Differential binding of dexamethasone to ammonium sulfate precipitates of human adipose tissue cytosols

Saturation analysis of the binding of [ 3H]dexamethasone ([ 3H]DEX) to ammonium sulfate precipitates (ASPs) confirmed the presence of a limited-capacity, high-affinity binder in human adipose tissue cytosols. Various non-radioactive steroids competed with [ 3H]DEX for binding to the ASPs in the following sequence: dexamethasone (DEX) ≅ triamcinolone acetonide (TA) > progesterone (P) > estradiol (E2). The steroid specificity of the binder precipitated by AS was consistent with the specificities reported for glucocorticoid receptors in a number of systems. In order to investigate possible regional differences, glucocorticoid binding to ASPs derived from adipose tissues removed from two different sites in the same subject was quantitated. ASPs of human omental adipose tissue bound significantly more [ 3H]DEX than did similar preparations of subcutaneous adipose tissue from the abdominal wall (116 ± 32 vs. 50 ± 22 fmol/mg protein; mean ±SD; p < 0.02). The findings are consistent with reports from other laboratories suggesting that intra-abdominal fat is more responsive to glucocorticoids than is subcutaneous adipose tissue.