Afferent Innervation in the Mouse Cochlea

小鼠耳蜗的传入神经支配

• 批准号: 6588276
• 负责人: Howard W Francis
• 金额: $ 8.18万
• 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: 2003-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6588276
• 关键词: acoustic nerve; cochlea; ear hair cell; hearing disorders; histochemistry /cytochemistry; innervation; nerve; neural information processing; noise; synapses; transmission electron microscopy

DESCRIPTION (provided by applicant): The long-term goal of my research is to understand fundamental structure-function relationships in the cochlea of terrestrial mammals. Hair cell loss and stereocilia pathology can be found in cochlear regions where hearing is impaired, but not always. Afferent terminals on inner hair cells (IHC), however, undergo acute structural changes in response to noise, but the long-term effects on innervation density and synaptic morphology, and their implications for hearing are unknown. This study will first establish a frequency-place map for the C57BL/6J mouse cochlea, which will enable us to make structure-function correlations in the subsequent experiments. At present there is no conclusive map for any mouse strain. Using retrograde tracer injections into defined frequency regions of the cochlear nucleus, we will plot auditory nerve afferent projections into the organ of Corti. Once a frequency map is available, we will characterize the morphology, density, and organization of nerve terminals on IHCs at specific frequency locations (e.g. 16kHz) using electron microscopic analyses of serial sections. We will combine this analysis with an unbiased stereological protocol developed to use only a fraction of the sections for accurate and efficient study of synaptic morphology in several animals. Lastly, we will test the hypothesis that noise damage has a detrimental long term effect on the structure of afferent terminals and their synapses with IHCs, and that these changes are associated with permanent hearing loss. This aim will study the effects of noise on structure of the IHC-afferent interface at frequency locations corresponding to permanent threshold shift, using stereological techniques developed in the 2nd aim. The mouse is a useful model for auditory neuroanatomy because its small size makes for efficient microscopic analysis, and its genome is indispensable for transgenic and mutant creations. A better understanding of normal and abnormal synaptic structure at IHCs may provide new insights into the mechanisms of hearing loss and will increase opportunities for discovery and for the development of new therapies.

描述（由申请人提供）：我的研究的长期目标是了解陆生哺乳动物耳蜗中的基本结构 - 功能关系。在听力受损但并非总是如此的人工耳蜗区域中，可以发现毛细胞损失和立体感病理学。然而，对内毛细胞（IHC）的传入终端会对噪声响应急性结构变化，但是对神经密度和突触形态的长期影响及其对听力的影响是未知的。这项研究将首先建立C57BL/6J小鼠耳蜗的频率位图，这将使我们能够在随后的实验中建立结构 - 功能相关性。目前，没有任何小鼠菌株的结论图。将逆行示踪剂注射到人工耳蜗核的定义频率区域中，我们将在Corti器官中绘制听觉神经传入的投影。一旦获得了频率图，我们将使用串行段的电子显微镜分析来表征IHC在IHC上的神经终端的形态，密度和组织。我们将将这一分析与无偏见的立体方案相结合，以仅使用部分部分，以准确有效地研究几种动物的突触形态。最后，我们将检验以下假设：噪声损伤对传入终端的结构及其与IHC的突触有不利的长期影响，并且这些变化与永久性听力损失有关。这个目标将使用第二个目标中开发的立体技术研究噪声对与永久阈值相对应的频率位置的影响。该小鼠是听觉神经解剖学的有用模型，因为它的尺寸很小，可以进行有效的微观分析，并且其基因组对于转基因和突变体的创造是必不可少的。更好地了解IHC的正常和异常突触结构可能会提供有关听力损失机制的新见解，并将增加发现和开发新疗法的机会。