中文摘要：

目的探讨出生后早期暴露甲基汞（MMC）所致仔鼠神经行为的发育毒性及对甲状腺激素的干扰作用。方法将112只新生清洁级大鼠随机分为对照组（生理盐水）和低（0．5mg／kg）、中（1．0mg／kg）和高（2．0mg／kg）剂量MMC染毒组，每组28只。于出生后第2～8天，采用口服方式进行染毒，染毒容量为1．0ml／kg。评价仔鼠一般生理指标和反射行为发育，采用恋窝实验和水迷宫实验检测感官、认知和记忆，并检测血中游离甲状腺激素（T4）、三碘甲腺原氨酸（L）含量和促甲状激素（TSH）活性。结果与对照组相比，MMC染毒仔鼠的生长发育及一般神经行为发育基本无变化。在恋窝实验中，随着MMC染毒剂量的升高，仔鼠达标率呈下降趋势，达标仔鼠潜伏时间呈延长趋势。在传统水迷宫实验中，MMC染毒仔鼠游泳时间缩短；在反向水迷宫实验中，MMC染毒仔鼠游泳时间延长。与对照组比较，高剂量MMC染毒组仔鼠全血中游离T4含量较高，L含量较低，而MMC染毒组仔鼠全血中TSH活性均较高，差异有统计学意义（P〈0．05或P〈0．01）。结论出生后早期MMC暴露可明显影响仔鼠的感觉、学习和认知能力，其机制可能与甲状腺激素紊乱有关。

英文摘要：

Objective To explore the effects of early postnatal exposure to methylmercury chloride （MMC） on neurobehavior and thyroid hormone in pubertal rats. Methods Neonatal offspring at clean level were randomly divided into 4 groups, 28 in each： a saline control, a low-dose group （0.5 mg/kg bw）, a moderate-dose group （1.0 mg/kg bw） and a high-dose group （2.0 mg/kg bw）. Those model animals were treated orally from postnatal day 2 （PND2） to PND8. Traditional measurement of neurobehavioral developmental endpoints was performed as well as the estimation on thyroid hormone disruption. Results No significant differences in somatic and reflex development were observed between exposed groups and control. However, it was suggested a dose-dependent increase in animals which tended to travel longer latency to reach scent area in homing test. Juvenile rats showed delayed pattern to locate the submerged platform in reversal learning assessment while those animals exhibited contrarily in the traditional swim maze. Additionally,significant disruption on the thyroid hormone was observed in exposed animals, when compared with control. Conclusion Neonatal methylmercury exposure may significantly affect the sensing, studying and cognitive functions, which could be associated to the disruption of thyroid hormone.