Alpha-Conotoxin MII: A Selective Nicotinic Receptor Probe

描述（由申请人提供）：尼古丁通过不同的尼古丁乙酰胆碱受体家族（nachr）产生行为影响。尼古丁诱发的多巴胺释放被认为在尼古丁依赖的建立和维持中起着重要作用，这使得人们继续使用烟草产品，尽管它们对健康的危害众所周知。α -conotoxin MII是一种从捕食性锥蜗牛Conus magus中分离出来的毒素，它可以区分烟碱受体的亚群。在这项资助的第一个资助期，我们使用alpha-CtxMII来识别和分析调节尼古丁引起的多巴胺释放的nAChR种群。我们也开始研究慢性尼古丁暴露对这些受体的影响，以及它们如何在帕金森病模型中受到影响。为了增强α - ctxmii的有用性，我们还设计了包含新特性或增加其对特定nAChR群体选择性的变体。当前提案中概述的实验将进一步扩展这些研究。1)将使用慢性治疗和尼古丁亚基突变（单独或联合使用）来研究之前资助期表征的nAChR群体如何相互作用，以及它们调节的神经递质系统如何相互作用。2)开发新的α - ctxmii衍生物有两个目的。首先，制作alpha3beta2-nAChR亚型选择性衍生物（目前我们没有这样的化合物，但这是一种自然表达的nAChR亚型，需要进一步研究）。其次，生产基于α - ctxmii的放射性标签，保留原有的[125l] α - ctxmii的选择性（这是在以前的资助期开发的），但提高了分析性能。这将提高我们测量和研究这些重要nachr的能力。3)合成对α - 7亚型nAChRs具有选择性的α -conotoxin ArIB衍生物并对其进行表征。我们打算开发一系列有用的、高选择性的工具来研究这种自然发生的nAChR亚型。建议的研究将进一步深入了解自然发生的nachr的位置、数量和功能作用，以及它们之间的相互作用。很可能，这种不断增加的理解将反过来阐明哪些nAChR亚型与尼古丁依赖有关，从而有助于开发更有效的戒烟辅助工具。这些见解也可以指导设计针对其他疾病的尼古丁疗法。

DESCRIPTION (provided by applicant): Nicotine produces behavioral effects through a diverse family of nicotinic acetylcholine receptors (nAChRs). Nicotine-evoked dopamine release is thought to play an important role in the establishment and maintenance of nicotine dependence, which undelies peoples' continued use of tobacoo products, despite their well-known dangers to health. alpha-conotoxin MII is a toxin isolated from the predatory cone-snail Conus magus, which distinguishes between subsets of nicotinic receptors. In the first funding periods of this grant, we used alpha-CtxMII to identify and analyse the nAChR populations that modulate nicotine-evoke dopamine release. We also began to study the effects of chronic nicotine exposure on these receptors, and how they are affected in models of Parkinson's Disease. In order to enhance the usefulness of alpha-CtxMII, we have also engineered variants which have incorporate new properties or increased its selectivity for particular nAChR populations. Experiments outlined in the current proposal will extend these studies further. 1) Chronic treatment and nicotinic subunit mutation will be used (alone, and in combination) to investigate how the nAChR populations characterized in the previous funding period interact with each other, and with the neurotransmitter systems that they modulate. 2) New alpha-CtxMII derivatives will be developed with two aims. First, to make alpha3beta2-nAChR subtype selective derivatives (we do not have such a compound at present, but this is a natually-expressed nAChR subtype that requires further study). Second, to produce alpha-CtxMII-based radiolabels that retain the original selectivity of [125l]alpha-CtxMII (which was developed in the previous funding periods), but with improved assay performance. This will improve out ability to measure and study these important nAChRs. 3) Synthesize and characterize derivatives of alpha-conotoxin ArIB, which has selectivity for alpha7-subtype nAChRs. We intend to develop a series of useful, highly-selective tools for the study of this naturally-occurring nAChR subtype. The proposed studies will provide further insights into the locations, numbers and functional roles of naturally-occurring nAChRs, and the interactions between them. It is likely that this increased understanding will, in turn, illuminate which nAChR subtypes are implicated in nicotine dependence, and thus assist in attempts to develop more-effective smoking cessation aids. These insights may also guide the design of nicotinic therapies for other conditions.