丝状肌动蛋白在噪声致耳蜗不同阶段凋亡坏死毛细胞中的变化  

Changes of filamentous-actin at different stages of apoptotic and necrotic hair cells in rat cochleas induced by noise exposure

作　　者：杨卫平[1] 

机构地区：[1]解放军总医院耳鼻咽喉研究所,北京100853

出　　处：《临床耳鼻咽喉头颈外科杂志》2010年第13期608-612,共5页Journal of Clinical Otorhinolaryngology Head And Neck Surgery

基　　金：国家自然基金资助项目(No:30973304);十一五国家科技支撑计划项目(No:2006BAI02B06);解放军总医院苗圃基金(No:06MP29)

摘　　要：目的:通过观察丝状肌动蛋白(F-actin)在不同阶段凋亡、坏死毛细胞中的变化,揭示噪声性耳蜗毛细胞损伤早期的细胞形态学特征。方法:青年SD大鼠20只,接触噪声暴露的实验组及未接触噪声暴露的正常对照组动物各10只。将动物暴露于110 dB SPL,4 kHz窄带噪声,持续暴露8 h。稳态噪声暴露后接触155 dB SPL的脉冲噪声75次。噪声暴露前及噪声暴露后即刻、2周应用电反应测听仪检测不同频率短纯音(5、10和20 kHz)诱发的动物双侧听性脑干反应阈值(ABR)。听觉功能检测后处死动物,解剖取双侧耳蜗。采用DNA荧光染料碘化丙锭(PI)标记毛细胞核,异硫氰酸荧光素标记的鬼笔环肽染色毛细胞纤毛、表皮板的丝状肌动蛋白。以对照组动物耳蜗为对照,荧光显微镜下观察噪声暴露后大鼠耳蜗不同程度核固缩、核肿胀毛细胞的纤毛、表皮板F-actin表达的变化。结果:噪声暴露后即刻和2周不同频率短纯音诱发的ABR阈值均升高。荧光显微镜下观察发现,外毛细胞核肿胀时未见F-actin染色的改变;外毛细胞核型正常,但PI染色加深时,也未见F-actin的变化。外毛细胞核轻微固缩时,F-actin表达正常或轻度增强。外毛细胞核中度、重度毛细胞固缩时,F-actin染色变浅;外细胞核完全消失后,F-actin表达明显减弱或消失。结论:噪声暴露后耳蜗中凋亡、坏死的外毛细胞核变化早于纤毛及表皮板。F-actin可能在毛细胞凋亡中存在聚合和解聚2个过程,但其与毛细胞坏死过程无关。Objective：To observe the changes of filamentous-actin（F-actin） during process of apoptosis and necrosis in hair cells,and investigate the early mark for hair cells pathology following noise exposure.Method：Twenty young SD rats were used in present study.The animals were randomly assigned into two groups,10 animals were exposed noise and the remaining without exposure to noise served as normal control.The animals were exposed to a narrow band noise at 110 dB SPL for 8 hours.Immediately after exposure to continuous nose,the animals were exposed to 75 pairs of impulse noise at 155 dB SPL.The auditory brainstem response（ABR） thresholds of both ears elicited by tone bursts at 5,10 and 20 kHz were measured before,immediately and 2-week after the noise exposure.Animals were sacrificed and cochleae were quickly removed from the skull.Following fixation,whole specimens comprising the basilar membrane with Corti organ were separated from the modiolus.The organs of Corti were double stained with propidium iodide（PI）,a DNA intercalating fluorescent probe used to visualize the morphologic viability of hair cell nuclei,and FITC-labeled phalloidin,a F-actin intercalating fluorescent probe used to visualize the morphologic viability of cuticular plate and the stereocilia in the hair cells.Each organ of Corti was thoroughly examined using fluorescence microscopy.Result：The animals of test group exhibited a significant elevation of ABR threshold shifts at all tested frequencies after noise exposure immediately and 2-week.There was no detectable F-actin change in both the corresponding cuticular plates and the stereocilia in the OHCs undergoing necrosis.OHCs with slightly increased PI fluorescence and a relatively normal nuclear morphology exhibited normal level of F-actin activity.In the OHCs with mild nuclear condensation（about 3/4 of the normal size） exhibited normal or a slight increased F-actin fluorescence staining.In the OHCs with moderate or severe nuclear condensation（about 1/2 or 1/4 of the normal

关 键 词：丝状肌动蛋白 凋亡 坏死 毛细胞 噪声 大鼠 

分 类 号：R764.3[医药卫生—耳鼻咽喉科]