Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama, 359-8513, Japan.
Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, Saitama, 359-8513, Japan.
Sci Rep. 2021 Jul 19;11(1):14704. doi: 10.1038/s41598-021-94080-0.
Blast exposure can induce various types of hearing impairment, including permanent hearing loss, tinnitus, and hyperacusis. Herein, we conducted a detailed investigation of the cochlear pathophysiology in blast-induced hearing loss in mice using two blasts with different characteristics: a low-frequency dominant blast generated by a shock tube and a high-frequency dominant shock wave generated by laser irradiation (laser-induced shock wave). The pattern of sensorineural hearing loss (SNHL) was low-frequency- and high-frequency-dominant in response to the low- and high-frequency blasts, respectively. Pathological examination revealed that cochlear synaptopathy was the most frequent cochlear pathology after blast exposure, which involved synapse loss in the inner hair cells without hair cell loss, depending on the power spectrum of the blast. This pathological change completely reflected the physiological analysis of wave I amplitude using auditory brainstem responses. Stereociliary bundle disruption in the outer hair cells was also dependent on the blast's power spectrum. Therefore, we demonstrated that the dominant frequency of the blast power spectrum was the principal factor determining the region of cochlear damage. We believe that the presenting models would be valuable both in blast research and the investigation of various types of hearing loss whose pathogenesis involves cochlear synaptopathy.
爆炸暴露可引起多种类型的听力损伤，包括永久性听力损失、耳鸣和听觉过敏。在此，我们使用两种具有不同特性的爆炸对小鼠的爆震性听力损失的耳蜗病理生理学进行了详细研究：由激波管产生的低频占主导的爆炸和由激光照射产生的高频占主导的冲击波（激光诱导冲击波）。低频和高频爆炸分别导致感音神经性听力损失（SNHL）呈现低频和高频主导模式。病理学检查显示，爆震暴露后最常见的耳蜗病理学是突触病，其特征是内毛细胞的突触丢失而没有毛细胞丢失，这取决于爆炸的功率谱。这种病理变化完全反映了使用听觉脑干反应进行的 I 波幅度的生理分析。外毛细胞的纤毛束破坏也依赖于爆炸的功率谱。因此，我们证明了爆炸功率谱的主导频率是决定耳蜗损伤区域的主要因素。我们相信，所提出的模型在爆炸研究和各种涉及耳蜗突触病的听力损失的发病机制的研究中都具有重要价值。
