脑发育期甲状腺功能低下大鼠听觉中潜伏期反应的变化

目的：探讨脑发育期甲状腺功能低下（甲低）大鼠听觉中潜伏期反应（MLR）的变化。方法：孕鼠从孕第17天起及其仔鼠出生后起30天内饮含0．03％甲巯咪唑的自来水诱发脑发育期甲低仔鼠；甲低仔鼠生后1～30天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MLR，连续3个月动态观察甲低大鼠波峰潜伏期（PL）、波峰间潜伏期（IPL）和波幅的变化。结果：甲低组大鼠生后第20天时未能引出听觉MLR，生后30～90天的听觉MLR各波PL均明显长于对照组；替代治疗组大鼠MLR除生后20天和生后70天的P。波PL明显短于对照组及生后70天的P“波PL明显长于对照组外，各波PL在生后20-90天与对照组比较差异无显著意义。甲低组大鼠生后30～90天MLR的P0-Pa和Pa—Pb IPL均明显长于对照组；替代治疗组大鼠MLR除生后70天的P0-Pb IPL明显长于对照组外，其余IPL在生后20-90天与对照组比较差异无显著意义。甲低组大鼠生后30～90天MLR各波波幅明显小于对照组；替代治疗组大鼠除生后20天P0和Na波、生后30天P0波的波幅明显大于对照组外，其余各波波幅在生后20～90天与对照组比较差异无显著意义。结论：脑发育期甲低大鼠听觉MLR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。

The changes of MLR in rats with hypothyroidism in the period of brain development

Objeetive：To analyze the changes of MLR in rats with hypothyroidism in the period of brain development. Methods.. The rats with hypothyroidism in period of brain development were induced by 0.03% methimazole added in drinking water for their mother rats from the 17th pregnant day to the 30th postnatal day of their rat pups. Injection of L-T4 [20μg/（kg· d） ]into abdominal cavity of rats with hypothyroidism from 1st to 30th postnatal day was used for replacement of treatment. Serum FT3 and FT4 of the rats were determined by radioimmunoassay, and MLR was recorded with the summation-average technique of the computer from the skull surface of the rats on the 20th, 30th, 50th, 70th and 90th postnatal days. The changes of the peak latency （PL） , interpeak latency （IPL） and wave amplitude of MLR in rats with hypothyroidism were observed continuously for 3 months. Results.. MLR was not eyoked in the rats of the hypothyroidism group on the 20th postnatal day, and their PL of MLR were significantly longer than those of controls on the 30th to 90th. postnatal day. There was no significant difference between the PL of MLR of the replacement group and that of the control group on the 20th to 90th postnatal days except that their the PL of Wave P0 in the replacement group was obsviously shorter than lat of controls on the 20th and 70th postnatal day, their PL of Wave Pb of them was significantly longer lan that of controls on the 70th postnatal day. There was no significant difference of the amplitudes between the rats of the replacement group and that of the controls on the 20th to 90th postnatal days except that the amplitude of P0 on the 20th and 30th postnatal days and amplitude of Na on the 20th postnatal days in the replacement group was biger than that of the controls. Conclusions The development of MLR 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 immed