Characterization of Cholinergic Modulation of Dopamine Neurotransmission

描述（由申请人提供）：中边缘多巴胺（DA）系统的多巴胺能神经元从腹侧被盖区（VTA）投射到伏隔核（NAc）是许多药物滥用的共同靶点，并且被认为在成瘾的发展中起着核心作用。最近，一些研究表明，一种内源性神经化学物质用于调节这些DA神经元是乙酰胆碱（ACh）；然而，由于缺乏足够高的空间和时间分辨率监测体内乙酰胆碱的方法，在完整动物中表征这种调节的直接证据是缺乏的。因此，本提案中描述的研究旨在通过在碳纤维微电极上使用快速扫描循环伏安法（FSCV）在单独的实验（彼此不依赖）中监测该投影两端的神经化学物质来表征中脑边缘DA传输的胆碱能调节。由于该技术提供了出色的时间和空间分辨率，这种电化学方法非常适合于实时测量大脑中的化学变化。电化学数据将分析主成分回归，允许个别化学成分客观区分和选择性定量。具体目标包括新技术的开发（目标1）和现有分析和神经生物学方法的创新应用（目标2）。它们是：1；一种新的乙酰胆碱电化学检测方法的开发和表征，可用于快速监测该神经化学物质在VTA中的波动。2. VTA胆碱能化合物如何调节清醒动物NAc中多巴胺外排的时间动态的定量研究。更好地了解自然发生的DA传递的胆碱能调节可能揭示一套新的影响大脑奖励系统的化学机制和生理病理。

DESCRIPTION (provided by applicant): The dopaminergic neurons of the mesolimbic dopamine (DA) system projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) are a common target for many drugs of abuse, and are thought to play a central role in the development of addiction. Recently, several studies have suggested that one endogenous neurochemical that serves to regulate these DA neurons is acetylcholine (ACh); however, direct evidence characterizing this modulation in intact animals is lacking, due largely to the absence of methods for monitoring in vivo ACh at sufficiently high spatial and temporal resolution. Thus, the studies described in this proposal are designed to characterize the cholinergic modulation of mesolimbic DA transmission by monitoring neurochemicals at both ends of this projection in separate experiments (that are not dependent on one another) using fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes. This electrochemical approach is well suited for real-time measurements of chemical changes in the brain, due to the excellent temporal and spatial resolution afforded by the technique. Electrochemical data will be analyzed with principal component regression, allowing individual chemical components to be objectively distinguished and selectively quantitated. The specific aims involve both the development of new technology (Aim 1) and innovative applications of existing analytical and neurobiological methods (Aim 2). They are: 1. The development and characterization of a novel electrochemical detection method for ACh that can be used to rapidly monitor fluctuations of this neurochemical in the VTA. 2. A quantitative study of how cholinergic compounds in the VTA modulate the temporal dynamics of dopamine efflux in the NAc of an awake animal. A better understanding of the cholinergic regulation of naturally occurring DA transmission may reveal a novel set of chemical mechanisms and physiological pathologies affecting the brain's reward system. PUBLIC HEALTH RELEVANCE: Drug abuse and addiction are significant problems in the United States. Estimates of the total overall costs of substance abuse in the United States-including health- and crime-related costs as well as losses in productivity-exceed half a trillion dollars annually. The dopaminergic neurons of the mesolimbic dopamine system projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) are a common target for many drugs of abuse, and are thought to play a central role in the development of addiction. The focus of this research is to understand how the endogenous neuromolecule acetylcholine can act at dopamine cell bodies to regulate dopamine release from the terminals. This work may reveal a novel set of chemical mechanisms and physiological pathologies affecting the brain's reward system.