CURRENT TOPIC - THE PLACENTAL CORTICOTROPIN-RELEASING HORMONE-ADRENOCORTICOTROPIN AXIS

In this review the factors regulating production of corticotrophin-rel easing hormone (CRH) in intrauterine tissues are discussed and interac tions of placental CRH with placental pro-opiomelanocortin (POMC)/adre nocorticotrophin (ACTH) and prostaglandins (PG) are examined. Discrepa nt results concerning localization of immunoreactive (IR-) CRH and its binding protein (CRH-BP) and their mRNAs in intrauterine tissues are described, and these issues require further resolution. It is suggeste d that the CRH-ACT-PG axis in the placenta and choriodecidua may be im portant in relation to paracrine/autocrine regulation of uteroplacenta l blood flow, and in term and preterm labour. During the initial state s of preterm labour in the setting of infection, intrauterine cytokine s and other factors may stimulate CRH output, implying a role for the immune-neuroendocrine axes in this process. With loss of chronic troph oblasts in advanced infection leading to preterm labour, a major intra uterine site of CRH production may be lost and the influence of this p athway becomes minimal. At this time increased intrauterine prostaglan din synthesis, together with loss of prostaglandin dehydrogenase activ ity in the fetal membranes, may become the primary route leading to my ometrial activity and delivery.