不同碘水平对哺乳期母鼠和仔鼠碘代谢及甲状腺功能影响的研究

Mother-infant＇s iodine metabolism and thyroid function during lactation with different iodine intakes

目的 研究不同碘水平对哺乳期母鼠和仔鼠的碘代谢及甲状腺功能的影响.方法 Wistar母鼠随机分为4组：重度缺碘组（SID）,轻度缺碘组（MiID）,正常碘组（NI）,碘过量组（ExI）.所有大鼠均食用缺碘饲料,饮水给予不同剂量的碘化钾,喂养3个月后交配,检测哺乳14 d时母鼠及其仔鼠的尿碘、乳汁碘、血碘和血液甲状腺激素（TH）水平,测定母鼠甲状腺重量,观察母鼠和仔鼠甲状腺形态学改变.结果 （1）母鼠及仔鼠尿碘、乳汁碘和血碘均随饮食碘供给量的增加而增加,其组间变化幅度以尿碘为最高、乳汁碘次之、血碘最低.（2）与NI组比较,SID组母鼠血清TT44降低[（16.7±12.0对36.4±15.0）nmol/L,P〈0.05],TSH[（5.73＋2.90对1.38＋0.30）mIU/L,P〈0.01]和TT3/TT4比值（6.6＋2.7对2.1±0.3,P〈0.01）升高,仔鼠TT4[（10.6＋2.3对16.4±4.7）nmoL/L,P〈0.05]降低;MiID和ExI组无论母鼠和仔鼠均与NI组无明显差异.（3）SID组母鼠和仔鼠发生典型小滤泡增生性甲状腺肿,MiID组母鼠呈现轻度甲状腺肿,ExI组母鼠甲状腺呈现轻度多形性特征,而两组仔鼠甲状腺与NI组无明显差别.结论 重度缺碘会导致母-子甲状腺功能减退,但在轻度缺碘和碘过量时通过母体和仔代的代偿作用可以维持母-子正常的碘营养和甲状腺功能.

Objective To study mother and infant＇s iodine metabolism and thyroid function during lactation with different iodine intakes. Methods Wistar rats were randomly assigned to four groups with severe iodine deficiency （SID）, mild iodine deficiency （MiID）, normal iodine （NI）, and excessive iodine （ExI） intake respectively. All rats were fed on an iodine deficient food and drinking water with different quantities of potassium iodide for 3 months until mating. The urinary iodine, milk iodine, blood iodine, and thyroid hormones （TH） were detected in lactating mother and the offspring rats 14 days after birth. Thyroid weight of mother rats was determined. Thyroid morphology of mother and their offsprings was observed. Results （ 1） Iodine contents in urine, milk, and blood of lactating rats and the offsprings were increased with the increase of iodine supplied in diet. But the change in amplitude between groups was decreased in the other; urine iodine 〉 milk iodine 〉 blood iodine. （2） Serum TT4[ （16. 7±12. 0 vs 36.4±15. 0） nmol/L, P〈0.05] was significantly decreased, but TSH [（5.73±2.90vs 1. 38±0.30）mIU/L, P〈0.01]and TT3/TT4（6.6±2.7 vs 2. l±0.3,P〈0.01） were increased in lactating rats of SID group compared with NI, so as TT4（ 10.6±2. 3 vs 16.4±4. 7） nmol/L, P〈0.05 ] of offspring rats in SID, but were not in MiID and ExI groups. （3 ） Histological studies showed that small follicular thyroid nodules with follicular hyperplasia occurred in both lactating rats and their offsprings in the SID group, mild swelling in MiID group and polymorphism changes appeared in mother rats of ExI group, but no significant difference appeared in offsprings compared with NI group. Conclusions Severe iodine deficiency will lead to hypothyroidism in mother and infant, but normal iodine nutrition and thyroid function in mother and offspring were maintained through the compensatory action of mother and child in mild iodine deficiency and iodine excess.