噪声性阈移耳蜗螺旋器透射电镜观察

A Transmission Electron Microscope Observation of Spiral Organ of Cochleae with Noise-induced Threshold Shift

豚鼠分别暴露110dB SPL白噪声30min或120dB SPL白噪声150min。暴露前后不同时间分别测试皮层反应閾,并用透射电镜观察耳蜗螺旋器细胞内变化。结果表明:110dB噪声引起暂时性閾移(TTS),而120dB噪声一般形成永久性閾移(PTS)。TTS耳蜗病变局限在第3排外毛细胞,主要有静纤毛内肌丝解聚,细胞轻度水肿和空泡变性等表现,核下区和神经末梢正常。PTS耳蜗内毛细胞和第1排外毛细胞受损伤,静纤毛融合,表皮板穿孔,细胞内显著水肿,皮板下区透明化,表面囊肿胀和传出神经末梢大空泡形成。根据超微结构观察结果,探讨了TTS和PTS的形态学基础,毛细胞内病变的发展变化及病变的可逆性问题。

Guinea pigs were exposed to either 110dB SPL white noise for 30min (ITS group )or 120 dB SPL for 150 nun (PTS group). At varying postexposure intervals, threshold shifts were assessed using auditory cortex evoked response to tone bursts and intracellular ultrastructural changes in the spiral organ of cochleae were exmained with a transmission electron microscope.. The threshold shifts induced by 110dB noise were reversible while those induced by 120dB noise were generally irreversible. In the TTS cochleae, damage was confined to the third row of OHCs where depolymerization of actin filaments within the stereocilia, slight celluar swelling and small vacuolization were found. The subnuclear area and nerve-endings were not involved. In the PTS cochleae, the inner hair cells (IHCs) and the first row of OHCs were affected. The abnormilities consisted of ruptures and holes in the cuticular plates, fusion of stereocilia, marked edema, tranclucence of subcuticular region, swelling of submembraneous cisterns and large vesiculation in the efferent nerve-endings blow OHCs. Based on the ultrastructural observations, structural bases in cochleae for TTS and PTS, sequence of pathological changes in hair cells as well as reversibility of specific pathologies were suggested.