MORPHOLOGIC BASIS FOR CENTRAL VESTIBULAR INHIBITION

中枢前庭抑制的形态学基础

• 批准号: 3218310
• 负责人: Gay R Holstein
• 金额: $ 20.63万
• 依托单位: MOUNT SINAI SCHOOL OF MEDICINE OF CUNY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3218310
• 关键词: GABA receptor; Macaca fascicularis; afferent nerve; antireceptor antibody; brain mapping; cerebellar Purkinje cell; denervation; electron microscopy; gamma aminobutyrate; immunocytochemistry; neural degeneration; neuroanatomy; receptor binding; synapses; vestibular nuclei; vestibuloocular reflex

The objective of the proposed research is to visualize GABAergic neurons, terminals, and receptor sites m medial vestibular nucleus (MVN) of normal and surgically-manipulated animals in order to elucidate the anatomical basis for GABAergic control of this nucleus. This is basic information which is essential for understanding the organization of the vestibulo-ocular reflex (VOR). In addition, identification and characterization of baclofen-sensitive GABA-B binding sites in NM should lead to an understanding of how inhibition is mediated in neurons which are responsible for velocity storage, one component of the VOR. This objective will be accomplished using an immunocytochemical approach to specify the neurotransmitter-defined neuronal circuits at the light microscopic level, and to characterize and quantify the synaptic arrangements visible ultrastructurally. The studies will be based on single and double label immunocytochemical techniques employing anti-GABA antibodies to identify GABAergic elements, and antibodies directed against the p-chlorophenyl moiety of L-baclofen, a specific GABA-B receptor agonist, to identify baclofen-sensitive GABA-B binding sites in animals pretreated with the drug. The first specific aim is to localize and characterize the GABA and/or baclofen-immunoreactive cells and terminals present at different rostrocaudal levels of MVN of normal cynomolgus monkeys. The second specific aim is to examine immunocytochemically-reacted tissue from animals who have lost velocity storage due to midline medullary section of the vestibular commissural fibers. These studies will allow visualization of GABAergic interactions involving MVN neurons that participate in velocity storage. The third specific aim is to use nodulo-uvulectomized animals to examine degenerating GABAergic Purkinje cell afferents at various levels of MVN. The nodulus and ventral uvula exert inhibitory control of velocity storage, acting through GABA-B receptors. The fourth specific aim is to compare degeneration in MVN after nodulo-uvulectomy to that following ablation of the flocculus and paraflocculus. This lesion has no effect on velocity storage, but causes a loss of visual suppression and adaptation of VOR gain in response to visual stimuli. The proposed research will define the distribution and morphologic characteristics of the GABAergic neurons of MVN, including those with commissural axons, and those which receive afferents from the nodulus and ventral uvula, and the flocculus and paraflocculus. The studies will provide the first direct demonstration of the cellular distribution and subcellular localization of L-baclofen-sensitive GABA-B binding sites in normal and experimental monkey vestibular nuclear tissue. Combining morphological and physiological techniques, we expect to provide critical information about the alterations in synaptology that accompany specific manipulations of the central vestibular system. As such, these studies should help to specify the role of GABAergic inhibition in the VOR, in the organization of the velocity storage mechanism, and in the modulations in synaptology that underlie vestibular habituation and adaptation.

拟议研究的目的是可视化 GABA 能神经元， 正常的内侧前庭核（MVN）的末端和受体位点 和手术操作的动物，以阐明解剖学 该核的 GABA 能控制的基础。 这是基本信息 这对于理解该组织的组织至关重要 前庭眼反射（VOR）。 此外，识别和 NM 中巴氯芬敏感 GABA-B 结合位点的表征应 导致了解抑制是如何在神经元中介导的 负责速度存储，这是 VOR 的组成部分之一。 这 将使用免疫细胞化学方法来实现目标 指定光处神经递质定义的神经元回路 微观水平，并表征和量化突触 排列可见超微结构。 研究将基于 采用抗 GABA 的单标记和双标记免疫细胞化学技术 识别 GABA 能元件的抗体，以及针对 L-巴氯芬的对氯苯基部分，一种特定的 GABA-B 受体 激动剂，以确定动物中巴氯芬敏感的 GABA-B 结合位点 用药物进行预处理。 第一个具体目标是定位和表征 GABA 和/或 巴氯芬免疫反应细胞和终端存在于不同的位置 正常食蟹猴的 MVN 头尾水平。 第二个 具体目的是检查免疫细胞化学反应的组织 由于中线髓质部分而失去速度存储的动物 前庭连合纤维。 这些研究将实现可视化 涉及 MVN 神经元的 GABA 相互作用 速度存储。 第三个具体目标是使用结节悬雍垂切除术 动物检查退化的 GABA 能浦肯野细胞传入 不同级别的 MVN。 结节和腹侧悬雍垂发挥抑制作用 通过 GABA-B 受体作用来控制速度存储。 第四个 具体目的是比较结节悬雍垂切除术后 MVN 的变性 絮球和副絮球消融后的情况。 这个病变 对速度存储没有影响，但会导致视觉抑制损失 VOR 增益响应视觉刺激的适应。 拟议的研究将定义分布和形态 MVN GABA 能神经元的特征，包括那些具有 连合轴突，以及那些接收来自结节和 腹侧悬雍垂、绒球和副绒球。 这些研究将 提供细胞分布的第一个直接演示 L-巴氯芬敏感的 GABA-B 结合位点的亚细胞定位 正常和实验猴前庭核组织。 组合 形态学和生理学技术，我们希望提供关键 有关伴随特定突触变化的信息 中枢前庭系统的操纵。 因此，这些研究 应该有助于明确 GABA 能抑制在 VOR 中的作用， 速度存储机制的组织以及调制 突触是前庭习惯和适应的基础。