内毛细胞缺损对噪声引起外毛细胞损害的潜在影响

Inner Hair Cell Missing Potentiates Noise Induced Outer Hair Cell Lesion

目的 观察噪声对正常灰鼠和内毛细胞缺损灰鼠的外毛细胞是否具有不同的破坏效应。方法 6只正常灰鼠和 12只卡铂致聋灰鼠作为受试对象。提前 30天给 12只灰鼠按照 10 0mg/kg的剂量腹腔注射卡铂 ,以达到预先选择性破坏其内毛细胞的目的。将 6只正常灰鼠和 6只经卡铂处理的灰鼠移入噪声室 ,在强度为 12 0dB、中心频率在 4kHz的脉冲噪声环境暴露 6小时 ;另外 6只经卡铂处理的灰鼠不经噪声暴露作为对照组。在噪声暴露后 30天取出耳蜗 ,常规制备耳蜗铺片 ,然后进行全耳蜗毛细胞计数 ,并将各组动物的毛细胞计数结果制备成平均受损情况分布图 ,观察和比较噪声引起的外毛细胞损害水平在具有正常内毛细胞的灰鼠和丧失内毛细胞的灰鼠是否存在差别。结果 单纯注射卡铂的灰鼠内毛细胞平均损失在 90 %左右 ,但外毛细胞无损害。经噪声暴露的正常灰鼠外毛细胞在耳蜗底回中部约相当于 4kHz共振频率区域平均损失 6 0 % ,但是在该区域两侧靠近底回和顶回的外毛细胞损失少于 2 0 %。预先经卡铂破坏 95 %内毛细胞的灰鼠经噪声暴露后 ,外毛细胞在耳蜗底回中部平均损失达到 90 % ,在该区域两侧的外毛细胞损失百分比大于 4 0 %。结论 内毛细胞缺损可以造成更多的外毛细胞在噪声刺激中被破坏 ,提示正常内毛细胞的存在可能有?

Objective To determine the different damage level in noise induced outer hair cell (OHC) lesion between normal and inner hair cell (IHC) deficient chinchillas.Methods Eighteen chinchillas were used in this study. 12 chinchillas were injected with carboplatin (100 mg/kg, IP) to eliminate inner hair cells. Six of them were terminated 30 days post-carboplatin as carboplatin control group. Another 6 chinchillas were exposed to a 120 dB 4 kHz impulse noise for 6 hours, and sacrificed 30 days after noise exposure as carboplatin plus noise group. In addition, six normal chinchillas were also exposed to noise, and terminated 30 days later as noise control group. The missing cochlear hair cells were quantified and compared in above three groups. Results 1. In carboplatin control group, 90 % IHCs were eliminated, however, most of OHCs were intact. 2. In noise control group, 60% OHCs were destroyed at the center of basal turn, and 20% OHC missing in this area. 3. In carboplatin plus noise group, 95% IHCs were missing due to carboplatin, and 90% OHCs were destroyed by the noise at the center of basal turn.Conclusion As a result of deficient IHCs potentiate impulse noise-induced acoustic trauma to outer hair cells. IHC may promote the resistance of OHC to acoustic overstimulation.