Zn2+, mitochondria and the induction of ischemic neurodegeneration

Zn2 , 线粒体与缺血性神经变性的诱导

• 批准号: 7789795
• 负责人: JOHN H WEISS
• 金额: $ 33.47万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-15 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7789795
• 关键词: Acidosis; Acids; Acute; Address; Binding; Brain; Brain Injuries; Buffers; Cations; Cell Death; Cell Membrane Permeability; Cells; Cerebral Ischemia; Cessation of life; Chelating Agents; Complex; Development; Discrimination; Divalent Cations; Event; Excision; Generations; Glucose; Glutamates; Hippocampus (Brain); Hour; Imaging Techniques; Individual; Injury; Intervention; Ions; Ischemia; Ischemic Brain Injury; Ischemic Neuronal Injury; Knock-out; Lead; Mediating; Membrane; Metals; Mitochondria; Modeling; Monitor; Morbidity - disease rate; Motion; Mouse Strains; Movement; Mus; Nerve Degeneration; Neuronal Injury; Neurons; Neurotransmitters; Oxidants; Oxidative Stress; Oxygen; Pathway interactions; Phase; Play; Preparation; Presynaptic Terminals; Process; Proteins; Reperfusion Therapy; Role; Route; Seizures; Simulate; Slice; Source; Staging; Stroke; Synapses; Synaptic Transmission; Testing; Therapeutic Intervention; Time; Transgenic Mice; Transgenic Organisms; Zinc; aging population; base; brain tissue; channel blockers; chelation; cyclophilin D; deprivation; effective therapy; extracellular; hippocampal pyramidal neuron; human MT3 protein; injured; insight; loss of function; metallothionein III; mitochondrial dysfunction; mortality; neuron loss; novel strategies; public health relevance; response; uptake

DESCRIPTION (provided by applicant): Ischemic brain injuries are leading causes of morbidity and mortality to the aging population, but current therapy is poor in part because of our limited understanding of pathogenic mechanisms leading to neuronal loss. A critical trigger of the injury process seems to be acute energy loss, leading to membrane depolarization, excessive release of the excitatory neurotransmitter glutamate and neuronal Ca2+ accumulation. A large and persistent Ca2+ rise ("Ca2+ deregulation") seems to be indicative of neuronal death. Recent evidence implicates critical contributions of another divalent cation, Zn2+, which is abundant in the brain and is normally very tightly regulated. However after ischemia or prolonged seizures, free Zn2+ accumulates in neurons, and observations that Zn2+ chelation is protective implicates a role in neuronal death. Culture studies have revealed that exogenously applied Zn2+ can enter neurons and accumulate in mitochondria and powerfully disrupt their function. However, little is known about mechanisms of injury caused by the accumulation of endogenous Zn2+ in native brain tissues. The proposed project thus seeks to address the following hypothesis: Accumulation of Zn2+ in hippocampal pyramidal neurons contributes critically to the initiation of ischemic neuronal injury, in part via deleterious interactions with mitochondria. Preliminary studies indicate that endogenous Zn2+ accumulates in pyramidal neurons in hippocampal slices subjected to oxygen glucose deprivation (OGD), prior to detectable Ca2+ accumulation, and that the Zn2+ appears to enter mitochondria and contribute to the induction of Ca2+ deregulation and cell death. Aim I will apply fluorescent imaging techniques (using both single cell and bulk loaded indicators) to acute hippocampal slices to examine Zn2+ accumulation in CA1 neurons during OGD, examine its interactions with mitochondria and determine its contributions to Ca2+ deregulation and cell death during acute OGD, and the subsequent reperfusion period. This key aim will seek to provide the first rigorous examination of the above hypothesis, and examine a range of interventions that may offer protection while helping to elucidate the sequence of events involved in the triggering and expression stages of injury. Aim II will use a range of approaches to determine the sources and routes of the injurious Zn2+ accumulation. These issues of "where the Zn2+ comes from" are complex, yet crucial to development of optimal interventions. Aim III will use organotypic slice culture models to examine roles of Zn2+ in the triggering of delayed neurodegeneration (up to 3 days after the OGD), in order to examine downstream injury processes and test therapeutic interventions that may offer protection when delivered well after the ischemia. It is hoped that these studies will provide new insights as to the sequence of events involved in the triggering of ischemic neuronal injury which will lead to new and effective neuroprotective strategies. PUBLIC HEALTH RELEVANCE: Despite being a cause of tremendous morbidity to the aging population, treatment of stroke is presently poor in part because of limited understanding of the events set in motion by ischemia that culminate in loss of function and nerve cell death. In this study, nerve cells in slices of mouse brain will be examined during and after simulated ischemia to directly examine movements and effects of the metal ion, zinc, which seems to play critical yet presently poorly understood in the triggering of ischemic brain injury. It is hoped that these studies will provide new insights into critical early events in ischemia that will suggest new approaches for new and better treatments to decrease brain damage.

描述（由申请人提供）：缺血性脑损伤是对人口老龄化的发病率和死亡率的主要原因，但是当前的治疗部分是因为我们对导致神经元丧失的致病机制的理解有限。损伤过程的关键触发因素似乎是急性能量损失，导致膜去极化，过度释放兴奋性神经递质谷氨酸和神经元CA2+积累。大而持久的Ca2+上升（“ Ca2+放松管制”）似乎表明了神经元死亡。最近的证据暗示了另一个二价阳离子Zn2+的关键贡献，该阳离子在大脑中很丰富，通常受到非常严格的调节。然而，在缺血或长时间癫痫发作后，自由Zn2+在神经元中积聚，并且观察到Zn2+螯合是保护性的，这在神经元死亡中起了作用。培养研究表明，外源应用Zn2+可以输入神经元并在线粒体中积累并有效破坏其功能。然而，关于内源性Zn2+在天然脑组织中的积累引起的损伤机制知之甚少。因此，拟议的项目旨在解决以下假设：Zn2+在海马锥体神经元中的积累，在某种程度上通过与线粒体的有害相互作用，对缺血性神经元损伤产生了严重贡献。 初步研究表明，在可检测到的Ca2+积累之前，内源性Zn2+在受氧气葡萄糖剥夺（OGD）的海马切片中积聚在锥体神经元中，并且Zn2+似乎进入线粒体并有助于Ca2+ ca2+ dereguluction and Cell Deereguluction and Cell Calluction和Cell Deptuluction+ Zn2+。目的我将应用荧光成像技术（同时使用单细胞和大量负载指标）将其应用于急性海马切片，以检查OGD期间CA1神经元中的Zn2+积累，检查其与线粒体的相互作用，并确定其对CA2+急性OGD和急性OGD期间的CA2+消失和细胞死亡的贡献。这个主要目的将寻求对上述假设进行第一次严格检查，并检查一系列可能提供保护的干预措施，同时帮助阐明触发和表达阶段涉及的事件的顺序。 AIM II将使用一系列方法来确定有害Zn2+积累的来源和路线。这些“ Zn2+来自哪里”的问题是复杂的，但对于最佳干预措施的发展至关重要。 AIM III将使用器官型切片培养模型来检查Zn2+在延迟神经变性（OGD后长达3天）触发Zn2+的作用，以检查下游损伤过程并测试治疗性干预措施，这些干预措施在缺血后提供良好时可能提供保护。 希望这些研究将提供有关触发缺血性神经元损伤的事件序列的新见解，这将导致新的有效的神经保护策略。 公共卫生相关性：尽管是对人口衰老的巨大发病率的原因，但目前，中风的治疗却很差，部分原因是缺血所设定的事件有限，导致功能丧失和神经细胞死亡的损失。在这项研究中，将在模拟缺血期间和之后检查小鼠大脑切片中的神经细胞，以直接检查金属离子锌的运动和作用，该锌似乎在触发缺血性脑损伤的过程中起着关键但目前尚不清楚的理解。希望这些研究能够为缺血中关键的早期事件提供新的见解，这些见解将为您提供新的和更好的治疗方法，以减少脑损伤。