高碘摄入对大鼠乳腺和胎盘钠碘转运体mRNA表达的影响

Effects of High Levels Iodine Intake through Meal on mRNA Expression of Placental and Breast NIS in Rats

目的研究不同高碘水平饮食对孕期母鼠胎盘和哺乳期母鼠乳腺钠-碘转运体(Na+-I-symporter,NIS)mRNA水平表达的影响。方法将断乳后1个月的健康Wistar大鼠按体重随机分为适碘组(NI)、10倍碘(10HI)组、100倍碘(100HI)组,每组30只,雌∶雄比例为2∶1,其碘摄入量估计分别为6.15、61.5、615.0μg/d。染毒3个月后,采用过硫酸铵消化-砷铈催化分光光度法测定母鼠尿碘含量,分别在母鼠孕期第17天和母鼠哺乳期第10天,用反转录-聚合酶链式反应(RT-PCR)测定母鼠胎盘、乳腺钠-碘转运体(NIS)mRNA水平表达强度。结果10HI组、100HI组尿碘含量中位数分别为3597.5、25404.3μg/L,高于NI组(344.7μg/L),差异均有统计学意义(P<0.05);且尿碘中位数随着饮食中碘含量的增加而增加。与NI组比较,100HI组孕期胎盘中NIS mRNA的AR值和10HI组和100HI组哺乳期乳腺中NISmRNA的AR值均较低,经LSD检验,差异均有统计学意义(P<0.01);且AR值随着摄入碘量的增加而降低。结论高碘摄入抑制胎盘和乳腺中NIS的表达,此机制对子代有着重要的保护作用。

Objective To study the effects of excessive iodine intake through the meal on the expression of mRNA of placental NIS in pregnant rat and breast NIS in lactating rats. Methods Wistar rats, weaning one month, were randomly divided into three groups according to the body weights, i.e., normal iodine (NI), ten fold high iodine(10HI), one hundred fold high iodine(100HI), the ratio of female and male was 2∶1. Iodine intake of the groups were about 6.15, 61.5 and 615.0 mg/d respectively. After 3 months of treatment, the urine iodine was determined by As-Ce-catalytic spectrophotometry. The rats mated and had offspring. Their placenta and breasts were taken on the seventeenth day of pregnancy and tenth day of lactation respectively. Then NIS mRNA expression was determined by RT-PCR. Results The urine iodine increased with the increase of the iodine intake. The urine iodine and iodine intake showed the parallel magnification. Compared with the NI group,AR value of the placental NIS mRNA in 100HI group and the breast NIS mRNA in 10HI and 100HI group significantly decreased. Conclusion Excessive iodine intake may down-regulate the expression of the placental and breast NIS, which presents a protective effect on offspring.