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目的探讨失重及飞船舱内噪声复合因素对豚鼠听功能的损伤作用,及其对凋亡标志物Caspase-3在豚鼠内耳表达的影响。方法 36只豚鼠随机分为4组,其中对照组6只,单纯失重组(A组)、单纯噪声组(B组)及失重+噪声组(C组)各10只。单纯失重组(A组)仅给予后肢悬吊模拟失重处理;单纯噪声组(B组)仅给予模拟飞船舱内噪声暴露;噪声+失重组(C组)同时给予噪声暴露和模拟失重的复合因素处理。实验前、暴露后即刻和恢复3天测试听性脑干反应阈值。于暴露后8小时和3天两个时间点取耳蜗,利用免疫组织化学染色方法显示凋亡标志物Cas pase-3在实验动物内耳毛细胞、血管纹及螺旋神经节细胞中的表达。结果在暴露后8小时和恢复后3天两个时间点上,A组ABR阈值分别与B组、C组比较差异有统计学意义(p<0.05),而B组与C组间差异无统计学意义(P>0.05)。在暴露前后,A组分别与B组、C组比较差异有统计学意义(p<0.05),而B组与C组间差异无统计学意义(P>0.05)。比较在恢复前后ABR,A组与C组间差异无统计学意义(P>0.05),B组分别与A组、C组比较差异有统计学意义(p<0.05)。Caspase-3免疫组化结果显示,单纯失重组(A组)、单纯噪声组(B组)和失重+噪声组(C组)在暴露后、恢复3天两个时间点上,毛细胞和血管纹Caspase-3表达均为阳性。三个实验组暴露后螺旋神经节的凋亡标志物Caspase-3表达均为阳性,其中A、C组为强阳性表达,B、C组为弱阳性表达。而恢复3天后,A组动物Caspase-3表达为阴性,较实验后表达明显降低,B、C组动物Caspase-3表达均为阳性,较暴露后表达有所增强。结论失重和模拟飞船噪声均可造成豚鼠ABR阈值的升高,当两者复合作用时,噪声暴露可能对其造成的听力损失的影响更大。相比于单纯噪声暴露,失重与噪声因素复合作用时可减缓听力恢复的进程。二者复合作用引起的听力损失与内耳毛细胞、螺旋神经节和血管纹细胞的凋亡有关。
Objective To investigate the effect of weightlessness and spaceborne cabin noise composite on auditory function in guinea pigs and its effect on the expression of Caspase-3 in the inner ear of guinea pigs. Methods Thirty - six guinea pigs were randomly divided into 4 groups, including 6 in the control group, 10 in the simple weightless group (group A), simple noise group (group B) and weightlessness + noise group (group C). The simple weightless group (Group A) only received simulated weightlessness of hindlimb suspensions; the pure noise group (Group B) only gave noise exposure of the simulated spacecraft; the noise plus weightless group (Group C) gave both noise exposure and simulated weightlessness deal with. The threshold of auditory brainstem response was tested immediately before and 3 days after exposure. The cochleas were harvested at 8 and 3 days after exposure. The expression of Caspase-3, an apoptotic marker, in the inner ear hair cells, vasculature and spiral ganglion cells was detected by immunohistochemical staining. Results There were significant differences in ABR thresholds between group B and group C at 8 hours after exposure and at 3 days after recovery (p <0.05), but no statistical differences between group B and group C Significance (P> 0.05). Before and after exposure, the difference between group A and group B and group C was statistically significant (p <0.05), but there was no significant difference between group B and group C (P> 0.05). There was no significant difference in ABR between before and after recovery (P> 0.05). There was significant difference between group A and group C (P <0.05). The results of Caspase-3 immunohistochemistry showed that after two days of recovery, the hair loss and noise were significantly higher in simple weight group (group A), simple noise group (group B) and weightlessness + noise group (group C) Caspase-3 expression were positive. The expression of Caspase-3, a marker of apoptosis in the spiral ganglion, was positive in three experimental groups after exposure. The positive expression of Caspase-3 in group A and C was weakly positive. After 3 days of recovery, the expression of Caspase-3 in group A was negative, which was significantly lower than that in group B. Caspase-3 expression was positive in groups B and C, which was increased after exposure. Conclusion Both weightlessness and simulated spacecraft noise can cause the increase of ABR threshold in guinea pigs. When the two are combined, noise exposure may have a greater impact on hearing loss. Compared with simple noise exposure, weight loss and noise factors can slow down the process of hearing recovery. The combined effect of hearing loss and the inner ear hair cells, spiral ganglion and vascular cell apoptosis.