Effects of TrkB Activation on Abnormalities in Neocortical FS interneuron

TrkB 激活对新皮质 FS 中间神经元异常的影响

• 批准号: 10393566
• 负责人: David Allan Prince
• 金额: $ 34.44万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10393566
• 关键词: Action Potentials; Affect; Agonist; Axon; Brain; Brain-Derived Neurotrophic Factor; Calcium; Cells; Chronic; Confocal Microscopy; D Cells; Data; Dendrites; Development; Electroencephalography; Electrophysiology (science); Epilepsy; Epileptogenesis; Etiology; Failure; Frequencies; Functional disorder; Genes; Genetic; High temperature of physical object; Hot Spot; Impairment; Implant; In Vitro; Incidence; Induced Hyperthermia; Inhibitory Synapse; Injury; Interneuron function; Interneurons; Label; Lasers; Length; Long-Term Effects; Maintenance; Maps; Measures; Membrane; Modeling; Monitor; Mus; Myoepithelial cell; Neocortex; Nerve; Neurons; Neuropil; Neurotrophic Tyrosine Kinase Receptor Type 2; Parvalbumins; Pharmaceutical Preparations; Predisposition; Presynaptic Terminals; Probability; Property; Prophylactic treatment; Proteins; Pyramidal Cells; Reporting; Research; Saline; Scanning; Seizures; Severities; Slice; Sodium Channel; Somatostatin; Structure; Synapses; Synaptic Transmission; Temperature; Testing; antagonist; axonal sprouting; biocytin; brain dysfunction; childhood epilepsy; comorbidity; confocal imaging; de novo mutation; density; dravet syndrome; experimental study; gamma-Aminobutyric Acid; gephyrin; hippocampal pyramidal neuron; immunocytochemistry; improved functioning; in vivo; inhibitory neuron; mouse model; neocortical; nerve supply; nervous system disorder; neuronal cell body; novel strategies; postsynaptic; presynaptic; preventable epilepsy; sensor; small molecule; synaptogenesis; synaptotagmin II; transmission process; treatment effect

Abnormalities in parvalbumin (PV) and somatostatin (SOM) interneurons are reported in a number of neurological disorders, including epilepsy. Therapy that improves function of defective interneurons is not available. Structural development and maintenance of interneurons is dependent on trophic support provided by brain derived neurotrophic factor (BDNF) activation of TrkB receptors. In the undercut (UC) model of epileptogenic neocortical injury, chronic activation of TrkB-Rs with a selective small molecule partial agonist (LM22A-4, “LM” below) has long-term effects to reverse structural and functional abnormalities in inhibitory terminals of PV interneurons, enhance GABA release and increase the threshold for evoking epileptiform activity and seizures. In order to determine whether these effects will be applicable to treatment or prevention of epilepsy in other models with different causes for seizures, such as genetic epilepsies, the Dravet syndrome (DS) mouse will be used in some experiments. Decreases in a membrane sodium channel in PV interneurons in DS mice causes decreased release of the inhibitory transmitter GABA, and development of spontaneous and high temperature-induced seizures. A variety of experimental approaches in DS and UC mice will be used to determine whether chronic treatment with LM, by increasing GABA release from nerve terminals of SOM and PV interneurons, or inducing new inhibitory synapse formation, will enhance inhibition in cortical networks and suppress epileptiform discharges: 1) immunocytochemistry and confocal imaging will be used to assess alterations in PV and SOM presynaptic terminals, including changes in expression of VGAT- and GAD65/67- IR, and the calcium sensor protein synaptotagmin 2; 2) analysis of density of SOM/- and PV/gephyrin close appositions to test for new inhibitory synapse formation induced by TrkB activation; 3) electrophysiological analysis of basic properties of inhibitory synaptic transmission from PV interneurons to pyramidal neurons of in vitro slices to detect effects of TrkB activation on unitary IPSCs, release probability and transmission failures; 3) laser scanning photostimulation of cortical slices from PV/CHR2 and SOM/CHR2 mice to map the distribution and strength of inhibitory connectivity in neocortical inhibitory circuits; and 4) video/EEG monitoring of implanted mice to assess effects of treatment with LM on spontaneous seizures and hyperthermia-induced seizures. Results of these experiments will provide information about mechanisms leading from interneuronal abnormalities to development of epilepsy and a potential approach to prophylaxis of epileptogenesis by enhancing trophic support of interneurons.

据报道，在许多神经元中，小清蛋白（PV）和生长抑素（SOM）中间神经元的表达减少。 神经系统疾病，包括癫痫。改善有缺陷的中间神经元功能的疗法不是 available.中间神经元的结构发育和维持依赖于提供的营养支持 通过脑源性神经营养因子（BDNF）激活TrkB受体。在底切（UC）模型中， 致痫性新皮层损伤，选择性小分子部分激动剂慢性激活TrkB-Rs （LM 22 A-4，下文“LM”）具有逆转抑制性细胞凋亡中的结构和功能异常的长期作用。 PV中间神经元终末，增强GABA释放，提高诱发癫痫样放电的阈值 活动和癫痫。为了确定这些效应是否适用于治疗或预防 癫痫在其他模型中具有不同的癫痫发作原因，如遗传性癫痫，Dravet综合征 (DS)将在一些实验中使用小鼠。PV中间神经元中膜钠通道减少 在DS小鼠中，导致抑制性递质GABA的释放减少， 和高温诱发的癫痫将在DS和UC小鼠中使用各种实验方法 以确定是否与LM慢性治疗，通过增加GABA释放从神经末梢的SOM 和PV中间神经元，或诱导新的抑制性突触形成，将增强皮层网络中的抑制 并抑制癫痫样放电：1）免疫细胞化学和共聚焦成像将用于评估 PV和SOM突触前末梢的改变，包括VGAT-和GAD 65/67- 2）分析SOM/-和PV/gephyrin的密度接近 并置以测试由TrkB活化诱导的新抑制性突触形成; 3）电生理学 PV中间神经元到海马锥体神经元抑制性突触传递的基本特性分析 体外切片以检测TrkB活化对单一IPSC、释放概率和传递失败的影响; 3)激光扫描光刺激PV/CHR 2和SOM/CHR 2小鼠的皮质切片，以绘制 新皮层抑制回路中抑制连接的分布和强度;以及4）视频/EEG监测 以评估LM治疗对自发性癫痫发作和高血压诱导的 癫痫发作这些实验的结果将提供信息的机制，导致神经元间 癫痫发生的异常和预防癫痫发生的潜在方法， 增强中间神经元的营养支持。