Alteration of gene expression profile of cerebelllar neuron-enriched cultures from neonatal rats by nicotine, acetamiprid, or imidacloprid treatment [imidacloprid]

Neonicotinoids are considered safe because of their low affinities to mammalian nicotinic acetylcholine receptors (nAChRs) relative to insect nAChRs. However, because of importance of nAChRs in mammalian brain development, there remains a need to establish the safety of chronic neonicotinoid exposures with regards to children’s health. Here we examined the effects of long-term (14 days) and low dose (1 µM) exposure of neuron-enriched cultures from neonatal rat cerebellum to nicotine and two neonicotinoids: acetamiprid and imidacloprid. Immunocytochemistry revealed no differences in the number or morphology of immature neurons or glial cells in any group versus untreated control cultures. However, a slight disturbance in Purkinje cell dendritic arborization was observed in the exposed cultures. Next we performed transcriptome analysis on total RNAs using microarrays, and identified significant differential expression (p < 0.05, q < 0.05, =1.5 fold) between control cultures versus nicotine-, acetamiprid-, or imidacloprid-exposed cultures in 34, 48, and 67 genes, respectively. Common to all exposed groups were nine genes essential for neurodevelopment, suggesting that chronic neonicotinoid exposure alters the transcriptome of the developing mammalian brain in a similar way to nicotine exposure. Our results highlight the need for further careful investigations into the effects of neonicotinoids in the developing mammalian brain.新烟碱类杀虫剂（Neonicotinoids）因相较于昆虫烟碱型乙酰胆碱受体（nAChRs），对哺乳动物烟碱型乙酰胆碱受体（nAChRs）的亲和力更低，故而常被认为具有安全性。然而，鉴于烟碱型乙酰胆碱受体在哺乳动物脑发育中的关键作用，仍需明确慢性新烟碱类杀虫剂暴露对儿童健康的安全性影响。本研究以新生大鼠小脑来源的富集神经元培养物为模型，针对尼古丁与两种新烟碱类杀虫剂——啶虫脒（acetamiprid）、吡虫啉（imidacloprid）开展了为期14天的长期低剂量（1 µM）暴露实验。免疫细胞化学检测结果显示，与未处理的对照组相比，各暴露组的未成熟神经元与神经胶质细胞的数量及形态均无显著差异。但在暴露处理的培养物中，可观察到浦肯野细胞（Purkinje cell）的树突分支出现轻微紊乱。随后，我们通过微阵列（microarrays）技术对总RNA进行转录组分析，结果表明：相较于对照组，尼古丁、啶虫脒、吡虫啉暴露组分别有34、48和67个基因出现显著差异表达（p < 0.05，q < 0.05，差异倍数≥1.5倍）。所有暴露组共有的9个基因均为神经发育所必需的基因，这提示慢性新烟碱类杀虫剂暴露与尼古丁暴露类似，均可改变发育中哺乳动物大脑的转录组特征。本研究结果凸显了针对新烟碱类杀虫剂对发育中哺乳动物大脑的影响开展进一步严谨研究的必要性。