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

项目总结 神经肽，垂体腺苷环化酶激活多肽(PACAP)，已被发现 通过基因敲除来抑制酒精摄取，但大脑区域和蛋白质亚型通过 这种情况的发生还有待确定。而两种PACAP亚型中表达较高的PACAP38是 发现会影响一系列行为，包括焦虑和抑郁，我们最近的研究集中在 PACAP27的表达更有选择性，似乎几乎没有这样的关联。我们发现了 在边缘系统的一个关键节点的神经元中，PACAP27的密度明显高于PACAP38， 丘脑室旁核(PVT)，在与药物相关的乙醇中起主要作用 喝酒。此外，这些含有PACAP27的神经元尤其密集在后(P)亚区。 PVT，我们之前已经证明激活pPVT可以减少酒精饮用量。因此， 根据已发表的初步结果，我们假设PACAP27在PVT的神经元中， 具体地说，在pPVT中，抑制乙醇摄入(Aim 1)；这些影响是通过PACAP27施加的 向伏隔核外壳投射(NAcSh)(目标2)。为了测试这一点，Aim 1调查了特定的 假设PACAP在pPVT细胞中的表达具有抑制酒精饮酒的功能，最低限度 对焦虑和抑郁样行为的影响。为了实现这一点，拟议的实验将使用 过表达AAV或shRNA沉默AAV的方法：(1)确定增加PACAP的效果 饮酒后pPVT的表达；(2)评估降低内源性PACAP的作用 饮酒后pPVT中PACAP的表达，以及(3)研究PACAP在大鼠体内的表达。 情绪行为的PPVT。接下来，Aim 2调查了来自pPVT的PACAP27的假设 通过向NAcSh的投射抑制酒精的饮用。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)确定主要的 PACAP27从pPVT的投射，(2)确定PACAP激动剂和 主投射区域的拮抗剂(S)，以及(3)确定PACAP27对酒精摄取的影响是否 由于pPVT的直接投影。总之，这些拟议的研究应该会通过以下方式使公共卫生受益 提供了对一种未被充分研究的多肽亚型的洞察力，但几乎没有已知的行为影响，这最终可能 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.