高碘对智力影响的实验观察

The experiment study of high iodine on intelligence

目的证实高碘是否象缺碘一样引起脑发育障碍并探讨高碘损伤智力的可能机制。方法采用随机区组实验方法，用高碘饮水复制高碘甲状腺肿动物模型，观察高碘甲肿孕鼠之１５日龄仔鼠的大脑组织形态和超微结构，３０日龄仔鼠的学习记忆能力。结果①３０日龄仔鼠学习记忆能力降低，表现为水迷宫时间延长，错误次数增多，正确率下降。②大脑组织超微结构显示：高碘引起神经细胞核肿胀变性，染色质片状丢失，线粒体肿胀变性、嵴断裂，轴突、树突内微管、微丝减少，神经纤维髓鞘形成障碍，突触前后膜结构模糊，突触小泡减少等，只是损伤程度较低碘组轻。结论提示高碘同缺碘一样除引起甲状腺肿外，尚可对大脑形态和功能发育造成一定损伤。

Objective To verify whether high iodine will hinder brain development just like low iodine does and to inquire the probable mechanism of high iodine on intelligence.Methods This study succeeded in replicating mice goiter model of high iodine with water containing high level of iodine for three months by randomized block desigh.Brain morphological changes and ultra structure of 15 days postnatal mice and capacity of study and memory of 30 days postnatal mice which born to mothers with high iodine goiter were observed.Results ①High iodine significantly declined the capacity of study and memory in young mice and they showed longer water maze time and much more errors.②The ultra structure of cortex showed that neuron nuclear was damaged,nuclear swelled and denatured,chromatin obviously decreased,mitochondrial swelled,membrane dissolved,mitochondrial cristae fractured,microtuble and microfilament of axon and dendrites reduced,myilin sheath formation of nerve fibrea was obstructed,the structure of the presynaptic and postsynaptic membrane of synapse was obsecured,synaptic vesicles significantly reduced but the harming degree was slighter than that of low iodine group.Conclusions This study suggested that high iodine not only resulted in thyroid,but also damaged cortex morphyology and fuctional development just as low iodine does.