脑发育期甲状腺功能低下大鼠脑干听觉诱发电位慢成分的变化

THE CHANGES OF SC-BAEP IN RATS WITH HYPOTHYROIDISM IN THE PERIOD OF BRAIN DEVELOPMENT

目的:探讨脑发育期甲状腺功能低下大鼠脑干听觉诱发电位慢成分(SC-BAEP)的变化。方法:孕鼠从孕17d至仔鼠生后30d饮0.03%甲巯咪唑的自来水诱发脑发育期甲状腺功能低下仔鼠;甲低大鼠生后1～30d腹腔注射左旋甲状腺素(20μg/kg/d)进行替代治疗;放射免疫法测定大鼠血清FT3和FT4;计算机平均叠加技术颅表记录大鼠SC-BAEP,连续3个月动态观察甲低大鼠波峰潜伏期(PL)和波幅的变化。结果:甲低组大鼠生后20d时未能引出SC-BAEP,生后30d、50d、70d和90dSC-BAEP的SC波PL均明显长于对照组,波幅明显小于对照组;替代治疗组大鼠SC-BAEP的SC波PL和波幅在生后20d、30d、50d、70d和90d与对照组比较无显著性差异。结论:脑发育期甲状腺功能低下大鼠SC-BAEP的发育明显延缓,及早补充甲状腺素能显著改善其脑发育障碍。

Objective：To study the changes of SC - BAEP in thrats with hypothyroidism in the period of brain development. Methods： The rats with hypothyroidism in the period of brain development were induced by 0. 03% methimazole added in drinking water for their mother rats from the pregnant day 17 to the postnatal day 30 of their rat pups. Injection of L - T4 （20μg/kg/d） into abdominal cavity of the rats witn hypothyroidism from postnatal day 1 to 30 was used for replacement treatment. Serum FT3 and FT4 of the rats was determined by radioimmunoassay, and SC - BAEP was recorded with the summation - average technique of computer from the skull surface of the rats at postnatal day 20,30,50,70and 90. The changes of the peak latency （PL） and wave amplitude of SC - BAEP in the rats mith hypothyroidism had been observed continu- ously for 3 months. Results：SC - BAEP was not evoked in the rats of hypothyroidism group at postnatal day 20, and the PL of SC - BAEP was significantly longer than that of control group at postnatal day 30 to 90. The wave amplitude of SC - BAEP in the rats of hypothyroidism group was much smaller than that of control ones at postnatal day 30 to 90. There was no significant difference of the amplitudes between the rats of replacement group and that of control noes at postnatal day 20 to 90. Conclusion： The development of SC - BAEP was significantly retarded in the rats with hypothyroidism in the period of brain development, and the retardation of brain development could be improved significantly by the replacement of thyroxine immedieatly.