冲击波对豚鼠耳蜗螺旋神经节细胞Caspase-3的影响及与听阈阈移相关性研究

Expressions of caspase-3 protein in spiral ganglion cell following guinea pigs cochlear damage caused by shock wave

目的:探讨气体冲击致豚鼠耳蜗损伤后耳蜗螺旋神经节细胞中Caspase-3的表达及与听阈阈移的相关性,对冲击波的致聋机制进行探讨。方法:20只豚鼠随机分为2组,实验组用气体冲击致伤装置对豚鼠耳蜗致伤,实验前后测试听力,12h后处死动物制作耳蜗标本,透射电镜、原位末端标记技术观察耳蜗螺旋神经节细胞凋亡情况及免疫组化法测定Caspase-3的表达。结果:实验组听性脑干反应(ABR)阈值较正常对照组明显上升,听力下降明显。透射电镜观察,实验组螺旋神经节细胞的细胞器损伤严重,核变形,线粒体肿胀,粗面内质网增多;正常对照组螺旋神经节细胞核无变化,结构正常。原位末端标记显示,实验组耳蜗螺旋神经节细胞出现凋亡现象,愈近底回愈多,愈近顶回则愈少,正常对照组无凋亡现象。免疫组化显示,实验组耳蜗螺旋神经节细胞Caspase-3表达阳性,正常对照组无阳性表达。结论:气体冲击致豚鼠耳蜗损伤可致耳蜗螺旋神经节细胞发生凋亡并Caspase-3阳性表达,导致听力下降。

Objective To investigate the expressions of caspase-3 protein in spiral ganglion cell （SGC） and its correlation with auditory threshold shift following guinea pigs cochlear damage caused by air blast, to further study the mechanism of blast trauma causing deafness. Methods Twenty guinea pigs were randomly divided into control group and experimental group. Experimental group： by using air blast device to cause guinea pigs cochlear damage. Auditory threshold was tested before and after experiment for all the animals. Animals were killed and cochleas were taken for study after 12 hours. Apoptosis of SGC was observed through TEM, TUNEL and expression of caspase-3 was tested by immunohistochemical method. Results Test of auditory threshold： the AB threshold of experimental group were apparently higher than control groups, auditory function of experimental group was injured severely. The ultrastruetural changes of SGC： cellular organs of SGC were damaged severely in experimental group. Nucleoli were distorted, mitochondria swelled, the number of rough ebdoplasnic reticulum （REM） was increased. In control groups, the nucleoli of SGC weren＇ t distorted; the structure of mitochondria was normal. TUNEL showed that apoptosis of SGC was noted in experimental group, the apoptosis cells in basal turn were more than apical turn. No apoptosis was detected in control groups. Caspase-3 masculine reaction staining only appeared in experimental group samples. Conclusion Cochlear damage caused by air blast could induce the apoptosis of spiral ganglion cell and increase expression of caspase-3 in guinea pigs.