Molecular Bases for Effects of Nicotine

描述（由申请人提供）：本项目的长期目标是确定慢性尼古丁暴露是否以及如何改变神经系统功能。该项目基于中心假设，即长期暴露于尼古丁会诱导不同烟碱乙酰胆碱受体（nAChR）亚型的数量和功能发生长期变化。这些影响与尼古丁依赖、烟草制品使用、烟草相关疾病、预防、限制或停止烟草使用的治疗以及神经和精神疾病的治疗具有潜在相关性。 初步研究结果表明，我们的假设，慢性尼古丁暴露导致（i）持续失活的nAChR功能和（ii）增加nAChR的数量通过两个因果关系和机制不同，翻译后过程。尼古丁效应的剂量和时间依赖性被假定为nAChR亚型特异性，其他药物改变nAChR数量和功能的药理学特征也是如此。这个多层次项目的一个主要目的是确定暴露于尼古丁或相关物质对不同人类nAChR亚型功能的影响。另一个主要目的是确定这些药物对nAChR数量的影响。对于这两个目的，研究将涉及α 1 β 1 γ δ-（肌肉型）、α 3 α 5 β 4-（自主）、α 4 β 2-（脑尼古丁结合）和α 7-（自主或脑神经毒素结合）nAChR，这些nAChR通过模型细胞系天然和/或异源表达。将确定尼古丁细胞处理的时间（起效和恢复）和剂量依赖性效应。还将使用其他药物单独或与尼古丁组合获得时间和剂量曲线，以评估它们是否模拟或阻断尼古丁的作用，将通过电生理记录和离子通量测定来定量nAChR功能活性。放射性配体结合和免疫测定将用于定量nAChR并评估其亚细胞分布和代谢。nAChR的化学反应性和突变研究将被用于建立尼古丁和其他药物作用机制。 这些研究意义重大，因为它们将为慢性尼古丁作用于神经系统功能调节的位点和机制提供新的视角。还将深入了解尼古丁依赖的分子基础。将确定受慢性尼古丁暴露影响最大的特定nAChR亚型。还将深入了解阻断或模拟尼古丁作用的药物种类。总的来说，这些知识将有利于发展治疗情绪，认知和其他神经系统疾病的策略。

DESCRIPTION (provided by applicant): The long-term goal of this project is to establish whether and how chronic nicotine exposure alters nervous system function. The project is based on the central hypothesis that extended exposure to nicotine induces long-lasting changes in numbers and function of diverse nicotinic acetylcholine receptor (nAChR) subtypes. These effects have potential relevance for nicotine dependence, use of tobacco products, tobacco-related diseases, treatments to prevent, limit or cease tobacco use, and therapies for neurological and psychiatric disorders. Preliminary findings suggest our hypothesis that chronic nicotine exposure causes both (i) a persistent inactivation of nAChR function and (ii) an increase in numbers of nAChR via two causally- and mechanistically-distinct, posttranslational processes. Dose- and time-dependence of nicotine's effects are postulated to be nAChR subtype-specific, as are pharmacological profiles for other drugs acting to alter nAChR numbers and function. One principal aim of this multi-layered project is to establish effects of exposure to nicotine or related substances on function of diverse, human nAChR subtypes. The other principal aim is to determine effects of those agents on numbers of nAChR. For both aims, studies will involve alpha1 beta1 gamma delta- (muscle-type), (alpha3 alpha5 beta4- (autonomic), alpha4 beta2-(brain nicotine-binding), and alpha7- (autonomic or brain neurotoxin-binding) nAChR expressed naturally and/or heterologously by model cell lines. Time (onset of effects and recovery)- and dose-dependent effects of cell treatment with nicotine will be established. Time and dose profiles will also be obtained using other drugs alone or in combination with nicotine to assess whether they mimic or block nicotine's effects, nAChR functional activity will be quantified by electrophysiological recording and ion flux assays. Radioligand binding and immuno- assays will be used to quantitate nAChR and to assess their subcellular distribution and metabolism. Chemical reactivity of nAChR and mutational studies will be among those used to establish mechanisms involved in effects of nicotine and other drugs. These studies are significant because they will provide new perspectives on sites and mechanisms of chronic nicotine action in the modulation of nervous system function. Insights will also be provided into molecular bases of nicotine dependence. Specific nAChR subtypes that are affected most powerfully by chronic nicotine exposure will be identified. Insights will also be provided into the kinds of drugs that block or mimic nicotine's actions. Collectively, this knowledge will benefit development of strategies to treat mood, cognitive, and other nervous system disorders.