模拟风洞噪声对豚鼠听功能及内耳细胞凋亡的影响

The Effect of Wind Tunnel Noise on Hearing and Inner Ear Apoptosis in Guinea Pigs

目的探讨模拟风洞噪声对豚鼠听功能及其内耳毛细胞、螺旋神经节细胞凋亡的影响。方法 24只豚鼠随机分为对照组(6只)及实验组(18只),实验组豚鼠暴露于模拟风洞噪声环境中,分别于模拟风洞噪声暴露前(Pr)、暴露1天(E1)、3天(E3)、7天(E7)、暴露后3天(R3)、7天(R7)检测其双耳听性脑干反应(ABR)阈值,并于噪声暴露3天(E3)、7天(E7)及暴露后7天(R7)取实验动物耳蜗行连续冰冻切片,免疫组织化学染色观察Caspase-3在内耳毛细胞及螺旋神经节细胞中的表达。结果实验组动物各时间点ABR阈值:噪声暴露1天(E1)(35.73±8.11dB SPL)、3天(E3)(43.91±6.32dB SPL)、7天(E7)(53.18±6.28dB SPL)的ABR反应阈较噪声暴露前(22.50±5.98dB SPL)明显增高(P<0.01),且暴露时间越长增高越明显。噪声暴露后3天(R3)(46.40±11.59dBSPL)ABR反应阈较噪声暴露7天(E7)(53.18±6.28dB SPL)有降低(P<0.05),噪声暴露后7天(R7)(35.38±11.63dB SPL)ABR反应阈较噪声暴露后3天(R3)(46.40±11.59dB SPL)进一步降低(P<0.01)。豚鼠内耳免疫组织化学观察凋亡标志物Caspase-3结果显示,模拟风洞噪声暴露引起豚鼠内耳螺旋神经节细胞及毛细胞中Caspase-3表达较正常对照组明显增高,且于噪声暴露7天(E7)达最高,暴露后7天(R7)后豚鼠内耳Caspase-3的表达较前明显减少。结论模拟风洞噪声可致豚鼠听功能的损伤,损伤程度在一段时间内与噪声暴露累积量呈正相关。噪声暴露结束后,听功能可部分恢复。同时,内耳凋亡标志物Caspase-3的表达和听功能呈现相同趋势。

Objective To observe the effect of wind tunnel noise on hearing and the expression of apoptotic marker Caspase--3 in hair cells and spiral ganglion cells of guinea pigs. Methods Twendy four guinea pigs were randomly divided into two groups, 6 in control group, 18 in noise exposure group. The noise group was exposed to simulated wind tunnel noise environment. Bilateral auditory brainstem response threshold （ABR） were tested re spectively pr-noise exposure, El, E3, E7 and R3, R7. Cochlear frozen sections were performed to observe the ex pression of Caspase- 3, the apoptotic marker in the hair cells and spiral ganglion cells of two group by immunohisto chemical staining, the time point were pre-noise exposure （pr）, at 3 days since exposure （E3）, 7 days since expo sure（E7）, and 7 days since the end of exposure （R7）, respectively. Results At E1（35.73±8. lldB SPL）, E3（43.91± 6.32 dB SPL）, E7（53.18±6.28 dB SPL）, ABR threshold of the noise group were significantly higher than that of pr（22. 50±5.98 dB SPL） （P〈0.01）, and the longer the exposure, the higher the ABR thresholds. At R3 （46.40±11.59 dB SPL）, ABR thresholds recovered from that of E7（53.18±6.28 dB SPL） （P〈0.05）, while the ABR thresholds at R7 （35.38±11.63 dB SPL） further recovered from that of R3 days（46.40±11.59 dB SPL） （P〈0.01）. Immunohistochemi- cal staining shewed that： the expression of apoptosis marker Caspase-3 was significantly higher than that of the control group after noise exposure in guinea pig inner ear hair cells and spiral ganglion cells, and reach the highest at E7. At R7, Caspase-3 expression significantly decreased compared with the previous. Oonclusion Dosure to the wind tunnel noise en vironment can lead to hearing impairment in guinea pigs, while the degree of injury is positively correlated with noise accu mulation in this study. After recovery from the noise exposure for afew days, hearing loss can partially restore. Mean while, the expression of apoptotic markers in the inner ear and hearing loss shows the same trend.