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）：成熟的中枢神经系统神经元具有显着的结构可塑性内在能力。这意味着它们通过增殖新的脊柱来适应急性损伤，如果这些新的脊柱得到巩固，可能会重新连接现有的大脑回路。在局灶性缺血中，ATP 耗尽导致 Na+/K+ 泵衰竭，导致缺氧去极化 (AD)，并在半暗带中反复出现类似 AD 的梗死周围去极化 (PID)。驱动和维持 AD 传播的质膜离子选择性功能崩溃，导致神经元和胶质细胞在数十秒内急剧肿胀，并伴有树突珠状形成和脊柱损失。几分钟之内，反复出现的 PID 在缺血核心边缘开始，在接下来的 1-2 天内将神经元损伤扩大到半暗带。拟议研究的直接目标是利用体外和体内缺血模型来解决这些维持的去极化在诱发急性树突损伤中的作用。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情况。我们发现，在哇巴因或氧糖剥夺 (OGD) 诱导的 Na+/K+ 泵抑制作用的几分钟内，树突会变成串珠状，并且刺会消失。我们已经证明，冷、哇巴因或 OGD 的泵抑制会迅速引起树突珠状形成，并伴有脊柱损失。我们还表明，正常静息电位下的完整神经元膜传导水的能力很差，无法抵抗急性渗透压。中风或感冒期间需要维持去极化，以使神经元肿胀并引起树突珠和脊柱损失。在复温过程中，成熟神经元上新棘的快速增殖揭示了随着树突结构的恢复，响应急性损伤的适应性突触发生。目前还不清楚这些新的刺会持续多久，或者它们在激活后是否会被消除或稳定。因此，该项目的具体目标是：1）研究急性切片中AD介导的损伤和树突结构恢复的动态。 2）评估体内半暗带募集期间和中风后突触回路长期恢复期间树突损伤的动态。 3）研究冷诱导去极化过程中枝晶结构变化的离子机制。 4) 确定成熟神经元上形成的新棘在全局突触激活时是否被保留或消除。在目标 1 和 4 中，我们的突触研究将把现场记录的功能数据与 2 光子激光扫描显微镜 (2PLSM) 的结构数据关联起来。在目标 2 中，将使用 2PLSM 对急性和慢性小鼠模型中风期间的核心、半暗带和未受影响的皮质区域的体内树突结构进行实时成像。我们将直接将损伤与血流和反复去极化联系起来。在目标 3 中，2PLSM 将与细胞内记录相关联，以检查海马切片中的树突珠状形成和恢复。研究结果将解决神经元如何严重受损、如何恢复以及促进其恢复的方法。