钙蛋白酶在卡那霉素致毒豚鼠耳蜗中的表达

摘要

目的 探讨钙蛋白酶(calpain)在卡那霉素(kanamycin,KM)致耳中毒豚鼠耳蜗的表达.方法 将豚鼠随机分成对照组、KM 3 d组、KM 7 d组和KM 14 d组,应用免疫组织化学SABC(streptavidin-biotin peroxidae complex,链霉亲合素-生物素过氧化物酶复合物)法和显微图像分析技术检测耳蜗中钙蛋白酶的表达,用药前后给予短纯音刺激检测听性脑干反应阈值,观察豚鼠听力的变化.结果 对照组calpain 1阳性免疫反应主要见于耳蜗毛细胞、螺旋神经节、血管纹和螺旋韧带,以螺旋神经节的染色较深,而其它部位均呈阴性.肌肉注射KM后,calpain 1在耳蜗中的阳性反应部位与对照组大致相同,显微图像分析结果表明,随着给药天数的增加,calpain 1在耳蜗上述部位的阳性反应逐渐减弱.Calpain 2在各组豚鼠耳蜗中的表达部位与calpain 1的相同,显微图像分析结果提示,随着给药天数的增加,calpain 2在耳蜗上述部位的阳性反应逐渐增强.结论 正常豚鼠耳蜗中有calpain1和calpain 2的表达.注射KM后,随着给药天数的增加,calpain 1在耳蜗的表达逐渐减弱,而calpain 2的表达则逐渐增强,提示calpain 2可能参与了卡那霉素致耳中毒的过程.%Objective To investigate expression of calpains in the cochlea in kanamycin (KM) -poisoned guinea pigs. Methods Guinea pigs were randomly assigned to serve as controls or to receive KM for 3, 7 or 14 days. SABC im-munohistochemistry and imaging analysis were used to examine expression of calpain 1 and calpain 2. Auditory brainstem responses (ABRs) were used to determine auditory thresholds and their changes. Results Immunoreactivity for clapin 1 was mainly seen in the hair cell, spiral ganglion, stria vascularis and spiral ligament in the control group, with greater staining in the spiral ganglion. The location of calpain 1 expression in the cochlea was similar in the control and KM treatment groups. Imaging analysis indicated that calpain 1 immuncorectivity gradually decreased with increasing days of KM treatment. The location of calpain 2 expression was similar to that of calpain 1 expression, but imaging analysis indicated that calpain 2 immuncorectivity gradually increased with increasing days of KM treatment. Conclusion Expression of calpain 1 and calpain 2 is visible in the cochleae of normal guinea pigs. Along with increasing duration of KM treatment, the expression of calpain 1 decreases while the expression of calpain 2 increases, suggesting that calpain 2 may participate in KM-induced ototoxicity.