PACAP signaling in stress and anxiety

描述（由申请人提供）：暴露于压力下引发精神疾病的机制尚不清楚。最近的研究表明，应激激活和改变大鼠大脑中的垂体腺苷酸环化酶激活多肽（PACAP）系统。用单一的PACAP治疗模拟应激诱导的PACAP功能的增加会导致持续（持续超过1周）的声惊增加，这是一种常用于临床前和临床焦虑研究的测量方法。相比之下，单次CRF治疗导致惊吓增加，并在24小时内恢复正常。PACAP能够在大鼠的焦虑相关行为中产生持久的增加，使其与CRF区别开来，并使其成为压力研究的重要新目标。事实上，新的证据表明，PACAP参与了人类严重和衰弱的焦虑形式的发展，包括创伤后应激障碍（PTSD），其关键标志是惊吓（过度唤醒）的持续增加。本研究旨在探讨PACAP信号在大鼠应激和焦虑相关行为中的神经生物学作用。考虑到迫切需要新的治疗压力相关疾病的方法，Aim 1将专注于识别能够阻断PACAP的急性和/或长期行为效应的药物。我们将研究对PACAP （PAC1）受体和VIP/PACAP （VPAC1）受体具有选择性的药物类别，这两种药物之前都没有在应激研究中进行过测试，以及kappa-阿片受体（KOR）拮抗剂，它已被证明可以阻断应激效应。这项工作可能加速药物开发，同时为机制研究提供新的方向。目的2将研究PACAP产生持久效应的机制。研究集中在终纹床核（BNST）上，因为(i) BNST是PACAP神经支配的主要目标，（ii）应激增加了PACAP在BNST中的表达，（iii） PACAP直接注入BNST会产生持久的高唤醒。一组研究探讨了增强或破坏CREB（腺苷酸环化酶的下游靶点）的功能如何影响基线和pacap增强的惊吓。另一组研究将扩展我们的新数据，通过检查增强或破坏miR134功能如何影响基线和PACAP增强的惊吓，表明PACAP而不是CRF导致miR134的显著下调，miR134是一种负性调节神经元脊柱密度和体积的非编码RNA。这项工作可能会确定细胞内的过程，可以靶向药物开发。目的3将确定PACAP是否会产生其他PTSD症状，包括持续性快感缺乏、社交退缩、注意力缺陷和恐惧消退障碍。这项工作可能表明，PACAP治疗提供了一种全面模拟创伤后应激障碍各种症状的方法。目的4研究PACAP效应的强度和持久性的性别差异，这可能会确定调节应激反应的其他因素。总的来说，提出的研究可能会对焦虑障碍的病因产生见解，并促进抗压力药物的发展。

DESCRIPTION (provided by applicant): The mechanisms by which exposure to stress triggers mental illness are not understood. Recent work shows that stress activates and modifies PACAP (pituitary adenylate cyclase-activating polypeptide) systems in the rat brain. Mimicking stress-induced increases in PACAP function with a single PACAP treatment causes persistent (lasting more than 1 week) increases in acoustic startle, a measure often used in both preclinical and clinical studies of anxiety. In contrast, a single CRF treatment causes increases in startle that normalize within 24 hr. PACAP's ability to produce long-lasting increases in an anxiety-related behavior in rats differentiates it from CRF and makes it an important new target for stress research. Indeed, new evidence suggests that PACAP is involved in the development of severe and debilitating forms of anxiety in humans, including post-traumatic stress disorder (PTSD), a key sign of which is persistent increases in startle (hyperarousal). This proposal examines the neurobiology of PACAP signaling in stress- and anxiety-related behaviors in rats. Considering the urgent need for new treatments for stress-related disorders, Aim 1 will focus on identifying agents that can block the acute and/or long-lasting behavioral effects of PACAP. We will examine classes of agents that are selective for PACAP (PAC1) receptors and VIP/PACAP (VPAC1) receptors, neither of which has been previously tested in stress studies, as well as kappa-opioid receptor (KOR) antagonists, which have been shown to block stress effects. This work may hasten medication development while providing new directions for mechanistic research. Aim 2 will examine the mechanisms by which PACAP produces persistent effects. Studies focus on the bed nucleus of the stria terminalis (BNST) because (i) the BNST is a major target of PACAP innervation, (ii) stress increases PACAP expression in the BNST, and (iii) infusion of PACAP directly into the BNST produces long-lasting hyperarousal. One set of studies examines how enhancing or disrupting the function of CREB, a downstream target of adenylate cyclase, affects baseline and PACAP-enhanced startle. Another set of studies will extend our new data showing that PACAP but not CRF causes marked downregulation of miR134, a non-coding RNA that negatively regulates neuronal spine density and volume, by examining how enhancing or disrupting miR134 function affects baseline and PACAP-enhanced startle. This work may identify intracellular processes that can be targeted for medication development. Aim 3 will determine if PACAP produces other signs of PTSD, including persistent anhedonia, social withdrawal, deficits in concentration, and impairments in fear extinction. This work may establish that PACAP treatment provides an approach that comprehensively models the myriad symptoms of PTSD. Aim 4 examines sex differences in the strength and persistence of PACAP effects, which may identify still other factors that regulate stress responsiveness. Collectively, the proposed studies may yield insights on the etiology of anxiety disorders and facilitate the development of anti-stress medications.