Effects of TrkB Activation on Abnormalities in Neocortical FS Interneurons

TrkB 激活对新皮质 FS 中间神经元异常的影响

• 批准号: 9231510
• 负责人: David Allan Prince
• 金额: $ 34.42万
• 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 2018-07-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9231510
• 关键词: Affect; Aftercare; Agonist; Anatomy; Animals; Antibodies; Area; Biological Neural Networks; Brain; Brain Diseases; Brain-Derived Neurotrophic Factor; Cells; Cerebral cortex; Chemicals; Chronic; Cognition; Cognitive; Computer software; Computers; Conflict (Psychology); Confocal Microscopy; Conotoxin; Data; Defect; Dependence; Development; Electroencephalography; Engineering; Epilepsy; Failure; Frequencies; Generations; Glutamates; Goals; Growth; Hot Spot; Human; Image; Imaging Techniques; In Vitro; Incidence; Individual; Injury; Interneuron function; Interneurons; Kinetics; Lasers; Lead; Length; Maintenance; Maps; Measures; Military Personnel; Modeling; Mus; Nerve; Nerve Growth Factors; Neurons; Neurotrophic Tyrosine Kinase Receptor Type 2; Output; Partial Epilepsies; Patch-Clamp Techniques; Pharmaceutical Preparations; Phosphotransferases; Physiologic pulse; Play; Post-Traumatic Epilepsy; Presynaptic Terminals; Process; Property; Proto-Oncogene Proteins c-akt; Public Health; Pyramidal Cells; Rattus; Rodent; Role; Saline; Scanning; Sensory; Sensory Disorders; Severe Concussions; Slice; Staining method; Stains; Structural defect; Structure; Testing; Trauma; Traumatic Brain Injury; Traumatic injury; Tropomyosin; biocytin; chemical release; experimental study; gamma-Aminobutyric Acid; hippocampal pyramidal neuron; improved; improved functioning; induced pluripotent stem cell; injured; light microscopy; microscopic imaging; motor disorder; neocortical; neuronal cell body; presynaptic; prevent; prophylactic; public health relevance; receptor; small molecule; transmission process

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) results in abnormalities in cerebral cortex and disorders of sensory and motor function, cognitive abnormalities and epilepsy. The potential development of epilepsy by the large number of individuals, who have survived severe concussive injury during recent conflicts, emphasizes the need for understanding the underlying pathophysiological processes and the development of prophylactic strategies (Garga and Lowenstein, 2006). A goal of this project is to obtain basic information on approaches that may improve or prevent such posttraumatic abnormalities. Injury to nerve cells that release the chemical transmitter GABA is a common result of TBI. Improvement in the structure and function of these inhibitory cells, "interneurons", may prevent some of the consequences of injury, including epilepsy. Preliminary results show that fast-spiking (FS) inhibitory interneurons, the most common type of interneuron in cortex, have abnormal nerve processes and defects in releasing GABA in areas of cortical injury produced by partially cutting connections with surrounding brain ("undercuts"). Undercut cortex becomes hyperexcitable due to this and other defects and often generates epileptiform electrical activity that resembles EEG activity in human focal epilepsy. A neurotrophic protein BDNF, and its receptor TrkB, are important for development, growth and maintenance of interneurons, and are reduced in the injured area, leading to the hypothesis that TrkB activation may correct abnormalities in FS or other interneurons and improve function in the injured cortex. To test this hypothesis, undercuts will be made in anesthetized rodents, and animals treated with a newly- engineered "small" molecule, LM22A-4, that enters the brain and activates the TrkB receptor. After treatment for ~2 weeks, rodents are re-anesthetized, and standard in vitro slice and patch clamp techniques used to obtain recordings from single interneurons and excitatory cells in areas of injury from drug-treated animals and saline controls. Activities of individual nerve cells and large groups of neurons ("field potentials") will be analyzed with appropriate software. Laser-activated release of the excitatory chemical transmitter, glutamate, will be used to map changes in excitatory and inhibitory connections in neural networks within individual slices, and effects of chronic LM22A-4 treatment. The structure of single cells will be measured after filling them with a marker called biocytin, staining slices with antibodies, and using computer-controlled microscopic imaging techniques, including light and confocal microscopy. The aims of these experiments are to determine whether activation of the TrkB receptor will improve the anatomical and functional abnormalities in FS interneurons, restore normal release of GABA and favorably affect nerve circuits in the injured cortex.

描述（由申请人提供）：创伤性脑损伤（TBI）导致大脑皮层异常、感觉和运动功能障碍、认知异常和癫痫。在最近的冲突中，许多人在严重震荡性损伤中幸存下来，他们可能会发展为癫痫，这强调了了解潜在病理生理过程和制定预防策略的必要性（Garga和Lowenstein，2006）。该项目的一个目标是获得有关可能改善或预防这种创伤后异常的方法的基本信息。释放化学递质GABA的神经细胞损伤是TBI的常见结果。改善这些抑制性细胞（“中间神经元”）的结构和功能，可能会预防一些损伤的后果，包括癫痫。初步结果表明，快速尖峰（FS）抑制性中间神经元，在皮层中最常见的中间神经元类型，有异常的神经突起和缺陷，释放GABA的皮质损伤的地区所产生的部分切断连接与周围的大脑（“底切”）。由于这种缺陷和其他缺陷，底切皮层变得过度兴奋，并且经常产生类似于人类局灶性癫痫中的EEG活动的癫痫样电活动。神经营养蛋白BDNF及其受体TrkB对于中间神经元的发育、生长和维持是重要的，并且在损伤区域中减少，导致TrkB活化可以纠正FS或其他中间神经元的异常并改善损伤皮质的功能的假设。为了验证这一假设，将在麻醉的啮齿动物中进行底切，并用一种新设计的“小”分子LM 22 A-4治疗动物，该分子进入大脑并激活TrkB受体。处理约2周后，将啮齿动物再次麻醉，并使用标准体外切片和膜片钳技术从药物处理的动物和盐水对照的损伤区域中的单个中间神经元和兴奋性细胞获得记录。单个神经细胞的活动 并且用适当的软件分析大的神经元组（“场电位”）。兴奋性化学递质谷氨酸盐的激光激活释放将用于绘制单个切片内神经网络中兴奋性和抑制性连接的变化以及长期LM 22 A-4治疗的影响。在用一种称为生物胞素的标记物填充它们，用抗体染色切片，并使用计算机控制的显微成像技术，包括光学和共聚焦显微镜，测量单细胞的结构。这些实验的目的是确定TrkB受体的激活是否会改善FS中间神经元的解剖学和功能异常，恢复GABA的正常释放，并有利地影响受损皮层中的神经回路。