Mechanisms of anesthetic-induced synaptic plasticity

麻醉诱导的突触可塑性机制

• 批准号: 10395513
• 负责人: Jimcy Platholi
• 金额: $ 33.63万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10395513
• 关键词: Acute; Alleles; Anesthesia procedures; Anesthesiology; Anesthetics; Biosensor; Brain; Brain-Derived Neurotrophic Factor; Caucasians; Cellular biology; Clinical Trials; Codon Nucleotides; Cognitive; Cognitive deficits; Data; Dendritic Spines; Depressed mood; Development; Elderly; Exocytosis; Fiber; Fluorescence Microscopy; Functional disorder; General anesthetic drugs; Genetic Polymorphism; Genetic Variation; Glutamates; Goals; Golgi Apparatus; Hand; Hippocampus (Brain); Human; Human Genetics; Imaging Techniques; Impaired cognition; Impairment; Incidence; Individual; Intervention; Isoflurane; Knock-in Mouse; Knowledge; Laboratories; Lead; Learning; Memory; Memory impairment; Mission; Modeling; Molecular; Molecular Target; Morphology; Mus; Neurocognitive; Neurons; Neurosciences; Operative Surgical Procedures; Outcome; Patients; Perioperative; Pharmacology; Photometry; Play; Postoperative Period; Prevention; Procedures; Public Health; Quality of life; Recovery; Research; Risk; Risk Assessment; Risk Factors; Role; Shapes; Signal Pathway; Signal Transduction; Single Nucleotide Polymorphism; Site; Slice; Stains; Structure; Synapses; Synaptic Transmission; Synaptic Vesicles; Synaptic plasticity; Testing; Time; Transgenic Mice; United States National Institutes of Health; Vertebral column; Vulnerable Populations; behavior test; behavioral study; density; design; experience; experimental study; functional disability; functional outcomes; improved; in vivo; innovation; live cell imaging; loss of function; medically necessary care; mouse model; nervous system disorder; neurocognitive disorder; older patient; optogenetics; postsynaptic; presynaptic; release factor; sevoflurane; synaptic function; time use; transmission process

Project Summary Genetic polymorphisms have recently emerged as risk factors for neurocognitive disorder (NCD) following anesthesia and surgery, but there is a gap in our understanding whether or how synaptic dysfunction plays a role in these cognitive deficits. Such knowledge is critical to assessing the risk of necessary medical procedures that require anesthesia, particularly in vulnerable populations. The long-term goal of this proposal is to define the cellular and molecular mechanisms of sustained general anesthetic actions on synaptic plasticity. The overall objective in this application is to identify signaling pathways involved in persistent structural dendritic spine changes following anesthetic exposure. Dendritic spines are postsynaptic structures on mature synapses that are critical for learning and memory and are associated with cognitive and developmental dysfunction in multiple neurological disorders. The central hypothesis is that general anesthetics reduce brain-derived neurotrophic factor (BDNF) release, resulting in impaired presynaptic function, alterations in dendritic spine structure, and deficits in neuronal activity and spatial learning and memory. This hypothesis has been formulated on the basis of preliminary data obtained in the applicant’s laboratory. The rationale for the proposed research is that, once it is known how anesthetics induce permanent spine loss, pharmacological manipulation of these molecular targets during anesthesia or design of new anesthetic agents that avoid these effects will be possible. Guided by compelling preliminary data, this hypothesis will be tested by three specific aims: 1) Identify the role of BDNF in reducing synaptic vesicle (SV) exocytosis by volatile anesthetics; 2) Define the role of BDNF in volatile anesthetic- induced changes on dendritic spine density and morphology; and 3) Elucidate the role of BDNF in isoflurane- induced effects on hippocampal-dependent synaptic plasticity. For Aim 1, proven optogenetic biosensors (BDNF- pH, vGlut1-pH and the Ca2+ indicator GCaMP6), already established as feasible in the applicant’s hands, will be used to test anesthetic effects on BDNF release and the impact of these changes on inhibition of Ca2+ entry and SV exocytosis. For Aim 2, structural spine changes due to reduced BDNF will be investigated in dissociated hippocampal cultures and intact brain slices using time-lapse fluorescence microscopy and Golgi staining, respectively. For Aim 3, the functional outcome of reduced BDNF signaling by isoflurane on real-time neuronal activity corresponding to impairments in learning and memory will be assessed with fiber photometry and behavioral testing. These functional and structural studies will be conducted with or using neurons or slices from transgenic mice with reduced BDNF secretion due to a common human polymorphism (Val66Met) recently identified as a risk factor for NCD. This model provides an innovative approach to elucidate mechanisms underlying anesthetic-induced pre- and post-synaptic dysfunction associated with impairments in learning and memory. Prevention of long-term synaptic deficits following anesthesia in at-risk individuals have broad translational importance to preoperative risk assessment and anesthesia recovery.

项目概要 最近，遗传多态性已成为神经认知障碍 (NCD) 的危险因素 麻醉和手术，但我们对突触功能障碍是否或如何发挥作用的理解存在差距。 这些认知缺陷中的作用。这些知识对于评估必要医疗程序的风险至关重要 这需要麻醉，特别是对于弱势群体。该提案的长期目标是定义 持续全身麻醉作用对突触可塑性的细胞和分子机制。整体 本申请的目的是确定参与持久性结构树突棘的信号通路 麻醉暴露后的变化。树突棘是成熟突触上的突触后结构， 对学习和记忆至关重要，并与多种认知和发育功能障碍有关 神经系统疾病。中心假设是全身麻醉药会减少脑源性神经营养 因子（BDNF）释放，导致突触前功能受损、树突棘结构改变，以及 神经元活动以及空间学习和记忆的缺陷。这一假设的提出是基于 在申请人实验室获得的初步数据。拟议研究的基本原理是，一旦 已知麻醉剂如何导致永久性脊柱损失，对这些分子靶标的药理操作 在麻醉过程中或设计新的麻醉剂来避免这些影响将是可能的。指导者 有了令人信服的初步数据，该假设将通过三个具体目标进行检验：1）确定 BDNF 在 通过挥发性麻醉剂减少突触小泡（SV）胞吐作用； 2) 定义BDNF在挥发性麻醉剂中的作用- 诱导树突棘密度和形态的变化； 3) 阐明 BDNF 在异氟醚中的作用 对海马依赖性突触可塑性的诱导作用。对于目标 1，经过验证的光遗传学生物传感器（BDNF- pH、vGlut1-pH 和 Ca2+ 指示剂 GCaMP6) 已在申请人手中确定为可行，将 用于测试麻醉对 BDNF 释放的影响以及这些变化对抑制 Ca2+ 进入和 SV胞吐作用。对于目标 2，将在解离体中研究由于 BDNF 减少而导致的结构脊柱变化。 使用延时荧光显微镜和高尔基体染色进行海马培养物和完整脑切片， 分别。对于目标 3，异氟烷减少 BDNF 信号传导对实时神经元的功能结果 与学习和记忆障碍相对应的活动将通过纤维光度测定法进行评估， 行为测试。这些功能和结构研究将通过或使用神经元或切片进行 最近，由于常见的人类多态性（Val66Met），转基因小鼠的 BDNF 分泌减少 被确定为非传染性疾病的危险因素。该模型提供了一种阐明机制的创新方法 潜在的麻醉引起的突触前和突触后功能障碍与学习和学习障碍有关 记忆。预防高危个体麻醉后长期突触缺陷具有广泛的意义 对术前风险评估和麻醉恢复的转化重要性。