Sato S, Hanew K, Sasaki A, Shimizu Y, Murakami O, Fukazawa H, Sakurada T, Saito S, Yoshinaga K
Tohoku J Exp Med. 1984 Dec;144(4):425-31. doi: 10.1620/tjem.144.425.
Thyroid hormones are known to exert some influence on prolactin (PRL) secretion indirectly via the hypothalamic dopaminergic system and directly at the level of pituitary gland. In order to study the effect of thyroid hormones on the activity of hypothalamic dopamine neurons, lactotrophs and thyrotrophs, we administered increasing doses of thyroid hormones to patients with primary hypothyroidism, and examined the changes of basal PRL, TSH and PRL responses to a dopamine receptor blocker (sulpiride). Among 24 patients with primary hypothyroidism, hyperprolactinemia was observed in 10 cases (18.0-236 ng/ml, mean +/- S.E. 58.6 +/- 20.0 ng/ml), while elevated TSH levels were observed in all of them (6.6-972 microU/ml, mean +/- S.E. 231.4 +/- 53.9 microU/ml). There was a significant negative relationship between plasma T3 or T4 levels and basal plasma TSH levels (p less than 0.05), whereas a poor correlation was observed between the thyroid hormones and basal plasma PRL levels (r = -0.25, p greater than 0.05). Following the administration of gradually increasing doses of thyroid hormones, plasma PRL showed paradoxical and transient increases, while plasma TSH decreased steadily. Plasma PRL response to sulpiride also became exaggerated during the treatment. The elevated basal PRL level and the enhanced response to sulpiride turned to be within the normal range when the patients became euthyroid by treatment. These results may indicate that thyroid hormones stimulate not only hypothalamic dopaminergic activity, but also the lactotroph activity in a long term hypothyroid state. Regarding the paradoxical elevation of basal PRL, one can postulate that the activation of lactotroph by a small dose of thyroid hormone may be able to overcome the hypothalamic dopaminergic inhibition.
已知甲状腺激素可通过下丘脑多巴胺能系统间接对催乳素（PRL）分泌产生某些影响，并直接作用于垂体水平。为了研究甲状腺激素对下丘脑多巴胺神经元、催乳素细胞和促甲状腺激素细胞活性的影响，我们对原发性甲状腺功能减退症患者给予递增剂量的甲状腺激素，并检测基础PRL、促甲状腺激素（TSH）以及PRL对多巴胺受体阻滞剂（舒必利）反应的变化。在24例原发性甲状腺功能减退症患者中，10例出现高催乳素血症（18.0 - 236 ng/ml，平均±标准误58.6±20.0 ng/ml），而所有患者的TSH水平均升高（6.6 - 972 μU/ml，平均±标准误231.4±53.9 μU/ml）。血浆T3或T4水平与基础血浆TSH水平之间存在显著负相关（p < 0.05），而甲状腺激素与基础血浆PRL水平之间的相关性较差（r = -0.25，p > 0.05）。给予逐渐递增剂量的甲状腺激素后，血浆PRL出现反常且短暂的升高，而血浆TSH则稳步下降。治疗期间血浆PRL对舒必利的反应也变得增强。当患者经治疗甲状腺功能恢复正常时，升高的基础PRL水平及对舒必利的增强反应均恢复至正常范围。这些结果可能表明，在长期甲状腺功能减退状态下，甲状腺激素不仅刺激下丘脑多巴胺能活性，还刺激催乳素细胞活性。关于基础PRL的反常升高，可以推测小剂量甲状腺激素对催乳素细胞的激活可能能够克服下丘脑多巴胺能抑制作用。
