MOLECULAR BIOLOGY OF COCHLEAR EFFERENT RECEPTORS

描述：这项建议的目标是研究分子 橄榄耳蜗传出神经递质的释放机制 影响耳蜗外毛细胞。有一种理论是关于 耳蜗传出神经对听力的贡献是它们保护了 高频声过刺激引起的耳聋，而另一种 理论上讲，它们可以在背景存在的情况下增强声音识别能力 噪音。高位投射的传出神经的初级神经递质 常见的神经细胞是乙酰胆碱(ACh)和降钙素基因相关肽 (CGRP)。拟议的实验将检验CGRP发挥作用的假设 通过启动一系列导致脱敏的事件而产生的影响 毛细胞上存在的胆碱能受体。 第一个具体目标是克隆ACh和CGRP的全长cDNA 以部分cDNA为探针的豚鼠耳蜗受体亚型 编码豚鼠A9、ACh和CGRP受体。原位杂交 技术将被用来确定豚鼠器官中的哪些细胞 科尔蒂表达这些受体。第二个具体目标将使用 免疫组织化学和免疫印迹技术验证其存在 耳蜗乙酰胆碱A9和降钙素基因相关肽传出的蛋白质分布 感受器。第三个具体目标是使用电生理学技术 为了研究克隆的CGRP和Ach受体是否能够 功能上的相互作用，使CGRP预先孵育产生第二信使 从而导致Ach受体脱敏。 从这些研究中获得的信息可能有助于未来的药物开发 针对耳蜗传出系统的治疗，因此有助于减少 慢性阻塞性肺疾病的发生和改善治疗 高频听力损失。

DESCRIPTION: The objective of this proposal is to study the molecular mechanisms by which neurotransmitters released by olivocochlear efferents influence outer hair cells (OHCs) of the cochlea. One theory about the contributions that cochlear efferents make to hearing is that they protect the cochlea from high frequency acoustic over-stimulation, whereas another theory is that they enhance sound recognition in the presence of background noise. The primary neurotransmitters of the efferents projecting on high frequency OHCs are acetylcholine (ACh) and calcitonin gene-related peptide (CGRP). The proposed experiments will test the hypothesis that CGRP exerts its effects by initiating a cascade of events resulting in desensitization of the cholinergic receptors present on OHCs. The first specific aim is to clone full-length cDNAs for ACh and CGRP receptor subtypes from the guinea pig cochlea using as probes partial cDNAs encoding the guinea pig a9 ACh and CGRP receptors. In situ hybridization techniques will be used to establish which cells in the guinea pig organ of Corti express these receptors. The second specific aim will use immunohistochemical and Western blotting techniques to verify the presence and distribution of proteins for the cochlear ACh a9 and CGRP efferent receptors. The third specific aim employs electrophysiological techniques to investigate whether the cloned CGRP and Ach receptors are able to interact functionally, such that CGRP preincubation causes second messenger effects, which leads to Ach receptor desensitization. Information gained from these studies may contribute to future drug therapies that target the cochlear efferents system, and thus, help decrease the occurrence of, and improve the treatment for patients with high-frequency hearing loss.