In vivo Profiling of Glial and Neuronal Activities in Psychostimulant Abuse

描述(申请人提供)：精神刺激剂滥用中神经胶质和神经元活动的活体分析(PI：Christina H Liu，PhD)药物成瘾是一种慢性大脑疾病，严重阻碍我们社会许多成员的生产力。最常用的滥用药物之一是苯丙胺。大多数关于苯丙胺的神经科学研究都集中在神经元对慢性药物暴露的形态和分子适应。来自细胞培养或脑片制备的电生理数据表明，药物滥用的一个重要组成部分是在反复接触苯丙胺引起的神经元激活过程中胶质细胞和神经元之间的相互作用。虽然我们知道神经胶质细胞对神经元的生存是必不可少的，为神经元提供关键的支持、营养和毒素清除，但我们对神经胶质细胞在药物成瘾中的作用的了解非常有限。为了克服这一限制，我们开发了一种新型的体内探针，利用活体大脑中暴露于苯丙胺后的磁共振成像(MRI)来可视化神经元和神经胶质细胞中基因活性的变化。我们已经证明了这种方法的实用性，用于区分表达不同但特定基因活性的细胞；即基于神经元的CFOS信使RNA(MRNA)从基于胶质细胞的GFAP mRNA上调。因为我们的检测技术不需要使用尸检样本，所以我们能够研究在接触药物期间和之后不同大脑基因活动的纵向轮廓。在这里，我们的目标是研究活着的C57Black6小鼠在苯丙胺敏化过程中的基因激活，这涉及到反复使用、戒除和再次暴露于该药物。我们将利用我们的新技术，使用mRNA靶向的MR对比探针来检测由于苯丙胺暴露在神经元和神经胶质细胞中引起的内源性基因活性的变化。本项目的研究对象是胶质纤维酸性蛋白(GFAP)的mRNAs和神经元CFos蛋白。我们这个项目的目标是使用这种新的MRI技术来加强目前对苯丙胺暴露不同阶段神经胶质细胞和神经细胞之间相互作用的理解。我们提出了以下具体目标：(1)确定MRI探针在活体大脑中的最佳剂量和保留曲线；(2)确定苯丙胺暴露后不同阶段小鼠脑内神经胶质细胞和神经细胞的基因活性谱；以及(3)探索苯丙胺成瘾表型形成过程中神经元介导的神经胶质反应。与公共健康相关：在这个项目中，我们将利用我们开发的一种新的磁共振成像(MRI)技术来检测受成瘾药物影响的活动物神经元和神经胶质细胞中基因表达的变化。该项目的目标是加强目前对苯丙胺暴露不同阶段神经胶质细胞和神经细胞之间相互作用的了解。这种增强将使对药物滥用和成瘾患者发生的神经生理事件的实时分析更近一步。

DESCRIPTION (provided by applicant): In vivo profiling of glial and neuronal activities in psychostimulant abuse (PI: Christina H Liu, PhD) Drug addiction is a chronic brain disorder that severely hampers productivity of many members of our society. One of the most used drugs of abuse is amphetamine. Most neuroscience studies on amphetamine have focused on the morphological and molecular adaptations of neurons in response to chronic drug exposure. Electrophysiological data from cell cultures or brain slice preparations show that an important component of drug abuse is the interaction that occurs between glia and neurons during neuronal activations arising from repeat exposure to amphetamine. Although we know that glial cells are essential to the survival of neurons, providing critical support, nutrition, and toxin clearance to the neurons, our understanding of the role of glia in drug addiction is very limited. To overcome this limitation, we have developed a novel in vivo probe to visualize the changes in gene activities in neurons and glia, using magnetic resonance imaging (MRI) in live brains after exposure to amphetamine. We have demonstrated the utility of this method for discrimination of cells that express different but specific gene activities; i.e., neuronal-based elevation of cfos messenger RNA (mRNA) from glia-based GFAP mRNA. Because our detection technique does not require the use of postmortem samples, we are able to study the longitudinal profiles of different cerebral gene activities during and after exposure to drugs. Here, we aim to study gene activation during amphetamine sensitization in living C57Black6 mice, which involves repeated usage of, abstinence from, and re-exposure to the drug. We will utilize our novel technique that uses mRNA-targeted MR contrast probes to detect altered endogenous gene activities that result from amphetamine exposure in neurons and glia. The targets to be investigated in this project are mRNAs of glial fibrillary acidic protein (GFAP) and neuronal cFos protein. Our goals for this project are to use this novel MRI technique to enhance current understanding of the interactions between glial and neuronal cells at different stages of amphetamine exposure. We propose the following specific aims: (1) determine the optimal dosage and retention profiles of MRI probes in live brains; (2) determine the gene activity profiles of glial and neuronal cells in mouse brains in vivo after amphetamine, at different stages of exposure; and (3) explore the neuron-mediated glial response in the development of the amphetamine addiction phenotype. PUBLIC HEALTH RELEVANCE: In this project, we will utilize a novel Magnetic Resonance Imaging (MRI) technique that we have developed to detect altered gene expression in neurons and glia of live animal affected by addictive drugs. The goals of this project are to enhance current understanding of the interaction between glial and neuronal cells at different stages of amphetamine exposure. Such enhancement will bring a step closer to real-time analysis of neurophysiologic events that occur in patients with substance abuse and addiction.