摘要
目的研究低碘膳食对大鼠脑组织同源盒基因Nkx-6.1、Nkx-6.2 mRNA表达的影响,探讨低碘导致脑发育迟滞的可能分子作用机制。方法20只雌性Wistar大鼠按体质量随机分为2组:低碘组和对照组,均饲以低碘饲料(含碘量为13.66μg/kg),分别饮用去离子水和含碘200μg/L的碘酸钾溶液,3个月时采用化学发光免疫分析法检测大鼠血清甲状腺激素水平,然后将雌鼠与正常饲养的Wistar雄鼠进行交配,分别取孕16d、新生期及生后20日龄仔鼠脑组织,采用实时荧光定量PCR检测Nkx-6.1、Nkx-6.2 mRNA的表达。结果①低碘组大鼠血清TT3、TT4、FT3、FT4水平[(0.89±0.20)、(0.32±0.16)nmol/L,(3.33±0.61)、(3.28±0.80)pmol/L]均明显低于对照组[(1.04±0.06)、(39.42±14.68)nmol/L,(4.83±0.33)、(26.99±4.48)pmol,t=2.71、6.52、5.70、12.89,P〈0.05或〈0.01]。②对照组孕16d、新生期及20日龄仔鼠脑组织Nkx-6.1 mRNA表达水平分别为(1.90±0.23)×10^-3、(1.86±0.40)×10^-4、(1.11±0.27)×10^-4,各日龄间比较差异有统计学意义(F=827.58.P〈0.01),随着日龄增加Nkx-6.1mRNA表达水平明显下降.两两比较差异均有统计学意义(P均〈0.01);低碘组各日龄仔鼠脑组织Nkx-6.1mRNA表达水平分别为(1.16±0.16)×10^-3、(3.44±0.49)×10^-4、(3.58±0.64)×10^-4,差异有统计学意义(F=297.25,P〈0.01),但变化趋势与对照组不同,孕16d表达水平最高,与新生期及20日龄比较,差异有统计学意义(P〈0.01);低碘组与对照组比较,孕16d明显降低(t=10.14,P〈0.01),而新生期及20日龄则明显增高(t值分别为9.69、13.81,P均〈0.01)。③对照组和低碘组各日龄仔鼠脑组织Nkx-6.2 mRNA表达水平分别为(1.03±0.19)×10^-2、(1.33±0.10)×10^-3、(8.79±0.87)×10^-2和(0.31±0.03)×10^-2、(1.53±0.13)×10^-3、(7.51±0.86)×10^-2,组间比较差异有统计学意义(F值分别为1293.02、1065.83,P均〈0.01),随着日龄增加,两组表达趋势一致,20日龄最高,孕16d次之,新生期最低;低碘组20日龄仔鼠与新生期及孕16d比较,差异有统计学意义(P均〈0.01),对照组新生期仔鼠与孕16d比较,差异有统计学意义(P〈0.01);低碘组与对照组比较,孕16d及20日龄明显降低(t值分别为14.35、4.05,P均〈0.01),而新生期仔鼠则明显增高(t=4.78,P〈0.01)。结论同源盒基因Nkx-6.1、Nkx-6.2 mRNA表达水平改变可能与低碘导致脑发育迟滞有关。
Objective To study the influence of low-iodine diet on the expression of homeobox gene Nkx- 6.1 and Nkx-6.2 in rat cerebrum tissue, and to explore the possible molecular mechanism of cerebrum development retardation caused by low-iodine. Methods Twenty female Wistar rats were randomly equally divided into two groups: low-iodine group and control group, both fed with low-iodine diet as low as 13.66 μg/kg determinated by spectrophotometry in Tianjin Institute of Endocrinology and the former with deionized water, the later 200 μg/L potassium iodate. Thyroid hormone level was detected using chemiluminescence immunoassay 3 months later and they were mated with male rats normally fed. Rats of 16-day pregnancy, new-born and 20th davs old were detected the content of Nkx-6.1 and Nkx-6.2 mRNA in the cerebrum tissue by real-time fluorescence quantitative PCR techniques. Results ①TT3, TT4, FT3 and FT4 levels of low-iodine group[ (0.89 ± 0.20), (0.32± 0.16)nmol/L, (3.33 ±0.61 ), (3.28 ± 0.80)pmol/L] were lower than the control group [ (1.04 ± 0.06), (39.42 ± 14.68)nmol/L, (4.83 ± 0.33), (26.99 ± 4.48)pmol, t = 2.71,6.52,5.70,12.89, all P 〈 0.05 or 0.01]. ②Nkx-6.1 mRNA expression level in 16- day pregnancy, new-born and 20th days old of control group was (1.90 ± 0.23) × 10^-3, (1.86 ± 0.40) × 10^-4, (1.11 ± 0.27) × 10^-4(F = 827.58, P〈 0.01 ), Nkx-6.1 mRNA expression level gradually decreased along with aging(all P 〈 0.05). The intra-group difference was significant (F = 297.25, P 〈 0.01 ) and the Nkx6.1 mRNA expression level during 16 days of pregnancy was the highest(P 〈 0.01 ). It was higher in the control group than in the low-iodine group during 16 days of pregnancy (t = 10.14, P 〈 0.01) as well as in the low-iodine group than in the control group during newborn and 20th days old(t = 9.69,13.81, all P 〈 0.01 ). ③Nkx-6.2 mRNA expression level in 16-day pregnancy, new-born and 20th days old of control group was respeetively(1.03 ± 0.19) × 10^-2, (1.33 ±0.10) × 10^-3,(8.79 ± 0.87) × 10^-2, and that of low-iodine group was (0.31± 0.03) × 10^-2, (1.53 ± 0.13) × 10^-3, (7.51 ± 0.86) × 10^-2. The intra-group difference was significant(F = 1293.02,1065.83, all P 〈 0.01 ). Nkx-6.2 expression level during 20th days old was the highest(P 〈 0.01 ) and that of newborn was the lowest(P 〈 0.01 ). The Nkx6.2 mRNA expression level in control group were higher than the low-iodine group during 16-day pregnancy and 20th days old(t = 14.35, 4.05, all P 〈 0.01). It was higher in the low-iodine group than in the control group during newborn (t = 4.78, P 〈 0.01 ). Conclusions The difference in the expression of Nkx-6.1 and Nkx-6.2 is highly related to the brain development retardation caused by low-iodine.
出处
《中国地方病学杂志》
CAS
CSCD
北大核心
2009年第5期488-492,共5页
Chinese Jouranl of Endemiology
基金
国家自然科学基金(30571617)
天津市科技发展计划“重中之重”学科建设项目(05YFCDSF02700)
关键词
基因
同源盒Nkx
聚合酶链反应
发育障碍
脑
Genes, homeobox
Polymerase chain reaction
Developmental disabilities, brain