Immunocytochemical visualization of L-baclofen-sensitive GABAB binding sites in the medial vestibular nucleus.
Immunocytochemical visualization of L-baclofen-sensitive GABAB binding sites in the medial vestibular nucleus.
复制标题
内侧前庭核中 L-巴氯芬敏感 GABAB 结合位点的免疫细胞化学可视化。
DOI：
10.1111/j.1749-6632.1992.tb25299.x
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发表时间：
1992
影响因子：
5.2
通讯作者：
Cohen,B
中科院分区：
文献类型：
--
作者：
Holstein,GR;Martinelli,GP;Cohen,B
速度储存导致眼球速度的缓慢变化，从而增强前庭反射（VOR）的低频特征。与速度储存相关的神经活动表现在内侧前庭核（MVN）细胞中。2此外，MVN神经元对γ -氨基丁酸（GABA）敏感，GABAB受体激动剂~-巴氯芬可抑制速度储存。这表明对速度存储的抑制控制是由gaba能、GABAB受体介导的突触机制施加的。本研究的目的是通过免疫细胞化学方法可视化MVN中l -巴氯芬敏感的GABAB结合位点，以表征这些突触相互作用。用戊二醛偶联的gamma-amino-beta-@-chloropheny1)丁酸（l -巴氯芬）l -对映体制备小鼠单克隆抗体。在预注射巴氯芬的大鼠和猴子的组织切片上，对l -巴氯芬包埋过氧化物酶-抗过氧化物酶免疫细胞化学进行超微结构定位研究（方法学细节见文献4）。注射盐水的对照动物暴露于一抗后无免疫反应性。此外，在没有初级抗血清的情况下，注射盐水和注射l -巴氯芬的动物的切片均未观察到免疫染色。免疫反应性存在于注射药物动物的MVN的离散神经元元件中。神经瘤中存在许多免疫染色的树突（图lA），通常参与具有非免疫反应性轴突谱的对称突触（图1B）。这些突触中的突触前元件通常包含松散排列的球形或椭球囊泡。树突元件上存在l -巴氯芬敏感的GABAB结合位点，表明突触前键是gaba能的。这种突触学代表了涉及GABAB受体的突触后抑制的形态学基础。偶见具有小线粒体和密集排列的球形或多形性突触囊泡的轴突末端被免疫染色（图2A）。这些钮扣与未标记的树突形成突触，这些树突也接受来自未标记的轮廓的接触。此外，还观察到两个含囊泡剖面之间的突触，其中只有一个元素被免疫染色（图2B）。这种突触学代表了突触前-的两种可能的形态底物
Velocity storage is responsible for producing slow changes in eye velocity that enhance the low-frequency characteristics of the vestibuloocular reflex (VOR).'Neural activity related to velocity storage is manifest in cells of the medial vestibular nucleus (MVN). 2 In addition, MVN neurons are sensitive to gamma-aminobutyric acid (GABA), and velocity storage is inhibited by the GABAB receptor agonist~-baclofen.~ This suggests that inhibitory control of velocity storage is exerted by GABAergic, GABAB receptor-mediated synaptology. The objective of the present work was to visualize immunocytochemically the L-baclofen-sensitive GABAB binding sites in MVN, in an effort to characterize these synaptic interactions. Mouse monoclonal antibodies were raised against the L-enantiomer of gamma-amino-beta-@-chloropheny1) butyric acid (L-baclofen) conjugated by glutaraldehyde to keyhole limpet hemocyanin. Preembedding peroxidase-antiperoxidase immunocytochemical studies of the ultrastructural localization of L-baclofen were conducted on tissue sections from baclofen-preinjected rats and monkeys (see Reference 4 for methodological details). Saline-injected control animals exposed to the primary antibody showed no immunoreactivity. In addition, no immunostaining was observed in sections from both saline-injected and L-baclofen-injected animals that were incubated in the absence of primary antiserum. Immunoreactivity was present in discrete neuronal elements of MVN from the drug-injected animals. There were many immunostained dendrites present in the neuropil (FIGURE lA), often participating in symmetric synapses with nonimmunoreactive axonal profiles (FIGURE 1B). The presynaptic elements in these synapses usually contained loosely packed spherical or ellipsoid vesicles. The presence of L-baclofen-sensitive GABAB binding sites on dendritic elements suggests that the presynaptic boutons are GABAergic. This synaptology represents a morphologic basis for postsynaptic inhibition involving GABAB receptors. Axon terminals with small mitochondria and densely packed spherical or pleomorphic synaptic vesicles were occasionally immunostained (FIGURE 2A). These boutons formed synapses with unlabeled dendrites, which also received contacts from unlabeled profiles. In addition, synapses between two vesicle-containing profiles were also observed, in which only one of the two elements was immunostained (FIGURE 2B). This synaptology represents two possible morphologic substrates for presynap-