title: Endogenous regulation of the GnRH receptor by GnRH in the human placenta.
abstract: Gonadotrophin releasing hormone (GnRH) plays an important regulatory role in the function and growth of human placenta, but its placental expression sites and co-localization with GnRH receptor (GnRH-R) are not well known. GnRH and GnRH-R expression has been found in both placenta and cultured trophoblasts; however, cultured trophoblastic cells very quickly lose GnRH-R message and subsequently receptor protein. Speculating that endogenously released GnRH induced this down-regulation, we determined GnRH-R in cultures of trophoblastic cells in the presence of a neutralizing anti-GnRH antibody. Cells incubated with this antibody showed a strong signal for the GnRH-R, while those cultured without did not (as analysed by immunofluorescence, reverse transcription-polymerase chain reaction, protein 'dot blot' and Western blotting). Furthermore, addition of the GnRH agonist buserelin led to a reduction of the receptor protein. We have therefore shown that GnRH released from trophoblastic cells down-regulates GnRH-R in these trophoblastic cells. Having previously shown that trophoblast layers were synchronously positive for GnRH and GnRH-R, these new findings support the hypothesis of an ultrashort feedback regulation of trophoblasts by GnRH involving autocrine regulation of GnRH-R.
authors.affiliation: Department of Gynaecology and Obstetrics, University of Ulm, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wolfahrt
authors.forename: B
authors.initials: B
authors.lastname: Kleine
authors.forename: H
authors.initials: H
authors.lastname: Jarry
authors.forename: W G
authors.initials: WG
authors.lastname: Rossmanith
mesh_terms: D015153:Blotting, Western / Q000379:methods; D002478:Cells, Cultured; D015536:Down-Regulation; D005260:Female; D005455:Fluorescent Antibody Technique; D007987:Gonadotropin-Releasing Hormone / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D010920:Placenta / Q000378:metabolism*; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism*; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism
chemical_list: D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone