Activity and dendritic structural rearrangements in the mature brain

成熟大脑的活动和树突结构重排

• 批准号: 7383760
• 负责人: SERGEI A KIROV
• 金额: $ 28.94万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7383760
• 关键词: Acute; Address; Area; Blood flow; Brain; Brain region; Cell membrane; Chronic; Condition; DNA Sequence Rearrangement; Data; Dendrites; Dendritic Spines; Distal; Electrophysiology (science); Event; Failure; Glucose; Goals; Hippocampus (Brain); Image; In Situ; In Vitro; Infarction; Injury; Ion Pumps; Ions; Ischemia; Ischemic Stroke; Knowledge; Laser Scanning Microscopy; Lead; Learning; Mediating; Membrane; Membrane Potentials; Middle Cerebral Artery Occlusion; Modeling; Neuronal Injury; Neurons; Numbers; Ouabain; Oxygen; Pharmaceutical Preparations; Photons; Process; Proliferating; Pump; Recovery; Recovery of Function; Recruitment Activity; Research; Research Personnel; Role; Slice; Sodium; Stress; Stroke; Structure; Swelling; Synapses; Testing; Time; Vascular blood supply; Vertebral column; Water; Work; cold temperature; day; deprivation; hemodynamics; hippocampal pyramidal neuron; in vivo; inhibitor/antagonist; mouse model; neural circuit; neurotransmitter release; post stroke; potassium ion; programs; response; synaptogenesis; time use

DESCRIPTION (provided by applicant): Mature CNS neurons have a significant intrinsic capacity for structural plasticity. This implies that they adapt to acute injury by proliferating new spines, which if consolidated, may rewire existing brain circuitry. In focal ischemia, failure of the Na+/K+ pump caused by depletion of ATP results in the anoxic depolarization (AD) with recurring AD-like peri-infarct depolarizations (PIDs) in the penumbra. The functional collapse of plasma membrane ion selectivity that drives and maintains the propagating AD, causes dramatic neuronal and glial swelling with dendritic beading and spine loss within tens of seconds. Within minutes, recurring PIDs initiate at the edge of the ischemic core, expanding neuronal damage into the penumbra during the next 1-2 days. The immediate goal of the proposed research is to address the role of these maintained depolarizations in evoking acute dendritic injury using in vitro and in vivo ischemia models. We can then test whether injury can be reduced and examine the long-term recovery of dendritic structure in vivo following focal stroke. We have discovered that dendrites become beaded and spines are lost within minutes of the Na+/K+ pump inhibition induced by ouabain or oxygen-glucose deprivation (OGD). We have shown that pump inhibition by cold, ouabain or OGD quickly elicits dendritic beading with spine loss. We have also shown that the intact neuronal membrane at normal resting potential poorly conducts water, resisting acute osmotic stress. A maintained depolarization as during stroke or cold is required to swell neurons and elicit dendritic beading and spine loss. The rapid proliferation of new spines on mature neurons during re-warming reveals an adaptive synaptogenesis in response to acute injury as dendritic structure recovers. It is unclear how long these newly spines persist or whether they are eliminated or stabilized when activated. Therefore the specific aims of this project are: 1) Investigate dynamics of AD-mediated injury and recovery of dendritic structure in acute slices. 2) Assess dynamics of dendritic injury during penumbra recruitment in vivo and during long- term recovery of synaptic circuitry post-stroke. 3) Study the ionic mechanisms underlying dendritic structural changes during the cold-induced depolarization. 4) Determine whether new spines formed on mature neurons are preserved or eliminated upon global synaptic activation. In aims 1 and 4, our synaptic studies will correlate functional data from field recordings with structural data from 2-photon laser scanning microscopy (2PLSM). In aim 2, in vivo dendritic structure during stroke in the core, penumbra and unaffected cortical regions from acute and chronic mouse models will be imaged in real time using 2PLSM. We will directly correlate injury with blood flow and with recurring depolarizations. In aim 3, 2PLSM will be correlated with intracellular recordings to examine dendritic beading and recovery in hippocampal slices. The results will address how neurons are acutely damaged, how they recover and ways to facilitate their recovery.

描述（由申请人提供）：成熟的CNS神经元具有结构可塑性的显着内在能力。这意味着它们通过扩散新刺来适应急性损伤，如果合并，则可能会重新布线现有的脑电路。在局灶性缺血中，由ATP耗尽引起的Na+/K+泵的失败导致缺氧去极化（AD），而Penumbra中反复出现的AD样围场去极化（PID）。质膜离子选择性的功能塌陷驱动和维持传播AD，引起急剧的神经元和神经胶质肿胀，而树突状珠子和脊柱损失在数十秒钟内。在几分钟之内，经常性的PID在缺血核的边缘启动，在接下来的1-2天内将神经元损伤扩展到半阴茎。拟议的研究的直接目标是解决这些维持的去极化在使用体外和体内缺血模型唤起急性树突状损伤中的作用。然后，我们可以测试是否可以减少损伤，并检查局灶性中风后体内树突结构的长期恢复。我们已经发现树突变成串珠，刺发生在乌巴因或氧气剥离（OGD）诱导的Na+/K+泵抑制后的几分钟内丢失。我们已经表明，通过冷，ouabain或OGD抑制泵的抑制作用迅速引起脊柱损失的树突串珠。我们还表明，在正常静止电势下完整的神经元膜导致水，可抵抗急性渗透应激。维持的去极化，因为在中风或冷时需要肿胀神经元，并引起树突状珠子和脊柱损失。新刺在重温期间成熟神经元的快速增殖表明，随着树突结构的恢复，急性损伤的适应性突触发生。目前尚不清楚这些新的棘突持续多长时间，或者在激活时是否被消除或稳定。因此，该项目的具体目的是：1）研究急性切片中AD介导的损伤和树突结构恢复的动力学。 2）评估在体内半半衰期募集过程和中风后长期恢复过程中的树突状损伤动力学。 3）研究冷诱导的去极化过程中树突状结构变化的离子机制。 4）确定在全局突触激活后是否保留或消除了在成熟神经元上形成的新刺。在AIMS 1和4中，我们的突触研究将将现场记录的功能数据与来自2光子激光扫描显微镜（2PLSM）的结构数据相关联。在AIM 2中，使用2PLSM实时成像，将从急性和慢性小鼠模型的核心，半阴茎和未受影响的皮质区域中的体内树突结构进行成像。我们将直接将损伤与血流以及重复的去极化相关。在AIM 3中，2PLSM将与细胞内记录相关，以检查海马切片中的树突串珠和恢复。结果将解决神经元如何严重损害，它们如何康复以及促进其康复的方法。