低碘膳食对大鼠脑组织中同源盒基因NKX－2.2表达的影响

目的：探讨低碘膳食对大鼠脑组织同源盒基因Nkx－2.2表达的影响，揭示低碘导致脑发育迟滞的可能分子作用机制。方法：雌性Wistar大鼠随机分为2组：低碘组和正常对照组，均饲以低碘饲料，分别饮用去离子水和碘酸钾溶液，3个月后分别取材于孕16天、新生及20日鼠龄低碘及正常仔鼠，实时荧光定量PCR检测其脑组织中Nkx－2.2 mRNA含量。结果：低碘组血清甲状腺激素水平明显低于对照组(P＜0.05或P＜0.01），建立缺碘Wistar大鼠动物模型。低碘及正常各年龄组的表达水平随着年龄增加表达趋势不一致，但均有明显差别（F=573.68、120.82, P<0.01)。各年龄组低碘及正常大鼠比较，孕16天正常鼠Nkx－2.2表达水平明显高于低碘鼠(t=6.86, P<0.01)，而新生及20日龄低碘鼠Nkx－2.2表达水平明显高于正常鼠(t=15.85、10.61, P<0.01)。结论：同源盒基因Nkx－2.2表达差异与低碘导致脑发育迟滞密切相关。

Effects of Low-iodine Diet on the Expression of Homeobox Gene NKX-2.2 in Rat Cerebrum Tissue

【Abstract】 Objective To explore the influence of low-iodine diet on the expression of homeobox gene NKX-2.2 in rat cerebrum tissue, and to explain the possible molecular mechanism of cerebrum development retardation caused by low-iodine. Methods Female Wistar rats were randomly divided into two groups：Low-iodine group and control group，both fed with low-iodine feed, given the deionized water and KIO3 solution respectively, They were drawn from the 16-day pregnancy, new-born and 20th days old low-iodine and normal age offspring after three months, and detect the content of NKX-2.2 mRNA in the cerebrum tissue by Real-time fluorescence quantitative PCR techniques. Results the thyroid hormone levels of low-iodine group in serum were significantly lower than the control group (P <0.05 or P <0.01), establish the model of iodine deficiency Wistar rats. Compared with low-iodine rats of several ages, the expression of Nkx-2.2 have significant differences with the growth of ages (F=386.37, P<0.01), the expression trend of normal group is difference but have significant difference among several ages(F=118.37, P<0.01); compared low-iodine rats groups in several ages with normal’s, the 16 days pregnant normal rats have obvious higher level of Nkx-2.2 expression than the low-iodine rats(t=8.814, P<0.01), while the Nkx-2.2 of new-born and 20 days old low-iodine rats express much higher than normal rats(t=4.319、9.971, P<0.01). Conclusion The difference in the expression of Nkx-2.2 is highly related to the brain development retardation caused by low-iodine.