ALPHA CONOTOXIN MII--SELECTIVE NICOTINIC RECEPTOR PROBE

ALPHA 芋螺毒素 MII--选择性烟碱受体探针

• 批准号: 6768730
• 负责人: MICHAEL J MARKS
• 金额: $ 26.02万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6768730
• 关键词: conotoxin; corpus striatum; frontal lobe /cortex; laboratory mouse; mutant; neuropharmacology; nicotine; nicotinic receptors; nucleus accumbens; protein structure function; receptor binding; receptor expression

DESCRIPTION (provided by applicant): Nicotine elicits behavioral effects through a diverse family of nicotinic acetyicholine receptors (nAChR) and nicotine evoked dopamine release is thought to play an important role in the establishment and maintenance of nicotine dependence. a-ConotoxinMll (aCtxMII), a toxin isolated from the predatory cone snail Conus magus, potently and selectively blocks a3b2-nAChR expressed in Xenopus oocytes and partially inhibits nicotine-stimulated dopamine release from rat striatal synaptosomes. During the initial funding period for this grant aCtxMII has been used to identify subsets of nAChRs in mouse brain. It was confirmed that aCtxMII inhibits some, but not all, nicotine-stimulated dopamine release in mouse striatum. As expected, b2 null mutants retained virtually no aCtxMII binding or nicotine-stimulated release. Surprisingly, the b3 null mutation eliminated most high affinity aCtxMII binding and aCtxMII-sensitive dopamine release. Equally surprising was the absence of an effect of the a3 null mutation on aCtxMII binding. Therefore, many native nAChRs that interact with aCtxMII are not the a3b2 subtype. Experiments outlined in the current proposal will use ligand binding and functional analyses to further examine the diversity of nAChR. 1) aCtxMII sensitivity of nAChR mediated dopamine release in striatum, nucleus accumbens, frontal cortex and olfactory tubercles of mice that have been mutated to eliminate the expression of specific nAChR subunits (initially a7, a5, b2, b3 and b4) will be evaluated to obtain information about the molecular composition and functional diversity of these important presynaptic nAChRs. 2) Regulation of nAChR binding and function by chronic nicotine treatment using both wild type and null mutant mice, with emphasis on those mutants that affect nAChRs that interact with aCtxMII, will also be examined. 3) Structural properties of the recently identified aCtxPWl, which differs markedly in structure from aCtxMII, but displays a similar pharmacological profile, will be evaluated to determine if this new toxin will prove to be superior or complementary reagent. The proposed studies will provide further insights into the nature of three novel, native nAChRs sensitive to inhibition by aCtxMII and may lead to better understanding of the basis of the effects of nicotine

描述（由申请人提供）： 尼古丁通过多种烟碱家族引起行为影响 乙酰胆碱受体（nAChR）和尼古丁被认为诱发多巴胺释放 在尼古丁的建立和维持中发挥重要作用 依赖性。 a-芋螺毒素Mll (aCtxMII)，一种从捕食锥体内分离出来的毒素 蜗牛 Conus magus，有效且选择性地阻断 a3b2-nAChR 在 非洲爪蟾卵母细胞并部分抑制尼古丁刺激的多巴胺释放 来自大鼠纹状体突触体。在本项目的初始资助期内 grant aCtxMII 已被用于鉴定小鼠大脑中 nAChR 的子集。它 已证实 aCtxMII 抑制部分但不是全部尼古丁刺激 小鼠纹状体释放多巴胺。正如预期的那样，b2 无效突变体保留 几乎没有 aCtxMII 结合或尼古丁刺激释放。令人惊讶的是， b3 无效突变消除了 aCtxMII 的最高亲和力结合 aCtxMII 敏感的多巴胺释放。同样令人惊讶的是，没有 a3 无效突变对 aCtxMII 结合的影响。因此，很多本土 与 aCtxMII 相互作用的 nAChR 不是 a3b2 亚型。实验 当前提案中概述的将使用配体结合和功能 分析以进一步检查 nAChR 的多样性。 1) aCtxMII 灵敏度 nAChR 介导纹状体、伏核、额叶皮质中多巴胺的释放 和小鼠的嗅结节已经发生突变以消除 特定 nAChR 亚基（最初为 a7、a5、b2、b3 和 b4）的表达为 评估以获得有关分子组成和功能的信息 这些重要的突触前 nAChR 的多样性。 2) nAChR结合的调节 和使用野生型和无效突变体进行慢性尼古丁治疗的功能 小鼠，重点关注那些影响与相互作用的 nAChR 的突变体 aCtxMII 也将接受检查。 3）最近的结构特性 鉴定出 aCtxPWl，其结构与 aCtxMII 显着不同，但是 显示相似的药理学特征，将进行评估以确定是否 这种新毒素将被证明是一种优越的或补充的试剂。拟议的 研究将进一步深入了解三种新颖的、本土的 nAChR 对 aCtxMII 的抑制敏感，可能有助于更好地理解 尼古丁作用的基础