Ultrastructural study of gap junctions between dendrites of parvalbumin-containing gabaergic neurons in various neocortical areas of the adult rat
Ultrastructural study of gap junctions between dendrites of parvalbumin-containing gabaergic neurons in various neocortical areas of the adult rat
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DOI：
10.1016/s0306-4522(03)00328-2
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发表时间：
2003-01-01
期刊：
影响因子：
3.3
通讯作者：
Kosaka, T
中科院分区：
文献类型：
--
作者：
Fukuda, T;Kosaka, T
白蛋白（PV） - 海马中含有GABA能神经元，形成双网络，由树突状间隙连接和相互抑制性突触连接在一起。最近的生理研究表明，皮质GABA能神经元之间的功能连通性相似，但是在电子显微镜水平上尚未对相应的结构进行完全分析。在这项研究中，我们检查了成熟新皮层中PV神经元之间间隙连接的详细超微结构特征。光显微镜观测和共聚焦激光扫描显微镜显示PV神经元之间频繁发生树突状接触。电子显微镜分析提供了直接的形态证据，证明了在视觉，听觉和体感皮层中22对PV-免疫反应树突之间存在间隙连接。它们的超微结构特征是免疫标记剖面的特征，与间隙连接的一般结构一致。在一种情况下，一个间隙连接与树突状化学突触并存，使混合突触。重要的是，我们还遇到了PV阳性和负面的非主要细胞衍生的树突之间的间隙。定量分析以16对PV阳性树突形成在体感皮质的额叶层中形成间隙连接的16对阳性树突。这些树突的直径范围为0.3至2.7妈妈，表明沿着树突树的近端轴沿着缝隙连接的不同位置，但大多数（81％）小于1妈妈。沿着膜的间隙连接的平均大小为0.22 +/- 0.09妈妈。通过使用此尺寸，估计连接电导的理论值为2.1-5.3 ns。体感皮质的基层层中PV神经元的树突是微观的重建光，并映射了与其他PV神经元的接触位点。尽管这些触点不一定意味着间隙连接耦合，但它们的数量（每个单元格5.3 +/- 2.3，n = 11）表明，来自单个PV神经元与他人的连通性程度少于10个耦合。 Sholl分析表明，它们的树突中只有38％发生在SOMA的200 MUN内。目前的研究表明，成熟的皮质PV神经元之间间隙连接的详细超微结构特征。这些特征不仅可以促进差异标记为神经元中的间隙连接，而且还通过启用其连接电导的理论估计来分析其功能方面。 （c）2003 IBRO。由Elsevier Science Ltd.出版。保留所有权利。
Parvalbumin (PV)-containing GABAergic neurons in the hippocampus form dual networks linked by both dendrodendritic gap junctions and mutual inhibitory synapses. Recent physiological studies have demonstrated similar functional connectivity among cortical GABAergic neurons, but the corresponding structures have not been fully analyzed at the electron microscopic level. In this study we examined detailed ultrastructural features of gap junctions between PV neurons in the mature neocortex. Light microscopic observations and confocal laser scanning microscopy revealed frequent dendrodendritic contacts between PV neurons. Electron microscopic analysis provided direct morphological evidence for the existence of gap junctions between 22 pairs of PV-immunoreactive dendrites in the visual, auditory, and somatosensory cortices. Their ultrastructural features that were characteristic of immunolabeled profiles were consistent with the general structure of gap junctions. In one case a gap junction coexisted with a dendrodendritic chemical synapse, making a mixed synapse. Importantly, we also encountered a gap junction between PV positive and negative, presumptive non-principal cell-derived, dendrites. Quantitative analysis was made in 16 pairs of PV positive dendrites forming gap junctions in the infragranular layers of the somatosensory cortex. Diameters of these dendrites ranged from 0.3 to 2.7 mum, suggesting diverse locations of gap junctions along the proximal-distal axis of dendritic trees, but the majority (81%) were less than 1 mum. The mean size of gap junctions along apposing membranes was 0.22+/-0.09 mum. By using this size, the theoretical value of a junctional conductance was estimated to be 2.1-5.3 nS. Dendrites of PV neurons in the infragranular layers of the somatosensory cortex were reconstructed light microscopically and the sites of contacts with other PV neurons were mapped. Although these contacts do not necessarily imply gap junctional coupling, their number (5.3+/-2.3 per cell, n = 11) suggested the degree of connectivity of less than 10 coupling from single PV neurons with others. Sholl analysis revealed that only 38% of their dendrites occurred within 200 mum from the soma.The present study demonstrated detailed ultrastructural features of gap junctions between mature cortical PV neurons. These features will facilitate not only identification of gap junctions in variously labeled neurons but also analysis of their functional aspects by enabling theoretical estimate of their junctional conductances. (C) 2003 IBRO. Published by Elsevier Science Ltd. All rights reserved.