Hair cell responses to ototoxic drugs

氨基糖苷类抗生素对于对抗危及生命的细菌感染至关重要。氨基糖苷 也会导致超过120，000人的永久性耳聋/平衡障碍和肾毒性 在美国，尤其是在婴儿和早产儿中。这项研究的长期目标是防止 耳蜗摄取氨基糖苷类药物，从而产生耳毒性，因此保留了听觉功能。 这项研究的重大进展表明，氨基糖苷类药物的细胞质摄取可以被 在体外感觉毛细胞中被阻断。在这个建议中，我们试图阻止耳蜗内的吸收， 氨基糖苷类从血管系统转运到体内耳蜗液和组织中，并防止 氨基糖苷类药物诱导的内耳感觉毛细胞死亡。我们的工作假设是： 药理学试剂可以减少耳蜗中的氨基糖苷类摄取和毒性。 该项目的具体目标是： 目的1：通过确定药理学药物如何改变氨基糖苷类药物的体外摄取， 模型细胞系和毛细胞外植体的细胞内环境以抑制氨基糖苷类摄取。我们将 监测钙浓度、pH水平、静息电位和膜电阻。 目的2：应用氨基糖苷类摄取抑制剂保护在体听功能和形态。我们将 使用听性脑干反应评估这些氨基糖苷类摄取抑制剂的疗效 听力测定、毛细胞形态的共聚焦显微镜检查和构建细胞耳蜗图。 目的3：确定氨基糖苷类药物从血管到感觉毛细胞的耳蜗内途径。我们 将使用耳蜗灌注技术，并对耳蜗液进行采样，以确定氨基糖苷类药物是否 通过内淋巴或外淋巴途径进入毛细胞。然后我们将验证氨基糖苷类 摄取抑制剂通过一种或两种途径减少氨基糖苷类的耳蜗内转运。 确定减少氨基糖苷类药物转运进入耳蜗和耳蜗内的机制， 确定目前可用的药物是否可以在救生期间保护听觉功能 氨基糖苷类抗生素治疗细菌感染。这可能导致新的联合治疗， 氨基糖苷类和（细胞）氨基糖苷类摄取抑制剂对更广泛的细菌感染。

Aminoglycoside antibiotics are essential for battling life-threatening bacterial infections. Aminoglycosides also cause permanent deafness/balance disorders and nephrotoxicity in more than 120,000 individuals each year in the US, particularly in infants and premature babies. The long-term goal of this research is to prevent cochlear uptake of aminoglycosides and thus ototoxicity, hence preserving auditory function. Significant progress in this research has revealed that the cytoplasmic uptake of aminoglycosides can be blocked in sensory hair cells in vitro. In this proposal we seek to block the intra-cochlear uptake and transport of aminoglycosides from the vasculature into the cochlear fluids and tissues in vivo, and prevent aminoglycoside-induced inner ear sensory hair cell death. Our working hypothesis is that: pharmacological agents can reduce aminoglycoside uptake and toxicity in the cochlea. The specific aims of this project are to: Aim 1: Regulate aminoglycoside uptake in vitro, by identifying how pharmacological agents change the intracellular milieu of model cell lines and hair cell explants to inhibit aminoglycoside uptake. We will monitor the calcium concentrations, pH levels, resting potential and membrane resistance. Aim 2: Preserve auditory function and morphology in vivo using inhibitors of aminoglycoside uptake. We will assess the efficacy of these aminoglycoside-uptake inhibitors using auditory brainstem response audiometry, confocal microscopy of hair cell morphology, and constructing cytocochleograms. Aim 3: Identify the intra-cochlear route of aminoglycosides from the vasculature to the sensory hair cells. We will use cochlear perfusion techniques, and sample cochlear fluids to determine if aminoglycosides take an endolymph or perilymph route to enter hair cells. We will then verify that aminoglycoside uptake-inhibitors reduce the intra-coch lear transport of aminoglycosides by one or both routes. Identification of mechanisms that reduce aminoglycoside transport into, and within, the cochlea will determine if currently-available Pharmaceuticals can preserve auditory function during life-saving aminoglycoside therapy of bacterial infections. This may lead to new co-therapeutic treatments with aminoglycosides and (cellular) aminoglycoside-uptake inhibitors against a wider range of bacterial infections.