Rubello D, Sonino N, Casara D, Girelli M E, Busnardo B, Boscaro M
Istituto di Semeiotica Medica, Università di Padova, Italy.
J Endocrinol Invest. 1992 Jun;15(6):437-41. doi: 10.1007/BF03348767.
It is known that glucocorticoids can influence anterior pituitary hormones other than ACTH. Their effects on the hypothalamic-pituitary-thyroid axis are controversial. To further investigate this issue, the acute and chronic effects of high plasma cortisol levels on TSH secretion were evaluated in 20 normal subjects and in 14 patients with Cushing's syndrome. In normals, high plasma cortisol levels were obtained by giving ACTH 250 micrograms or CRH 100 micrograms iv as a bolus or by an hydrocortisone 500 mg infusion over 1 h. Acute cortisol increase produced no effect both on basal and TRH-stimulated TSH secretion. In patients with Cushing's syndrome, basal TSH levels, low or suppressed, showed an impaired response to TRH, inversely correlated with urinary cortisol values. After successful surgery, TSH and its response to TRH became normal in concomitance with the normalization of plasma and urinary cortisol levels. Our data show the lack of an acute inhibitory effect of high plasma cortisol levels on TRH-TSH axis. However, after long-term exposure to high plasma cortisol levels, i.e. Cushing's syndrome, inhibition of both basal and TRH-stimulated TSH secretion was demonstrated. These findings indicate that only prolonged hypercortisolism does interfere with pituitary TSH secretion. The underlying mechanisms are still unclear.
已知糖皮质激素可影响促肾上腺皮质激素（ACTH）以外的垂体前叶激素。它们对下丘脑 - 垂体 - 甲状腺轴的影响存在争议。为了进一步研究这个问题，在20名正常受试者和14名库欣综合征患者中评估了高血浆皮质醇水平对促甲状腺激素（TSH）分泌的急性和慢性影响。在正常受试者中，通过静脉推注250微克促肾上腺皮质激素（ACTH）或100微克促肾上腺皮质激素释放激素（CRH），或在1小时内输注500毫克氢化可的松来获得高血浆皮质醇水平。急性皮质醇升高对基础和促甲状腺激素释放激素（TRH）刺激的TSH分泌均无影响。在库欣综合征患者中，基础TSH水平低或受到抑制，对TRH的反应受损，与尿皮质醇值呈负相关。成功手术后，随着血浆和尿皮质醇水平恢复正常，TSH及其对TRH的反应也恢复正常。我们的数据表明高血浆皮质醇水平对TRH - TSH轴缺乏急性抑制作用。然而，长期暴露于高血浆皮质醇水平，即库欣综合征后，基础和TRH刺激的TSH分泌均受到抑制。这些发现表明只有长期皮质醇增多症才会干扰垂体TSH分泌。其潜在机制仍不清楚。
