Ultrastructural characterization of substance-P-immunoreactive synaptic terminals in the cat's normal and rhizotomized trigeminal subnucleus caudalis.
Ultrastructural characterization of substance-P-immunoreactive synaptic terminals in the cat's normal and rhizotomized trigeminal subnucleus caudalis.
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DOI：
10.3109/08990229209144767
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发表时间：
1992
影响因子：
0.9
通讯作者：
M. A. Matthews;K. Hoffmann;J. Stover
中科院分区：
文献类型：
--
作者：
M. A. Matthews;K. Hoffmann;J. Stover
脱传入损伤通常在受影响的初级传入纤维的中央投射范围内引起短暂或永久的生理改变。异常的感觉知觉、感觉障碍和痛觉过敏是这种损伤的临床后遗症；然而，实验结果的脱指已经受到各种解释（罗丹和克鲁格，1984b）。神经化学研究表明，部分失传入神经元对P物质（SP）的敏感性增加。我们之前的研究（Hoffmann et al., 1991）主要在光镜水平上记录了三叉神经尾侧亚核（Vc）中sp免疫反应性（SPIR）钮扣的中度短暂丢失——这种丢失似乎优先影响稍大的、可能具有多个接触点的复杂钮扣。然而，尽管消除了三叉神经输入，较大的钮扣又出现了。因此，在本研究中，我们使用电子显微镜免疫细胞化学检查Vc，以记录这些随时间的变化，并澄清这种钮扣种群的结构和关系。SPIR扣发生在Vc明胶质的I和II级，直径在1 ~ 5微米之间，显示出透明和密集核囊泡的混合群体。大多数形成单个或多个轴突连接，但也有相当数量的轴突连接与spir标记和未标记的终端进行接触。少数似乎是典型肾小球的中心元素，特别是在II层度。同侧脊髓后根切断术后3 - 7天，明胶质的突触变性明显，常累及肾小球终末。然而，这些大多为spir阴性，主要发生在II级椎板。那些显示退行性特征的SPIR钮扣通常会形成单个或多个轴突接触，在某些情况下会形成扇形。到30天，大多数剩余的SPIR钮扣都很小，接触率较低；然而，其中一些是轴突的。此外，许多SPIR终末只有非常轻微的染色，这是对侧Vc中没有遇到的这种程度的特征。在第45天，复杂的SPIR扣在野外再次明显，一些显示密集的囊泡。还观察到两到四个SPIR轴突接触的发生率增加。最后，在这一阶段遇到的几乎所有SPIR钮扣都被强烈染色。这表明，这些改变代表了重叠的颈和颅初级传入神经对三叉神经根中断引起的部分传入神经脱连的代偿神经可塑性反应。（摘要删节为400字）
Deafferenting injuries often cause transient or permanent physiological alterations within the central projection field of affected primary afferent fibers. Aberrant sensory perceptions, dysesthesias, and hyperalgesias represent the clinical sequelae of such injuries; however, the results of experimental deafferentations have been subject to a variety of interpretations (Rodin and Kruger, 1984b). Neurochemical studies show an increased sensitivity of partially deafferented neurons to substance P (SP). Our previous studies (Hoffmann et al., 1991) documented, primarily at the light-microscopic level, a moderate transient loss of SP-immunoreactive (SPIR) boutons in the trigeminal subnucleus caudalis (Vc)--a loss that seemed to preferentially affect the slightly larger, possibly complex boutons with multiple contacts. However, despite the elimination of the trigeminal input, the larger boutons reappeared. In the present study, therefore, we examined Vc using electron-microscopic immunocytochemistry, in order to document these changes over time and to clarify the structure and relationships of this population of boutons. SPIR boutons occurred in lamina I and II degrees of the substantia gelatinosa of Vc, ranged in size from 1 to 5 microns in diameter, and displayed mixed populations of clear and dense-core vesicles. Most formed single or multiple axodendritic junctions, but a significant number engaged in axoaxonic contacts with both SPIR-labeled and unlabeled terminals. A small number appeared to be the central element of a typical glomerulus, particularly in lamina II degrees. Three to seven days following an ipsilateral retrogasserian rhizotomy, synaptic degeneration was evident in the substantia gelatinosa and often involved glomerular terminals. However, most of these were SPIR-negative and occurred primarily in lamina II degrees. Those SPIR boutons that displayed degenerative features often made single or multiple axodendritic contacts, and in some instances were scalloped. By 30 days, most remaining SPIR boutons were small, with a lower incidence of contacts; however, some of these were axoaxonic. In addition, many SPIR terminals were only very lightly stained--a feature not encountered to such an extent in the contralateral Vc. At 45 days, complex SPIR boutons were again evident in the field, and some showed densely packed vesicles. An increased incidence of clusters of two to four SPIR axoaxonic contacts was also observed. Finally, almost all SPIR boutons encountered at this stage were intensely stained. It is suggested that these alterations represent a compensatory neuroplastic response on the part of overlapping cervical and cranial primary afferents to the partial deafferentation resulting from the interruption of the trigeminal root.(ABSTRACT TRUNCATED AT 400 WORDS)