Synaptic effects of identified interneurons innervating both interneurons and pyramidal cells in the rat hippocampus
Synaptic effects of identified interneurons innervating both interneurons and pyramidal cells in the rat hippocampus
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DOI：
10.1016/s0306-4522(97)00055-9
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发表时间：
1997-08-01
期刊：
影响因子：
3.3
通讯作者：
Somogyi, P
中科院分区：
文献类型：
--
作者：
Cobb, SR;Halasy, K;Somogyi, P
γ-氨基丁酸能中间神经元塑造主细胞的活动，并且其自身受γ-氨基丁酸能输入的支配。为了直接确定GABA能神经支配的来源和机制，我们采用生物细胞素填充的微电极进行细胞内双记录，研究了成年大鼠海马CA 1区中间神经元对之间的突触相互作用。在4对突触偶联的中间神经元-中间神经元细胞对中，3对突触前细胞被鉴定为篮状细胞，优先支配锥体细胞的胞体和近端树突，但其中一个与另外两个不同的是其树突和轴突场的层状分布。第四突触前中间神经元位于放射层与分子陷窝层交界处，轴突在放射层内分叉。发现在所有四个突触前中间神经元中诱发的动作电位在其他同时记录的中间神经元（n=4）中诱发快速超极化抑制性突触后电位（在膜电位为-59 +/-2.8 mV时平均振幅为0.35 +/-0.10 mV）。此外，在随后记录的锥体细胞（n=4）中，三个突触前中间神经元也显示出产生类似的突触后反应。电子显微镜评价显示，突触前篮状细胞形成12个突触连接与perisomatic域（7个体突触和5个突触近端树突轴）的突触后中间神经元，除了支配随机选择的本地锥体细胞（50%体细胞和50%近端树突突触，n=12）相同的车厢。此外，光镜分析还表明，在篮子（12/12）和双层细胞（6/6）的autaptic自我神经支配。对一个篮状细胞的电子显微镜观察证实了它的五个终扣形成的六个自适应连接。总之，这些数据表明，几种不同类型的中间神经元对同一类型（篮状细胞）或不同类型的主细胞和局部中间神经元具有不同的输出。在突触后中间神经元和主细胞中，可能由GABA介导的快速突触效应是相似的。在GABA能细胞的输入中发现的这些额外的GABA来源可能有助于不同GABA能突触网络的差异时间模式。(C)1997年IBRO。出版社：Elsevier Science Ltd
GABAergic interneurons sculpt the activity of principal cells and are themselves governed by GABAergic inputs. To determine directly some of the sources and mechanisms of this GABAergic innervation, we have used dual intracellular recordings with biocytin-filled microelectrodes and investigated synaptic interactions between pairs of interneurons in area CA1 of the adult rat hippocampus.Of four synaptically-coupled interneuron-to-interneuron cell pairs, three presynaptic cells were identified as basket cells, preferentially innervating somata and proximal dendrites of pyramidal cells, but one differing from the other two in the laminar distribution of its dendritic and axonal fields. The fourth presynaptic interneuron was located at the border between strata lacunosum moleculare and radiatum, with axon ramifying within stratum radiatum. Action potentials evoked in all four presynaptic interneurons were found to elicit fast hyperpolarizing inhibitory postsynaptic potentials (mean amplitude 0.35 +/- 0.10 mV at a membrane potential of -59 +/- 2.8 mV) in other simultaneously recorded interneurons (n=4). In addition, three of the presynaptic interneurons were also shown to produce similar postsynaptic responses in subsequently recorded pyramidal cells (n=4). Electron microscopic evaluation revealed one of the presynaptic basket cells to form 12 synaptic junctions with the perisomatic domain (seven somatic synapses and five synapses onto proximal dendritic shafts) of the postsynaptic interneuron in addition to innervating the same compartments of randomly-selected local pyramidal cells (5O% somatic and 50% proximal dendritic synapses, n=12). In addition, light microscopic analysis also indicated autaptic self-innervation in basket (12 of 12) and bistratified cells (six of six). Electron microscopic investigation of one basket cell confirmed six autaptic junctions made by five of its boutons.Together, these data demonstrate that several distinct types of interneuron have divergent output to both principal cells and local interneurons of the same (basket cells) or different type. The fast synaptic effects, probably mediated by GABA in both postsynaptic interneurons and principal cells are similar. These additional sources of GABA identified here in the input to GABAergic cells could contribute to the differential temporal patterning of distinct GABAergic synaptic networks. (C) 1997 IBRO. Published by Elsevier Science Ltd.