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：
8575315
负责人：
HENRIQUE Prado VON GERSDORFF
金额：
$ 32.64万
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/8575315
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 Event Excitatory Postsynaptic Potentials Exhibits Exocytosis Fiber Fire - disasters Frequencies Future Glutamates 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 public health relevance 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）：固定神经终端的大花萼是电路中的关键元素，它计算哺乳动物听觉脑干中的声源定位。该突触的精确动作电位输出的精确时机被认为是核心这个任务。然而，由于难以记录和可视化神经元的神经元，在高频射击中调节和保留动作电位时的突触机制尚未得到充分了解。我们的实验室在脑干切片中启用了斑块夹的记录，当时他们完全获得了聆听和本地化声音的微调能力，从更成熟和成年的小鼠发育阶段开始。要测试的第一个假设是，在成熟的固定突触中观察到的自发微型兴奋性突触后电流（MEPSC）的幅度很大，是由于多物质释放的高度同步形式。我们建议，随着突触的成熟，这些大型和多功能的MEPSC是Ca2+通道逐渐更紧密耦合到停靠囊泡的自然结果。我们将以3-5 nm的分辨率重建成熟钙的活性区域，并将此信息与我们在单囊泡胞吐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，从储备库中快速依赖Ca2+的囊泡募集，这是由突触前Ca2+商店的开放触发的，在刺激性训练中以更加成熟的突触产生了瞬态EPSC增强或瞬时tetanic bebound。我们将通过使用药理学方法来检验该假设，该方法可以阻止Ca2+浓度增加或阻止Ca2+存储的释放Ca2+。要检验的第三个假设是突触后MNTB主细胞树突在缩短兴奋性突触后电位（EPSP）衰减方面起着重要作用。我们假设诱发的EPSP的这种“树突速度”增强了高频刺激触发的突触后尖峰的精度。最后，为了研究成人样MNTB主细胞及其树突的被动和主动性能，我们将使用贴片钳和Ca2+成像技术。这将使我们能够构建MNTB单元如何整合突触输入的现实计算机模型，并发射动作潜力，以保留传入的声音信号的时机。