Presynaptic Mechanisms of Neurotransmission in NTS

NTS 中神经传递的突触前机制

• 批准号: 7019876
• 负责人: Michael Christian Andresen
• 金额: $ 33.52万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7019876
• 关键词: afferent nerve; baroreceptors; baroreflex; calcium channel; calcium flux; cranial nerves; fluorescent dye /probe; glutamates; heart innervation; laboratory rat; neuroimaging; neuropeptide receptor; neurotransmitter transport; opioid receptor; potassium channel; sodium channel; solitary tract nucleus; synaptic vesicles; vasopressins; voltage /patch clamp

DESCRIPTION (provided by applicant): Beat to beat regulation of the cardiovascular system depends on an intact baroreflex. This reflex arc first synapses in the nucleus tractus solitarius (NTS) where glutamate is released. Baroreflex function is compromised in common life threatening disease states: hypertension, shock, and heart failure. Work in large, accessible CNS terminals suggests that the presynaptic control of glutamate release involves ion channels and 2nd messenger systems that regulate vesicle exocytosis. Glutamate regulation differs across neurons, but the mechanisms are poorly understood. Reflex pathways regulating the cardiovascular and respiratory systems depend on brainstem neurons and these reflexes are initiated by cranial nerve primary afferents acting within the nucleus tractus solitarius (NTS). Little is known about how primary afferents behave centrally. The small size of these terminals has made direct investigation difficult. We have developed methods to permit patch clamp recording from single nerve terminals in NTS. Our Research Plan will use these methods to address our driving hypothesis that important mechanisms of regulation in NTS depend on the identity of the afferent neuron. Our Preliminary Work demonstrates that NTS neurons offer a unique opportunity because: 1. we can directly visualize, identify, stimulate and electrophysiologically record from single nerve terminals, 2. NTS receives pharmacologically distinguishable afferent terminals that form subclasses known to arise from molecularly distinct peripheral neurons, 3. Subsets of these terminals can be labeled to provide links to functionally distinct afferents. Our Plan encompasses the efforts of two labs with complementary expertise suited to this problem. We will use direct patch recording and stimulation of single terminals, as well as imaging, to study the mechanism of frequency dependent synaptic depression and peptide modulation of glutamate release. The work capitalizes on using markers of primary afferent terminals to distinguish the various sub classes (TRPV1 and P2X3; C- and A-type afferent terminals, respectively). Specific Aims concern differential sodium, potassium and calcium channel expression across A- and C-type cranial afferent synaptic terminals plus the presence of new presynaptic mechanisms regulating synaptic cleft calcium. The different sub classes of afferent nerve terminal will be also be compared in terms of their control of glutamate release and modulation by peptides.

描述（由申请人提供）：心血管系统的逐搏调节取决于完整的压力反射。这种反射首先是孤束核（NTS）中释放谷氨酸的突触。压力感受反射功能在常见的危及生命的疾病状态下会受到损害：高血压、休克和心力衰竭。在大型、可访问的中枢神经系统终端中的研究表明，突触前对谷氨酸释放的控制涉及离子通道和调节囊泡胞吐作用的第二信使系统。不同神经元的谷氨酸调节有所不同，但其机制尚不清楚。调节心血管和呼吸系统的反射通路依赖于脑干神经元，这些反射是由作用于孤束核（NTS）内的脑神经初级传入神经发起的。人们对初级传入神经如何集中表现知之甚少。这些终端尺寸较小，导致直接调查变得困难。我们已经开发出允许从 NTS 中的单个神经末梢进行膜片钳记录的方法。我们的研究计划将使用这些方法来解决我们的驱动假设，即 NTS 的重要调节机制取决于传入神经元的身份。我们的初步工作表明，NTS 神经元提供了独特的机会，因为：1. 我们可以直接从单个神经末梢进行可视化、识别、刺激和电生理记录，2. NTS 接收药理学上可区分的传入终端，这些传入终端形成已知由分子不同的周围神经元产生的亚类, 3. 这些终端的子集可以被标记以提供到功能上不同的传入的链接。我们的计划涵盖了两个具有适合该问题的互补专业知识的实验室的努力。我们将使用直接贴片记录和单终端刺激以及成像来研究频率依赖性突触抑制和谷氨酸释放的肽调节的机制。该工作利用初级传入终端的标记来区分各种子类（TRPV1 和 P2X3；分别为 C 型和 A 型传入终端）。具体目标涉及 A 型和 C 型颅传入突触末梢钠、钾和钙通道表达的差异，以及调节突触裂钙的新突触前机制的存在。传入神经末梢的不同亚类也将在其对谷氨酸释放的控制和肽的调节方面进行比较。