphological and functional maturation—can be observed in vitro. Using these cultures，an excitatory Ca2+-influx assay was employed as an indicator of neural physiological activity. Significant excitatory Ca2+ influxes were evoked by ACE，IMI，and nicotine at concentrations greater than 1 μM in small neurons in cerebellar cultures that expressed the mRNA of the α3，α4，and α7 nAChR subunits. The firing patterns，proportion of excited neurons，and peak excitatory Ca2+ influxes induced by ACE and IMI showed differences from those induced by nicotine. However，ACE and IMI had greater effects on mammalian neurons than those previously reported in binding assay studies. Furthermore，the effects of the neonicotinoids were significantly inhibited by the nAChR antagonists mecamylamine，α-bungarotoxin，and dihydro-β-erythroidine.