Nicotinic Receptors in Cochlear Hair Cell Physiology

耳蜗毛细胞生理学中的烟碱受体

• 批准号: 6614802
• 负责人: Paul A Fuchs
• 金额: $ 3.83万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6614802
• 关键词: RNase protection assay; South America; Xenopus oocyte; acetylcholine; cochlea; computer program /software; ear hair cell; efferent nerve; electrophysiology; embryonic stem cell; gene targeting; genetically modified animals; in situ hybridization; innervation; laboratory mouse; laboratory rat; molecular cloning; neuropharmacology; neurotransmitter agonist; neurotransmitter antagonist; nicotinic receptors; protein structure function; receptor expression; synapses; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant) Recent years have seen important developments in the study of hearing, especially the emergence of molecular genetics to probe the underlying mechanisms of hearing loss. It is estimated that 1 in every 1,000 newborns is profoundly deaf, while nearly 1 in 20 has a significant hearing impairment. In more than half of these cases, the cause is genetic. As of February 2002, twenty-nine specific genes have been associated with different forms of nonsyndromic human deafness. In addition, many other gene products involved in normal cochlear function have been identified. The foreign collaborator (Elgoyhen) cloned and characterized two novel nicotinic receptor genes (alpha 9 and alpha 10) that are expressed in cochlear hair cells. Alpha 9 and 10 encode receptor proteins that mediate the effect of acetylcholine (ACh) released by efferent neurons onto cochlear hair cells. The Principal Investigator (Fuchs) showed that calcium entry through the ACh receptor leads to hair cell hyperpolarization, reducing transmitter release to cause a loss of tuning and sensitivity in the auditory nerve fibers. This FIRCA proposal brings together the expertise of the Fuchs and Elgoyhen laboratories to conduct a series of electrophysiological and molecular genetic experiments to elucidate the properties and function of these cholinergic receptors in hair cell physiology. The long-term goal of this proposal is to define the physiological role of the hair cell's cholinergic receptor. In addition, it is expected that the results obtained will contribute to our understanding of the role of efferent cholinergic input in the genesis and potential treatment of hearing impairment produced by loud sound or ototoxic drugs. The immediate aims of this application are three-fold: first, the pharmacological and physiological comparison of recombinant alpha9/alpha10 receptors expressed in Xenopus laevis oocytes with native cholinergic receptors of inner and outer hair cells in acute cochlear explants; second, the characterization of the ontogeny of cholinergic responses in inner hair cells and third, the physiological analysis of synaptic contacts onto inner and outer hair cells in mice with genetic modifications in the Acra9 gene, namely the alpha9 null mutant mouse and a knock-in mouse bearing a gain of function mutation. This research will be done primarily in Argentina at INGEBI (National Research Council) in collaboration with Ana Belen Elgoyhen as an extension of NIH grant #R01 DC01508.

描述（由申请人提供） 近年来，在听力研究中有了重要的发展，尤其是分子遗传学的出现，以探测听力损失的潜在机制。据估计，每1,000名新生儿中有1个具有深刻的聋子，而近20分之一的听力障碍会严重。在这些情况的一半以上，原因是遗传。截至2002年2月，29个特定基因与不同形式的非综合性人类耳聋有关。此外，已经确定了许多其他参与人工耳蜗功能的基因产品。外国合作者（Elgoyhen）克隆并表征了两个在耳蜗细胞中表达的新型烟碱受体基因（Alpha 9和Alpha 10）。 Alpha 9和10编码受体胆碱（ACH）的受体蛋白，由传出神经元释放到耳蜗毛细胞上。主要研究者（FUCHS）表明，通过ACH受体的钙进入会导致毛细胞超极化，从而减少了发射器释放，从而导致听觉神经纤维中的调整和灵敏度的丧失。这项FIRCA提案汇集了Fuchs和Elgoyhen实验室的专业知识，以进行一系列电生理和分子遗传实验，以阐明这些胆碱能受体在毛细胞生理学中的特性和功能。该提议的长期目标是定义毛细胞胆碱能受体的生理作用。另外，预计获得的结果将有助于我们理解源代胆碱能输入在大声声音或耳毒性药物产生的听力障碍的起源和潜在治疗中的作用。该应用的直接目的是三倍：首先，在急性神经露天露天植物中内毛和外毛细胞的天然胆碱能受体中表达的重组α9/alpha10受体的药理和生理比较；其次，内毛细胞中胆碱能反应的个体发育的表征，第三，在ACRA9基因中具有遗传修饰的小鼠内部和外毛的突触接触的生理分析，即Alpha9 Null突变小鼠，以及敲入功能突变的敲击小鼠。这项研究将主要在英格比（国家研究委员会）与Ana Belen Elgoyhen合作，作为NIH授予＃R01 DC01508的扩展。