大鼠海马内谷氨酸神经元与GABA神经元之间突触联系的免疫电镜双标研究

A DOUBLE LABELING IMMUNOELECTRON MICROSCOPIC STUDY OF THE SYNAPTIC CONNECTIONS BETWEEN GLUTAMIC ACID NEURONS AND GABA NEURONS IN THE HIPPOCAMPUS OF RATS

为了探讨神经递质在癫痫发病机理中的作用，用包埋前免疫电镜双标法研究了正常大鼠海马ＣＡ_１，区谷氨酸（Ｇｌｕ）神经元与ＧＡＢＡ神经元之间的突触联系。先用ＤＡＢ为呈色剂显示ＧＡＢＡ免疫反应，然后以钼酸铵－ＴＭＢ法显示Ｇｌｕ免疫反应，再进行免疫电镜包埋。观察发现：在海马ＣＡ_１区锥体细胞层有许多Ｇｌｕ免疫反应阳性神经元；在锥体细胞层、多形层和辐状层可见一些ＧＡＢＡ免疫反应阳性神经元，胞体为锥体或多角形。在多形层还可见ＧＡＢＡ阳性树突与Ｇｌｕ阳性轴突形成对称性树－轴突触，在辐状层可见ＧＡＢＡ阳性轴突与Ｇｌｕ阳性树突形成对称性轴－树突触。此外，在多形层和辐状层内尚可见到Ｇｌｕ阳性轴突与Ｇｌｕ阳性树突之间形成对称性轴－树型自调节突触，ＧＡＢＡ阳性轴突之间形成对称性和非对称性轴－轴型自调节突触。上述结果首次证实在海马ＣＡ_１区兴奋性Ｇｌｕ神经元与抑制性ＧＡＢＡ神经元之间存在着复杂的突触联系，从而为不同神经递质参与癫痫发病机理提供了超微结构依据。

In order to explore the roles of different neurotransmitters in epileptic pathogenesis, the synaptic connections between glutamic acid neurons and GABA neurons in normal rat hippocampus were studied by pre-embedding double labeling immunoelectron microscopy,i.e. ,the GABA immunoreaction was first demonstrated by chromogen DAB,then the Glu immunoreaction was demonstrated by molybdic acid-TMB method.After being stabilized by DAB-cobalt chloride,the sections were processed for electron microscopic embedding,Under electron microscope, it was observed that there were many Glu immunoreaction-positive neurons in the pyramidal layer of hippocampal CA_1 area and some GABA immunoreaction-positive neurons with pyramidal or polygonal perikarya in the pyramidal,polymorphic and radiant layer of CA_1 area. There were also symmetric dendro-axonic synapses formed by GABA-positive dendrites and Glu-positive axons in the polymorphic layer an d symmetric axo-dendritic synapses formed by GABA-positive axons and Glu-positive dendrites in the radiant layer,In addition,there were symmetric autoregulatory axodendritic synapses between Glu-positive axons and dendrites and autoregulatory axo-axonic synapses(both symmetric and asymmetric)between GABA positive axons, Above mentioned results identified that there were complex synaptic regulatory relationships between excitatory Glu neurons and inhibitory GABA neurons in the hippocampal CA_1 area for the first time,thereby,provided ultrastructural evidence for different neurotransmitters participating in epileptic pathogenesis.