GABAERGIC INTERNEURONS ARE THE MAJOR POSTSYNAPTIC TARGETS OF MEDIAN RAPHE AFFERENTS IN THE RAT DENTATE GYRUS
GABAERGIC INTERNEURONS ARE THE MAJOR POSTSYNAPTIC TARGETS OF MEDIAN RAPHE AFFERENTS IN THE RAT DENTATE GYRUS
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DOI：
10.1111/j.1460-9568.1992.tb00861.x
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发表时间：
1992-02-01
影响因子：
3.4
通讯作者：
FREUND, TF
中科院分区：
文献类型：
--
作者：
HALASY, K;MIETTINEN, R;FREUND, TF
以菜豆白细胞凝集素（Phaseolusvulgaris leucoagglutinin）为顺行示踪剂，结合埋藏后γ-氨基丁酸（GABA）免疫染色和埋藏前钙结合蛋白D28 k、小清蛋白和GABA免疫染色，研究了大鼠齿状回中缝正中神经轴突的终止方式。GABA免疫金染色后发现，大多数（73.7%）的顺行标记的中缝结与GABA免疫反应的突触后靶，主要是树突状轴和胞体的突触接触。包埋前的顺行示踪剂和GABA的免疫细胞化学双染色证实了电子显微镜的结果，并表明，静脉曲张中缝正中神经轴突建立多个与梭形中间神经元在门和不同类型的篮状细胞在颗粒细胞层的接触。一些神经支配的细胞被证明含有钙结合蛋白D28 k，而GABA能中间神经元含有另一种钙结合蛋白，小清蛋白，从未见过收到多个接触来自中缝起源的轴突。我们的研究结果表明，多巴胺能中缝正中神经纤维通过局部抑制性中间神经元影响齿状颗粒细胞的放电。使用这些具有广泛局部连接的中间神经元作为单突触靶点的机制可以解释该通路在控制海马电活动中的巨大功效。
The termination pattern of median raphe axons was studied in the rat dentate gyrus using Phaseolus vulgaris leucoagglutinin as an anterograde tracer, in combination with postembedding immunostaining for gamma-aminobutyric acid (GABA), and pre-embedding immunostaining for calbindin D28k, parvalbumin and GABA. Postembedding immunogold staining for GABA revealed that the majority (73.7%) of anterogradely labelled median raphe boutons make synaptic contacts with GABA-immunoreactive postsynaptic targets, mainly with dendritic shafts and perikarya. Pre-embedding immunocytochemical double staining for the anterograde tracer and GABA confirmed the electron microscopic results and showed that varicose median raphe axons establish multiple contacts with fusiform interneurons in the hilus and different types of basket cells in the granule cell layer. Some of the innervated cells were shown to contain calbindin D28k, whereas GABAergic interneurons containing another calcium-binding protein, parvalbumin, were never seen to receive multiple contacts from axons of raphe origin. Our results suggest that serotonergic median raphe fibres influence the firing of dentate granule cells via local inhibitory interneurons. The mechanism of using these interneurons with extensive local connections as monosynaptic targets may explain the great efficacy of this pathway in the control of hippocampal electrical activity.