MOLECULAR BIOLOGY OF COCHLEAR EFFERENT RECEPTORS

描述：本提案的目的是研究 橄榄耳蜗传出神经释放神经递质的机制 影响耳蜗的外毛细胞（OHC）。 一种关于 耳蜗传出神经对听力的贡献在于它们保护 耳蜗从高频声过度刺激，而另一个 理论上说，它们可以在有背景的情况下增强声音识别 噪声 传出神经投射到高位的主要神经递质 常见的OHC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， 通过引发一系列导致脱敏的事件， 存在于外毛细胞上的胆碱能受体。 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α 9 ACh和CGRP受体。 原位杂交 技术将被用来确定哪些细胞在豚鼠器官， Corti表达这些受体。 第二个具体目标将使用 免疫组织化学和蛋白质印迹技术，以验证存在 耳蜗ACh α 9和CGRP传出纤维的蛋白分布 受体。 第三个具体目标采用电生理技术 研究克隆的CGRP和Ach受体是否能够 在功能上相互作用，例如CGRP预孵育引起第二信使 作用，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 针对耳蜗传出神经系统的治疗，从而有助于减少 的发生，并改善患者的治疗 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.