Laboratoire Récepteurs et Canaux loniques Membranaires, UPRES EA2647/USC INRA 2023, IFR 149 QUASAV, Université d'Angers, UFR de Sciences, 2 Bd. Lavoisier 49045 Angers, France.
Adv Exp Med Biol. 2010;683:1-10. doi: 10.1007/978-1-4419-6445-8_1.
A major criteria initially used to localize cholinergic neuronal elements in nervous systems tissues that involve acetylcholine (ACh) as neurotransmitter is mainly based on immunochemical studies using choline acetyltransferase (ChAT), an enzyme which catalyzes ACh biosynthesis and the ACh degradative enzyme named acetylcholinesterase (AChE). Immunochemical studies using anti-ChAT monoclonal antibody have allowed the identification of neuronal processes and few types of cell somata that contain ChAT protein. In situ hybridization using cRNA probes to ChAT or AChE messenger RNA have brought new approaches to further identify cell bodies transcribing the ChAT or AChE genes. Combined application of all these techniques reveals a widespread expression of ChAT and AChE activities in the insect central nervous system and peripheral sensory neurons which implicates ACh as a key neurotransmitter. The discovery of the snake toxin alpha-bungatoxin has helped to identify nicotinic acetylcholine receptors (nAChRs). In fact, nicotine when applied to insect neurons, resulted in the generation of an inward current through the activation of nicotinic receptors which were blocked by alpha-bungarotoxin. Thus, insect nAChRs have been divided into two categories, sensitive and insensitive to this snake toxin. Up to now, the recent characterization and distribution pattern of insect nAChR subunits and the biochemical evidence that the insect central nervous system contains different classes of cholinergic receptors indicated that ACh is involved in several sensory pathways.
一种主要的标准最初被用于定位涉及乙酰胆碱 (ACh) 作为神经递质的神经系统组织中的胆碱能神经元成分，主要基于使用胆碱乙酰转移酶 (ChAT) 的免疫化学研究，ChAT 是一种催化 ACh 生物合成的酶，以及名为乙酰胆碱酯酶 (AChE) 的 ACh 降解酶。使用抗 ChAT 单克隆抗体的免疫化学研究允许鉴定含有 ChAT 蛋白的神经元过程和少数类型的细胞体。使用 ChAT 或 AChE 信使 RNA 的 cRNA 探针进行原位杂交已带来了进一步鉴定转录 ChAT 或 AChE 基因的细胞体的新方法。所有这些技术的联合应用揭示了 ChAT 和 AChE 活性在昆虫中枢神经系统和外周感觉神经元中的广泛表达，这表明 ACh 是一种关键的神经递质。蛇毒素 alpha-bungatoxin 的发现有助于鉴定烟碱型乙酰胆碱受体 (nAChRs)。事实上，尼古丁应用于昆虫神经元时，通过激活烟碱受体产生内向电流，而 alpha-bungarotoxin 会阻断这些受体。因此，昆虫 nAChRs 已分为两类，对这种蛇毒素敏感和不敏感。到目前为止，昆虫 nAChR 亚基的最新特征和分布模式以及昆虫中枢神经系统中存在不同类别的胆碱能受体的生化证据表明，ACh 参与了几种感觉途径。
