A correlative study of RU38486 biopotency and competition with [3H]dexamethasone for receptors in the rat central nervous system.

Dexamethasone inhibitory action on the release of adrenocorticotrophin has been studied using in vitro anterior pituitary preparations. This inhibition is reversed when the animal is given the antiglucocorticoid compound RU38486 simultaneously with dexamethasone. RU38486 acts at the receptor level and in the cytosolic binding study, it competes with [3H]dexamethasone for the binding sites in pituitary. Such competition is even more pronounced in hypothalamus and hippocampus, indicating that RU38486 also exert its antagonistic action at these sites.