Human chorionic gonadotropin secretion from the early human placenta: in vitro regulation by progesterone and its antagonist

The endocrine function of human placenta: an overview

During pregnancy, several tightly coordinated and regulated processes take place to enable proper fetal development and gestational success. The formation and development of the placenta is one of these critical pregnancy events. This organ plays essential roles during gestation, including fetal nourishment, support and protection, gas exchange and production of several hormones and other mediators. Placental hormones are mainly secreted by the syncytiotrophoblast, in a highly and tightly regulated way. These hormones are important for pregnancy establishment and maintenance, exerting autocrine and paracrine effects that regulate decidualization, placental development, angiogenesis, endometrial receptivity, embryo implantation, immunotolerance and fetal development. In addition, because they are released into maternal circulation, the profile of their blood levels throughout pregnancy has been the target of intense research towards finding potential robust and reliable biomarkers to predict and diagnose pregnancy-associated complications. In fact, altered levels of these hormones have been associated with some pathologies, such as chromosomal anomalies or pre-eclampsia. This review proposes to revise and update the main pregnancy-related hormones, addressing their major characteristics, molecular targets, function throughout pregnancy, regulators of their expression and their potential clinical interest.

Time-dependent action of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) and its metabolite DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) on human chorionic gonadotropin and progesterone secretion

Explants of human placenta were used to study the effects of two isomers of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) [p,p'-DDT and o,p'-DDT] and their DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) metabolites [p,p'-DDE and o,p'-DDE] on the secretion of progesterone and human chorionic gonadotropin (hCG). Explants were treated with 1, 10, 100 or 1000 ng/ml of each compound for 24 h or 72 h. We found opposite effects (stimulatory after short-term and inhibitory after long-term exposure) of all compounds on progesterone secretion. However, both short- and long-term exposure to all investigated compounds caused decreased hCG secretion. In conclusion, we suggest the existence of a local axis between steroid hormones and hCG in placenta. DDT (which has estrogenic properties) increases progesterone secretion and consequently decreases hCG secretion. After long-term exposure, the low level of hCG is insufficient to stimulate progesterone.