Margioris A N, Grino M, Rabin D, Chrousos G P
Developmental Endocrinology Branch, National Institute of Child Health and Human Development, Bethesda, MD 20892.
Adv Exp Med Biol. 1988;245:389-98. doi: 10.1007/978-1-4899-2064-5_30.
Maternal plasma bound and free cortisol rises during pregnancy, while maternal plasma IR-ACTH is initially low but soon rises inspite of the further increase of plasma free cortisol. This rise of plasma ACTH during pregnancy, can not be attributed to changes of plasma levels of estrogens or progesterone. It is possible that the human placenta is responsible for the rise in maternal plasma ACTH during pregnancy. There are two possible mechanisms by which this effect could occur: 1) by the placental secretion of CRH into the maternal circulation, which stimulates the maternal pituitary to secrete ACTH, and 2) the secretion of placental POMC-derived peptides. Recent data indicate that the human placenta is capable of both of these actions: A) The POMC and CRH genes are expressed in human placenta; B) the human term placenta is able to secrete both CRH and POMC-derived peptides in vitro; C) the CRH present in the plasma of pregnant women is bioactive and in sufficient levels to be effective on maternal pituitary; D) synthetic hCRH can stimulate the release of placental POMC peptides in vitro. We conclude that the human placenta may be a modulator of the HPA axis during pregnancy in a number of possible ways. Additional experimental work should clarify the intriguing interaction between the HPA axis and the human placenta during pregnancy, labor and delivery.
孕期母体血浆中结合型和游离型皮质醇水平升高，而母体血浆中免疫反应性促肾上腺皮质激素（IR-ACTH）最初较低，但尽管血浆游离皮质醇进一步增加，其水平很快上升。孕期血浆促肾上腺皮质激素的这种升高不能归因于雌激素或孕激素血浆水平的变化。人类胎盘可能是孕期母体血浆促肾上腺皮质激素升高的原因。这种效应可能通过两种机制发生：1）胎盘将促肾上腺皮质激素释放激素（CRH）分泌到母体循环中，刺激母体垂体分泌促肾上腺皮质激素；2）胎盘分泌源自阿黑皮素原（POMC）的肽。最近的数据表明，人类胎盘能够进行这两种活动：A）POMC和CRH基因在人类胎盘中表达；B）足月人类胎盘在体外能够分泌CRH和源自POMC的肽；C）孕妇血浆中存在的CRH具有生物活性，且水平足以对母体垂体产生作用；D）合成的人促肾上腺皮质激素释放激素（hCRH）在体外能够刺激胎盘POMC肽的释放。我们得出结论，人类胎盘可能以多种可能的方式在孕期调节下丘脑-垂体-肾上腺（HPA）轴。更多的实验工作应阐明孕期、分娩期和产程中HPA轴与人类胎盘之间有趣的相互作用。
