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PLoSONE：歐食品安全局對兩種新煙堿亮紅燈( 二 )

新煙堿神經系統發育歐食品安全局


在1月的評估中，EFSA認為有3種新煙堿類物質與蜜蜂的健康水平關系最密切，它們是噻蟲嗪（thiamethoxam）、噻蟲胺（clothianidin）和吡蟲啉 。盡管工作還在繼續，但有關另外兩種化合物——啶蟲脒和噻蟲啉（thiacloprid）——對蜜蜂影響的評估目前暫時被擱置 。
與此同時，EFSA也在著手調查新煙堿類物質對人體的影響 。這些化學物質的作用相當于昆蟲煙堿型乙酰膽堿受體的激動劑，但它們對于哺乳動物的影響尚沒有完全搞清 。EFSA明確指出由一個來自日本東京的研究團隊在去年發表的一篇論文對其結論產生了影響 。
【PLoSONE：歐食品安全局對兩種新煙堿亮紅燈】由東京醫學科學大都會研究所的Junko Kimura-Kuroda及同事在《公共科學圖書館-綜合》上發表的這篇論文發現，啶蟲脒和吡蟲啉在培養的大鼠神經細胞中引發了與在尼古?。焿A）中觀察到的類似的反應 。研究人員指出，考慮到尼古丁有可能破壞人類的大腦發育，因此新煙堿類物質“也可能對人類健康產生不利影響，尤其是對大腦的發育” 。
在對該項研究及其他證據進行評估后，EFSA認為，各種可接受的有關這兩種化學物質的暴露水平被大大降低了 。盡管EFSA承認，可用的證據“有限”，并建議進行更為深入的研究，但該局強調，所有的新煙堿類物質都應該就其潛在的發育神經毒性展開評估 。
新煙堿類殺蟲劑的作用機制主要是通過選擇性控制昆蟲神經系統煙堿型乙酰膽堿酯酶受體，阻斷昆蟲中樞神經系統的正常傳導，從而導致害蟲出現麻痹進而死亡 。由于該類殺蟲劑具有獨特的作用機制，與常規殺蟲劑沒有交互抗性，其不僅具有高效、廣譜及良好的根部內吸性、觸殺和胃毒作用，而且對哺乳動物毒性低，可有效防治同翅目、鞘翅目、雙翅目和鱗翅目等害蟲，對用傳統殺蟲劑防治產生抗藥性的害蟲也有良好的活性 。新煙堿類殺蟲劑既可用于莖葉處理、也可用于土壤、種子處理 。
生物谷推薦的英文摘要

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.