The impact of synaptic cleft pH fluctuations on short-term synaptic plasticity

突触间隙pH波动对短期突触可塑性的影响

• 批准号: 10335210
• 负责人: GREGORY TALISKER MACLEOD
• 金额: $ 32.15万
• 依托单位: FLORIDA ATLANTIC UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10335210
• 关键词: Acid-Base Imbalance; Acids; Action Potentials; Address; Affect; Alkalinization; Beds; Behavior; Brain; Ca(2+)-Transporting ATPase; Cells; Chemicals; Data; Disease; Drosophila genus; Electrophysiology (science); Employment; Environment; Epilepsy; Event; Face; Genetic Techniques; Glutamate Receptor; Goals; Heterogeneity; Imaging Techniques; In Vitro; Individual; Intellectual functioning disability; Investigation; Measurement; Mediating; Molecular Genetics; Mutation; Neuromuscular Junction; Neurons; Neurotransmitters; Probability; Reagent; Recording of previous events; Research; Resolution; Role; Signal Transduction; Speed; Synapses; Synaptic Cleft; Synaptic Vesicles; Synaptic plasticity; Techniques; Testing; Time; Training; alkalinity; base; detector; experimental study; extracellular; fluorescence imaging; insight; millisecond; nervous system disorder; neural circuit; neurotransmission; neurotransmitter release; novel; postsynaptic; predictive test; presynaptic; quantum; voltage

Synaptic strength is subject to activity-dependent changes over periods of milliseconds to minutes, a phenomenon referred to as short-term synaptic plasticity (STSP). STSP has a direct influence on computations performed by neural circuits and must be understood to fully understand brain function. The synaptic environment is subject to significant activity-dependent pH fluctuations but their impact on the pH-sensitive mechanisms underlying neurotransmission is rarely considered despite their likely influence of multiple mechanisms underlying STSP. We have developed fluorescent genetically-encoded pH indicators allowing single action potential resolution of pH dynamics in the synaptic cleft of the Drosophila NMJ. Our preliminary data reveal the surprising extent to which the cleft alkalinizes (see preliminary data) and it is highly likely that this also happens at vertebrate synapses that employ the Ca2+/H+ exchanging plasmamembrane Ca2+-ATPase (PMCA). Furthermore, our preliminary data point to cleft alkalinization potentiating both quantal size and Ca2+ entry during burst firing. Our long-term goal is to elucidate the means by which pH fluctuations are incorporated into STSP mechanisms. Within this proposal we will examine the hypothesis that activity-dependent cleft alkalinization has been incorporated into gain mechanisms that sustain neurotransmission during burst firing. Using molecular genetic techniques, electrophysiology and fluorescence imaging we will test our working hypotheses that presynaptic voltage-gated Ca2+ channels (VGCCs) and postsynaptic ionotrophic glutamate receptors (iGluRs) are potentiated by alkalinization at their extracellular faces in the cleft. Our Research Strategy is broken down into three separate aims: Aim 1: Elucidate the influence of synaptic cleft alkalinization on presynaptic Ca2+ entry during bursts. Aim 2: Elucidate the mechanisms by which synaptic cleft alkalinization affects quantal size during bursts. Aim 3: Investigate the impact of neurotransmitter release on cleft pH change at individual active zones. Here we develop a test bed for investigating the contribution of activity-dependent pH fluctuations to mechanisms underlying STSP. Beyond their immediate employment in addressing the aims above, the reagents we develop will be useful for subsequent investigations into the contribution of pH-sensitive STSP mechanisms to circuit function and behavior in Drosophila, potentially providing insight into neurological disorders with an acid-base imbalance component such as seizure disorders and certain intellectual disabilities.

突触强度在毫秒至几分钟的时期内会受到活动依赖性变化，这是一种现象 称为短期突触可塑性（STSP）。 STSP对执行的计算有直接影响 神经回路，必须理解以充分理解大脑功能。突触环境受到 显着的活动依赖性pH波动，但它们对pH敏感机制的影响 尽管神经传递可能会影响STSP的多种机制，但很少考虑神经传递。 我们已经开发了荧光遗传编码的pH指标，允许pH的单个动作电位分辨率 果蝇NMJ突触裂缝中的动力学。我们的初步数据揭示了令人惊讶的程度 裂解碱化（请参阅初步数据），很有可能在脊椎动物突触上发生这种情况 采用CA2+/H+交换质子膜Ca2+-ATPase（PMCA）。此外，我们的初步数据指向 在爆发期间，碱化碱化增强了数量大小和Ca2+进入。我们的长期目标是 阐明将pH波动纳入STSP机制的均值。在这个建议中，我们 将研究以下假设 在爆发过程中维持神经传递的机制。使用分子遗传技术， 电生理学和荧光成像我们将测试我们的工作假设，这些假设是突触前门控的 Ca2+通道（VGCC）和突触后离子营养性谷氨酸受体（iGlurs）通过碱化增强 在裂缝中的细胞外脸上。 我们的研究策略分为三个单独的目标： AIM 1：阐明突触裂口碱化对突发前突触前Ca2+进入的影响。 AIM 2：阐明突触裂碱性碱化会影响爆发过程中的量化的机制。 AIM 3：研究神经递质释放对单个活动区域裂变变化的影响。 在这里，我们开发了一个测试床，以研究活动依赖性pH波动对机制的贡献 基础STSP。除了他们在解决上述目标方面的直接就业外，我们开发的试剂将会 可用于随后研究pH敏感的STSP机制对电路功能的贡献 和果蝇的行为，有可能对神经系统疾病的见解，酸碱失衡 癫痫发作和某些智力残疾等组成部分。