The dorsal raphe and CRF: making the connections

描述(申请人提供)：在美国，抑郁症和焦虑症是导致发病率、死亡率和残疾的主要原因之一，与暴露在压力下高度相关。5-羟色胺神经传递受损似乎是导致抑郁和焦虑症状的中心机制。以往的研究表明，中缝背侧的促肾上腺皮质激素释放因子(CRF)受体激活是应激对5-羟色胺能系统产生影响的关键机制。然而，CRF对中缝背侧的影响因剂量、核内位置和受体特异性而异。CRF投射到中缝背侧的来源及其受中缝背侧输出调节的可能性也是未知的。几种神经肽在应激反应中的作用也没有越来越多地被认为是与5-羟色胺共同传递的，这可能参与了慢性应激的影响。我将使用5-羟色胺能细胞系RN46A-B14来模拟CRF受体激活对5-羟色胺能神经元的剂量反应和第二信使效应，以帮助阐明CRF在那里的直接影响。利用一种新的逆行基因转移系统，犬腺病毒-2，1将确定CRF投射到中缝背侧不同亚区的来源，该亚区被怀疑是杏仁核和终纹床核的中央核。我还将确定背侧中缝到这些区域的相互投射，描绘可能构成内在神经调节的回路，这一现象可能是与压力相关的一些长期行为改变的基础。最后，我还将制造一只条件基因敲除TPH2转基因小鼠，并确定犬腺病毒-Cre重组酶载体在特定路径上特异性改变5-羟色胺能传递的能力。这一方法论将使我能够将5-羟色胺的作用与多肽共同传递体在行为中的作用分开。这些研究将有助于开发技术，以了解CRF投射到背侧中缝的作用，以及背侧中缝输出在调节与焦虑和抑郁相关的行为的回路中的作用。这项基础研究对公共卫生的重要性是巨大的。了解压力传递的机制为干预这一过程提供了机会。鉴于压力在许多精神疾病的发展和复发中的作用，能够中断压力背景的交流将对许多类型的精神疾病的治疗和预防都是一种恩惠，包括抑郁症和焦虑症。这项研究将有助于为此类干预措施的合理发展提供必要的信息。

DESCRIPTION (provided by applicant): Depression and anxiety disorders are among the leading causes of morbidity, mortality, and disability in the United States, and are highly associated with exposure to stress. Impaired serotonin neurotransmission appears to be a central mechanism inducing depressive and anxiety symptoms. Previous studies have suggested that corticotropin releasing factor (CRF) receptor activation in the dorsal raphe, a major source of serotonin to the forebrain, is a critical mechanism underlying stress effects on serotonergic systems. However, the effects of CRF on dorsal raphe vary depending on dose, location within the nucleus, and receptor specificity. The origin of CRF projections to the dorsal raphe, and their potential to be regulated by dorsal raphe outputs is also unknown. Nor are the roles in stress response of the several neuropeptides increasingly recognized as co-transmitters with serotonin that may be involved in the effects of chronic stress. I will use a serotonergic cell line, RN46A-B14 to model the dose response and second messenger effects of CRF receptor activation on serotonergic neurons, helping to elucidate the direct effects of CRF there. Using a novel retrograde gene transfer system, canine adenovirus-2, 1 will determine the origins of CRF projection to the various subregions of the dorsal raphe, suspected to be the central nucleus of the amygdala and bed nucleus stria terminalis. I will also determine reciprocal projections of the dorsal raphe to these regions, delineating the circuitry that could underlie intrinsic neuromodulation, a phenomena that may underlie some of the long lasting behavioral alterations associated with stress. Finally, I will also produce a conditional knockout Tph2 transgenic mouse and determine the ability of a canine adenovirus-Cre recombinase vector to specifically alter serotonergic transmission in defined pathways. This methodology will allow me to separate the role of serotonin from the role of peptide co-transmitters in behavior. These studies will help develop technologies to understand the role of CRF projections to the dorsal raphe, and the role of dorsal raphe outputs in modulating circuits that underlie behavior related to anxiety and depression. The public health importance of this basic research is substantial. Understanding the mechanisms by which stress is communicated opens opportunities for intervening in this process. Given the role of stress in the development and recurrence of many psychiatric disorders, the ability to disrupt the communication of stress context would be a boon for both the treatment and prevention of many types of mental illness, including depression and anxiety disorders. This research will help provide the information necessary for the rational development of such interventions.