Pituitary adenylate cyclase-activating polypeptide 27 in the paraventricular thalamus and its projections: Role in ethanol drinking

项目摘要 神经肽，垂体腺苷酸环化酶激活多肽（PACAP），先前已被证明 通过基因敲除来抑制乙醇摄入，但大脑区域和蛋白质异构体， 这种情况仍有待查明。虽然两种PACAP亚型中表达更高的PACAP 38， 发现影响一系列行为，包括焦虑和抑郁，我们最近的研究集中在 选择性表达的PACAP 27越多，似乎几乎没有这种关联。我们发现 在边缘系统的关键节点的神经元中，PACAP 27比PACAP 38明显更致密， 丘脑室旁核（PVT），在药理学相关的乙醇中起主要作用 喝酒此外，这些含PACAP 27的神经元在海马后区（p）特别密集。 我们先前已经证明pPVT激活可以减少乙醇饮用。因此，在本发明中， 基于已发表的初步结果，我们假设PVT神经元中的PACAP 27， 特别是在pPVT中，抑制乙醇摄入（目标1）;这些作用通过PACAP 27发挥 投射到核壳（NAcSh）（目的2）。为了验证这一点，目标1调查了具体的 假设pPVT细胞中PACAP表达起到抑制饮酒作用， 对焦虑和抑郁行为的影响。为了实现这一点，拟议的实验将使用一个 使用过表达AAV或shRNA沉默AAV方法来（1）确定增加PACAP的作用， （2）评估降低内源性PACAP的作用， pPVT中的PACAP表达，以及（3）研究增加pPVT中PACAP表达的影响。 pPVT对情绪行为的影响接下来，目的2研究了来自pPVT的PACAP 27 通过向NAcSh的投射来抑制乙醇饮用。因此，拟议的实验将使用 解剖学、免疫组织化学、药理学和化学遗传学技术，以（1）识别原发性 pPVT中PACAP 27的预测，（2）确定PACAP激动剂对乙醇摄入的影响， 拮抗剂，以及（3）确定PACAP 27对乙醇摄入的影响是否 由于pPVT的直接投射。总之，这些拟议的研究应该有利于公共卫生， 提供了对一种未充分研究的肽同种型的深入了解，这种肽同种型具有很少的已知行为效应， 导致治疗酒精使用障碍的创新药物疗法。

PROJECT SUMMARY The neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), has previously been shown through genetic knockout to suppress ethanol intake, but the brain regions and protein isoforms through which this occurs remain to be identified. While the more highly expressed of the two PACAP isoforms, PACAP38, is found to affect a range of behaviors, including anxiety and depression, our recent studies focus attention on the more selectively-expressed PACAP27, which appears to have few such associations. We have found PACAP27 to be significantly more dense than PACAP38 in neurons of a key node of the limbic system, the paraventricular nucleus of the thalamus (PVT), which has a major role in pharmacologically-relevant ethanol drinking. Moreover, these PACAP27-containing neurons are particularly dense in the posterior (p) subregion of the PVT, and we have previously shown that activation of the pPVT can decrease ethanol drinking. Thus, building on published and preliminary results, we hypothesize that PACAP27 in neurons of the PVT, specifically in the pPVT, suppresses ethanol intake (Aim 1); and these effects are exerted through PACAP27 projections to the nucleus accumbens shell (NAcSh) (Aim 2). To test this, Aim 1 investigates the specific hypothesis that expression of PACAP in cells of the pPVT functions to inhibit ethanol drinking, with minimal effects on anxiety- and depressive-like behavior. To accomplish this, the proposed experiments will use an overexpression AAV or an shRNA silencing AAV approach to (1) determine the effects of increasing PACAP expression in the pPVT on ethanol drinking, (2) assess the effects of decreasing endogenous PACAP expression in the pPVT on ethanol drinking, and (3) investigate the effects of increasing PACAP expression in the pPVT on emotional behavior. Next, Aim 2 investigates the hypothesis that PACAP27 from the pPVT suppresses ethanol drinking through projections to the NAcSh. Thus, the proposed experiments will use anatomical, immunohistochemical, pharmacological, and chemogenetic techniques, to (1) identify the primary projections of PACAP27 from the pPVT, (2) determine the effects on ethanol intake of PACAP agonists and antagonists in the major projection region(s), and (3) establish if the effects of PACAP27 on ethanol intake are due to direct projections from the pPVT. Together, these proposed studies should benefit public health by offering insight into an understudied peptide isoform with few known behavioral effects, which could ultimately lead to innovative drug therapies for treating alcohol use disorder.