Strbák V, Macho L, Skultétyová M, Michalicková J, Pohlová G
Endocrinol Exp. 1983 Oct;17(3-4):219-35.
Reported values of the concentration of thyroid hormones in milk vary substantially. There are some doubts on the specificity of methods used for their estimation. We aimed, therefore, to study the effects of mother milk on thyroid function parameters in sucklings as well as at the effect of milk secretion on maternal thyroid. According to Fukuda et al. [1980] the lactation induces a hypothyroid state in the rat (high TSH, low thyroid hormones in maternal plasma). In our study the weaning of 18-day old rats resulted in gradual decrease of T4 in suckling plasma through 24 h followed with a transient thyroid activation. Thyroidectomy of lactating rats resulted in a transient decrease of T4 in sucklings. The difference in mother milk intake achieved by different litter size also affected the thyroid function of sucklings. The pups from small size litters (more milk consumption) had low thyroid secretion rate and low plasma TSH, while the level of T4 in plasma was high under a higher growth rate and accelerated overall maturation. All these results suggest an exogenous intake of thyroid hormones in suckling rat. We found that lactation in women resulted in lower T4 and higher TSH in plasma as compared to women who had interrupted their lactation. In the next part of our study more than 80 infants were longitudinally followed and sampled at birth (cord blood), at 2, 6 and 10 weeks and at 4, 6, 9 and 12 months. Only moderate differences were found at 4 months (high rT3) in breast fed infants and 9 at months (high T3 in plasma of infants weaned during the first week of life) when the data were evaluated according to the type of feeding. Thyroid activity of human milk was tested by feeding thyroidectomized rats with a diet containing human milk. Although plasma TSH was affected by such a diet, we did not detect any T4 and T3 in plasma of thyroidectomized rats which probably refects low calculated intake of hormones with the diet. We conclude that the lactation affects the thyroid economy of maternal organisms. Maternal milk definitely affects thyroid function parameters in the rat, while the effect on infant thyroid is more difficult to demonstrate.
报道的母乳中甲状腺激素浓度值差异很大。用于评估其浓度的方法的特异性存在一些疑问。因此，我们旨在研究母乳对哺乳幼崽甲状腺功能参数的影响，以及乳汁分泌对母体甲状腺的影响。根据福田等人[1980年]的研究，哺乳会使大鼠处于甲状腺功能减退状态（母体血浆中促甲状腺激素高，甲状腺激素低）。在我们的研究中，18日龄大鼠断奶后，哺乳幼崽血浆中的甲状腺素（T4）在24小时内逐渐下降，随后甲状腺出现短暂激活。对哺乳大鼠进行甲状腺切除会导致哺乳幼崽的T4短暂下降。不同窝仔数导致的母乳摄入量差异也影响了哺乳幼崽的甲状腺功能。来自小窝仔数（母乳消耗量更大）的幼崽甲状腺分泌率低，血浆促甲状腺激素低，而血浆中T4水平高，生长速度更快，整体成熟加速。所有这些结果表明哺乳幼崽有外源性甲状腺激素摄入。我们发现，与停止哺乳的女性相比，哺乳期女性血浆中的T4较低，促甲状腺激素较高。在我们研究的下一阶段，对80多名婴儿进行了纵向跟踪，并在出生时（脐带血）、2周、6周和10周以及4个月、6个月、9个月和12个月时进行采样。根据喂养方式评估数据时，仅在4个月时发现母乳喂养婴儿有中度差异（反三碘甲状腺原氨酸[rT3]高），在9个月时发现出生第一周断奶的婴儿血浆中三碘甲状腺原氨酸[T3]高。通过用含有人乳的饮食喂养甲状腺切除的大鼠来测试人乳的甲状腺活性。虽然这种饮食会影响血浆促甲状腺激素，但我们在甲状腺切除大鼠的血浆中未检测到任何T4和T3，这可能反映了饮食中激素的计算摄入量较低。我们得出结论，哺乳会影响母体的甲状腺生理状态及物质代谢。母乳肯定会影响大鼠的甲状腺功能参数，而对婴儿甲状腺的影响则更难证明。
