Biopotency of corticosterone and dexamethasone in causing glucocorticoid receptor downregulation.
The biopotencies of dexamethasone and corticosterone in causing glucocorticoid receptor downregulation in the AtT-20 cell were assessed and compared to their affinity for the isolated, cytosolic glucocorticoid receptor. Dexamethasone depleted receptor by 50% at a concentration of 4.6 nM. Its Kd for the receptor was 9.1 nM. The comparable values for corticosterone were 520 and 18.8 nM respectively. These results suggest that receptor depletion is a receptor mediated process; at some point the steroid must be bound to receptor in order to cause depletion. Further, the discrepancies between the two values for corticosterone support the hypothesis that it is the transformed receptor that is depleted.
D000818:Animals; D002478:Cells, Cultured; D003345:Corticosterone / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D051379:Mice; D010911:Pituitary Neoplasms / Q000032:analysis; D011965:Receptors, Glucocorticoid / Q000032:analysis / Q000187:drug effects*
D011965:Receptors, Glucocorticoid; D003907:Dexamethasone; D003345:Corticosterone