Brain Noradrenergic Neurons, Peptides and Stress

描述(申请人提供)：一致的研究结果表明，应激相关的神经激素促肾上腺皮质激素释放因子(CRF)作为去甲肾上腺素能蓝斑(LC)的神经调节剂，在应激过程中调节这一前脑投射系统的活动。CRF诱导的LC激活对应激反应的认知方面可能很重要，如唤醒增加和注意力改变，因此可能是适应性的。然而，应激史改变了LC-去甲肾上腺素系统对CRF的敏感性，这可能是与应激相关的精神障碍的某些症状(例如，高度唤醒，注意力难以集中)的基础。这一建议将促进我们对CRF改变LC活性的细胞机制、应激诱导可塑性的潜在机制以及CRF-LC相互作用可能影响认知的后果的理解。最近出现的针对CRF-R1受体的抗血清将用于表征和量化CRF-R1在LC内神经化学识别的细胞突起上的定位(AIM 1)。CRF-R1受体的内化和运输将在超微结构水平上被检测，这些大鼠已经在LC中服用了CRF，或者已经强烈暴露于应激源。LC活性的变化将与CRF-R1细胞易位指数(AIM2)相关。将使用多种方法来确定在有应激史的大鼠中观察到的LC对CRF敏感性的突触后变化的细胞机制(目标3)。这些方法包括1)逆转录聚合酶链式反应(RT-PCR)检测LC中CRF受体mRNA的变化；2)Western印迹分析检测LC中CRF受体的蛋白水平，以及与CRF-R1激活相关的信号级联成分的水平；3)受体内化和再循环的超微结构分析。最后，AIM 4被设计用来确定CRF调节LC去甲肾上腺素能系统对前脑活动和由注意到感觉刺激控制的行为的影响。在感觉刺激(胡须垫刺激)过程中，LC中CRF对功能连接网络(胡须垫-桶野皮质)神经元整体活动的影响将被量化。此外，还将确定LC中CRF对触须垫刺激所控制的行为的影响。这些研究将促进我们对应激对LC-去甲肾上腺素系统的急性影响的细胞机制、该系统应激诱导可塑性的机制以及该系统在应激认知反应中的作用的理解。

DESCRIPTION (provided by applicant): Convergent findings suggest that the stress-related neurohormone, corticotropin-releasing factor (CRF) serves as a neuromodulator in the noradrenergic nucleus locus coeruleus (LC) to regulate the activity of this forebrain-projecting system during stress. CRF-induced LC activation may be important for cognitive aspects of the stress response, such as increased arousal and alterations in attention, and therefore may be adaptive. However, a history of stress alters the sensitivity of the LC-noradrenergic system to CRF and this may underlie certain symptoms of stress-related psychiatric disorders (e.g., hyperarousal, difficulty concentrating). This proposal will advance our understanding of the cellular mechanisms by which CRF alters LC activity, the mechanisms underlying stress-induced plasticity and consequences of CRF-LC interactions that may impact on cognition. An antiserum directed against the CRF-R1 receptor that has recently become available will be used to characterize and quantify the localization of CRF-R1 on neurochemically identified cellular processes within the LC (AIM 1). Internalization and trafficking of the CRF-R1 receptor will be examined at the ultrastructural level in rats that have been administered CRF in the LC or that have been acutely exposed to stressors. Changes in LC activity will be correlated to indices of CRF-R1 cellular translocation (AIM 2). A variety of approaches will be used to determine the cellular mechanisms underlying postsynaptic changes in LC sensitivity to CRF that are observed in rats with a history of stress (AIM 3). These include 1) reverse transcriptase-polymerase chain reaction (RT-PCR) to measure changes in CRF-receptor mRNA in the LC, 2) Western blot analysis to measure protein levels in the LC of CRF receptors, as well as levels of components of the signaling cascade linked to CRF-R1 activation, and 3) ultrastructural analysis of receptor internalization and recycling. Finally, AIM 4 is designed to determine the consequences of CRF modulation of the LC-noradrenergic system on forebrain activity and behavior controlled by attention to sensory stimuli. The effect of CRF in the LC on activity of ensembles of neurons in a functionally-connected network (whiskerpad-barrelfield cortex) during sensory stimulation (whiskerpad stimulation) will be quantified. Additionally, the effect of CRF in the LC on behavior controlled by whiskerpad stimulation will be determined. Together these studies will advance our understanding of the cellular mechanisms underlying the acute effects of stress on the LC-norepinephrine system, mechanisms underlying stress-induced plasticity of this system and the role of this system in cognitive responses to stress.