Nolten W E, Rueckert P A
Am J Obstet Gynecol. 1981 Feb 15;139(4):492-8. doi: 10.1016/0002-9378(81)90331-8.
Biologically active plasma free cortisol increases markedly in pregnancy. In this investigation the free cortisol index (FFI) in the plasma of pregnant and nonpregnant women was measured by a charcoal adsorption technique. The circadian FFI patterns were virtually identical in the two groups, but in gravid women there was a substantial and sustained elevation of the FFI. Sequential studies during gestation and post partum revealed increasing responsiveness of the maternal adrenal glands to adrenocorticotropic hormone (ACTH) and decreasing suppressibility of the FFI by dexamethasone as pregnancy advanced. Persistence of normal circadian rhythmicity in spite of a continuously elevated FFI and resistance to dexamethasone suppression suggest control of cortisol secretion by normal regulatory mechanisms in pregnancy with resetting of the maternal feedback mechanisms to higher levels. This resetting and the lack of manifestations of cortisol excess in pregnancy might result from tissue refractoriness to cortisol. Elevated free cortisol would be needed to maintain homeostasis. The necessary increase in the production of cortisol could be facilitated by an enhanced responsiveness of the maternal adrenal glands to ACTH.
生物活性血浆游离皮质醇在孕期显著增加。在本研究中，采用活性炭吸附技术测定了孕妇和非孕妇血浆中的游离皮质醇指数（FFI）。两组的昼夜FFI模式基本相同，但妊娠女性的FFI有显著且持续的升高。孕期和产后的系列研究显示，随着妊娠进展，母体肾上腺对促肾上腺皮质激素（ACTH）的反应性增加，而地塞米松对FFI的抑制性降低。尽管FFI持续升高但昼夜节律仍正常，以及对地塞米松抑制有抵抗性，这表明孕期皮质醇分泌受正常调节机制控制，且母体反馈机制重置为更高水平。这种重置以及孕期无皮质醇过量表现可能是由于组织对皮质醇的不应性。维持内环境稳定需要升高的游离皮质醇。母体肾上腺对ACTH反应性增强可能有助于促进皮质醇产生的必要增加。
