Modulation of Exocytosis and Excitability in Mature Auditory Brainstem Neurons

成熟听觉脑干神经元胞吐作用和兴奋性的调节

基本信息

批准号：
8968241
负责人：
HENRIQUE Prado VON GERSDORFF
金额：
$ 32.56万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-12-01 至 2017-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8968241
关键词：
AMPA Receptors Action Potentials Adult Affect Age Animals Auditory Brain Brain Stem Buffers Cell Nucleus Cells Computer Simulation Coupling Data Dendrites Docking Egtazic Acid Electrophysiology (science)Event Excitatory Postsynaptic Potentials Exhibits Exocytosis Fiber Fire - disasters Frequencies Future Glutamates Health Hearing Hearing problem Imagery Imaging Techniques Indium Lead Length Measures Medial Membrane Mus Nerve Neurons Output Phosphorus 32 Physiological Play Procedures Property Research Resolution Rodent Role Ryanodine Signal Transduction Slice Sound Localization Source Speed Staging Stimulus Structure-Activity Relationship Synapses Techniques Temperature Testing Time Training Vesicle Weaning Work aging population auditory pathway channel blockers hearing impairment improved insight juvenile animal mature animal mouse development myelination neuronal cell body neurotransmitter release novel patch clamp postnatal postsynaptic presynaptic prevent ranpirnase sound synaptic depression transmission process trapezoid body treatment strategy

项目摘要

DESCRIPTION (provided by applicant): The large calyx of Held nerve terminal is a pivotal element in the circuitry that computes sound source localization in the mammalian auditory brainstem. Precise timing of action potential output from this synapse is thought to be central for this task. However, the synaptic mechanisms that modulate and preserve action potential timing during high frequency firing are not well understood in mature animals because of the difficultly of recording and visualizing neurons in the heavily myelinated adult brainstem. Our lab has pioneered patch clamp recordings in brainstem slices from more mature and adult-like stages of mouse development, when they fully acquire their fine-tuned ability to hear and localize sound. The first hypothesis to be tested is that the large amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs) observed in mature calyx of Held synapses is due to a highly synchronous form of multiquantal release. We suggest that these large and multiquantal mEPSCs are a natural consequence of the progressively tighter coupling of Ca2+ channels to docked vesicles as the synapse matures. We will reconstruct the active zones of mature calyces at a resolution of 3-5 nm and correlate this information with our quantal analysis at the single vesicle exocytosis level. Novel insights into the structure and function relationship of auditory synapses will thus be revealed. The second hypothesis to be tested is that a fast Ca2+-dependent recruitment of vesicles from a reserve pool, triggered by the opening of presynaptic Ca2+ stores, produces a transient EPSC enhancement, or a late-tetanic rebound, during a stimulus train in more mature synapses. We will test this hypothesis by using pharmacological approaches that either block increases in Ca2+ concentration or block the Ca2+ stores from releasing Ca2+. The third hypothesis to be tested is that postsynaptic MNTB principal cell dendrites play a major role in shortening the excitatory postsynaptic potential (EPSP) decay. We hypothesize that this "dendritic speeding" of the evoked EPSP enhances the precision of postsynaptic spikes triggered by afferent fiber stimulation at high frequencies. Finally, to study the passive and active properties of the adult-like MNTB principal cells and their dendrites we will use patch-clamp and Ca2+ imaging techniques. This will allow us to build realistic computer models of how the MNTB cell integrates synaptic inputs and fires action potentials to preserve the timing of incoming sound signals.

描述（由申请人提供）：Held 神经末梢的大花萼是计算哺乳动物听觉脑干中声源定位的电路中的关键元件。该突触输出动作电位的精确时间被认为是这个任务。然而，在成熟动物中，由于难以记录和可视化重度髓鞘化成年脑干中的神经元，因此在高频放电过程中调节和保持动作电位时序的突触机制尚未得到很好的了解。我们的实验室率先在小鼠发育的更成熟和类成人阶段的脑干切片中进行膜片钳录音，当时它们完全获得了聆听和定位声音的微调能力。第一个要测试的假设是，在成熟的 Held 突触花萼中观察到的自发性微型兴奋性突触后电流 (mEPSC) 的大幅度变化是由于高度同步形式的多量子释放造成的。我们认为，这些大的、多量子的 mEPSC 是随着突触成熟，Ca2+ 通道与对接囊泡逐渐紧密耦合的自然结果。我们将以 3-5 nm 的分辨率重建成熟肾盏的活性区域，并将这些信息与我们在单囊泡胞吐作用水平上的定量分析相关联。因此，将揭示对听觉突触的结构和功能关系的新见解。要测试的第二个假设是，由突触前 Ca2+ 储存的开放触发，从储备库中快速依赖 Ca2+ 募集囊泡，在更成熟的刺激序列中产生短暂的 EPSC 增强或后期强直性反弹。突触。我们将使用阻止 Ca2+ 浓度增加或阻止 Ca2+ 储存释放 Ca2+ 的药理学方法来检验这一假设。第三个要测试的假设是，突触后 MNTB 主细胞树突在缩短兴奋性突触后电位 (EPSP) 衰减方面发挥着重要作用。我们假设诱发 EPSP 的这种“树突加速”提高了高频传入纤维刺激触发的突触后尖峰的精度。最后，为了研究类成人 MNTB 主细胞及其树突的被动和主动特性，我们将使用膜片钳和 Ca2+ 成像技术。这将使我们能够建立真实的计算机模型，了解 MNTB 细胞如何整合突触输入并激发动作电位，以保留传入声音信号的时间。