Astrocyte-mediated mechanisms of cocaine seeking

项目总结/摘要 复发倾向是成瘾的一个标志性特征。因此，了解细胞机制 对复发脆弱性负责是成瘾研究的一个重要焦点。一个重要的和 在对多种药物滥用的反应中观察到的长期细胞适应是星形胶质细胞的下调。 谷氨酸转运体GLT-1。然而，关于药物自我给药如何影响 星形胶质细胞GLT-1表达以外，或星形胶质细胞如何可能有助于药物寻找机制。 在之前的K99/R 00奖项期间收集的结果表明，GLT-1的恢复表达对于 多种化合物降低大鼠自身复发的行为测量的作用机制， 成瘾的管理和恢复模型。初步数据还表明， 可卡因引起的GLT-1伴随着胶质细胞酸性蛋白（GFAP）表达的减少， 回缩的星形胶质细胞在脑桥核的核心。星形胶质细胞收缩的特征是减少 表面积、体积和突触接触减少。这一发现代表了一种迄今为止未被重视的 可卡因使用对星形胶质细胞生物学的基本后果。因此，GLT-1表达降低是一个重要因素。 这是长期使用可卡因后星形胶质细胞生物学大规模适应的组成部分。这些 这些发现导致了一种假设，即可卡因戒断的大鼠中脑核中的星形胶质细胞收缩， 老鼠有助于突触适应，驱动可卡因寻求。为了验证这一假设， 该建议的目标是：（1）确定在成瘾周期中， 诱导星形胶质细胞（2）以确定星形胶质细胞收缩和突触形成之间的功能关系。 适应被认为是可卡因寻求的基础，（3）确定星形胶质细胞之间的关系， 停药后的退缩和药物寻求。这些问题将通过结合 可卡因自我给药与可卡因寻求的行为措施，高分辨率成像， 荧光标记的星形胶质细胞和全细胞膜片钳电生理学。这些研究将提供 新的见解如何可卡因依赖性适应星形胶质细胞动力学有助于细胞和 以精神兴奋剂成瘾为特征的行为病理学。这些研究还将提供重要的 星形胶质细胞作为药物使用靶点的翻译潜力信息 紊乱

Project Summary/Abstract Propensity toward relapse is a hallmark feature of addiction. Hence, understanding the cellular mechanisms responsible for relapse vulnerability represents an important focus of addiction research. One significant and long-lasting cellular adaptation observed in response to multiple drugs of abuse is downregulation of astroglial glutamate transporter GLT-1. However, relatively very little is known about how drug self-administration affects astrocytes beyond GLT-1 expression, or how astrocytes may contribute to mechanisms of drug seeking. Results collected during the preceding K99/R00 award indicate that restored expression of GLT-1 is pivotal to the mechanism of action of multiple compounds that reduce behavioral measures of relapse in the rat self- administration and reinstatement model of addiction. Preliminary data also indicate that downregulation of GLT-1 by cocaine is accompanied by reduced expression of glial fibrillary acidic protein (GFAP) and a retraction of astrocytes in the nucleus accumbens core. Astrocyte retraction is characterized by decreased surface area, volume, and decreased synaptic contacts. This finding represents a heretofore-unappreciated fundamental consequence of cocaine use on astrocyte cell biology. Thus, decreased GLT-1 expression is a component of larger-scale adaptions in astrocyte biology that occur following chronic cocaine use. These findings have led to the hypothesis that astrocyte retraction in the nucleus accumbens of cocaine-withdrawn rats contributes to synaptic adaptations that drive cocaine seeking. In order to test this hypothesis, the specific goals of this proposal are: (1) to determine when during the addiction cycle the morphological effects on astrocytes are induced (2) to determine the functional relationship between astrocyte retraction and synaptic adaptations believed to underlie cocaine seeking, and (3) to determine the relationship between astrocyte retraction and drug seeking after cessation of drug use. These questions will be addressed by combining rat cocaine self-administration with behavioral measures of cocaine seeking, high-resolution imaging of fluorescently labeled astrocytes, and whole cell patch-clamp electrophysiology. These studies will provide novel insight into how cocaine-dependent adaptations in astrocyte dynamics contribute to the cellular and behavioral pathologies characteristic of psychostimulant addiction. These studies will also provide important information toward the translational potential of astrocytes as a pharmacotherapeutic target for substance use disorders.