a CILcare. 2214, Boulevard de la Lironde , Parc Scientifique Agropolis , Montpellier , France.
b Correlative Microscopy and Electron Tomography Platform , Hopital Saint Eloi , Montpellier , France.
Int J Neurosci. 2019 Jun;129(6):580-587. doi: 10.1080/00207454.2018.1552693. Epub 2018 Dec 20.
Hearing loss is the most common form of sensory impairment in humans. Short impulses of a high intensity noise can trigger sudden hearing loss, which is generally irreversible and associated with structural tissue damage of the cochlea and auditory nerve. It is well established that myelination is essential for the rapid propagation of action potentials along axons, and that Schwann cells are responsible for myelin sheath production in the peripheral nervous system. In the cochlea, spiral ganglion neuron axons are myelinated by Schwann cells. This myelin contributes to axonal protection and allows for efficient action potential transmission along the auditory nerve. For this reason, here we studie the morphological changes on cochlear hair cells and myelin sheaths of the auditory nerve, directly linked to hearing impairment induced by acoustic trauma.
To study the auditory functions, auditory brainstem responses and distortion products were measured at baseline, 2 days, and 21 days after trauma in rats. Then, scanning and transmission electron microscopy techniques were performed to analyze cochleae and the auditory nerve at 21 days after trauma.
We observed that acoustic trauma induced cochlear outer hair cell loss and fusion of inner hair cell stereocilia. We also observed an axonal loss and myelin sheath disorganization of the auditory nerve.
These data confirm that a strong acoustic trauma induced histological changes in the cochlea and auditory nerve, leading to permanent hearing loss.
听力损失是人类最常见的感觉障碍形式。高强度的短脉冲噪声可引发突发性听力损失，这种听力损失通常是不可逆的，并伴有耳蜗和听神经的结构组织损伤。髓鞘形成对于轴突中动作电位的快速传播至关重要，这一点已得到充分证实，而施万细胞负责外周神经系统髓鞘的产生。在耳蜗中，螺旋神经节神经元轴突由施万细胞髓鞘化。这种髓鞘有助于轴突保护，并允许沿听神经有效传播动作电位。基于此，我们研究了与声创伤引起的听力损伤直接相关的耳蜗毛细胞和听神经髓鞘的形态变化。
为了研究听觉功能，在创伤后 2 天和 21 天测量大鼠的听性脑干反应和畸变产物。然后，在创伤后 21 天，进行扫描和透射电子显微镜技术分析耳蜗和听神经。
我们观察到，声创伤导致外毛细胞丧失和内毛细胞静纤毛融合。我们还观察到听神经轴突丢失和髓鞘紊乱。
这些数据证实，强烈的声创伤可引起耳蜗和听神经的组织学变化，导致永久性听力损失。
