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Type: Journal article
Title: Identification and characterization of a corticotrophin-releasing hormone recptor in human placenta
Author: Clifton, V.
Robinson, P.
Owens, P.
Smith, R.
Citation: European Journal of Endocrinology, 1995; 133(5):591-597
Publisher: Scandinavian University Press
Issue Date: 1995
ISSN: 0804-4643
Statement of
Vicki L Clifton, Phillip C Owens, Phillip J Robinson and Roger Smith
Abstract: Corticotrophin-releasing hormone (CRH) causes vasodilatation in the human fetal-placental circulation and has paracrine actions in placental tissue, suggesting that CRH receptors may be present in the human placenta. We have now identified and characterized placental CRH binding sites and compared them to those described previously in human myometrium and rat pituitary. Radiolabelled ovine CRH binding to placental membranes was pH-, time-, temperature- and divalent cation-dependent and was reversible in the presence of 1 mumol/l unlabelled ovine CRH. Scatchard analysis of placentae delivered vaginally or by elective caesarean section revealed dissociation constants (Kd) of 214.5 +/- 84 pmol/l (N = 8) and 45.4 +/- 23.9 pmol/l (N = 9), respectively. The Kd for caesarean placental binding sites was similar to that of human myometrium (59.6 pmol/l, N = 3) and rat pituitary (82.5 pmol/l, N = 3) receptors. However, in vaginally delivered placentae the CRH binding sites had a much lower affinity (p < 0.05). The receptor densities (Bmax) of vaginally delivered and caesarean-delivered placentae were 28.6 +/- 9.6 and 6.1 +/- 2.8 fmol/mg, respectively (p < 0.05). Chemical cross-linking studies using disuccinimidyl suberate indicated that the molecular weight of the CRH receptor in the placenta and rat pituitary is 75 kD. We conclude that there is a high-affinity population of CRH binding sites in the human placenta that are physicochemically similar to pituitary and myometrial CRH receptors. The CRH receptor properties in the placenta change in response to labour, when CRH levels in maternal blood are highest, suggesting that placental CRH may regulate its receptor.
Keywords: Myometrium
Pituitary Gland
Rats, Sprague-Dawley
Iodine Radioisotopes
Corticotropin-Releasing Hormone
Receptors, Corticotropin-Releasing Hormone
Pregnancy Proteins
Chromatography, High Pressure Liquid
Labor, Obstetric
Hydrogen-Ion Concentration
Molecular Weight
DOI: 10.1530/eje.0.1330591
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Appears in Collections:Aurora harvest
Obstetrics and Gynaecology publications

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