颈交感神经干离断对豚鼠噪声性听力损失的保护作用

Protective effect of transection of cervical sympathetic trunk on noise-induced hearing loss in guinea pigs

目的:探讨颈交感神经干离断术(TCST)对豚鼠噪声性听力损失(NIHL)的保护作用。方法:36只豚鼠随机等分为3组:手术组、假手术组和空白对照组。手术组予以TCST。假手术组仅予以暴露出颈上交感神经节和颈交感神经干,但不切断。上述两组于手术后第4天进行噪声暴露。空白对照组不予以手术和噪声暴露。全部实验豚鼠分别于手术前(T0)、噪声暴露前(T1)、停止噪声暴露后(T2)3个时间点予以测量听性脑干反应(ABR)阈值、血浆超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。最后一次检测ABR阈值后立即处死各组豚鼠,行耳蜗基底膜染色铺片,观察耳蜗外毛细胞受损情况。结果:(1)噪声暴露后,手术组和假手术组ABR阈值均高于空白对照组(P<0.01),且假手术组ABR阈值高于手术组(P<0.01);(2)在噪声暴露后,3组之间的SOD活性和MDA含量差异均有统计学意义(P<0.05);(3)手术组和假手术组的耳蜗外毛细胞均有不同程度的受损,其中以假手术组受损较为严重。结论:TCST对豚鼠NIHL具有一定的保护作用,增加SOD和降低MDA可能是其保护作用的机制之一。

Objective To investigate the protective effect of transection of cervical sympathetic trunk （TCST） on the noise-induced hearing loss （NIHL） in guinea pigs. Methods Thirty-six guinea pigs were ran- domly divided into three groups （n = 12）： the operation group, the sham group and the blank control group. TCST was performed in the operation group, while the cervical sympathetic trunk in the sham group was only exposed and separated. The auditory brainstem response （ABR） thresholds was measured. Levels of superoxide dismutase （SOD） and malondialdehyde （MDA） in pasma were detected before operation （To）, before noise exposure （T1） and on the time of stopping noise exposure （T2）, respectively. The damage situation of the outer cochlear hair cells was also checked. Results （1） At the time of T2, ABR thresholds of operation group and sham group were higher than that of the blank control group （P 〈 0.01）, and ABR thresholds of the sham group are higher than the of the operation group （P 〈 0.05）. （2） Levels of SOD and MDA post-noise exposure （T2） were significantly different among the three groups （P 〈 0.05）. （3） Injured hair ceils were more serious in the sham group than that in the operation group. Conclusion TCST has protective effect on NIHL in guinea pigs through increasing SOD and decreasing MDA.