Mastorakos G, Ilias I
Endocrine Unit, Evgenidion Hospital, University of Athens, Greece.
Ann N Y Acad Sci. 2000;900:95-106. doi: 10.1111/j.1749-6632.2000.tb06220.x.
During pregnancy, placenta-derived CRH increases exponentially in the plasma. Circulating levels of CRH-binding protein decrease considerably in the last trimester of pregnancy, resulting in further elevation of bioavailable plasma CRH. The adrenal glands during pregnancy gradually become hypertrophic because of the increase in ACTH, which parallels that of CRH. Thus, pregnancy is a transient period of relative hypercortisolism. The activation of the hypothalamic-pituitary-adrenal axis during pregnancy has been proposed to function as a biological clock. In this model, the placenta is perceived as a stress-sensitive organ and placental CRH as a timing starter, determining a preterm, term, or postterm labor. During pregnancy, as well as during the immediate postpartum period, the hypothalamic maternal CRH secretion is suppressed, because of the circulating levels of cortisol. Hypothalamic CRH secretion normalizes within 12 weeks. This transient postpartum maternal hypothalamic CRH suppression, together with the steroid withdrawal that follows parturition, might be causally related to the mood disorders and the vulnerability to autoimmune diseases such as thyroiditis or rheumatoid arthritis often observed during the postpartum period.
在怀孕期间，胎盘来源的促肾上腺皮质激素释放激素（CRH）在血浆中呈指数级增加。在妊娠晚期，CRH结合蛋白的循环水平显著下降，导致血浆中生物可利用的CRH进一步升高。由于促肾上腺皮质激素（ACTH）增加，孕期肾上腺逐渐肥大，这与CRH的增加平行。因此，怀孕是一个相对高皮质醇血症的短暂时期。有人提出，孕期下丘脑-垂体-肾上腺轴的激活起到生物钟的作用。在这个模型中，胎盘被视为一个对压力敏感的器官，胎盘CRH被视为计时启动器，决定早产、足月产或过期产。在怀孕期间以及产后即刻，由于皮质醇的循环水平，下丘脑母体CRH分泌受到抑制。下丘脑CRH分泌在12周内恢复正常。产后母体下丘脑CRH的这种短暂抑制，连同分娩后随之而来的类固醇撤退，可能与产后经常观察到的情绪障碍以及易患自身免疫性疾病如甲状腺炎或类风湿性关节炎有因果关系。
