The measurement of glucocorticoid receptors in human placental cytosol.
Cytosol preparations of human term placenta in Tris-HCl buffer containing dithiothreitol were incubated with [3H]dexamethasone at 4 degrees C. Under these conditions the specific binding of [3H]dexamethasone was low when compared with cytosol preparations of sheep fetal lung or ovine placenta. The inclusion of sodium molybdate in the homogenization buffer and the removal of endogenous steroids by treating the cytosol with charcoal before incubation led to a faster and increased uptake of [3H]dexamethasone by human placenta. Scatchard plot analysis of the data showed that the placenta possesses a single class of high-affinity (Kd = 13 +/- 2 nM) low-capacity (193 +/- 34 fmol/mg protein) binding sites for [3H]dexamethasone. The binding of [3H]dexamethasone was reversible and was not due to plasma contamination. The specificity of the binding sites was confirmed by competition experiments in which the highest displacement of [3H]dexamethasone from the binding sites was caused by natural and synthetic corticosteroids. These findings indicate that the human placenta at term contains specific glucocorticoid receptors in high concentrations.
D001667:Binding, Competitive; D002606:Charcoal / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008982:Molybdenum / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013256:Steroids
D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D013256:Steroids; D002606:Charcoal; D003907:Dexamethasone; D008982:Molybdenum; C024687:sodium molybdate(VI)