Brain Noradrenergic Neurons, Peptides and Stress

描述（由申请人提供）：趋同的研究结果表明，应激相关的神经激素，促肾上腺皮质激素释放因子（CRF）作为去肾上腺素能蓝斑核（LC）的神经调节剂，在应激时调节这一前脑投射系统的活动。crf诱导的LC激活可能对应激反应的认知方面很重要，例如觉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 -去甲肾上腺素能系统对CRF的敏感性，这可能是应激相关精神障碍的某些症状的基础（例如，过度觉醒，难以集中注意力）。这一建议将促进我们对CRF改变LC活性的细胞机制、应力诱导可塑性的机制以及可能影响认知的CRF-LC相互作用的后果的理解。最近可用的针对CRF-R1受体的抗血清将用于表征和量化LC内神经化学鉴定的细胞过程中CRF-R1的定位（AIM 1）。在LC中给予CRF或急性暴露于应激源的大鼠中，将在超微结构水平上检查CRF- r1受体的内化和转运。LC活性的变化与CRF-R1细胞易位相关（AIM 2）。多种方法将用于确定在应激史大鼠中观察到的LC对CRF敏感性突触后变化的细胞机制（AIM 3）。这些包括1)逆转录聚合酶链反应（RT-PCR）来测量LC中CRF受体mRNA的变化，2)Western blot分析来测量CRF受体LC中的蛋白质水平，以及与CRF- r1激活相关的信号级联成分水平，以及3)受体内化和再循环的超微结构分析。最后，AIM 4旨在确定CRF调节lc -去甲肾上腺素能系统对由注意感觉刺激控制的前脑活动和行为的影响。在感觉刺激（须垫刺激）期间，LC中CRF对功能连接网络（须垫-桶场皮层）神经元群活动的影响将被量化。此外，还将确定LC中CRF对须垫刺激控制的行为的影响。总之，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、应激诱导的该系统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.