Objective To inject PPTA into the cochlea of guinea pigs through scala tympani fenestration ,to study the protective effect of PPTA injection on the cochlear damage induced by gentamicin and mechanism of oxy-gen free radical .Methods Randomly divided were the guinea pigs with normal hearing into three groups :the con-trol group ,GM group and PPTA group .We injected the artificial perilymph 10μl /d into cochlea through scala tym-pani fenestration on control group for 3 days ,injected GM 160 mg · kg -1 · d-1 on GM group for 3 days ,injected the PPTA 10 μl /d into the cochlea through scala tympani fenestration and injected GM 160 mg · kg -1 · d-1 at the same time on PPTA group for 3 days .We tested ABR and analyzed the hearing changes .We tested the OFR level reacted by SOD and GSH of the cochlea tissue .SEM and TEM were performed to observe the change of cell mor-phology .Results For ABR ,the control group was 12 .75 ± 3 .796 ,GM group 28 .230 ± 4 .953 ,PPTA group23 .47 ±9 .211 dB SPL(P<0 .05) .For SOD ,the normal group was 50 .241 ± 9 .080 ,GM group 28 .230 ± 4 .953 ,PPTA group 43 .089 ± 4 .587 U/mgprot(P<0 .05) .For GSH ,the normal group was 3 .03 ± 0 .33 ,GM group 1 .51 ± 0 .13 ,PP-TA group 2 .50 ± 0 .16 Ggsh/L(P<0 .05) .The changes of hair cells of PPTA group were obviously less severe than that of GM group .For TEM ,the changes of spiral ganglion and stria vascularis of PPTA group were obviously less severe than that of GM group .Conclusion Injecting PPTA through scala tympani fenestration can protect cochlea by generating the excess of OFR when confronting against GM .%目的：观察盐酸椒苯酮胺（peperphentonamine hydrochloride ，PPTA）对豚鼠庆大霉素（gentamicin ， GM ）耳蜗损伤的保护作用及机制。方法将听力正常的45只健康豚鼠随机分为空白对照组、GM 组和PPT A组，每组15只。空白对照组行鼓阶开窗微孔注入人工外淋巴液10μl／d ，连用3天；GM 组给GM 160 mg · kg -1· d-1肌肉注射，连用3天；PPT A组行鼓阶开窗微孔技术注入PPT A 10μl／d和肌肉注射GM 160 mg · kg -1· d-1注，连用3天。分别于用药前和用药3天后对三组动物行听性脑干反应（auditory brainstem response ，ABR）测试；第二次ABR测试后处死豚鼠，取出耳蜗，检测各组豚鼠耳蜗组织中过氧化物歧化酶（superoxide dismutase ，SOD）、谷胱甘肽（glutathione ，GSH）含量，并以扫描电镜和透射电镜观察耳蜗细胞形态学改变。结果空白对照组、GM 组、PPT A组ABR反应阈实验前比较差异无统计学意义，用药三天后分别为12．75±3．80、47．75±11．08、23．47±9．21 dB SPL ，各组间比较差异有统计学意义（P＜0．001）；空白对照组、GM组、PPTA组SOD值比值分别为50．24±9．08、28．23±4．95、43．09±4．59 U／mgprot ，PPTA组SOD值显著高于GM 组（P＜0．001）；空白对照组、GM 组、PPTA组GSH值分别为3．03±0．33、1．51±0．13、2．50±0．16 Ggsh／L ，PPTA组GSH值显著高于GM 组（P＜0．001）；扫描电镜观察PTTA组耳蜗各回外毛细胞肿胀、倒伏、缺失等较GM组轻，内毛细胞正常，而GM组内毛细胞亦有轻微损伤；透射电镜观察PPT A组耳蜗毛细胞肿胀、线粒体体聚集等改变明显轻于GM 组。结论经鼓阶开窗微孔技术注入PPT A可通过清除GM 产生的过量氧自由基从而发挥耳蜗保护作用。
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