THE PRESENCE OF CORTISOL RECEPTORS IN THE HUMAN AMNION

Cytosol extracts of human amnion tissue contained high affinity bindin g of cortisol (K-a=2.48+/-1.06x10(9) M-1; n=30) and low capacity bindi ng of cortisol (N-max=279+/-15.5 fmol mg(-1) protein). Kinetic studies of cortisol binding resulted in a similar value of K-a to that obtain ed by Scatchard analysis. Nuclear extracts of amnion tissue contained high affinity binding of cortisol (K-a=5.8+/-1.91x10(7) M-1) and low b inding capacity (N-max=91.4+/-21.4 fmol mg(-1) protein). K-a values we re an order of magnitude higher in cytosol than in blood serum when am nion and blood were obtained from the same individuals. Differences in competitive ligand binding, especially dexamethasone, were observed b etween the amnion receptor and transcortin in serum. Gel permeation ch romatography gave only one peak at 320 kDa for amnion receptor and onl y one peak at 48 kDa for transcortin from serum. When amnion tissue wa s incubated with or without cortisol, cytosol receptor activity was si gnificantly lower in cortisol treated tissue than in control. The nucl ear extracted receptor activity was significantly higher in cortisol t reated tissue than control. The K-a values from cortisol treated tissu e were significantly lower from control. Together the data support the presence of a specific cortisol receptor in the human amnion that is different from transcortin. (C) 1997 Elsevier Science Ltd. All rights reserved.