PACAP-Dependent Coordination of Glutamate Signaling between Neurons and Astrocytes

项目摘要/摘要 谷氨酸信号转导失调是药物成瘾病理基础的核心组成部分 可卡因和许多其他物质。神经科学和其他领域的最新进展清楚地证明了 谷氨酸编码信号的分子和细胞基础比以前复杂得多。 被认可了。特别是，越来越明显的是，星形胶质细胞是最多的 人类大脑中丰富的细胞，释放谷氨酸，对神经回路活动产生复杂的调节。 这种新形式的谷氨酸编码的细胞间信号可能是理解病理的关键 谷氨酸产生自星形胶质细胞长期用药产生谷氨酸释放机制等系统 XC-(SXC)，被可卡因改变。虽然这些发现提出了许多问题，这些问题可能是 了解人脑中的谷氨酸信号，这项提议将集中在这个问题上，如何 神经元调节星形胶质细胞释放谷氨酸以控制神经网络活动和相关行为 可卡因成瘾。我们将检验这一假设，即这是通过神经肽垂体的作用实现的。 腺苷环化酶激活多肽(PACAP)，我们认为它是一个未知的成分 伏核(NAC)中的谷氨酸信号转导。在支持方面，我们发现A)PACAP mRNA是 B)PACAP受体在NAC星形胶质细胞和投射到 黑质(SN)而不是腹侧苍白球(Vp)，C)PACAP可刺激下丘脑谷氨酸的释放。 星形胶质细胞通过增加系统XC-(SXC)，D)PACAP的应用抑制NAC的eEPSCs 中棘神经元(MSN)投射到黑质(SN)，但不投射到腹侧苍白球(E) NAC内微量输注PACAP可阻止可卡因恢复。在这个提案中，我们将检验这一假设 PACAP是一种神经肽，调节星形胶质细胞和谷氨酸受体释放谷氨酸 神经元为NAC传出通路提供一种新形式的通路特异性调节。在目标1中，我们将 研究PACAP诱导SXC活性增加的分子基础，并确定SXC PACAP抑制NAC-SN MSN中的eEPSC并阻止可卡因的恢复是必要的。在……里面 为了达到这个目的，我们还将研究PACAP是否增加了星形细胞释放谷氨酸的机制，而不是 SXC。在目标2中，我们将研究PACAP触发的星形胶质细胞-神经元信号形式的可能性 需要神经元谷氨酸受体的调节才能产生相关的生理变化 NAC传出和行为的输出。我们还将探讨PACAP是否改变突触前谷氨酸 放手。在目标3中，我们将研究内源性PACAP的作用，以了解这种神经肽是否是一种 NAC中谷氨酸信号的未知成分，以及它是否是药物的关键决定因素- 寻求行为。

Project Summary/Abstract Dysregulation of glutamate signaling is a core component of the pathological basis of drug addiction involving cocaine and many other substances. Recent progress in neuroscience and other fields clearly establishes that the molecular and cellular basis of glutamate-encoded signaling is vastly more complex than previously recognized. In particular, it is becoming increasingly evident that astrocytes, which are among the most abundant cells in the human brain, release glutamate to produce complex regulation over neural circuit activity. This novel form of glutamate-encoded intercellular signaling may be critical to understanding the pathological glutamate produced by long-term drug use since astrocytic glutamate release mechanisms, such as system xc- (Sxc), are altered by cocaine. While these discoveries raise numerous questions that may be essential in understanding glutamate signaling in the human brain, this proposal will focus on the question, how do neurons regulate glutamate release from astrocytes to control neural network activity and behaviors relevant to cocaine addiction. We will test the hypothesis that this is achieved by the actions of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP), which we believe to be an unrecognized component of glutamate signaling in the nucleus accumbens (NAc). In support, we have found that A) PACAP mRNA is expressed in NAc afferents, B) PACAP receptors are expressed in NAc astrocytes and neurons projecting to the substantia nigra (SN) but not the ventral pallidum (VP), C) PACAP stimulates glutamate release from astrocytes by increasing the activity of system xc- (Sxc), D) PACAP application depresses eEPSCs in NAc medium spiny neurons (MSNs) projecting to the substantia nigra (SN) but not the ventral pallidum, and E) intra-NAc micro-infusion of PACAP blocks cocaine reinstatement. In this proposal, we will test the hypothesis that PACAP is a neuropeptide that regulates glutamate release from astrocytes and glutamate receptors on neurons to provide a novel form of pathway-specific regulation of NAc efferent pathways. In Aim 1, we will examine the molecular basis of PACAP-induced increases in Sxc activity and determine whether Sxc regulation is necessary for PACAP to depress eEPSCs in NAc-SN MSNs and block cocaine reinstatement. In this aim, we will also examine if PACAP increases glutamate from astrocytic release mechanisms other than Sxc. In Aim 2, we will examine the possibility that the form of astrocyte-neuron signaling triggered by PACAP require the regulation of neuronal glutamate receptors to produce the relevant changes in physiology that gate the output of NAc efferents and behavior. We will also explore whether PACAP alters presynaptic glutamate release. In Aim 3, we will investigate the role of endogenous PACAP to learn whether this neuropeptide is an unrecognized component of glutamate signaling in the NAc, and whether it is a key determinant of drug- seeking behavior.