Cholinergic synapses in the central nervous system: studies of the immunocytochemical localization of choline acetyltransferase.
Cholinergic synapses in the central nervous system: studies of the immunocytochemical localization of choline acetyltransferase.
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DOI：
10.1002/jemt.1060150103
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发表时间：
1990-05
期刊：
影响因子：
--
通讯作者：
C. Houser
中科院分区：
文献类型：
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作者：
C. Houser
胆碱能突触可以通过使用胆碱乙酰转移酶（ChAT）的单克隆抗体和特异性抗血清在免疫细胞化学制剂中鉴定，ChAT是乙酰胆碱（ACh）的合成酶和胆碱能神经元的特异性标记物。电子显微镜研究表明，在许多脑区的光镜标本中观察到的纤维和静脉曲张是小直径的无髓鞘轴突和含囊泡的终扣。标记的终扣通常含有透明的囊泡和一个或多个线粒体轮廓。这些终扣中的许多形成突触接触，并且突触通常是对称型的，显示薄的突触后密度和相对短的接触区。然而，ChAT标记的突触与不对称的连接也被观察到，它们的频率在不同的大脑区域之间变化。未标记的树突轴是最常见的突触后元件，在几乎所有的区域检查，虽然其他神经元的元素，包括树突棘和神经元胞体，也收到一些胆碱能神经支配。ChAT标记的终扣与同一大脑区域内的几种不同类型的未标记神经元形成突触接触。这些发现与中枢神经系统许多部位的胆碱能神经支配的一般弥散模式一致。尽管ChAT标记的突触的特征有许多相似之处，但在脑区域内和脑区域之间的胆碱能神经支配似乎存在一些异质性。ChAT免疫反应终扣的大小，突触接触的类型，和主要的突触后元素的差异。因此，胆碱能系统提出了有趣的挑战，为未来的研究的形态组织和相关功能的胆碱能突触。
Cholinergic synapses can be identified in immunocytochemical preparations by the use of monoclonal antibodies and specific antisera to choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine (ACh) and a specific marker for cholinergic neurons. Electron microscopic studies demonstrate that the fibers and varicosities observed in light microscopic preparations of many brain regions are small-diameter unmyelinated axons and vesicle-containing boutons. The labeled boutons generally contain clear vesicles and one or more mitochondrial profiles. Many of these boutons form synaptic contacts, and the synapses are frequently of the symmetric type, displaying thin postsynaptic densities and relatively short contact zones. However, ChAT-labeled synapses with asymmetric junctions are also observed, and their frequency varies among different brain regions. Unlabeled dendritic shafts are the most common postsynaptic elements in virtually all regions examined although other neuronal elements, including dendritic spines and neuronal somata, also receive some cholinergic innervation. ChAT-labeled boutons form synaptic contacts with several different types of unlabeled neurons within the same brain region. Such findings are consistent with a generally diffuse pattern of cholinergic innervation in many parts of the central nervous system. Despite many similarities in the characteristics of ChAT-labeled synapses, there appears to be some heterogeneity in the cholinergic innervation within as well as among brain regions. Differences are observed in the sizes of ChAT-immunoreactive boutons, the types of synaptic contacts, and the predominant postsynaptic elements. Thus, the cholinergic system presents interesting challenges for future studies of the morphological organization and related function of cholinergic synapses.