Control of Junctional Conductance at Auditory Afferents

听觉传入处连接电导的控制

• 批准号: 6441180
• 负责人: Alberto E Pereda
• 金额: $ 33.75万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-01-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6441180
• 关键词: Mauthner's neuron; acoustic nerve; afferent nerve; calcium flux; calmodulin dependent protein kinase; cell cell interaction; chemical structure function; confocal scanning microscopy; electron microscopy; electrophysiology; gap junctions; glutamates; goldfish; immunocytochemistry; membrane channels; neural conduction; neural information processing; neural inhibition; neural transmission; neuroregulation; phosphoprotein phosphatase; protein localization; single cell analysis; somatostatin; synapses

DESCRIPTION (provided by applicant): The long-term objective of the proposed research is to study the role and properties of electrical synaptic transmission via gap junctions in the CNS, in particular in the auditory system. The experimental model involves identified mixed electrical and chemical, (glutamatergic) synapses between eighth nerve auditory primary afferents and the goldfish Mauthner (M-) cell. While most studies of gap junction function utilize exogenous expression systems, this preparation uniquely allows continuous monitoring and quantification of changes in junctional conductance in vivo. Both components of the synaptic response exhibit activity-dependent modifications on their strength that is mediated via activation of NMDA receptors. Paired intradendritic and single afferent recordings, molecular biology techniques, and immunocytochemistry, will be used to test specific hypotheses and mechanisms underlying modifications of electrical transmission induced by eighth nerve tetani, determinants of bi-directional communication and the identity of specific gap junction proteins. Aim 1 explores the cellular and molecular mechanisms underlying activity-dependent modification (potentiation and depression) of gap junctional conductance. It is based on data suggesting that changes in electrical coupling at single terminals following brief tetani can be in the form of both depressions and potentiations. I will explore the roles of elevated levels of postsynaptic calcium/calmodulin-dependent kinase II (CamKIl), protein phosphatases and agents interfering with postsynaptic exofendocytosis on unitary and population synaptic responses. Aim 2 is to investigate the possibIe role of somatostatin in activity-dependent plasticity of these junctions. This peptide is co-localized with glutamate at presynaptic terminals and preliminary data shows that its application enhances both components of the synaptic response. Since both somatostatin and glutamate are likely to be co-released during tetani, I propose to explore their possible functional interactions and underlying intracellular mechanisms. Aim 3 concerns identification of the neuron-specific gap junction proteins at these connections. Sub-cellular distributions of antibodies specific to various connexins will be analyzed with immunocytochemistry, using confocal and freeze-fracture electron microscopy, and single cell RT-PCR of the coupled cells. The proposed research addresses the concept that intercellular coupling through gap junction channels is dynamic, based on its functional interaction with neighboring glutamatergic synapses and peptidergic transmission. These modulatory phenomena could constitute a widespread property of electrical synapses in general, relevant not only to normal brain function in structures such as the retina, inferior olive, and neocortex where both forms of transmission co-exist, but also to numerous health-related issues such as epilepsy.

简介(由申请人提供)：建议的长远目标 研究是研究电突触的作用和特性 通过中枢神经系统中的缝隙连接传递，特别是在听觉中 系统。实验模型包括已识别的混合电气和 第八神经听觉初级之间的化学(谷氨酸能)突触 传入细胞和金鱼Mauthner(M-)细胞。虽然大多数关于GAP的研究 连接功能利用外源表达系统，该制剂 独一无二地允许持续监控和量化 体内结电导。突触反应的两个组成部分 在其强度上表现出活动依赖的修饰，这是通过 激活NMDA受体。成对的树突内传入和单一传入 将使用录音、分子生物学技术和免疫细胞化学。 测试特定的假设和潜在的修改机制 第八神经强直诱发的电传递，决定因素 双向交流与特定缝隙连接的同一性 蛋白质。目标1探索细胞和分子机制 缝隙连接蛋白的活性依赖性修饰(增强和抑制) 电导。它基于的数据表明，电气耦合的变化 在单一终端，短暂的破伤风可能以两种形式出现 沮丧和兴奋。我将探讨高水平的 突触后钙/钙调蛋白依赖蛋白II(CamKIl) 磷酸酶及干扰突触后胞外吞噬的物质 单一和群体突触反应。目标2是调查是否有可能 生长抑素在这些连接的活性依赖可塑性中的作用。这 肽与谷氨酸共定位于突触前终末，并初步 数据显示，它的应用增强了突触的两个组成部分 回应。因为生长抑素和谷氨酸很可能是同时释放的 在破伤风期间，我建议探索它们可能的功能相互作用和 潜在的细胞内机制。目标3涉及识别 神经元特异性缝隙连接蛋白位于这些连接。亚细胞 不同连接蛋白特异性抗体的分布将用 免疫细胞化学，使用共聚焦和冷冻断裂电子显微镜， 偶联细胞的单细胞RT-PCR。 拟议的研究解决了这样一个概念，即细胞间的耦合通过 间隙结通道是动态的，基于其与 邻近的谷氨酸能突触和肽能传递。这些 调制现象可以构成电学的一种普遍性质 一般而言，突触不仅与结构中的正常大脑功能有关 如视网膜、下橄榄和新皮质，这两种形式的 传播共存，但也对许多与健康有关的问题，如 癫痫。