Characterization of urocortin in human pregnancy

Objective To examine whether urocortin is produced locally to regulate uter o-placental vascular tone during pregnancy. Methods We examined the distribution of urocortin in human placenta, fetal membranes and uterine tissue at term in the presence and absence of labor u sing a urocortin antibody produced in our laboratory and the immunoperoxida se staining method. Subsequently, we tested urocortin secretion from chorio -decidual cells in vitro using an immunoblot technique. Then, we tested whe ther urocortin is present in maternal plasma throughout gestation using a r adioimmunoassay. A Sephadex G-50 column was used to examine whether immunor eactive urocortin (IR-urocortin) in maternal plasma is the same as syntheti c urocortin. Results IR-urocortin was observed in vascular smooth muscle of myometrium d ecidual stromal cells, syncytiotrophoblast and amnion epithelium. No differ ences in staining intensity for urocortin were detected between tissues obt ained in the absence or presence of labor. Staining intensity for IR-urocor tin was greatest in the decidua, suggesting this may be the main site of ur ocortin production. Positive staining for urocortin was observed in 40% of chorio-decidual cells with 34% of these cells secreting urocortin under bas al conditions. Urocortin was detectable in maternal plasma from 16 weeks ge station and concentrations did not change as gestation progressed. IR-uroco rtin in the maternal plasma eluted from a Sephadex G-50 column at the same site as synthetic urocortin and had a calculated retention cc-efficient of 0.44. Conclusion This study indicates that urocortin is produced by the decidua d uring human pregnancy and is detectable in maternal plasma. These data are consistent with the hypothesis that urocortin is produced locally by the de cidua and may act to regulate utero-placental blood flow.