GASTRIN-RELEASING PEPTIDE-LIKE IMMUNOREACTIVITY IS PRESENT IN HUMAN MATERNAL AND FETAL-PLACENTAL MEMBRANES

Extracts of human term amnion, placenta, and chorion/decidual tissue ( n = 5) contained gastrin-releasing peptide-like immunoreactivity (GRPL I) in amounts of 4.7 +/- 2.9 (pmol/g wet wt; mean +/- SEM), 3.6 +/- 1. 1 and 2.9 +/- 1.5, respectively. Using C-terminally directed antisera and gel filtration chromatography and reverse-phase highperformance li quid chromatography (HPLC), each tissue contained molecular forms cons istent with the presence of GRP(1-27) and GRP(18-27) but also containe d larger amounts of two GRPLI peaks, which apparently are novel GRP-li ke peptides. In contrast, tissue extracts of human fetal lung containe d only GRP(1-27), GRP(14-27), and GRP(18-27). Using RT-PCR and specifi c GRP primers and probes, messenger RNA encoding for GRP was readily d emonstrable from 6-weeks gestation throughout pregnancy to term in ful l-thickness membranes, placental villi, and decidua. Positive immunohi stochemical staining for GRP occurred in extravillous trophoblasts in decidual septa and fetal membranes, cytotrophoblasts, syncytiotrophobl ast, and certain stromal cells in placental villi and amniotic epithel ium. GRPLI and GRP messenger RNA were present from the earliest dates examined (6-9 weeks) throughout pregnancy to term. Given the proven tr ophic nature of GRP and related peptides, these peptides may play impo rtant roles in maternal, placental, and fetal development-during human pregnancy.