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目的探讨噪声损伤后豚鼠外毛细胞发生凋亡的通路及其机制。方法分离解剖对照组(12只)和噪声暴露组(12只)豚鼠耳蜗,利用免疫荧光抗体和免疫荧光染料,分别染色细胞核、线粒体、凋亡诱导因子(apoptosis inducing factor,AIF)和半胱氨酸天冬氨酸蛋白酶3(Caspase 3),按表面制备法行耳蜗铺片,观察凋亡和坏死毛细胞内的荧光信号。结果对照组正常耳蜗毛细胞内没有激活的 Caspase 3,AIF 分布在毛细胞的线粒体内。实验组动物暴露于声压级120 dB 的白噪声环境中每天4 h,连续2 d 后,耳蜗外毛细胞出现死亡,表现为坏死和凋亡两种方式,但以凋亡为主。在凋亡的外毛细胞中,Caspase 3被激活,AIF 从线粒体转移到细胞核中;而在坏死的外毛细胞中,没有 Caspase3的激活,只有 AIF 自线粒体向细胞核的转移。结论噪声损伤后耳蜗外毛细胞的凋亡以 Caspase 依赖型的通路为主;线粒体释放的 AIF 在外毛细胞死亡通路中起重要作用。
Objective To investigate the pathway and mechanism of apoptosis in guinea pig outer hair cells after noise damage. Methods The cochlear of guinea pigs were dissected from the control group (12 rats) and noise exposure group (12 rats). Immunofluorescence and immunofluorescence staining were used to stain the nucleus, mitochondria, apoptosis inducing factor (AIF) and cysteamine Acid aspartate protease 3 (Caspase 3), according to the surface preparation of cochlear implants, apoptotic and necrotic hair cells observed fluorescent signal. Results There was no activated Caspase 3 in the normal cochlear hair cells in the control group. AIF was distributed in mitochondria of hair cells. The experimental group was exposed to white noise with a sound pressure level of 120 dB per day for 4 hours. After 2 consecutive days, the outer hair cells of the cochlea showed death, showing necrosis and apoptosis, but mainly apoptosis. In apoptotic outer hair cells, Caspase 3 is activated and AIF translocates from the mitochondria to the nucleus. In necrotic outer hair cells, there is no activation of Caspase 3, but only AIF translocates from the mitochondria to the nucleus. Conclusion Apoptosis of outer hair cells in the cochlea is dominated by Caspase-dependent pathways. AIF released by mitochondria plays an important role in the pathways of death of outer hair cells.