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: 8393468
• 负责人: JOHN H WEISS
• 金额: $ 31.65万
• 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/8393468
• 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.

描述（由申请人提供）：缺血性脑损伤是老年人发病和死亡的主要原因，但目前的治疗效果不佳，部分原因是我们对导致神经元损失的致病机制了解有限。损伤过程的一个关键触发因素似乎是急性能量损失，导致膜去极化、兴奋性神经递质谷氨酸的过度释放和神经元 Ca2+ 积聚。大量且持续的 Ca2+ 升高（“Ca2+ 失调”）似乎表明神经元死亡。最近的证据表明另一种二价阳离子 Zn2+ 的重要贡献，它在大脑中含量丰富，并且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，游离 Zn2+ 在神经元中积聚，并且观察到 Zn2+ 螯合具有保护作用，这表明其在神经元死亡中发挥作用。培养研究表明，外源施用的 Zn2+ 可以进入神经元并在线粒体中积累，并强烈破坏其功能。然而，对于内源性 Zn2+ 在天然脑组织中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：海马锥体神经元中 Zn2+ 的积累对缺血性神经元损伤的发生至关重要，部分是通过与线粒体的有害相互作用实现的。初步研究表明，在可检测到的 Ca2+ 积累之前，内源性 Zn2+ 在氧糖剥夺 (OGD) 的海马切片中的锥体神经元中积累，并且 Zn2+ 似乎进入线粒体并有助于诱导 Ca2+ 失调和细胞死亡。目标我将应用荧光成像技术（使用单细胞和大量加载指示剂）到急性海马切片，以检查 OGD 期间 CA1 神经元中 Zn2+ 的积累，检查其与线粒体的相互作用，并确定其对急性 OGD 期间以及随后的再灌注期 Ca2+ 失调和细胞死亡的贡献。这一关键目标将寻求对上述假设进行首次严格检验，并检验一系列可能提供保护的干预措施，同时帮助阐明损伤触发和表达阶段所涉及的事件顺序。目标 II 将使用一系列方法来确定有害 Zn2+ 积累的来源和途径。 “Zn2+ 从何而来”这些问题很复杂，但对于制定最佳干预措施至关重要。 Aim III 将使用器官切片培养模型来检查 Zn2+ 在触发延迟性神经变性（OGD 后最多 3 天）中的作用，以检查下游损伤过程并测试在缺血后很久提供保护的治疗干预措施。希望这些研究将为触发缺血性神经元损伤所涉及的事件序列提供新的见解，从而产生新的有效的神经保护策略。