目的 探讨噪声暴露后听觉损伤的可能机制.方法 将22只正常雄性SD大鼠随机分为噪声组(14只)和对照组(8只),对照组不作任何处理,噪声组大鼠左耳外耳道口暴露于中心频率16kHz、带宽一个倍频程、声强116dB SPL噪声环境中1小时,右耳用耳模橡胶封堵;于暴露前及暴露后第7天分别检测两组大鼠双耳听性脑干反应(auditory brainstem response,ABR)反应阈,采用蛋白质印迹(Western blot)方法检测噪声暴露后第7天大鼠下丘中小清蛋白(parvalbumin,PV)、钙视网膜蛋白(calretinin,CR)及钙结合蛋白D-28K(calbindin D-28K,CB)表达水平的变化.结果 噪声组大鼠在噪声暴露后第七天暴露耳8、12、16、20、24、32kHz ABR反应阈较暴露前显著提高(P<0.001),非暴露耳及对照组大鼠各频率ABR反应阈无明显变化;噪声暴露后第七天,噪声组暴露侧下丘中PV和CR的表达量(PV0.81±0.24,CR0.82±0.33)较非暴露侧(PV0.67±0.19,CR0.62±0.23)显著增加(P<0.05),且噪声组大鼠非暴露侧下丘中PV及CR表达量较对照组双侧平均表达量(PV0.41±0.10,CR0.53±0.18)亦显著增加(P<0.05);噪声组两侧下丘中CB的平均表达量(0.63±0.10)较对照组(0.79±0.12)下降(P<0.05).结论 噪声暴露使大鼠暴露耳ABR反应阈升高,且导致下丘中PV、CR表达水平升高及CB表达水平下降,其改变可能与噪声暴露后耳聋、耳鸣的发病机制有关.%Objective To study the possible mechanism of hearing impairment after noise exposure .Methods Adult SD rats (n=14) were monaurally exposed to a loud noise (16 kHz ,one octave band pass (116 dB SPL)) for 1-hour ,or left as non-exposed controls (n=8) .The ABR was measured before and on the 7th day following unilateral noise exposure .All the Animals were euthanased at 7th day following acoustic trauma .We used Western blots to quantify protein levels of PV ,CR and CB in the inferior colliculus .Results The auditory thresholds in 8 , 12 ,16 ,20 ,24 ,and 32 kHz of all the ears exposed to noise showed a significant increase (P<0 .001) .Compared to the sham -exposed controls ,noise-exposed animals had significantly higher levels of PV and CR and lower levels of CB in both the ipsilateral and contralateral IC than controls (P<0 .05) .Respectively ,all the noise-exposed ani-mals had higher levels of PV and CR in the ipsilateral IC than ipsilateral side (P<0 .05) .Conclusion These studies display a significant threshold shift and changes on the expressions of PV ,CR and CB in IC following acoustic trau-ma ,which may be related to noise deafness ,tinnitus and other series of auditory dysfunction .
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