Determination of Metabolic State of Hair Cell Mitochondria by FLIM

描述（由申请人提供）：感觉神经性听力损失的直接原因是不可替代的耳蜗毛细胞的死亡，但毛细胞对各种创伤和疾病的选择性脆弱性的潜在基础尚不清楚。一个突出的理论是毛细胞无法应对代谢需求，从而引发线粒体半胱天冬酶介导的细胞凋亡，但这一理论的证据是间接的。正如我们在这里所展示的，现在可以通过尼古丁腺嘌呤二核苷酸（氧化磷酸化的中间体）的还原释放来评估毛细胞线粒体的氧化代谢状态。本提案旨在支持该成像技术在毛细胞代谢成像问题上的应用。我们进一步要求支持来验证假设，即耳蜗外毛细胞与内毛细胞、基底毛细胞与根尖毛细胞的易感性差异，与各自毛细胞群体代谢反应的差异相关。我们认为，提出的发展和实验代表了活毛细胞氧化代谢定量新时代的第一步，这将大大增加我们对规范和病理耳蜗生理学许多方面的理解。耳聋是人群致残的一个主要原因，随着人口老龄化，耳聋的重要性可能会增加。耳聋的主要形式被称为感音神经性耳聋，它涉及到不可替代的毛细胞的丧失，这可能是由于无法应对代谢挑战。我们的项目是评估一种量化活毛细胞代谢状态的新方法。

DESCRIPTION (provided by applicant): The proximate cause of sensorineural hearing loss is the death of irreplaceable cochlear hair cells, but the underlying basis of the selective vulnerability of hair cells to a variety of traumas and diseases is unknown. A prominent theory is the inability of hair cells to cope with metabolic demands, which would thereby trigger mitochondrial caspase- mediated apoptosis, but evidence for this theory is indirect. As we here show, it is now possible to assess the state of oxidative metabolism in hair cell mitochondria from the emissions of reduced nicotine adenine dinucleotide, an intermediate in oxidative phosphorylation. This proposal seeks support to develop application of this imaging technique to the problem of metabolic imaging in hair cells. We further request support to test the hypothesis that known differences in the vulnerability of cochlear outer hair cells compared to inner hair cells, and of basal turn hair cells compared to apical turn hair cells, correlate with differences in metabolic responses in the respective hair cell populations. The proposed development and experiments, we believe, represent the first steps in a new era of quantitation of oxidative metabolism in living hair cells that will greatly add to our understanding of many aspects of normative and pathological cochlear physiology. PUBLIC HEALTH RELEVANCE Narrative Deafness is a major cause of disability in the population and is likely to increase in significance as the population ages. The major form of deafness, called sensorineural, involves the loss of irreplaceable hair cells, which may be due to an inability to cope with metabolic challenges. Our project is to evaluate a new method of quantifying the metabolic state of living hair cells.