Analysis of ultrashort feedback regulation in human placenta: synthesis and secretion of GnRH by human trophoblastic cells.
BACKGROUND
Gonadotropin-releasing hormone (GnRH) presumably controls placental growth and functions by autocrine/paracrine mechanisms, and is therefore an important part of the neuroendocrine network in human placenta.


OBJECTIVE
Our earlier work had indicated that GnRH was expressed in human placenta; in extension to these findings, we wanted to analyse synthesis and release of GnRH by trophoblastic cells. GnRH-associated peptide, co-linearly synthesised with GnRH, was used as indicator of actual peptide synthesis.


METHODS
First, we immunised rabbits with lipopeptides containing partial sequences of GnRH-associated peptide (GAP) and developed antibodies for immunohistochemical staining. Second, we set up a competitive enzyme immunoassay to measure GnRH: Non-biotinylated GnRH, GnRH analogues or trophoblastic cell culture supernatants were used to inhibit binding of biotinylated des-pGlu1-GnRH to a monoclonal anti-GnRH antibody.


RESULTS
a) Placental sections stained positive for GAP in the layers of trophoblastic cells. b) GnRH could be detect by a competitive EIA in supernatants of placental cultures in concentrations between 200 and 5 nM.


CONCLUSIONS
GnRH is synthesised and released by trophoblastic cells.
Kleine
B
B
Department of Gynaecology and Obstetrics, University of Ulm, Germany. bernhard.kleine@medizin.uni-ulm.de
Kienle
A
A
Poettich
M
M
Wolfahrt
S
S
Jarry
H
H
Rossmanith
W G
WG
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D005246:Feedback; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis* / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000032:analysis* / Q000276:immunology; D011817:Rabbits; D014327:Trophoblasts / Q000378:metabolism*
D011498:Protein Precursors; C050502:gonadotropin releasing hormone associated peptide; D007987:Gonadotropin-Releasing Hormone