Control of Junctional Conductance at Auditory Afferents

听觉传入处连接电导的控制

• 批准号: 6622180
• 负责人: Alberto E Pereda
• 金额: $ 34.01万
• 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/6622180
• 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.

描述（由申请人提供）：拟议的长期目标 研究的目的是研究电突触的作用和性质， 通过CNS中的间隙连接的传输，特别是在听觉系统中， 系统实验模型涉及识别混合电气和 第八神经听觉初级神经之间的化学（突触） 传入神经和金鱼Mauthner（M-）细胞。虽然大多数关于差距的研究 连接功能利用外源表达系统，该制剂 独特地允许连续监测和量化 体内连接电导。突触反应的两个组成部分 在其强度上表现出活性依赖性修饰， NMDA受体的激活。成对树突内和单个传入 记录，分子生物学技术和免疫细胞化学，将被用于 测试特定的假设和机制的修改， 第八神经强直引起的电传递， 双向通讯和特定缝隙连接的身份 proteins.目的1探索细胞和分子机制， 间隙连接的活性依赖性修饰（增强和抑制） 电导它是基于数据表明，电耦合的变化， 在短暂强直后的单个终端， 抑郁和增强。我将探讨高水平的 突触后钙/钙调蛋白依赖性激酶II（CamKII），蛋白质 磷酸酶和干扰突触后外吞作用的药物 单一和群体突触反应。目标二是调查 生长抑素在这些连接的活性依赖性可塑性中的作用。这 肽与谷氨酸在突触前末端共定位， 数据显示，它的应用增强了突触的两个组成部分， 反应由于生长抑素和谷氨酸可能共同释放 在破伤风期间，我建议探索它们可能的功能相互作用， 潜在的细胞内机制。目标3涉及确定 神经元特异性间隙连接蛋白在这些连接。亚细胞 将分析各种连接蛋白特异性抗体的分布， 免疫细胞化学，使用共聚焦和冷冻断裂电子显微镜， 以及偶联细胞的单细胞RT-PCR。 拟议的研究解决的概念，细胞间耦合通过 缝隙连接通道是动态的，基于其与 邻近的神经元能突触和肽能传递。这些 调制现象可以构成一个普遍的性质， 突触，不仅与正常的大脑功能有关， 如视网膜、下橄榄核和新皮层， 传播共存，但也有许多与健康有关的问题， 癫痫