Department of Otolaryngology-Head and Neck Surgery, China Medical University Hospital, and Graduate Institute of Clinical Medical Science, Department of Anatomy, School of Medicine, China Medical University, Taichung, Taiwan.
BMC Neurosci. 2011 Feb 22;12:21. doi: 10.1186/1471-2202-12-21.
Hyperbaric oxygen therapy (HBOT) is a known adjuvant for treating ischemia-related inner ear diseases. Controversies still exist in the role of HBOT in cochlear diseases. Few studies to date have investigated the cellular changes that occur in inner ears after HBOT. Nitric oxide, which is synthesized by nitric oxide synthase (NOS), is an important signaling molecule in cochlear physiology and pathology. Here we investigated the effects of hyperbaric oxygen on eardrum morphology, cochlear function and expression of NOS isoforms in cochlear substructures after repetitive HBOT in guinea pigs.
Minor changes in the eardrum were observed after repetitive HBOT, which did not result in a significant hearing threshold shift by tone burst auditory brainstem responses. A differential effect of HBOT on the expression of NOS isoforms was identified. Upregulation of constitutive NOS (nNOS and eNOS) was found in the substructures of the cochlea after HBOT, but inducible NOS was not found in normal or HBOT animals, as shown by immunohistochemistry. There was no obvious DNA fragmentation present in this HBOT animal model.
The present evidence indicates that the customary HBOT protocol may increase constitutive NOS expression but such upregulation did not cause cell death in the treated cochlea. The cochlear morphology and auditory function are consequently not changed through the protocol.
高压氧疗法（HBOT）是治疗与缺血相关的内耳疾病的已知辅助疗法。HBOT 在耳蜗疾病中的作用仍存在争议。迄今为止，很少有研究调查 HBOT 后内耳中发生的细胞变化。一氧化氮（NO）是由一氧化氮合酶（NOS）合成的，是耳蜗生理学和病理学中的重要信号分子。在这里，我们研究了高压氧对豚鼠重复 HBOT 后鼓膜形态、耳蜗功能和耳蜗亚结构中 NOS 同工型表达的影响。
重复 HBOT 后鼓膜仅有轻微变化，不会导致听性脑干反应的听阈明显改变。HBOT 对 NOS 同工型的表达有不同的影响。免疫组织化学显示，HBOT 后耳蜗亚结构中组成型 NOS（nNOS 和 eNOS）上调，但在正常或 HBOT 动物中未发现诱导型 NOS。在这个 HBOT 动物模型中没有明显的 DNA 片段化。
目前的证据表明，常规的 HBOT 方案可能会增加组成型 NOS 的表达，但这种上调不会导致治疗耳蜗中的细胞死亡。因此，该方案不会改变耳蜗形态和听觉功能。
