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: 8484109
• 负责人: David Allan Prince
• 金额: $ 34.41万
• 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 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8484109
• 关键词: Affect; Aftercare; Agonist; Animals; Antibodies; Area; Biological Neural Networks; Brain; Brain Diseases; Brain-Derived Neurotrophic Factor; Cells; Cerebral cortex; Chemicals; Chronic; Cognition; Computer software; Computers; Conflict (Psychology); Confocal Microscopy; Conotoxin; Data; Defect; Dependence; Development; Electroencephalography; Engineering; Epilepsy; Failure; Figs - dietary; Frequencies; Generations; Glutamates; Goals; Growth and Development function; Hot Spot; Human; Image; Imaging Techniques; In Vitro; Incidence; Individual; Injury; Interneurons; Kinetics; Lasers; Lead; Length; Maintenance; Maps; Measures; Microscopic; Military Personnel; Modeling; Motor; Mus; Nerve; Nerve Growth Factors; Neurons; Neurotrophic Tyrosine Kinase Receptor Type 2; Output; Partial Epilepsies; Patch-Clamp Techniques; Pharmaceutical Preparations; Phosphotransferases; Physiologic pulse; Play; Presynaptic Terminals; Process; Property; Proto-Oncogene Proteins c-akt; Public Health; Pyramidal Cells; Rattus; Rodent; Role; Saline; Scanning; Sensory Disorders; Sensory Process; Slice; Staining method; Stains; Structure; Testing; Trauma; Traumatic Brain Injury; Tropomyosin; biocytin; chemical release; cognitive function; gamma-Aminobutyric Acid; hippocampal pyramidal neuron; improved; improved functioning; injured; light microscopy; neocortical; neuronal cell body; presynaptic; prevent; prophylactic; public health relevance; receptor; research study; 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）导致大脑皮层异常以及感觉和运动功能障碍、认​​知异常和癫痫。在最近的冲突中，大量在严重脑震荡中幸存下来的人可能会患上癫痫，这强调了了解潜在的病理生理过程和制定预防策略的必要性（Garga 和 Lowenstein，2006）。该项目的目标是获得有关可以改善或预防此类创伤后异常的方法的基本信息。释放化学递质 GABA 的神经细胞受伤是 TBI 的常见结果。这些抑制性细胞（“中间神经元”）的结构和功能的改善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）抑制性中间神经元是皮质中最常见的中间神经元类型，其神经过程异常，并且在因部分切断与周围大脑的连接（“底切”）而产生的皮质损伤区域释放 GABA 方面存在缺陷。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脑电图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、生长和维持非常重要，并且在损伤区域中减少，因此推测 TrkB 激活可能会纠正 FS 或其他中间神经元的异常并改善受损区域的功能皮质。为了检验这一假设，我们将在麻醉的啮齿动物和用新设计的“小”分子 LM22A-4 治疗的动物身上进行底切，该分子进入大脑并激活 TrkB 受体。治疗约 2 周后，重新麻醉啮齿动物，并使用标准体外切片和膜片钳技术来获取药物治疗动物和盐水对照损伤区域的单个中间神经元和兴奋性细胞的记录。单个神经细胞的活动 将使用适当的软件分析大群神经元（“场电位”）。激光激活释放兴奋性化学递质谷氨酸，将用于绘制单个切片内神经网络兴奋性和抑制性连接的变化，以及长期 LM22A-4 治疗的效果。在用一种称为生物胞素的标记物填充单细胞、用抗体对切片进行染色并使用计算机控制的显微成像技术（包括光学显微镜和共聚焦显微镜）后，将测量单细胞的结构。这些实验的目的是确定 TrkB 受体的激活是否会改善 FS 中间神经元的解剖和功能异常，恢复 GABA 的正常释放并有利地影响受损皮层的神经回路。