Unconventional Synaptic Modulation at the Vertebrate Neuromuscular Junction

脊椎动物神经肌肉接头的非常规突触调节

基本信息

批准号：
8035588
负责人：
CLARK A LINDGREN
金额：
$ 35.18万
依托单位：
GRINNELL COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-09-01 至 2014-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8035588
关键词：
2-arachidonylglycerol Ablation Acetylcholine Acute Address Antibodies Behavior Binding CNR1 gene Carboxypeptidase Cell physiology Cells Chemical Synapse Complement Complex Confocal Microscopy Data Dipeptides Disease Elements Endocannabinoids Enzymes Exercise Fatigue Fluorescence Fluorescent in Situ Hybridization Foundations Functional disorder Glutamate Carboxypeptidase II Glutamates Human Investigation Knowledge Laboratories Learning Lizards Location Measures Mediating Mental Depression Messenger RNA Metabolism Metabotropic Glutamate Receptors Molecular Genetics Motor Motor Neurons Muscarine Muscarinic Acetylcholine Receptor Muscarinic M1 Receptor Muscarinic M3 Receptor Muscarinics Muscle Muscle Cells Muscular Dystrophies N-Methylaspartate N-acetylaspartate N-acetylaspartylglutamate Nerve Nervous system structure Neuraxis Neuroglia Neuromodulator Neuromuscular Junction Neurons Neurotransmitters Nitric Oxide Nitric Oxide Synthase Optics Pain Pathology Peptides Peripheral Phase Presynaptic Terminals Procedures Prostaglandin-Endoperoxide Synthase Prostaglandins Receptor Activation Research Resolution Role Schizophrenia Schwann Cells Series Signal Pathway Signal Transduction Source Stroke Surface Synapses Synaptic plasticity System Techniques Testing Therapeutic Uses Time Traumatic Brain Injury Work base cyclooxygenase 2 extracellular immunoreactivity improved information processing inhibitor/antagonist metabotropic glutamate receptor 3 neuromuscular neurotransmitter release postsynaptic presynaptic public health relevance receptor research study rimonabant synaptic depression

项目摘要

DESCRIPTION (provided by applicant): Neurons communicate at chemical synapses. Synapses assemble neurons into networks of neurons and these networks create the remarkable abilities of the nervous system to perceive the world, process information, and direct behavior. Synapses also endow the nervous system with the ability to change over time - that is, to learn. Unconventional neuromodulators, such as nitric oxide, endocannabinoids, and prostaglandins, have been known about for many years; however, their participation in synaptic modulation at the vertebrate neuromuscular junction (NMJ), where a motor nerve synapses onto a muscle cell, is a more recent finding. Despite its apparent simplicity, the NMJ employs a surprisingly complex array of signaling pathways that modulate its activity. Using a muscle from the green anole lizard, which has been shown by my laboratory to undergo a biphasic modulation of neurotransmitter release that involves nitric oxide and the endocannabinoid 2-Arachidonoylglycerol (2-AG), will be used to address five questions regarding the mechanisms and/or roles of these unconventional neuromodulators. The first question will determine whether the synaptic depression mediated by 2-AG improves neuromuscular endurance by reducing ACh release during periods of intense, unremitting activity (e.g. exercise). If true, this will not only reveal a basic function of endocannabinoids at the NMJ, but may also have important implications for the therapeutic use of modulators of the endocannabinoid system (e.g. rimonabant). Nitric oxide (NO) is essential for synaptic modulation induced by the activation of muscarinic receptors at the NMJ. In fact, disruption of NO synthesis at the NMJs of humans with muscular dystrophy may contribute to fatigue. The second question will use a fluorescence-based technique for measuring NO to determine whether the muscle is the source of the NO that is essential for muscarinic-receptor dependent modulation at the NMJ. The third question follows closely from the second and will determine whether glutamate or the dipeptide N-acetylaspartylglutamate (NAAG) activates the synthesis of NO. NAAG has been implicated in numerous pathologies including pain, traumatic brain injury, schizophrenia and stroke. Although vertebrate motor neurons have long been known to express high levels of NAAG, the function of this peptide at the NMJ has not been rigorously explored. The final two questions will focus on the function of perisynaptic Schwann cells (PSCs), glial cells intimately associated with the pre- and postsynaptic elements of the NMJ. Preliminary work has implicated the prostaglandin PGE2-G in the second phase of muscarinic modulation at the NMJ. Activation of muscarinic ACh receptors is predicted to induce the synthesis of the enzyme cyclooxygenase (COX) in the PSCs, which will then convert 2-AG to PGE2-G. This prediction will be tested by measuring levels of COX mRNA using quantitative PCR and determining its location using fluorescence in situ hybridization. These studies, along with an electrophysiological investigation of NMJs at which the PSCs have been acutely ablated by a complement-mediated procedure, will further our knowledge of glial cell function in synaptic plasticity at the NMJ with likely implications for synaptic modulation in the peripheral and central nervous system. PUBLIC HEALTH RELEVANCE: Using electrophysiological, optical and molecular genetic approaches at the vertebrate neuromuscular junction this research will explore five fundamental hypotheses about the involvement of unconventional synaptic plasticity at the chemical synapse. The findings from this research will have direct relevance to the therapeutic use of modulators of the endocannabinoid system (e.g. rimonabant). It will also provide basic knowledge that may better inform our understanding of muscular dystrophy and numerous other diseases that are caused by the dysfunction of glial cells or the peptide N-acetylaspartylglutamate (NAAG).

描述（由申请人提供）：神经元通过化学突触进行通信。突触将神经元组装成神经元网络，这些网络创造了神经系统感知世界、处理信息和指导行为的非凡能力。突触还赋予神经系统随时间变化的能力，即学习能力。非常规神经调节剂，例如一氧化氮、内源性大麻素和前列腺素，早已为人所知。然而，它们参与脊椎动物神经肌肉接头（NMJ）（运动神经突触到肌肉细胞）的突触调节是最近的发现。尽管 NMJ 表面上很简单，但它却采用了一系列极其复杂的信号通路来调节其活性。我的实验室已证明绿变色龙的肌肉可以对神经递质释放进行双相调节，其中涉及一氧化氮和内源性大麻素 2-花生四烯酰甘油 (2-AG)，将用于解决有关机制的五个问题和/或这些非常规神经调节剂的作用。第一个问题将确定 2-AG 介导的突触抑制是否通过减少剧烈、不间断活动（例如运动）期间乙酰胆碱的释放来改善神经肌肉耐力。如果属实，这不仅将揭示内源性大麻素在 NMJ 的基本功能，而且还可能对内源性大麻素系统调节剂（例如利莫那班）的治疗用途产生重要影响。一氧化氮 (NO) 对于 NMJ 毒蕈碱受体激活诱导的突触调节至关重要。事实上，患有肌营养不良症的人 NMJ 中一氧化氮合成的破坏可能会导致疲劳。第二个问题将使用基于荧光的技术来测量 NO，以确定肌肉是否是 NMJ 毒蕈碱受体依赖性调节所必需的 NO 来源。第三个问题紧随第二个问题，将确定谷氨酸或二肽 N-乙酰天冬氨酰谷氨酸 (NAAG) 是否激活 NO 的合成。 NAAG 与多种疾病有关，包括疼痛、创伤性脑损伤、精神分裂症和中风。尽管长期以来已知脊椎动物运动神经元表达高水平的 NAAG，但这种肽在 NMJ 中的功能尚未得到严格探索。最后两个问题将集中于突触周围雪旺细胞 (PSC) 的功能，这是与 NMJ 的突触前和突触后元件密切相关的神经胶质细胞。初步工作表明前列腺素 PGE2-G 参与 NMJ 毒蕈碱调节的第二阶段。预计毒蕈碱 ACh 受体的激活会诱导 PSC 中环氧合酶 (COX) 的合成，然后将 2-AG 转化为 PGE2-G。该预测将通过使用定量 PCR 测量 COX mRNA 水平并使用荧光原位杂交确定其位置来进行测试。这些研究，连同对 NMJ 的电生理学研究（其中 PSC 已被补体介导的程序急剧消融），将进一步加深我们对 NMJ 突触可塑性中神经胶质细胞功能的了解，并可能对外周和中枢的突触调节产生影响。神经系统。公共健康相关性：本研究将在脊椎动物神经肌肉接头处使用电生理学、光学和分子遗传学方法，探索关于化学突触非常规突触可塑性参与的五个基本假设。这项研究的结果将与内源性大麻素系统调节剂（例如利莫那班）的治疗用途直接相关。它还将提供基础知识，帮助我们更好地了解肌营养不良症以及由神经胶质细胞或肽 N-乙酰天冬氨酰谷氨酸 (NAAG) 功能障碍引起的许多其他疾病。