The presence and function of GnRH in human early placenta

Fresh human placental tissues at 6-20 weeks of gestation and term placenta were used in this work. We have found as follows; 1) using RIA, the GnRH concentrations are low during 5-8 weeks of gestation and increased gradually to term. 2) immunohistochemistry demonstrated that GnRH immune-positive granules were found to be localized in the cytotrophoblast. 3) using anti-idiotypic GnRH antiserum, GnRH receptor immune-positive granules localized in the two layers of trophoblast, but more strong in the syncytiotrophoblast. The positive staining was also localized in the endoplasmic reticular revealed by EM. 4) using perfusion model, the synthetic GnRH is shown to stimulate the hCG secretion from perfused placental villi. 5) study of placental GnRH, we conducted to isolated and purified GnRH-like peptide-tentative named hpGnRH, their migration time of HPCE and amino acid composition are different with 6 kinds of known GnRH. These results suggest that the GnRH may play an important role in the placental hormone's synthesis and secretion and the human placenta (especially in early placenta) also possesses its an own GnRH-like peptide.