细胞凋亡与激光对内耳损伤关系的研究

Apoptosis and the injury of the inner ear

目的研究激光对内耳的损伤过程中细胞凋亡最终是否参与,并探讨激光对内耳损伤的机制。方法选用健康雄性听力正常的豚鼠24只,随机分成对照组及实验A、B、C组,每组6只。对照组只打开听泡暴露圆窗龛,实验组分别以平均功率为1 W、3 W及5 W的超脉冲CO2激光在豚鼠左耳耳蜗底周造孔。术前1 d和处死前分别检测豚鼠听性脑干反应(auditory brainstem response,ABR)。术后1 d断头处死豚鼠,扫描电镜形态学观察,DNA末端转移酶介导的缺口末端标记法(TUNEL)检测细胞凋亡。结果实验B组和实验C组术后ABRIII波阈值较术前提高(P<0.05)。实验C组外毛细胞纤毛散乱,并有散在缺失,实验B组外毛细胞纤毛稍散乱,无缺失,而对照组和实验A组基本正常。实验C组耳蜗螺旋神经节细胞、耳蜗神经细胞及外毛细胞等处见明显凋亡阳性细胞,实验B组上述部位仅见散在少量凋亡阳性细胞,而对照组和实验A组未见明显改变。结论高峰功率激光对内耳的结构和功能有损伤,细胞凋亡在其中起了重要作用。

Objective To investigate whether or not apoptosis participates in the final injury of inner ear caused by laser,and explore the mechanism of the injury.Methods Twenty-four male guinea pigs with normal hearing were divided into the control group,in which only the otocyst was opened to expose the round window niche and experimental groups A,B and C.Each group had six guinea pigs.The last three groups underwent the fenestration on the basal turn of the left cochlea with superpulse CO2 laser at a power of 1 W,3 W and 5 W respectively.Auditory brainstem response（ABR）was recorded one day before the operation and antemortem.Scanning electron microscopy was used to evaluate cochlear morphology.The TUNEL method was used to detect apoptotic cells in the inner ear.Results The thresholds of postoperative ABR were higher than those preoprative in experimental groups B and C（P0.05）.The cilla of hair cells mostly disappeared with spaces between the hair cells in experimental group C,were partially scattered in experimental B compared with the control group and group A which were normal.Obvious TUNEL-positive cells could be detected in spiral ganglion cells,cochlear nerve cells,outer hair cells in group C,while few were found in group B compared with the control group and group A which appeared normal.Conclusions The high peak power superpulse CO2 laser could damage the cochlear morphology and function of the guinea pig,and apoptosis plays a critical roll in it.