高频连续噪声对豚鼠听阈及耳蜗结构的影响

目的研究高频连续噪声暴露对豚鼠听阈及耳蜗结构的影响。方法16只雄性花色豚鼠随机分为噪声暴露组和对照组,每组8只豚鼠。噪声暴露组豚鼠于噪声暴露前测定听觉脑干反应阈值(auditorybrainstem responses,ABR),每日接触中心频率为4 kHz、倍频程、100 dB(A)声压级(sound pressure level,SPL)连续噪声,每天8 h,连续7 d;末次噪声暴露结束后第8天,测定ABR后处死豚鼠,取耳蜗,进行组织病理学、透射电镜及扫描电镜的观察。对照组豚鼠不接触噪声,于相应时间点测定ABR,其他处理同噪声暴露组。结果噪声暴露组豚鼠在2,4,8 kHz处的阈移分别为13.4,31.3,31.9,耳蜗外毛细胞静纤毛发生散在缺失、倒伏,胞浆萎缩、空化,细胞核萎缩或消失,部分线粒体消失,个别线粒体发生髓样变。结论噪声暴露可提高豚鼠的听阈并对其耳蜗结构具有损伤作用。

Effects of Continuous High Frequency Noise Exposure on Hearing Threshold and Structure of Cochleae in Guinea Pigs

Objective To investigate the effects of continuous high frequency noise exposure on hearingthreshold and structural changes of cochleae in guinea pigs.Methods 16 male pigmented guinea pigs were randomly and equally divided into control group and exposed group.Prior to noise exposure,threshold of auditory brainstem responses(ABR)was recorded for the exposed group,afterward which was exposed to a(4 000 Hz) octave band noise at an intensity of(100 dB)(A)sound pressure level(SPL),8 hour a day consecutively for 7 days.Eight days after the ending of noise exposure,the ABR of each guinea pig was measured.Guinea pigs were then sacrificed and their cochleae were anatomized for histopathological,transmission electron microscopic and scanning electron microscopic observations.The guinea pigs of the control group were not exposed to noise and their ABR were recorded at relevant time-point as the exposed group followed by other procedures same as the exposed group.Results The threshold shifts at 2,4,8 kHz in the exposed group were 13.4,31.3,31.9 respectively.The noise exposure induced structural changes mainly were in the outer hair cells(OHCs),i.e.the OHCs stereocilia showed sporadic missing or disarrayed,the cell plasma of the OHCs showed withered and evacuated,the nuclei of the OHCs showed condensed or vanished,and some mitochondria showed vanished or degenerated.Conclusions The noise exposure might elevate the hearing threshold and damage the structure of the cochleae in guinea pigs.