不同碘营养水平对哺乳期大鼠甲状腺和乳腺钠碘转运体mRNA表达的影响

摘要

Objective To study the effects of different levels of iodine concentration on sodium/iodide symporter(NIS) mRNA expression of thyroid and breast in lactating rats, and to explore their mechanisms. Methods Thirty Wistar female rats weighted 40-60 g, having been weaned for one month, were randomly divided into three iodine(HI, 10 rats). Synthetic fodder and deionized dringking water containing iodine of 0, 150 and 3000 μg/L were respectively fed to the rats in 3 groups. After fed for 3 months, the rats mated and had offspring. Their mammary glands, thyroids and serum were sampled at lactation day 5. The serum iodine of lactating rats was determined by moderate acid digestion method. T_3, T_4 levels were determined by radioimmunoassay method. The expressions of NIS mRNA of mammary glands and thyroids were determined by real-time fluorescence quantitative PCR assay. Results Serum iodine, T_3, T_4 and expression of NIS mRNA in lactating rats were statistically significant between 3 groups(F=499.94,16.67,8.49, H=7.58, all P < 0.05). The mean value of serum iodine of LI group[(17.38±3.27)μg/L] was lower than that Of AI group[(43.42±6.92)μg/L, P< 0.05], and the value of HI group[(350.10±38.46)μg/L] was higher than that of AI group(P < 0.05). Serum T_3 level in LI group[(1.11± 0.25)μg/L] and HI group[(1.61±0.33)μg/L] reduced obviously compared with that of AI group[(2.18±0.46) μg/L, all P< 0.05]. Serum T_4 level in LI group[(33.40±11.11)μg/L] and HI group[ (56.54±10.38)μg/L] had no statistical significance, but the level of serum T_4 in LI group was lower than that in HI group(P < 0.05). The NIS mRNA expression of thyroid in LI group(0.280±0.030) was higher than that in AI group(0.240±0.030, P<0.05), but it was lower in HI group (0.069±0.037). NIS mRNA expression of lactating mammary in HI group (0.027±0.007) was lower than that in AI group(P < 0.05). Conclusions Mild iodine deficiency can increase the level of NIS mRNA expression of thyroid and protect the mother from damage caused by low-iodine, but no obvious protective effect on the next generation has been found. High-iodine inhibits NIS mRNA expression in thyroid and breast, thus protecting mother and its next generation from the high-iodine hazards.%目的 观察不同碘营养水平对哺乳期大鼠甲状腺和乳腺钠碘转运体(NIS)mRNA表达水平的影响.方法 Wistar大鼠30只,体质量40～60 g.按体质量将大鼠随机分成3组:低碘组(去离子水),适碘组(含碘150 μg/L的去离子水),高碘组(含碘3000μg/L的去离子水),3组均喂合成饲料.喂养3个月后,与雄鼠合笼交配,待母鼠哺乳5 d后处死,取母鼠乳腺、甲状腺及血清.采用温和酸消化法测定血清碘,放射免疫分析法测定血清T_3、T_4水平,实时荧光定量PCR法检测乳腺和甲状腺NIS mRNA表达.结果 哺乳期大鼠血清碘、T_3、T_4、NIS mRNA表达,组间比较差异有统计学意义(F值分别为499.94、16.67、8.49,H=7.58,P均<0.05).血清碘适碘组[(43.42±692)μg/L]高于低碘组[(17.38±3.27)μg/L,P<0.05],高碘组[(350.10±38.46)μg/L]高于适碘组(P<0.05).血清T_3水平,低碘组、高碘组[(1.11±0.25)、(1.61±0.33)μg/L]低于适碘组[(2.18±0.46)μg/L,P均<0.05].血清T_4水平,低碘组[(33.40±11.11)μg/L]低于高碘组[(56.54±10.38)μg/L,P<0.05].甲状腺NIS mRNA表达水平低碘组(0.280±0.030)高于适碘组(0.240±0.030,P<0.05).高碘组(0.069±0.037)低于适碘组(P<0.05).哺乳期乳腺NIS mRNA表达水平高碘组(0.027±0.007)低于适碘组(0.051±0.019,P<0.05).结论 轻度低碘能够提高甲状腺NIS mRNA表达,保护母体免受低碘的危害,但对下一代的保护作用不明显或没有保护作用;高碘抑制甲状腺和乳腺NIS mRNA表达,保护母体及下一代免受高碘的危害.