The Ultrastructure of Perisynaptic Glia in the Nucleus Tractus Solitarii of the Adult Rat: Comparison Between Single Synapses and Multisynaptic Arrangements
The Ultrastructure of Perisynaptic Glia in the Nucleus Tractus Solitarii of the Adult Rat: Comparison Between Single Synapses and Multisynaptic Arrangements
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DOI：
10.1002/glia.21135
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发表时间：
2011-04-01
期刊：
影响因子：
6.2
通讯作者：
Kessler, Jean-Pierre
中科院分区：
文献类型：
--
作者：
Chounlamountry, Keodavanh;Kessler, Jean-Pierre
星形胶质细胞现在被认为是神经元的重要伙伴。特别是，它们在谷氨酸能传递中发挥重要作用，包括通过摄取使递质失活。在这里，我们研究了孤束核（NTS）中星形胶质细胞的组织，NTS 是位于尾髓质的感觉核。特别关注突触周围星形胶质细胞过程。使用神经胶质谷氨酸转运蛋白的免疫检测、体视学方法和连续重建，在光学和电子显微镜水平上进行研究。在NTS中，星形胶质细胞表达的主要谷氨酸转运蛋白是GLT1。星形胶质细胞突起的体积分数和星形胶质细胞膜的密度分别达到15％和2.8μm(2)μm(-3)。尽管星形胶质细胞突起相对丰富，我们发现 NTS 谷氨酸突触并不完全被神经胶质细胞包围。对 43 个重建的不对称连接进行了测量，这些连接要么是单个突触 (n = 22)，要么是参与多突触排列的突触 (n = 21)。平均而言，单个突触的周边有 58% 与星形胶质细胞突起接触。在多突触排列中，神经胶质覆盖范围仅限于突触直径的外部，平均为该外部的 50%。 NTS 突触的神经胶质细胞不完全覆盖可能会使谷氨酸从突触间隙扩散出来，并激活突触外受体以及邻近突触的受体。特别是，在多突触排列中，缺乏干预神经胶质细胞可能有利于各个接触之间的功能耦合。 (C) 2011 Wiley-Liss, Inc.
Astrocytes are now considered as essential partners of neurons. In particular, they play important roles in glutamatergic transmission, including transmitter inactivation by uptake. Here, we investigated the organization of astroglia in the Nucleus Tractus Solitarii (NTS), a sensory nucleus located in the caudal medulla. Special attention was given to perisynaptic astroglial processes. Investigations were performed at the light and electron microscope levels, using immunodetection of glial glutamate transporters, stereological methods, and serial reconstruction. In the NTS, the main glutamate transporter expressed by astrocytes was GLT1. The volume fraction of astrocyte processes and the density of astrocyte membranes reached 15% and 2.8 mu m(2) mu m(-3), respectively. In spite of the relative abundance of astrocyte processes, we found that NTS glutamatergic synapses were not entirely surrounded by glia. Measurements were performed on 43 reconstructed asymmetric junctions which were either single synapses (n = 22) or synapses involved in multisynaptic arrangements (n = 21). Single synapses had 58% of their perimeter contacted by astrocyte processes on average. In multisynaptic arrangement, glial coverage was restricted to the outer part of synaptic diameters and amounted to 50% of this outer part on average. Incomplete glial coverage of NTS synapses may allow glutamate to diffuse out of the synaptic cleft and to activate extrasynaptic receptors as well as receptors from neighboring synapses. Especially, in multisynaptic arrangements, the lack of intervening glia may favor functional coupling between individual contacts. (C) 2011 Wiley-Liss, Inc.