【作者】 李岩；

【导师】 李兰英；

【作者基本信息】 天津医科大学 ， 病理学， 2005， 硕士

【摘要】 本实验在碘水平异常大鼠的大脑、小脑及海马中观察了Ⅱ型、Ⅲ型脱碘酶（D2,D3）表达的变化情况;同时观察了三碘甲状腺原氨酸和甲状腺原氨酸（T₃、T₄）对体外培养大脑细胞中Ⅱ型、Ⅲ型脱碘酶表达的影响以及不同的碘水平对体外大脑细胞生长及分化的影响。 在体实验选用断乳后1个月健康Wistar大鼠（纯系封闭群）按性别、体重随机分为6组:LI（低碘）组;NI（正常碘）组;5HI（5倍高碘）组;10HI（10倍高碘）组;50HI（50倍高碘）组;100HI（100倍高碘）组;并按不同的时间点各组分为三批:3个月、6个月及12个月。LI组饲低碘饲料,饮去离子水;NI组饲正常碘饲料,饮自来水;HI组饲正常碘饲料,在饮用水中分别加入不同剂量的碘化钾（KI）,使各组摄入碘水平呈倍数关系。3个月、6个月时,分别测定各组大鼠的尿碘水平,股动脉取血测定血清中T₃、T₄,同时处死动物,一部分取全脑测D2的活性;一部分脑组织分为大脑、小脑、海马三个部分,提取组织总RNA,利用半定量逆转录-聚合酶链式反应（RT-PCR）的方法,分析各组动物不同脑分区中D2,D3的表达。结果显示:（1） 碘摄入量与尿碘水平相关性好,不同碘水平的动物模型复制是成功的:（2） 3个月时LI组血清FT₄和TT₄水平下降,TT₃、FT₃水平不降低或代偿性升高,rT₃生成量减少;D2活性升高,D2mRNA保持稳定;D3表达量很小,几乎测不到。（3） 3个月时,HI组随着碘摄入的增加,血清TT₄、TT₃、FT₄、FT₃、rT₃浓度均出现逐渐降低趋势,其中FT₃浓度自10HI组起即显著低于NI组;50HI组FT₃、rT₃浓度及100HI组5种激素浓度均显著低于NI组;D2活性随摄入碘增加而逐渐降低,100HI组D2活性达到最低,D2mRNA在各组仍无显更多还原

【Abstract】 For realizing the impact on brain development of iodine excess, expressions of type 2, type 3 iodothyronine deiodinase (D2, D3) were detected in vivo and in vitro tests. Based on the successful establishment of animal model of iodine deficiency and iodine excess, the changes of iodothyronine deiodinases mRNA in cerebrum, cerebella and hippocampus of different iodine intake animal have been observed. In vitro, 100nM T3 or 100nM T4 acted on the cultured neural cell at different time. The impact of TH on D2mRNA and D3mRNA has been observed by semi-quantity RT-PCR. The survival of neural cell in iodine excess has been revealed by MTT.In vivo study, 1 month Wistar rats were divided into six groups randomly base on sex and weight. Rats of LI (low iodine intake) group were given low iodine diet and deionized water. Animals in NI (normal iodine intake) group were fed with normal iodine diet and tap water. In HI (high iodine intake) group, 5 times, 10 times, 50times and 100 times iodine respectively added into tap water, and then gave different animals. And these rats in HI group were also fed with normal iodine diet. After 3 months, 10 rats in each group were sacrificed. The following indicators were measured: urinary iodine, serum TT3 TT4 FT3 FT4 rT3, activities of D2 in brain, D2mRNA and D3mRNA in cerebrum, cerebella, and hippocampus. And 6 months later, the same test was also completed. The results showed: (1) The relativity of iodine intake and urinary iodine wasexcellent. Animal model was successful. (2) In 3 months later study, serum TT4 FT4 of LI group was significantly lower than that of NI group and serum TT3 FT3 was stable. The quantity of rT3 was markedly lesser than normal level. D2 activity was significantly higher in LI group than that of other groups. D2mRNA had no significant difference among groups. D3mRNA was so little that can’t be detected. (3) Serum TT3 TT4 FT3 FT4 rT3 in HI groups had a decreasing tendency. Serum FT3 in 10HI, 50HI and 100HI groups were all significantly lower than that of NI group. In 100HI group, five thyroid hormones in serum all decreased markedly. D2 activity had a decreasing tendency too in HI groups. D2mRNA kept a steady level. D3mRNA increased in some animals of HI groups. (4) In 6 months later study, serum thyroid hormones in LI group decreased evidently. Rats in HI groups showed hypothyroidism symptoms. D2 activity decreased markedly in LI group and HI groups. D2mRNA had no difference among groups. D3mRNA also increased in some animals of HI groups.In vitro study, the Wistar rat fetal cerebral hemispheres at 15-18 days of gestation were dissected, dissociated, and planted into DMEM/F12 growth medium. The cell types were identified by immunocytochemistry method. This study included two parts. One part was to observe D2mRNA and D3mRNA in cultured neural cell after treatment of T3, T4 or dexamethasone (Dex). After 12 days cultured, neural cells were divided into T3 treatment group, T4 treatment group, Dex treatment group and control group. Respectively after 1, 2, 4 and 6 hours collected neural cells of four groups for semi-quantity RT-PCR. The other part was to observe the survival of neural cell in different concentration of iodine excess. Different concentrations of KI or KIO3 were added into neural cell, detected MTT 3 days, 7 days and 10 days later respectively. The results showed: (1) Neuron and astrocyte were更多还原