Beta-Amyloid Blockade of Hippocampal Nicotinic Alpha7-R*

阿尔茨海默病药物发现。阿尔茨海默病是一种生理上毁灭性的疾病，随着人口老龄化，它有可能达到流行病的程度。胆碱能缺陷是阿尔茨海默病的一个被广泛认可的方面，现在被认为包括尼古丁信号作为一个关键组成部分。最有趣的烟碱受体之一是由α 7亚基组成的亚型，因为它在神经系统中广泛表达，并且对钙具有较高的相对渗透性，使其能够控制多种细胞功能。最近有研究表明，含有alpha7的受体在pM- nM范围内与β -淀粉样肽（氨基酸1-42）结合。哺乳动物海马体是研究这种相互作用的一个有趣系统，因为含有alpha7的受体相对丰富，海马体主要参与记忆形成，而记忆形成是阿尔茨海默病的主要靶点。在初步研究中，我们发现在nM范围内的β -淀粉样肽可逆地抑制培养海马神经元上含有α 7的烟碱受体。令人惊讶的是，外源性应用的某些肽可以快速和可逆地增强含有α 7的受体反应的数量级。这提出了一种真正的可能性，即能够进入同一位点的药物可能能够补偿β -淀粉样蛋白对受体的抑制。该试点提案将研究β -淀粉样肽与海马含α 7受体在功能和物理上的相互作用。此外，它将验证外源应用适当的调节分子将克服β -淀粉样肽介导的抑制的假设。该方法将使用来自神经元的全细胞膜片钳记录（通常在穿孔膜片模式下），同时从多孔快速涂抹器按所需序列涂抹测试化合物。使用放射性标记探针的竞争结合实验也将用于评估直接相互作用。功能表征将包括在含α 7受体的培养中对自发突触事件的调节，并确定β -淀粉样肽在缺乏候选增强剂的情况下对调节的影响。如果这项初步研究证明是成功的（正如初步实验鼓励我们认为的那样），结果将为随后的全面随访分析β -淀粉样蛋白对含有尼古丁受体的中枢神经系统的影响，分析阿尔茨海默氏症脑组织中α - 7受体在疾病中的具体参与，以及评估能够穿过血脑屏障并原位增强受体的化合物作为可能的治疗策略提供基础。

Alzheimer's Disease Drug Discovery. Alzheimer's disease is a physiologically devastating condition that is threatening to reach epidemic proportions as the population ages. Cholinergic deficit is a widely recognized aspect of Alzheimer's disease, and is now thought to include nicotinic signaling as a critical component. One of the most interesting nicotinic receptors is the subtype composed of alpha7 subunits because it is widely expressed in the nervous system and has a high relative permeability to calcium which enables it to control diverse cellular functions. Recently it has been shown that alpha7-containing receptors bind the beta-amyloid peptide (amino acids 1-42) in the pM- nM range. The mammalian hippocampus is an interesting system for studying such interactions because alpha7-containing receptors are relatively abundant there, and the hippocampus is centrally involved in memory formation which is a major target of Alzheimer's disease. In preliminary studies we have found that the beta-amyloid peptide in the nM range reversibly inhibits alpha7-containing nicotinic receptors on hippocampal neurons in culture. Surprisingly, certain peptides applied exogenously can quickly and reversibly potentiate the alpha7- containing receptor response by an order of magnitude. This raises the real possibility that drugs capable of accessing the same site may be able to compensate for beta-amyloid inhibition of the receptors. This pilot proposal will examine the interactive of beta-amyloid peptide with hippocampal alpha7-containing receptors both functionally and physically. In addition, it will test the hypothesis that exogenous application of appropriate regulatory molecules will overcome the inhibition mediated by beta-amyloid peptide. The approach will use whole-cell patch clamp recording (usually in perforated patch mode) from the neurons while applying test compounds in desired sequences from a multi-bore rapid applicator. Competition binding experiments with radiolabeled probes will also be used to assess direct interactions. Functional characterization will include modulation of spontaneous synaptic events in the cultures by alpha7-containing receptors, and determining the impact of beta-amyloid peptide on the modulation in the presence of absence of the candidate potentiators. If this pilot study proves successful (as the preliminary experiments encourage us to think it will), the results will provide the basis for a subsequent full-scale follow-up to analyze beta-amyloid effects on CNS alpha7-containing nicotinic receptors, to analyze Alzheimer's brain tissue for specific involvement of alpha7-receptors in the disease, and to evaluate compounds capable of crossing the blood-brain barrier and potentiating the receptors in situ as a possible therapeutic strategy.