Role of Microglia in Cocaine Actions

项目总结/摘要-项目3 项目3的目标是解决小胶质细胞在调节纹状体转录适应中的作用， 中棘神经元（MSN）由可卡因自我管理触发。小胶质细胞有助于正常大脑 通过支持神经元存活和去除非功能性神经元和突触来促进发育和功能。 我们已经发现，切除小胶质细胞会导致对可卡因或其他药物的行为反应大幅增加。 D1多巴胺受体激动剂以及MSN上树突棘密度的增加。这些发现 提出了这样的假设，即小胶质细胞可能发挥稳态作用，以对抗过度的 多巴胺能传递，如可卡因暴露所见。我们还发现10-15%的小胶质细胞 在纹状体，而不是其他大脑区域，表达D1受体，提高了新的可能性，直接影响 可卡因（通过增加多巴胺能传递）对小胶质细胞的影响。我们现在建议充分描述 小胶质细胞在自我给药模型中控制可卡因行为反应的影响。这将 包括描绘纹状体中所有小胶质细胞作用以及D1+所起的可能的选择性作用 小胶质细胞和D1受体信号在这些小胶质细胞。接下来我们将描述 小胶质细胞-再次D1+和D1-亚群-对可卡因自身给药影响基因表达的能力 纹状体D1型和D2型MSNs的表达谱，分别检查丘脑核 和背侧纹状体。我们还将描述可卡因自身诱导的基因表达的变化， 在纹状体内的小胶质细胞自身的D1+和D1-亚群中施用。这些实验 通过几种新的遗传突变小鼠品系， 纹状体内的小胶质细胞亚群与分离的神经元和小胶质细胞的RNA-seq组合 甚至在单细胞水平上。这些对可卡因的调查为后续研究奠定了基础， 小胶质细胞在阿片类药物作用以及在人类物质使用障碍。总的来说，该提案具有 提供关于小胶质细胞在药物治疗的病理生理学中的作用的范式转变信息的潜力 成瘾

PROJECT SUMMARY/ABSTRACT– PROJECT 3 Project 3's objective is to address the role of microglia in modulating transcriptional adaptations in striatal medium spiny neurons (MSNs) triggered by cocaine self-administration. Microglia contribute to normal brain development and function by supporting neuronal survival and removing non-functional neurons and synapses. We have found that ablation of microglia causes a robust increase in behavioral responses to cocaine or to a D1 dopamine receptor agonist as well as an increase in dendritic spine density on MSNs. These findings suggest the hypothesis that microglia may function homeostatically to oppose conditions of excessive dopaminergic transmission, such as seen with cocaine exposure. We also have found that 10-15% of microglia in striatum, but not other brain regions, express the D1 receptor, raising the novel possibility of direct effects of cocaine (via increased dopaminergic transmission) on microglia. We now propose to fully characterize the influence of microglia in controlling behavioral responses to cocaine in self-administration models. This will include delineating a role for all microglia in striatum as well as a possible selective role played by D1+ microglia and by D1 receptor signaling within those microglia. We will next characterize the influence of microglia—again D1+ and D1- subpopulations—on the ability of cocaine self-administration to influence gene expression profiles in the D1-type and D2-type MSNs of striatum, separately examining nucleus accumbens and dorsal striatum. We will also characterize the changes in gene expression induced by cocaine self- administration in D1+ and D1- subpopulations of microglia themselves within striatum. These experiments are made possible by several novel lines of genetic mutant mice that enable the selective manipulation of microglial subpopulations within striatum combined with RNA-seq of isolated neuronal and microglia cell types—and even at the single cell level. These investigations of cocaine set the stage for follow up studies of microglia in opiate action as well as in humans with substance use disorders. Overall, the proposal has the potential to provide paradigm-shifting information about the role of microglia in the pathophysiology of drug addiction.