声损伤中声预处理的听力保护作用及其MDA机制  

Protective effect of sound preconditioning on hearing and its malondialdehyde mechanism in acoustic trauma

作　　者：文文[1] 张琰敏[1] 杜丽[1] 刁明芳[1] 刘海瑛[1] 邵艳[1] 高文元[1] 

机构地区：[1]第二军医大学基础医学部生理学教研室,上海200433

出　　处：《第二军医大学学报》2005年第11期1239-1242,共4页Academic Journal of Second Military Medical University

基　　金：国家自然科学基金(30470419)

摘　　要：目的:观察声预处理对噪声性听力损失的保护作用,并从氧自由基途径探讨其机制.方法:32只雄性豚鼠随机分为声预处理+强噪声暴露组(A组),单纯强噪声暴露组(B组),仅预处理组(C组),无噪声对照组(D组),每组8只.A组豚鼠先经声预处理(87 dB白噪声暴露10 d,每天5 h),无噪声情况下恢复48 h后再暴露110 dB白噪声5 h.B组不经声预处理,直接暴露相同110 dB白噪声5 h.C组豚鼠仅接受声预处理(同A组).A、B、C 3组动物在噪声暴露前后分别测定听觉脑干诱发电位(ABR)阈值,D组动物在实验开始和结束各测定1次ABR.分别计算4组动物听力阈移.在最后1次测定ABR之后,将A、B、C、D 4组动物同时处死,取耳蜗,用TBA荧光法测定耳蜗组织匀浆中脂质过氧化产物丙二醛(MDA)含量. 结果:C、D组动物阈移平均值范围为0.83～2.5 dB和0～1.36 dB,两组相比无统计学差异.A、B两组动物在强噪声暴露后24 h,A组click平均阈移为12.5 dB,短纯音(4、6、8 kHz)平均阈移范围为13.75～16.25 dB;B组click平均阈移为30.83 dB,短纯音(4、6、8 kHz)平均阈移范围为35～35.83 dB,明显高于A组(P＜0.05).A、B、C、D 4组动物耳蜗组织MDA含量为(164±18)、(188±24)、(149±14)和(146±11) nmol/L.统计结果表明,B组动物耳蜗组织MDA含量明显高于A组、C组、D组(P<0.05);而A组与C组和D组动物耳蜗组织MDA含量没有统计学差异. 结论:声预处理(87 dB 白噪声 10 d,每天5 h)不会造成豚鼠听力损失,并可以减轻随后强噪声(110 dB 白噪声 5 h)引起的听力损失;声预处理可能是通过降低MDA含量而发挥听力保护作用.Objective：To observe the protective effect of sound preconditioning on hearing in acoustic trauma and explore the relevant mechanism with regard to free oxygen radicals in the cochlea. Methods： Thirty-two male pigmented guinea-pigs were equally randomized into 4 groups：group A,sound preconditioning＋ intense noise exposure（n= 8）; group B, intense noise exposure（n= 8） ; group C, sound preconditioning（n = 8） ; and group D, quiet control（n = 8）. Group A was exposed to weak noise first （87 dB SPL white noise 5 h/d for 10 d） and then to intense noise（110 dB SPL white noise 5 h）; group B was exposed to the same intense noise only. The thresholds of auditory brainstem responses（ABRs） in group A,group B and group C were measured before and after exposure,and the threshold in group D was measured at the corresponding time points. After the last ABR measurement,all the animals were sacrificed and the cochleas were dissected to determine malondialdehyde（MDA） level with TBA（thiobarbituric acid） fluorophotometric method. Results：The auditory threshold of the guinea-pigs in the group D was relatively stable and the threshold shifts ranged from 0 to 1.36 dB. The average threshold shift of the group A was 12.5 dB（click） and 13.75-16.25 dB（4,6,8 kHz ） 24 h after exposure to intense noise. The threshold shifts of the group B at click and at tone （4,6,8 kHz） were 30.83 dB and 35-35.83 dB,much higher than those of group A（P〈0.05）. The MDA level in the quiet control group was（146±11） nmol/L . After noise exposure,the MDA level was（188±24） nmol/L in group B,（164±18） nmol/L in group A, （149± 14） nmol/L in group C, and（ 146±11 ） nmol/L in group D,with MDA level in group B significantly higher than those in group A, C and D（P〈0.05）, but with no significant differences found between group A, C and D. Conclusion： Sound preconditioning（87 dB SPL white noise 5 h/d for 10 d） brings no harm to the hearing of guinea-pigs and can protect the heari

关 键 词：声预处理 听觉丧失 噪声性 听力保护 氧自由基 丙二醛 

分 类 号：R764.433[医药卫生—耳鼻咽喉科]