The dorsal raphe and CRF: making the connections

描述（由申请人提供）：抑郁症和焦虑症是美国发病率、死亡率和致残的主要原因之一，并且与压力暴露高度相关。血清素神经传递受损似乎是诱发抑郁和焦虑症状的中枢机制。先前的研究表明，促肾上腺皮质激素释放因子（CRF）受体在中背（前脑5 -羟色胺的主要来源）的激活是应激对5 -羟色胺能系统影响的关键机制。然而，CRF对中缝背的影响取决于剂量、核内位置和受体特异性。CRF投射到背中缝的起源，以及它们受背中缝输出调节的可能性也尚不清楚。在应激反应中，几种神经肽的作用也越来越被认为是与血清素共同递质，可能参与慢性应激的影响。我将使用血清素能细胞系RN46A-B14来模拟CRF受体激活对血清素能神经元的剂量反应和第二信使效应，帮助阐明CRF在那里的直接作用。利用一种新的逆行基因转移系统，犬腺病毒- 2,1将确定CRF投射到中缝背各亚区的起源，怀疑是杏仁核中央核和床纹终核。我还将确定中缝背到这些区域的相互投影，描绘可能构成内在神经调节的电路，这种现象可能构成与压力有关的一些长期行为改变的基础。最后，我还将生产条件敲除Tph2转基因小鼠，并确定犬腺病毒- cre重组酶载体在特定途径中特异性改变血清素能传播的能力。这种方法将使我能够将血清素的作用与肽共递质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投射到中脑背的作用，以及中脑背输出在调节电路中的作用，这些电路是焦虑和抑郁相关行为的基础。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所起的作用，破坏压力环境的交流的能力对于治疗和预防许多类型的精神疾病，包括抑郁症和焦虑症，都是一个福音。这项研究将有助于为合理制定此类干预措施提供必要的信息。

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.