Dopaminergic Regulation of Pyramidal Cells

锥体细胞的多巴胺能调节

基本信息

批准号：
8370366
负责人：
ARIEL Y DEUTCH
金额：
$ 38.97万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-12-15 至 2017-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8370366
关键词：
Agonist Animals Antibiotics Architecture Astrocytes Attenuated Autopsy Axon Biochemical Brain Ceftriaxone Cells Chronic Cognitive deficits Complex Cystine Data Dendrites Dendritic Spines Denervation Development Dialysis procedure Dopamine Functional disorder Glial Fibrillary Acidic Protein Glutamate Transporter Glutamate-Ammonia Ligase Glutamates Homeostasis Kynurenic Acid Lead Length Maintenance Measurement Measures Mediating Mental disorders Methods Microdialysis Monitor NR1 gene Neurons Persons Pharmaceutical Preparations Pharmacological Treatment Pharmacotherapy Physiological Play Prefrontal Cortex Prevention Process Proteins Pyramidal Cells Rattus Regulation Reporting Schizophrenia Series Signal Transduction Supporting Cell Synapses Testing Time Vertebral column antiporter cell type density extracellular in vivo metabotropic glutamate receptor 2 metabotropic glutamate receptor 3 nerve supply nervous system disorder neuron loss novel patch clamp prevent receptor research study response selective expression transmission process treatment effect

项目摘要

DESCRIPTION (provided by applicant): Among the structural changes present in schizophrenia is a decrease in dendritic spine density of pyramidal cells (PCs) in the prefrontal cortex (PFC). Glutamatergic mechanisms are critical to spine development and maintenance. Extracellular glutamate (Glu) levels are determined by a complex interplay between astrocytes and neurons, with astrocytes selectively expressing several proteins that coordinately regulate extracellular Glu. We have found that PFC dopamine (DA) denervation results in a marked decrease in dendritic spine density. We posit that cortical dopamine depletion results in increased neuronally-derived glutamatergic drive onto the dendritic spines of PFC PCs, which sets into play astrocytic mechanisms to homeostatically dampen the increase in Glu and thereby prevent further spine loss and ultimately an excito- toxic loss of neurons. In order to tes this hypothesis, we propose a series of three interrelated specific aims. We will first determine f PFC DA denervation results in changes in key astrocytic factors that modulate extracellular Glu levels, including GLT1, mGluR3, xCT, and kynurenic acid. Changes in astrocytic proteins will be compared to changes in neuronal proteins (including VGluT1 and 2, GluN1 and 2, GluA1 and 2, and EAAC1) involved in glutamatergic transmission. Protein measurements will be performed at one week after DA denervation, when dendritic spine changes have not yet occurred, and three weeks after denervation, a time when dendritic spine numbers are decreased. In the second aim we will determine if extracellular Glu levels, which are derived from both astrocytes and neurons but which do not represent synaptic Glu, are changed in the DA-denervated PFC. We will also perform physiological experiments to monitor neuronally-derived synaptic Glu activity by recording sEPSCs and evoked EPSCs from layer V PCs using whole cell patch clamping. These measurements will be performed at one and three weeks after DA denervation to determine if changes in synaptic Glu precede changes in extracellular Glu. In the final aim we will pharmacologically modify key astrocytic processes and determine if these changes prevent or reverse dendritic spine loss seen in response to DA denervation. As one example, we will determine if treatment of PFC DA-denervated animals with the antibiotic ceftriaxone (CEF), which increases expression of the astrocytic Glu transporter GLT1 and thereby decreases extracellular Glu levels, modifies the effect of DA denervation on spine number. Chronic treatment with CEF will be started on the day after DA denervation to assess prevention of spine loss. We will also start CEF treatment at three weeks after DA denervation, with drug treatment continuing for three weeks, in order to assess if induction of GLT1 attenuates or reverses spine loss once the dsytrophic changes in PC dendrites have occurred. Similarly, we will examine the effects of an mGluR2/3 receptor agonist and kynurenic acid. PUBLIC HEALTH RELEVANCE: The prefrontal cortex (PFC) of persons with schizophrenia is smaller than the PFC in persons without neurological or psychiatric disease, but there is no overall loss of cells. Instead, the architecture of cortical neurons is distorted and the cells los dendritic spines, small protrusions which receive incoming excitatory signals from other neurons. We propose that changes in astrocytes, a type of cell previously thought to be a "support" cell in the brain but now known to have much broader functions, compensates for the process that causes dendritic spine loss, and that astrocytic proteins may be novel targets for new drug therapies for schizophrenia.

描述（由申请人提供）：精神分裂症中存在的结构变化之一是前额皮质（PFC）中锥体细胞（PC）的树突棘密度降低。谷氨酸能机制对于脊柱的发育和维护至关重要。细胞外谷氨酸 (Glu) 水平由星形胶质细胞和神经元之间复杂的相互作用决定，星形胶质细胞选择性表达几种协调调节细胞外谷氨酸的蛋白质。我们发现 PFC 多巴胺 (DA) 去神经导致树突棘密度显着降低。我们假设皮质多巴胺耗竭导致神经源性谷氨酸能对 PFC PC 树突棘的驱动增加，从而启动星形胶质细胞机制来稳态抑制 Glu 的增加，从而防止进一步的树突棘损失，并最终防止神经元的兴奋性毒性损失。为了检验这一假设，我们提出了一系列三个相互关联的具体目标。我们将首先确定 f PFC DA 去神经导致调节细胞外 Glu 水平的关键星形细胞因子的变化，包括 GLT1、mGluR3、xCT 和犬尿酸。星形胶质细胞蛋白的变化将与参与谷氨酸能传递的神经元蛋白（包括 VGluT1 和 2、GluN1 和 2、GluA1 和 2 以及 EAAC1）的变化进行比较。蛋白质测量将在 DA 去神经支配后一周进行，此时树突棘变化尚未发生，以及去神经支配后三周，此时树突棘数量减少。在第二个目标中，我们将确定来自星形胶质细胞和神经元但不代表突触 Glu 的细胞外 Glu 水平在 DA 去神经支配的 PFC 中是否发生变化。我们还将进行生理实验，通过使用全细胞膜片钳记录 sEPSC 和从 V 层 PC 诱发的 EPSC 来监测神经源性突触 Glu 活性。这些测量将在 DA 去神经后一周和三周进行，以确定突触 Glu 的变化是否先于细胞外 Glu 的变化。在最终目标中，我们将从药理学角度修改关键的星形胶质细胞过程，并确定这些变化是否可以预防或逆转因 DA 去神经支配而出现的树突棘损失。作为一个例子，我们将确定用抗生素头孢曲松 (CEF) 治疗 PFC DA 去神经动物是否会改变 DA 去神经对脊柱数量的影响，抗生素头孢曲松 (CEF) 会增加星形胶质细胞 Glu 转运蛋白 GLT1 的表达，从而降低细胞外 Glu 水平。 CEF 慢性治疗将在 DA 去神经术后第二天开始，以评估脊柱损失的预防情况。我们还将在 DA 去神经后三周开始 CEF 治疗，药物治疗持续三周，以评估一旦 PC 树突发生营养不良变化，GLT1 的诱导是否会减轻或逆转脊柱损失。同样，我们将检查 mGluR2/3 受体激动剂和犬尿酸的作用。公共卫生相关性：精神分裂症患者的前额皮质 (PFC) 小于无神经或精神疾病患者的 PFC，但总体上没有细胞损失。相反，皮质神经元的结构被扭曲，细胞失去了树突棘，即接收来自其他神经元的兴奋信号的小突起。我们提出，星形胶质细胞的变化补偿了导致树突棘损失的过程，星形胶质细胞以前被认为是大脑中的“支持”细胞，但现在已知其具有更广泛的功能，并且星形胶质细胞蛋白可能是新的靶标用于治疗精神分裂症的新药。