IDENTIFICATION AND ISOLATION OF CORTICOTROPIN-RELEASING HORMONE-POSITIVE CELLS FROM THE HUMAN PLACENTA

During human pregnancy, plasma corticotrophin-releasing hormone (CPH) levels rise from undetectable amounts prior to 20 weeks gestation to r each a peak near term, with an exponential rise during the final 5 wee ks of gestation. Within hours of parturition plasma levels fall and ra pidly return to undetectable baseline measurements. The appearance of CRH in maternal plasma has been attributed to the placental production and subsequent release into the maternal circulation of this hormone. Previous studies have shown that human placental extracts contain a C RH-like peptide and this has been reinforced by the observation of CRH mRNA in placental tissue. Initial attempts to identify, the site of p roduction using immunocytochemistry have led to conflicting results. T his study attempts to clarify, this situation by using a variety of hi ghly specific anti-CRH antibodies to show tire cellular expression of placental CRH. Intense CRH staining was observed in the syncytial trop hoblast layer in first trimester and term chorionic villi, whilst the underlying cytotrophoblast appeared to be negative. The fetal membrane s also contained CRH immunoreactivity with the cytotrophoblast cells i n the chorionic membrane displaying the most intense staining. CRH imm unoactivity was also observed in the amnion and in some cells in the d ecidua. As a model of cellular CRH expression, cytotrophoblast cells f rom term chorionic membrane were isolated and shown to be positive for CRH.