不同噪声环境对豚鼠噪声性听力损失的影响

Effects of different noisy environments on noise-induced hearing loss in guinea pigs

目的 探讨强噪声暴露后不同噪声环境对豚鼠听力损失的影响.方法 30只豚鼠按数字表法随机分为5组,每组6只：A、B、C、D组分别于110 dB声压级（sound pressure level,SPL）白噪声暴露4h后继续84 dB SPL噪声暴露4、8、24、0 h;E组,不施加噪声暴露.噪声暴露前1d、暴露后1、7d进行3次听性脑干反应（auditory brainstem response,ABR）测定.测试完毕后,取血浆测试超氧化物歧化酶（SOD）活力、丙二醛（MDA）含量和总一氧化氮合酶（TNOS）活力.结果 强噪声暴露后,D组豚鼠出现噪声性听力损失.噪声暴露后7d,与D组相比,A、B组短声ABR阈值降低（P＜0.05）、永久性听阈移位降低（P＜0.05）.噪声暴露后1d,与D组相比,A、B、C组12、24 kHz处TTS降低（P＜0.05）.噪声暴露后7 d,与D组[（1.21±0.34） tμmol/L]相比,A、B组MDA含量[分别为（2.51 ±0.44）、（2.57±0.57） μmol/L]增加（JP＜0.05）;A、C组TNOS活力降低（P＜0.05）.结论 噪声暴露后1d,中等水平噪声环境对强噪声暴露所致的低频听力损失的恢复有一定的促进作用;噪声暴露后7d,对强噪声暴露所致的高频听力损失的恢复有一定的促进作用.

Objective To investigate the effects of different noisy environments on hearing loss after severe noise exposure in guinea pigs.Methods Thirty guinea pigs were randomly divided into 5 groups,each consisting of 6 animals.The guinea pigs in group A,B,C and D were subjected to noise at 84 decibels sound pressure level （dB SPL） for 4,8,24 and 0 hours respectively after traumatic noise exposure; the guinea pigs in group E were kept in quiet cages.Auditory brainstem response was determined at 3 time points：Ⅰ day before,1 day after and 7 days after noise exposure.Blood plasma was obtained to determine the active levels of SOD,TNOS and the content of MDA at the end of the experiment.Results The guinea pigs in group D developed noise-induced hearing loss following traumatic noise exposure.At the seventh day after exposure,the thresholds of C-ABR and PTS in group A[（2.51 ± 0.44）μmol/L] and B [（2.57 ± 0.57）μmol/L] decreased,as compared with that of group D[（1.21 ±0.34） μmol/L] （P ＜0.05）.At the first day after exposure,TTS for group A,B and C decreased,as compared with that of group D （P ＜ 0.05） at frequencies of 12 kHz and 24 kHz.At the seventh day after exposure,the content of MDA increased （P ＜ 0.05） for group A and B,while the activity of TNOS for group A and C decreased （P ＜ 0.05）,as compared with that of group D.Conclusions Moderate level of noise environment seemed to have some effects on the recovery of noise-induced hearing loss at low frequencies one day after noise exposure,while exposure to moderate noisy environment might also have some effects on the recovery of noise-induced hearing loss at high frequencies,7 days after noise exposure.