高胆红素血症对新生豚鼠畸变产物耳声发射的影响

Effect of Hyperbilirubinemia on Distortion Product Otoacoustic Emissions in Newborn Guinea Pigs

目的通过动态观察高胆红素血症新生豚鼠畸变产物耳声发射(DPOAE)及其对侧抑制现象的变化,探讨高胆红素血症对耳蜗和/或脑干听觉传出通路内侧耳蜗橄榄系统功能的影响。方法 20只新生豚鼠分为实验组和对照组各10只,分别腹腔注射胆红素100μg/g和等量生理盐水。两组于给药前、给药后2、4、6、8小时在对侧耳无声刺激及70dBSPL白噪声刺激两种条件下测试DPOAE,观察两组DPOAE及对侧抑制现象的动态变化。给药后8小时行全耳蜗基底膜铺片定量观察毛细胞损伤情况。结果对照组给药前后DPOAE幅值无变化,对侧抑制现象始终存在。实验组给药后DPOAE幅值逐步下降,给药后2小时起对侧抑制现象消失,其中5只豚鼠在给药后8小时DPOAE幅值及对侧抑制现象呈现不同程度的恢复。两组豚鼠耳蜗基底膜铺片观察毛细胞形态未见异常。结论高胆红素血症早期可能损害耳蜗毛细胞的主动机械活动及耳蜗传出神经系统,此损害部分为可逆性的。DPOAE及其对侧抑制现象是评估胆红素脑病严重程度的有效指标。

Objective To explore the function of cochlea and medial olivo cochlear system （MOCs） in hyperbilirubinemic guinea pigs by detecting the distortion product otoacoustic emissions（DPOAEs）and contralateral suppression（CS）. Methods The DPOAEs amplitude was measured with and without 70 dB SPL white noise contralat eral stimulation in the ears of 20 healthy newborn guinea pigs, which were randomly divided into two groups（control group and experimental group）. DPOAE was recorded at 2, 4, 6 and 8 hours after peritoneal injection of saline for control group,and bilirubin for experimental group. Cochleogram was obtained from cochlear surface preparation in experimental group after the test. Results There was no statistical change in DPOAEs amplitude and CS in control group. However, the amplitude of DPOAEs decreased in experimental group, the contralateral acoustic stimulation had no significant effect on amplitude of DPOAEs measured ipsilaterally after bilirubin injection. There was part of recovery on amplitude of DPOAEs and CS in five guinea pigs with no abnormalities in cochlear hair cells in experimental group at 8 hours after peritoneal injection. Conclusion Our findings suggest that hyperbilirubinemia results in impairment of MOCs and mechanical activities of cochlear hair cells. The bilirubin injected animals showed some part of reversal of abnomalities. The DPOAEs and CS could be an effective ways to evaluate the severity of bilirubin en cephalopathy.