Level of glucocorticoid receptors in male rat liver under stress

The binding of dexamethasone and corticosterone by specific glucocorticoid cytoplasmic liver receptors has been studied in intact, adrenalectomized and stressed male Wistar rats. The dissociation constants measured for receptor-hormone complexes were 7.2 x 10(-9) M for dexamethasone and 5.0 x 10(-9) M for corticosterone. Under 48 hour immobilisation stress, the number of binding sites on a dexamethasone-binding receptor was found to diminish from 2.9 x 10(-13) mol/mg protein (for intact rats) to 0.8 x 10(-13) mol/mg protein (for stressed rats). The amount of binding sites on a transcortin-like receptor decreased from 10 x 10(-14) mol/mg protein (in the intact rats) to 2.8 x 10(-14) mol/mg protein (in the stressed ones). Thus above data indicated certain reduction in binding site number for dexamethasone and corticosterone on the specific cytoplasmic receptors of rat liver under immobilisation stress.