Identification of signal substances in synapses made between primary afferents and their associated axon terminals in the rat trigeminal sensory nuclei
Identification of signal substances in synapses made between primary afferents and their associated axon terminals in the rat trigeminal sensory nuclei
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DOI：
10.1002/(sici)1096-9861(20000313)418:3
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发表时间：
2000-03
影响因子：
2.5
通讯作者：
Y. Bae;H. Ihn;M. Park;O. Ottersen;M. Moritani;A. Yoshida;Y. Shigenaga
中科院分区：
文献类型：
--
作者：
Y. Bae;H. Ihn;M. Park;O. Ottersen;M. Moritani;A. Yoshida;Y. Shigenaga
研究了大鼠三叉神经感觉核复合体（TSNC）中初级传入终末（PAT）及其相关突触前终末之间的关系，特别是氨基酸递质谷氨酸（Glu）和γ-氨基丁酸（GABA）。用辣根过氧化物酶结合霍乱毒素B亚单位（CT B-HRP）顺行标记三叉神经节的初级传入终末，切片进行电子显微镜检查。用免疫胶体金法对主核（Vp）、口核和极间核（Vdm）的背内侧部分和尾核（Vc）的III/IV层连续切片进行Glu和GABA免疫染色。三叉神经节的示踪剂CTB-HRP优先标记有髓鞘初级传入神经。免疫组化切片显示，大多数标记的PAT富含Glu的免疫反应性（IR）。Glu‐IR PAT含有清晰、圆形的突触囊泡，并与胞体或树突形成不对称的突触接触。它们通常位于突触后至未标记的轴突终末，轴突终末充满透明、圆形、椭圆形和扁平囊泡（p末端）的混合物，具有对称的突触连接。在Vdm中，每个Glu-IR PAT的胞体或初级树突上的突触频率高于Vp或Vc层III/IV。Vp中每Glu‐IR PAT的p‐末端接触频率高于Vdm和Vc层III/IV。GABA抗血清免疫组化切片显示，大多数轴突终末突触前的PATs富含GABA的三个核。GABA-IR轴突终末及其突触后PAT分别具有与p-末端及其突触后Glu-IR PAT相似的超微结构特征。本研究表明，具有大口径纤维的初级传入神经元使用谷氨酸作为神经递质，并受到GABA能纤维的突触前调制。神经学比较杂志418：299-309，2000.© 2000 Wiley利斯公司
The relationships between primary afferent terminals (PATs) and their associated presynaptic terminals in the rat trigeminal sensory nuclear complex (TSNC) were examined with special reference to amino acid transmitters glutamate (Glu) and gamma‐aminobutyric acid (GABA). Primary afferent terminals anterogradely labeled from the trigeminal ganglion with the B subunit of cholera toxin conjugated to horseradish peroxidase (CTB‐HRP) were sectioned for electron microscopy. Serial sections from the principal nucleus (Vp), dorsomedial parts of the oral and interpolar nuclei (Vdm), and lamina III/IV of caudal nucleus (Vc) were immunostained for Glu and GABA by using a postembedding immunogold technique. The tracer, CTB‐HRP to the trigeminal ganglion, preferentially labeled myelinated primary afferents. Sections immunostained with Glu antiserum showed that most labeled PATs were enriched with immunoreactivity (IR) for Glu. The Glu‐IR PATs contained clear, round, synaptic vesicles and formed asymmetric synaptic contacts with somata or dendrites. They were frequently postsynaptic to unlabeled axon terminals filled with a mixture of clear, round, oval, and flattened vesicles (p‐endings), with symmetric synaptic junctions. The frequency of synapses onto somata or primary dendrites per Glu‐IR PAT was higher in the Vdm than in either the Vp or Vc lamina III/IV. The frequency of contacts of the p‐endings per Glu‐IR PAT was higher in the Vp than in the Vdm and Vc lamina III/IV. Sections immunostained with GABA antiserum showed that most axon terminals presynaptic to PATs were enriched with GABA in the three nuclei. The GABA‐IR axon terminals and their postsynaptic PATs had a similar ultrastructural character to p‐endings and their postsynaptic Glu‐IR PATs, respectively. The present study suggests that primary afferent neurons with large‐caliber fibers use glutamate as a neurotransmitter and are subject to presynaptic modulation by GABAergic fibers. J. Comp. Neurol. 418:299–309, 2000. © 2000 Wiley‐Liss, Inc.