噪声对豚鼠耳蜗基底膜乙酰化组蛋白H2B表达的影响

摘要

目的 观察噪声性聋豚鼠耳蜗基底膜毛细胞乙酰化组蛋白H2B表达水平的变化,探讨组蛋白乙酰化与噪声性听力损失的相关性.方法 成年雄性白色红目豚鼠60只随机分为噪声组和对照组,两组豚鼠分别进行听性脑干反应(ABR)检测后,噪声组给予高强度窄带噪声(122 dB SPL,3小时)暴露,对照组不予任何处理;噪声组于噪声暴露后1小时、3天、7天、14天和21天分别行ABR检测;并以免疫荧光染色和Western blot方法检测两组豚鼠耳蜗基底膜听觉细胞中乙酰化组蛋白H2B的表达水平.结果 噪声暴露后1小时、 3天、7天、14天、21天噪声组豚鼠ABR各频率反应阈均较噪声暴露前及对照组显著增高,且随时间的延长听力逐渐恢复,14天时趋于稳定,达到永久性阈移.免疫荧光染色显示在噪声组豚鼠耳蜗内外毛细胞及Hensen''s细胞中乙酰化组蛋白H2B荧光强度较正常对照组减弱,Western blot结果显示噪声组豚鼠耳蜗基底膜中乙酰化组蛋白H2B的表达(H2B-AcK5/β-actin比值为0.310 2±0.083 9)较对照组(0.617 9±0.126)明显下调,两组差异有统计学意义(P<0.01).结论 噪声可导致豚鼠内耳感觉细胞乙酰化组蛋白H2B表达水平下降,乙酰化组蛋白失衡有可能参与了噪声性聋的发生.%Objective To study the changes of acetyl-histone H2B in the cochlear hair cells of the guinea pig model of noise-induced hearing loss (NIHL).Methods Sixty guinea pigs were randomly divided into control and noise-exposure group.Thirty guinea pigs in the noise-exposure group were exposed to narrowband noise at 122 dB SPL for 3 hours , while thirty guinea pigs in the control group were not exposed to noise.Auditory thresholds were assessed by auditory brainstem response (ABR), prior to noise in two groups and 3, 7,14 and 21 days after noise exposure in the noise group.Then we investigated the expression of acetyl-histone H2B levels in the sensory cells of basilar membrane after noise expose by immunofluorescence staining and western blot.Results Compared with pre-exposure hearing, ABR thresholds were increased at 1h, 3, 7, 14 and 21 days after noise exposure, and recovered gradually with time and reached a permanent threshold shift at 14 days.The expression of acetyl-histone H2B was down-regulated in the hair cells and Hensen''s cells of the guinea pig cochlea after the noise expose , The ratio of H2B-AcK5 / β-actin was 0.6179±0.1260 in the control group and 0.3102±0.0839 in the noise group, and the difference was statistically significant (P<0.01).Conclusion Noise decreased the inner ear sensory cells histone acetylation level and histone acetylation imbalance may be involved in the occurrence of NIHL.