INTRODUCTION Noise-induced hearing loss (NIHL) is an increasing problem in society and accounts for a third of all cases of acquired hearing loss. NIHL is caused by formation of reactive oxygen species (ROS) in the cochlea causing oxidative stress. Hydrogen gas (H2) can alleviate the damage caused by oxidative stress and can be easily administered through inhalation. OBJECTIVES To present a protocol for untargeted metabolomics of guinea pig perilymph and investigate the effect of H2 administration on the perilymph metabolome of noise exposed guinea pigs. METHODS The left ear of guinea pigs were exposed to hazardous impulse noise only (Noise, n = 10), noise and H2 (Noise + H2, n = 10), only H2 (H2, n = 4), or untreated (Control, n = 2). Scala tympani perilymph was sampled from the cochlea of both ears. The polar component of the perilymph metabolome was analyzed using a HILIC-UHPLC-Q-TOF-MS-based untargeted metabolomics protocol. Multivariate data analysis (MVDA) was performed separately for the exposed- and unexposed ear. RESULTS MVDA allowed separation of groups Noise and Noise + H2 in both the exposed and unexposed ear and yielded 15 metabolites with differentiating relative abundances. Seven were found in both exposed and unexposed ear data and included two osmoprotectants. Eight metabolites were unique to the unexposed ear and included a number of short-chain acylcarnitines. CONCLUSIONS A HILIC-UHPLC-Q-TOF-MS-based protocol for untargeted metabolomics of perilymph is presented and shown to be fit-for-purpose. We found a clear difference in the perilymph metabolome of noise exposed guinea pigs with and without H2 treatment.

中文翻译：

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一种基于LCMS的针对耳蜗周淋巴的非靶向代谢组学方案：强调氢气对噪声暴露的豚鼠内耳的代谢作用。

引言噪声诱发的听力损失（NIHL）是社会上日益严重的问题，占所有获得性听力损失病例的三分之一。NIHL是由于在耳蜗中形成活性氧（ROS）引起氧化应激所致。氢气（H2）可以减轻氧化应激所造成的损害，并且可以通过吸入轻松进行管理。目的提出一种针对豚鼠外周淋巴的非靶向代谢组学的方案，并研究H2给药对噪声暴露的豚鼠外周淋巴代谢组的影响。方法豚鼠的左耳只受到有害脉冲噪声（噪声，n = 10），噪声和H2（噪声+ H2，n = 10），仅H2（H2，n = 4）或未经治疗（对照， n = 2）。从两只耳朵的耳蜗取样斯卡拉鼓室周围淋巴。使用基于HILIC-UHPLC-Q-TOF-MS的非靶向代谢组学方案分析了淋巴代谢组的极性成分。分别对裸露和未暴露的耳朵进行多变量数据分析（MVDA）。结果MVDA允许在暴露和未暴露的耳朵中分离噪声和噪声+ H2组，并产生15种代谢物，其相对丰度有所不同。在暴露和未暴露的耳朵数据中发现了七个，其中包括两种渗透保护剂。八种代谢物是未暴露耳朵所独有的，包括许多短链酰基肉碱。结论提出了一种基于HILIC-UHPLC-Q-TOF-MS的非靶向性外周血脂代谢组学方案，该方案适用于目的。我们发现，在有和没有进行H2治疗的情况下，暴露于噪音的豚鼠的外周血淋巴细胞代谢组之间存在明显差异。