Effects of Acoustic Trauma on Age-Related Hearing Loss

描述(由申请人提供)：听力损失是一种常见的 老龄化，70%的美国老年人报告说有一定程度的听力或平衡 无序。导致这种年龄相关性听力损失的因素有很多，包括 暴露于环境噪音、某些疾病、药物引起的耳毒性，如 以及特定基因的遗传。人类和动物表现出很大的差异 在他们对噪音引起的听力损失的敏感性上，这表明 其他遗传或环境因素可能是这种退行性疾病的原因 进程。此应用程序中的实验旨在研究 使用AVEN模型，噪声暴露会导致与年龄相关的听力损失。 商业饲养用于肉类生产的肉鸡显示出大量的 年龄相关性进行性耳蜗性退行性变始于30周龄和 在66周大的时候产生严重的耳蜗病。饲养的蛋鸡 对于商业上的鸡蛋生产，在这些相同的条件下，表现出很小的或没有耳蜗性损伤 年龄。这两种鸟都生活在嘈杂的环境中，这表明肉鸡 鸟类更容易受到噪音引起的听力损失的影响。这个 在肉鸡中发现的耳蜗性退行性变更令人震惊，因为 鸟类具有不同寻常的能力来再生新的耳蜗感觉细胞(毛发 细胞)。我们将检查以下各项的相对贡献 噪声和遗传学对这种年龄相关的耳蜗变性的饲养 它们都在嘈杂和安静的环境中繁殖。在特定的年龄，我们将测量 失真产物耳声发射(DPOAEs)检测耳蜗毛细胞 功能，我们将使用扫描电子显微镜来评估耳蜗毛 细胞解剖学。通过在不同组之间量化比较这些措施，我们将 评估噪声暴露和遗传对年龄的相对贡献- 相关的听力损失。在第二组实验中，我们将展示一组 鸟儿对非常大的噪音很敏感。使用相同的解剖学和生理学方法 我们将确定耳蜗完整性、年龄和品种如何影响 耳蜗对短期噪声暴露的反应。除了这些措施外， 外周听功能，我们将检查两个解剖学指标 听觉中枢神经系统如何确定与年龄相关的耳蜗 退化和噪音会影响大脑功能。

DESCRIPTION (provided by applicant): Hearing loss is a common consequence of aging, with 70% of older Americans reporting some degree of hearing or balance disorder. Many factors contribute to this age-related hearing loss, including exposure to environmental noise, certain diseases, drug-induced ototoxicity, as well as inheritance of specific genes. Humans and animals show a wide variation in their susceptibility to noise-induced hearing loss, suggesting that additional genetic or environmental factors may contribute to this degenerative process. The experiments in this application are designed to investigate how noise exposure contributes to age-related hearing loss using an avian model. Broiler birds raised commercially for meat production show a substantial progressive age-related cochlear degeneration beginning at 30 weeks of age and producing severe cochlear damage by 66 weeks of age. Egg layer birds, raised commercially for egg production, show little or no cochlear damage at these same ages. Both breeds of birds live in a noisy environment, suggesting that broiler birds are substantially more susceptible to noise-induced hearing loss. The cochlear degeneration seen in broiler birds is even more striking because all birds have the unusual ability to regenerate new cochlear sensory cells (hair cells) following cochlear damage. We will examine the relative contributions of noise and genetics to this age-related cochlear degeneration by raising birds of both breeds in noisy and quiet environments. At specific ages we will measure distortion product otoacoustic emissions (DPOAEs) to test cochlear hair cell function, and we will use scanning electron microscopy to evaluate cochlear hair cell anatomy. By comparing these measures quantitatively between groups we will evaluate the relative contributions of noise exposure and genetics to age- related hearing loss. In a second set of experiments, we will expose groups of birds acutely to very loud noise. Using the same anatomical and physiological measures we will determine how cochlear integrity, age, and breed affect the cochlear response to short-term noise exposure. In addition to these measures of peripheral auditory function, we will examine two anatomical indices of the auditory central nervous system to determine how age-related cochlear degeneration and noise affect brain function.