The synaptic microcircuitry associated with primary afferent terminals in the interpolaris and caudalis of trigeminal sensory nuclear complex
The synaptic microcircuitry associated with primary afferent terminals in the interpolaris and caudalis of trigeminal sensory nuclear complex
复制标题
DOI：
10.1016/j.brainres.2005.08.042
复制
发表时间：
2005-10-26
期刊：
影响因子：
2.9
通讯作者：
Shigenaga, Y
中科院分区：
文献类型：
--
作者：
Bae, YC;Ahn, HJ;Shigenaga, Y
先前的超微结构研究表明，猫三叉神经感觉核复合体（TSNC）的校长（Vp）中个体低阈值机械感受传入神经上的轴轴接触数量高于口腔（Vo），这表明与初级传入神经相关的突触微电路在 TSNC 的感觉核中表现出独特的差异。为了解决这个问题，我们通过在猫的轴突内注射辣根过氧化物酶 (HR-P) 来分析与极间 (Vi) 和尾肌 (Vc，层 III/IV) 中快速适应触须传入末梢相关的突触微电路。在 Vi 和 Vc 中分别分析了 42 个和 65 个 HRP 标记的 bouton。标记的纽扣含有透明的球形囊泡。它们最常形成不对称的轴突突触，并且通常位于未标记的轴突末端的突触后，其中含有具有对称连接的多形性囊泡（p末端）。对单个按钮整个表面上突触接触的检查表明，传入按钮与 Vi 和 Vc 中的平均两个突触后目标发生接触。相比之下，Vi 中的轴轴接触和参与突触三联体的标记 bouton（其中 p 结尾同时接触 bouton 及其突触后目标）平均高于 Vc。这些结果表明，通过低阈值机械感受传入传递的感觉信息的输出在第一突触水平上受到负责感觉辨别功能的 Vi 中的突触前和突触后机制比负责感觉运动反射功能的 Vc 中的突触前和突触后机制更强的控制。 (c) 2005 Elsevier B.V. 保留所有权利。
Previous ultrastructural studies indicating a higher number of axoaxonic contacts on individual low-threshold mechanoreceptive afferents in the principalis (Vp) than in the oralis (Vo) of cat trigeminal sensory nuclear complex (TSNC) suggest that the synaptic microcircuitry associated with primary afferents manifests unique differences across the sensory nuclei of TSNC. To address this issue, we analyzed synaptic microcircuits associated with fast adapting vibrissa afferent terminals in the interpolaris (Vi) and caudalis (Vc, laminae III/IV) by using intraaxonal injections of horseradish peroxidase (HR-P) in cats. Forty-two and 65 HRP-labeled boutons were analyzed in the Vi and Vc, respectively. The labeled boutons contained clear, spherical vesicles. They most frequently formed asymmetric axodendritic synapses and were commonly postsynaptic to unlabeled axon terminals containing pleomorphic vesicles (p-endings) with symmetric junctions. The examination of synaptic contacts over the entire surface of individual boutons indicated that the afferent boutons made contacts with an average of two postsynaptic targets in the Vi and Vc. In contrast, axoaxonic contacts, and labeled boutons participating in synaptic triads, where p-endings contacted both the boutons and their postsynaptic targets, were, on average, higher in the Vi than in the Vc. These results suggest that the output of sensory information conveyed through low-threshold mechanoreceptive afferents is more strongly controlled at the level of the first synapse by presynaptic and postsynaptic mechanisms in the Vi responsible for sensory discriminative functions than in the Vc for sensorimotor reflexive functions. (c) 2005 Elsevier B.V. All rights reserved.