高胆红素血症新生大鼠耳蜗核NMDAR活性变化与听力损伤的实验研

目的：探讨高胆红素血症时听力损伤的机制及NMDAR活性变化在此损伤中的作用。方法：7 d龄 Sprague-Dawley大鼠60只，随机分为对照组和实验组，实验组又根据腹腔注射胆红素的剂量（100 μg/g和200 μg/g）分为M1、M2组，对照组以生理盐水取代胆红素溶液。测试各组动物脑干听觉诱发电位（ABR），检测血清胆红素浓度和脑组织胆红素含量，免疫组化SABC法测试大鼠耳蜗核NMDAR的活性变化。结果：M1组和M2组ABR反应阈明显升高，I、II、III波潜伏期及I～Ⅱ、Ⅱ～III、I～III波间期明显延长。M1组、M2组耳蜗核NMDAR免疫组化平均灰度值明显低于对照组，与脑组织胆红素含量呈显著负相关，与ABR反应阈亦呈显著负相关。结论：NMDAR活性升高在高胆红素血症听力损伤过程中发挥重要作用。［中国当代儿科杂志，2010，12（3）：201-204］

NMDAR expression in the cochlear nucleus and hearing damage in neonatal rats with hyperbilirubinemia

Objective To study the role of N-methyl-D-aspartate-receptor(NMDAR)expression in the development of hearing damage in neonatal rats with hyperbilirubinemia.Methods Sixty seven-day-old Sprague-Dawley rats were randomly injected with bilirubin of 100μg/g(low-dose treatment group)or 200μg/g(high-dose treatment group)or normal saline(control group).Auditory brainstem response(ABR)was examined.The concentrations of bilirubin in blood and brain were measured.NMDAR expression in the cochlear nucleus slices was examined by immunohistochemistry assay.Results ABR reflecting threshold obviously increased,and Ⅰ,Ⅱ and Ⅲ wave latency as well as Ⅰ-Ⅱ,Ⅱ-Ⅲ and ⅠⅢ interval were more prolonged in the two bilirubin treatment groups when compared with the control group.The NMDAR expression in the cochlear nucleuse in the two bilirubin treatment groups was obviously lower than that in the control group.The NMDAR expression in the cochlear nucleuse was negatively correlated with the brain bilirubin content and the ABR reflecting threshold in the two bilirubin treatment groups.Conclusions An increased NMDAR activity may play an important role in hearing damage following hyperbilirubinemia.