[Effects of high-dose iodine on brain development in mice]

It is an important topic in medicine and genetics, which has not yet been studied in depth, that whether high-dose iodine, especially iodine excess in mother's body, can cause impediment of brain development in babies as iodine deficiency do. An animal model of goiter was reconstructed in mice with feeding them water containing high level of iodine for three months. Weight of brain, protein and nucleic acid concentrations were measured in one-, seven-, 14-, 21- and 30-day old young mice, and morphological changes in the brain and their abilities of learning and memory were observed in 30-day old young mice, born to mothers with high-iodine goiter. Results indicated that weight of brain, protein content, ratio of protein to DNA, RNA content, and ratio of RNA to DNA all decreased significantly, and DNA content increased in the brain of high-iodine mice, as compared with those in normal iodine mice. Abilities of learning and memory in 30-day old mice decreased. And, those changes began from the seventh to 14th days after their birth. It suggests that excessive intake of iodine, as iodine deficiency, can not only cause high-iodine goiter, but also damage nervous system leading to retardation of brain development and impediment of its function.