胆红素对新生豚鼠蜗核损伤的动态研究

Dynamic Study on Cochlear Nucleus Damage Induced by Bilirubin in Infant Guinea

目的 探讨听性脑干反应 (ABR)在胆红素所致听力损伤中的监测价值。方法 2 0只新生 5日豚鼠随机分为胆红素组和对照组 ,胆红素组腹腔注射胆红素 (2 0 0 μg/ g) ,对照组腹腔注射相应体积的生理盐水 (0 1ml/g) ,于腹腔注射前和后 4h、 8h分别记录ABR并观察神经行为状况 ,每组各取 5只于腹腔注射后 4h、 8h分别行蜗核形态学观察。结果 注射胆红素后 ,ABR波潜伏期、波间期呈逐渐延长趋势 ,振幅呈逐渐下降趋势 ,其中波Ⅱ改变出现最早且最明显。用药后 4h ,无明显神经系统症状和形态学改变时 ,Ⅰ -Ⅱ波间期延长及波Ⅱ振幅下降与对照组及用药前比较差异有显著性 (P <0 0 1) ;用药后 8hABR改变更明显 ,同时伴有神经症状和镜下形态学改变 ,蜗核体积及大椭圆细胞截面积显著性减小 (P <0 0 1)。结论 ABR是监测胆红素所致听力损害早期的敏感指标 ,优于耳蜗电图和耳声发射等主要反映周围听觉系统功能状态的电生理技术 。

Objective The present experiment explores the predictive validity of auditory brainstem response (ABR) in determining auditory damage of bilirubin. Methods Twenty-two infant guinea pigs at 5 days of age were randomly divided into 2 equal groups respectively injected with crystal bilirubin(200μg/g) and a comparable volume of saline(0.1ml/g). ABR were recorded and nervous symptoms were observed before injection and after 4h, 8h of injection. Histological examinations of cochlear nucleus were conducted on 5 guinea pigs of each group after 4h, 8h of injection. Results After intraperitoneal injection of bilirubin, ABR wave latencies and interwave intervals increased and wave amplitudes decreased ,especially in wave Ⅱ. Significant differences(P<0.01) between groups were seen for increased ABRⅠ-Ⅱ interwave interval and decreased amplitude of wave Ⅱwithout any symptoms or morphometric abnormalities after 4h of bilirubin injection. Cochlear nucleus volume and cross-sectional area of spherical cells decreased significantly after 8h of bilirubin injection compared with other groups and clinical symptoms were also found besides ABR abnormalities (P<0.01). Conclusions ABR is a sensitive indicator in determining early bilirubin-induced auditory brainstem damage and is better than electrocochleography (ECG) and otoacoustic emission(OAE) which mainly reflect the function of peripheral auditory system. Regular ABR recordings in infants with hyperbilirubinea are very important.