高胆红素血症新生大鼠脑干听觉诱发电位快慢成分的变化

Changes of fast and slow components of brainstem auditory evoked potentials in the rat pups with hyperbilirubinemia

目的:探讨高胆红素血症新生大鼠脑干听觉诱发电位快成分(FC-BAEP)和慢成分(SC-BAEP)及脑干神经元线粒体超微结构的异常变化。方法:生后7天SD大鼠随机分为对照组(C组,17只)和两个实验组(T1和T2组,各17只)。T1和T2组大鼠生后7天和10天腹腔注射2g/L胆红素溶液,第二次腹腔注射6h后随机抽出7只断头取血用微量胆红素仪检测血清胆红素,其余大鼠生后17天和20天用诱发电位仪检测FC-BAEP和SC-BAEP,生后20天灌注固定、取耳蜗核进行透射电镜观察。结果:T1和T2组大鼠于生后10天腹腔注射6h后,血清胆红素浓度明显升高;T1和T2组大鼠生后17天三种刺激重复率(10/s,40/s,80/s)引导的FC-BAEP,除Ⅱ-Ⅳ波峰间潜伏期(IPL)外,各波波峰潜伏期(PL)和IPL显著延长,且T2组大鼠各波PL较T1组显著延长;T1和T2组大鼠生后20天三种刺激重复率引导的FC-BAEP,除刺激重复率10/s和40/s引导的Ⅱ-ⅣIPL外,各波PL和IPL显著延长;T1和T2组大鼠生后17天与20天刺激重复率10/s引导的SC-BAEP的PL显著延长,且T2组大鼠生后17天SC-BAEP的PL较T1组显著延长;T1和T2组大鼠耳蜗核电镜观察可见神经元线粒体肿胀变形、膜模糊不清和嵴断裂等。结论:高胆红素血症新生大鼠FC-BAEP和SC-BAEP及脑干神经元线粒体超微结构有显著异常变化,FC-BAEP与SC-BAEP的PL和IPL是早期监测胆红素诱发的听觉和脑损伤的客观灵敏指标。

Objective：To probe the changes of fast component of brainstem auditory evoked potentials （FC-BAEP）,slow component of brainstem auditory evoked potentials （SC-BAEP） and the mitochondrial ultrastructures of the neurons in the brainstem in the rat pups with hyperbilirubinemia.Methods：7 days old SD rat pups were randomly divided into control group （C,17 rat pups） and two test groups （T1,17 rat pups and T2,17 rat pups）.Bilirubin solutions （2 g/L） were injected into the abdominal cavity of the rat pups in the group T1 and T2 at the postnatal day 7 and 10.Six hours after the second injection,seven rat pups of each group were randomly selected to test serum bilirubin concentration via a micro-gauge.FC-BAEP and SC-BAEP were examined with an evoked potential recorder in the rest rat pups of each group at postnatal day 17 and 20.At the postnatal day 20,the endocardial perfusion was performed in these rat pups for the fixation of the brain,and then the brains were taken out.The cochlear nuclei were used for observation via electron microscope.Results：Six hours after the injection of bilirubin solution at the postnatal day 10,the serum bilirubin concentrations of the rat pups in group T1 and T2 were increased significantly.Except for Ⅱ～Ⅳ inter-peak latency（IPL）,all the peak latency（PL） and IPL of FC-BAEP evoked via three sound stimulating rates （10/s,40/s,80/s） at the postnatal day 17 prolonged significantly in the rat pups of group T1 and T2,and the PL in group T2 were much longer than that in group T1.Except for Ⅱ-Ⅳ IPL of FC-BAEP evoked via sound stimulating rates of 10/s and 40/s,all the PL and IPL at the postnatal day 20 prolonged significantly in the rat pups of group T1 and T2.The PL of SC-BAEP evoked via sound stimulating rate of 10/s at the postnatal day 17 and 20 in the rat pups of group T1 and T2 prolonged significantly,and the PL at the postnatal day 17 in group T2 were much longer than that of group T1.The changes of mitochondria of the neurons in the cochlear nuclei at the postnatal day 20 in the rat pups of group T1 and T2 were characterized by swell,the slurred membranes,the broken crista and so on.Conclusion：There were the abnormal changes of FC-BAEP,SC-BAEP and the mitochondrial ultrastructures of the neurons in the brainstem in the rat pups with hyperbilirubinemia.The PL and IPL of FC-BAEP and SC-BAEP could be taken as the objective and sensitive indexes for early monitoring the bilirubin-induced hearing loss and brain injury.