不同碘营养水平对妊娠期母鼠甲状腺功能的影响

The effect of different levels of iodine nutrition on rat maternal thyroid function during pregnancy

目的观察不同碘营养水平对妊娠期母鼠甲状腺功能的影响。方法断乳后1个月的Wistar大鼠225只，其中雌鼠165只，雄鼠75只，体质量80～100g。按体质量将雌鼠随机分为6组：对照组（NI组）、低碘1组（L11组）、低碘2组（L12组）、高碘1组（H11组）、高碘2组（H12组）以及未孕对照组（NNI组）。第1～5组各30只，第6组15只。L11、L12组：低碘饲料＋不含碘或含碘5μg／L的去离子水；H11、H12组：普通饲料＋含碘3000、10000μg／L的去离子水；NI、NNI组：普通饲料＋含碘50μ/L的去离子水。在12周后，将雌鼠（第6组除外）与雄鼠按2：1合笼交配，将受孕母鼠单笼喂养，分别在孕早期：（5±2）d、孕中期：（12±2）d、孕晚期：（17±2）d时处死孕鼠，取血和甲状腺。血清总甲状腺素（TT4）、游离甲状腺素（gr4）、总三碘甲腺原氨酸（TT3）、游离三碘甲腺原氨酸（FT3）、促甲状腺激素（TSH）测定采用放射免疫分析法。血清甲状腺球蛋白（TG）、甲状腺结合球蛋白（TBG）测定采用酶联免疫标记法。结果①甲状腺绝对质量、相对质量组间比较差异有统计学意义（F值分别为16．55、24．25，P〈0．01或〈0．05）。②孕早、孕中、孕晚期母鼠血清n、n组间比较差异有统计学意义（F值分别为5．02、13．4l、17．39，41．89、23．72、48．64，P〈0．01或〈0．05）。NI、H11、H12组不同孕期母鼠血清TT4、FT4组内比较差异有统计学意义（F值分别为3．27、6．98、8．22，8．65、29．68、7．90，P〈0．0l或〈0．05）。③孕早、孕晚期母鼠血清1Tr，组间比较差异有统计学意义（F值分别为3．59、8．22，P〈0．05或〈0．01）；孕中、孕晚期母鼠血清FTr，组间比较差异有统计学意义（F值分别为3．86、4．26，P〈0．05或〈0．01）。NI、L11、H11组不同孕期母鼠血清TT3组内比较差异有统计学意义（F值分别为8．77、7．11、6．28，P〈0．01或〈0．05）。④孕早、孕中、孕晚期母鼠血清TG、TBG组间比较差异有统计学意义（F值分别为5．47、3．62、9．35，4．15、13．16、22．78，P〈0．01或〈0．05）。H11组不同孕期母鼠血清TG组内比较和NI组血清TBG组内比较差异有统计学意义（F值分别为3．18、7．94，P均〈0．05）。⑤孕早、孕中、孕晚期母鼠血清TSH组间比较差异有统计学意义（F值分别为4．83、7．08、6．52，P均〈0．01）；5组不同孕期母鼠血清TSH组内比较差异有统计学意义（F值分别为3．26、8．89、11．45、4．04、3．78，P均〈0．05）。结论碘营养水平不同，能导致妊娠期母鼠甲状腺功能的变化。碘缺乏时母鼠血清TT4、FT4水平下降，碘过量时TT4、FT4水平增加。但由于机体存在代偿调节作用．母鼠血清TT3、FT3，水平变化不明显。

Objective To observe the effect of different levels of iodine nutrition on rat maternal thyroid function during pregnancy. Methods A total of 225 Wistar rats one month after weaning were involved in the study（female 165, male 60, body mass 80 to 100 g）. Female rats were randomly divided into six groups by body mass： control group（NI group）, iodine deficiency 1 and 2 groups（LI1, LI2 groups）, iodine excess 1 and 2 groups （HI1, HI2 groups）, and the control of not pregnant group（NNI group）. There were 30 rats in 1 - 5 groups and 15 rats in group 6. LI1, LI2 groups： low iodine diet ＋ deionized water of no iodine or iodine-containing 5 μg/L; HI1, HI2 groups： normal diet ＋ deionized water of iodine 3000, 10 000 μg/L; NI, NNI groups： normal diet ＋ deionizedwater of iodine-containing 50 μg/L. After 12 weeks, the females（except group 6） mated the male by 2 ： 1, and then each pregnant female rat was fed in a single cage. The female mice were sacrificed in the first（5 ± 2）d, the second （12 ± 2）d and the third trimesters of pregnancy （17 ± 2）d, respectively, and there blood samples and thyroid were obtained. Serum total thyroxine （TY4）, free thyroxine （FT4）, total triiodothyronine （TY3）, free triiodothyronine （FT3） and thyroid stimulating hormone （TSH） were determined by radioimmunoassay and serum thyroglobulin （TG） and thyroid-binding globulin （TBG） were determined by enzyme-linked immunosorbent assay. Results ①Thyroid absolute quality and relative quality was compared among groups, and the differences were statistically significant （F = 16.55, 24.25, F 〈 0.01 or 〈 0.05）. ②At the first, the second and the third trimesters of pregnancy, the differences of maternal serum TY4 and FT4 between groups were statistically significant（F= 5.02, 13.41, 17.39, 41.89, 23.72, 48.64, P 〈 0.01 or 〈 0.05）. Female rats in NI, HI1 and HI2 groups in different pregnant periods among inner groups were compared, and the differences of serum TT4 and FT4 were statistically significant（F= 3.27, 6.98, 8.22, 8.65, 29.68, 7.90, P 〈 0.01 or 〈 0.05）. ③ In the first and the third trimesters of pregnancy, maternal serum Tr3 was compared among groups, and the differences were statistically significant （F = 3.59, 8.22, P 〈 0.05 or 〈 0.01 ）; in the second and the third trimesters of pregnancy, maternal serum FT3 was compared among groups, and the difference was statistically signifieant（F = 3.86, 4.26, P 〈 0：05 or 〈 0.01）. Female rats in NI, LI1 and HI1 groups in different pregnant periods among inner groups were compared, and the differences of maternal serum TT3 were statistically significant（F = 8.77, 7.11, 6.28, P 〈 0.01 or 〈 0.05）. ④At the first, the second and the third trimesters of pregnancy, the differences of maternal serum TG and TBG were compared in groups, and the differences were statistically significant（F = 5.47, 3.62, 9.35, 4.15, 13.16, 22.78, P 〈 0.01 or 〈 0.05）. The differences of maternal serum TG of HI1 group and of serum TBG of NI group in different pregnant periods among inner groups were statistically significant（F = 3.18, 7.94, P 〈 0.05）. ⑤At the first, the second and the third trimesters of pregnancy, the differences of maternal serum TSH in groups were statistically significant（F = 4.83, 7.08, 6.52, P 〈 0.01 ） ; the differences of maternal serum TSH of all the 5 groups in different pregnant periods among inner groups were statistically significant （F = 3.26, 8.89, 11.45, 4.04, 3.78, P 〈 0.05）. Conclusions Different levels of iodine nutrition can cause changes in thyroid function in rats maternal thyroid function during pregnancy; serum TT4, FT4 level decreases when iodine deficiency, and increase with iodine excess. Serum TF3, FY3 level of does not changed significantly due to compensatory regulation of the body.