Characterization of Cholinergic Modulation of Dopamine Neurotransmission

描述(申请人提供)：中脑边缘多巴胺(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目标，被认为在成瘾的发展中发挥核心作用。最近，一些研究表明，调节这些DA神经元的一种内源性神经化学物质是乙酰胆碱(ACh)；然而，缺乏在完整动物中描述这种调节的直接证据，主要是由于缺乏在体内以足够高的空间和时间分辨率监测ACh的方法。因此，这项建议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)在不同的实验(彼此不依赖)中监测这种投射两端的神经化学物质，来表征中脑边缘DA传递的胆碱能调节。这种电化学方法非常适合于实时测量大脑中的化学变化，因为该技术提供了出色的时间和空间分辨率。电化学数据将用主成分回归进行分析，从而能够客观地区分和选择性地定量个别化学成分。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)。1.一种新的ACh电化学检测方法的建立和表征，该方法可用于快速监测VTA中ACh的变化。2.定量研究VTA中的胆碱能化合物如何调节清醒动物NAc中多巴胺外流的时间动态。更好地了解胆碱能对自然发生的DA传递的调节可能会揭示一套影响大脑奖赏系统的新的化学机制和生理病理。 与公共健康相关：药物滥用和成瘾在美国是严重的问题。据估计，美国药物滥用的总成本--包括与健康和犯罪相关的成本以及生产力损失--每年超过5000亿美元。中脑边缘多巴胺系统中的多巴胺能神经元从腹侧被盖区(VTA)投射到伏核(NAC)，是许多药物滥用的共同靶点，被认为在成瘾的形成中起着核心作用。这项研究的重点是了解内源性神经分子乙酰胆碱如何作用于多巴胺细胞体，以调节终末的多巴胺释放。这项工作可能会揭示一套影响大脑奖励系统的新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.