Heterogeneous properties of LC efferents to modality-specific terminal fields

描述（由申请人提供）：本项目的主要目标是确定支配大鼠前额叶和运动皮层子区域的蓝斑（LC）神经元的解剖组织、分子表型和电生理特性。前额叶皮层（PFC）包括其子区域眶额皮层（OFC）、内侧前额叶皮层（MFC）、额叶皮质（MFC）和额叶皮质（MFC）。 皮层（mPFC）和前扣带皮层（ACC）以及初级运动皮层（M1）由LC支配，并受到其初级递质去甲肾上腺素（NE）的调节作用。每个PFC子区域都调节执行功能的不同方面，这些执行功能在许多神经精神疾病中受到损害，包括ADHD，PTSD和精神分裂症。同样，NE系统也参与了许多PFC依赖性行为功能的控制，包括灵活和持续的注意力。拟议的研究的第一个目标将包括逆行追踪研究和免疫组化程序，以确定和表征的LC内的NE-含有神经元的子集，项目到每个PFC子区域。在这个和所有后续目标中，M1将作为非认知脑区进行比较。该项目的第二个目的是通过使用激光显微切割，RNA微阵列分析和qRT-PCR的组合检查其转录组及其对去甲肾上腺素能功能至关重要的选定基因的表达水平来确定每类投射细胞的分子互补。第三个目标是利用全细胞膜片钳技术，根据膜特性、突触反应性和对药物激活的敏感性，对单个LC-PFC和M1投射细胞进行分析。这些研究将提供一个更完整的了解LC-皮质投射的解剖，分子和生理属性，并挑战长期存在的概念，即LC是一个功能均匀的含NE神经元簇，同时在所有LC-去甲肾上腺素能终末场发挥统一的调制作用。相反，一般的工作假设是LC-NE系统通过模态特定终端字段的异构和异步调制来操作。这一新的理论构建对我们理解正常脑功能和治疗许多涉及去甲肾上腺素能和前额叶皮质功能障碍的神经精神疾病具有深远的意义。

DESCRIPTION (provided by applicant): The primary goal of this project is to determine the anatomical organization, molecular phenotype, and electrophysiological properties of locus coeruleus (LC) neurons that innervate sub-regions of the rat prefrontal and motor cortex. The prefrontal cortex (PFC) including its sub-regions the orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and anterior cingulate cortex (ACC), and the primary motor cortex (M1) are innervated by the LC and subject to the modulatory actions of its primary transmitter, norepinephrine (NE). Each of the PFC sub-regions mediates distinct aspects of executive function that are compromised in many neuropsychiatric disorders including ADHD, PTSD, and schizophrenia. Likewise, the NE system has been implicated in the control of many PFC-dependent behavioral functions including flexible and sustained attention. The first aim of the proposed research will include retrograde tracing studies and immunohistochemical procedures to identify and characterize the subsets of NE-containing neurons within the LC that project to each PFC sub-region. In this and all subsequent aims M1 will serve as a non-cognitive brain region for comparison. The second aim of the project will determine the molecular complement of each class of projection cells by examining their transcriptomes and their expression levels of selected genes that are critical for noradrenergic function using combinations of laser micro-dissection, RNA microarray analysis and qRT-PCR. The third aim will profile individual LC-PFC and M1 projection cells on the basis of membrane properties, synaptic responsiveness, and sensitivity to drug activation using whole cell patch clamp techniques. These studies will provide a more complete understanding of the anatomical, molecular, and physiological attributes of the LC-cortical projection and challenge the longstanding notion that the LC is a functionally homogeneous cluster of NE-containing neurons that exert uniform modulatory effects across all LC- noradrenergic terminal fields, simultaneously. Instead, the general working hypothesis is that the LC-NE system operates by heterogeneous and asynchronous modulation of modality-specific terminal fields. This new theoretical construct has far reaching implications for our understanding of normal brain function and treatment of many neuropsychiatric disorders that involve noradrenergic and prefrontal cortical dysfunction.