Understanding the temporal regulation of inhibitory synapse depression and elimination in the context of cerebral ischemia

了解脑缺血背景下抑制性突触抑制和消除的时间调节

• 批准号: 10157074
• 负责人: Joshua Daylon Garcia
• 金额: $ 3.56万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-03 至 2022-12-02
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10157074
• 关键词: Behavior; Behavioral Assay; Brain; Brain region; Calcineurin; Calcium; Cell Death; Cell Surface Receptors; Cell membrane; Cerebral Ischemia; Clathrin; Cognition; Data; Development; Disease; Down-Regulation; Electrophysiology (science); Endocytosis; Equilibrium; Event; Excision; Excitatory Synapse; Functional disorder; Future; Glucose; Hippocampus (Brain); Impairment; In Vitro; Inhibitory Synapse; Ischemia; Knowledge; Laboratories; Lead; Learning; Mediating; Memory; Mental Depression; Mentors; Modeling; Molecular; Mutation; Neurodevelopmental Disorder; Neurons; Output; Oxygen; Pathogenicity; Pathologic; Pathology; Phosphoric Monoester Hydrolases; Phosphorylation; Play; Population; Predisposition; Presynaptic Terminals; Protein Phosphatase 2A Regulatory Subunit PR53; Receptor Signaling; Regulation; Research; Research Project Grants; Resistance; Role; Schizophrenia; Serine; Signal Pathway; Signal Transduction; Site; Slice; Surface; Synapses; Synaptic plasticity; Testing; Therapeutic Intervention; Up-Regulation; Vulnerable Populations; Work; autism spectrum disorder; base; behavioral phenotyping; cell type; deprivation; experience; hippocampal pyramidal neuron; in vivo; in vivo Model; in vivo imaging; interest; mouse model; nervous system disorder; neural circuit; neuronal circuitry; neuronal excitability; novel; postsynaptic; prevent; programs; receptor; receptor downregulation; receptor expression; receptor internalization; scaffold; synaptic inhibition; trafficking

PROJECT SUMMARY/ABSTRACT Inhibitory synapses are crucial for maintaining correct neuronal excitability, which is important for efficient circuitry and proper brain function. Shifts in neuronal excitability have been implicated in a variety of neurological disorders, including ischemia. Based on cell-type specific vulnerabilities, the oxygen and glucose deprivation (OGD) observed in various brain regions including the hippocampus leads to differential effects that may alter neuronal long-term function. The hippocampus is particularly a vulnerable brain region that experiences either delayed cell-death in the CA1 region or resistance to delayed-cell death and shifts in long-term excitability in the CA3 region. Cell-type specific synaptic alterations to neuronal populations may contribute to these ischemic-induced changes. Even though alterations at excitatory synapses are well defined, our knowledge of alterations at the inhibitory synapse remain elusive. Inhibitory GABAA receptors (GABAARs) mediate the majority of fast synaptic inhibition in the brain. The number of postsynaptic GABAARs influences inhibitory strength; therefore, GABAAR trafficking to and from synaptic sites or the neuronal surface is an important regulator of overall inhibitory synaptic strength. During OGD, GABAARs are downregulated from the neuronal surface in hippocampal neurons. Moreover, GABAAR phosphorylation status influences the synaptic declustering or removal of receptors from the neuronal surface during OGD in hippocampal neurons. However, mechanisms that regulate these differences in either synaptic clustering or surface GABAAR expression following an ischemic insult in brain regions with varying susceptibilities remain undefined. In this project, I propose that GABAAR declustering and endocytosis mechanisms are differentially regulated in distinct neuronal populations during OGD to influence GABAAR downregulation based on region-specific vulnerability. Moreover, I hypothesize that these cell-type specific mechanisms drive increased neuronal excitability during OGD due to increase synaptic declustering and decreased surface expression of GABAARs in vulnerable neuronal populations. Based on this, I plan to investigate (i) mechanisms of synaptic GABAAR declustering and surface downregulation in hippocampal pyramidal neurons following OGD (ii) probe the temporal regulation to determine the sequential flow of events promoting GABAAR loss and (iii) use an in vivo model of cerebral ischemia to compare cell-type specific mechanisms in CA1 and CA3 hippocampus that may be differentially regulated based on neuronal susceptibility to OGD. Specifically, I plan to investigate the role of phosphatases in regulating GABAAR phosphorylation state to promote GABAAR declustering and endocytosis during OGD in both vulnerable neuronal populations. The results of this project will establish mechanisms that are specific to GABAAR downregulation in vulnerable populations during OGD, providing novel targets for future therapeutic intervention.

项目总结/摘要 抑制性突触对于维持正确的神经元兴奋性是至关重要的，这对于有效的 电路和正常的大脑功能神经元兴奋性的变化与多种神经系统疾病有关。 疾病，包括局部缺血。基于细胞类型特异性的脆弱性， (OGD)在包括海马体在内的各种大脑区域观察到的差异效应可能会改变 神经元的长期功能海马体是一个特别脆弱的大脑区域， CA 1区延迟的细胞死亡或对延迟细胞死亡的抵抗和长期兴奋性的变化 在CA 3地区。神经元群体的细胞类型特异性突触改变可能有助于这些 缺血引起的变化。尽管兴奋性突触的改变是明确的，但我们对 抑制性突触的改变仍然难以捉摸。 抑制性GABAA受体（GABAAR）介导脑中的大部分快速突触抑制。的 突触后GABAAR的数量影响抑制强度;因此，GABAAR的往返运输 突触位点或神经元表面是总体抑制性突触强度的重要调节器。期间 在海马神经元中，OGD、GABAAR从神经元表面下调。此外， 磷酸化状态影响突触的去簇或受体从神经元表面的去除 在海马神经元的OGD过程中。然而，调节这些差异的机制，无论是突触 具有不同耐受性的脑区域中缺血损伤后的簇集或表面GABAAR表达 仍然未定义。 在这个项目中，我提出GABAAR去簇和内吞机制受到不同的调节 在不同的神经元群体在OGD期间影响GABAAR下调基于区域特异性 易损性.此外，我假设这些细胞类型特异性机制驱动增加的神经元 兴奋性在OGD由于增加突触去簇和减少表面表达 GABAARs在脆弱的神经元群体。基于此，我计划研究（i）突触的机制， 海马锥体神经元GABAAR在OGD（ii）探针作用下的去簇和表面下调 时间调节，以确定促进GABAAR损失的事件的顺序流，以及（iii）使用一个 脑缺血的体内模型，以比较CA 1和CA 3海马中的细胞类型特异性机制， 可以基于神经元对OGD的易感性进行差异调节。具体来说，我计划调查 磷酸酶在调节GABAAR磷酸化状态以促进GABAAR去簇中的作用， 在两个脆弱的神经元群体中OGD期间的内吞作用。该项目的结果将建立 在OGD期间，GABAAR在脆弱人群中下调的特异性机制，提供了新的 未来治疗干预的目标。