条件性噪声听觉保护作用的频率特异性及耳蜗形态学研究

The Frequency Specificity to Protection Effect of Sound Conditioning and Cochlear Morphology

目的研究不同频率条件性噪声是否具有相应频率特异性的保护作用。方法根据给予不同的刺激声,将豚鼠分为8组:A^D组给予一次强度85 dB SPL或105 dB SPL,频率0.5 kHz或4 kHz的声刺激;E1~E4组先分别给予不同频率的条件性噪声预刺激,然后进一步给予强噪声暴露。对豚鼠进行噪声暴露前后听觉稳态反应(ASSR)检测,并对豚鼠耳蜗的基底膜铺片荧光染色进行形态学观察。结果单一频率噪声即可造成全频率的听力阈移,4 kHz的条件性噪声减小了高频噪声对于豚鼠听阈变化的影响。4 kHz条件噪声的频率特异性和保护作用比0.5 kHz的条件噪声明显,且在相同强度下4kHz会对豚鼠听力造成更大损伤。结论不同频率的条件性噪声对不同频率噪声损害的保护作用有明显差异,条件性噪声听觉保护作用具有明显的频率特异性。

Objective Observe sound conditioning of noise induced hearing loss protection. The frequency specificity has been significantly focused.Besides,underlying pathological changes of inner and outer hair cells were observed for further analyses. Methods Guinea pigs were evenly allocated into eight groups （group A to D, group E1 to E4） with different acoustic stimulations group, A to D were exposed to 0.5 kHz or 4 kHz at 85 dB SPL or 105 dB SPL for once while group El to E4 accepted pre-exposing acoustic stimulation before further noise exposures. ASSR was examined before and after the manipulation for analyzing the hearing threshold shifts of guinea pigs. Then, outer and inner cells of cochleae were observed with the surface preparation by using Hoechst immunofluorescence staining. Results It was more likely that 4 kHz sound conditioning decreased the threshold shift of high-frequency noise. It authenticates the existence of frequency specificity for sound conditioning. Particularly, the protective effect and frequency specificity of 4 kHz sound are considered to be more obvious than 0.5 kHz with the same intensity and 4 kHz noise may cause more severe hearing loss. Conclusion Different frequencies of sound conditioning for different noise damage have obvious difference effects. The protective effects of sound conditioning of the different frequencies have obvious frequency specificity.