Regulation of hydrocortisone binding sites by hydrocortisone in human bone marrow fibroblasts.

The incubation of human bone marrow fibroblasts with hydrocortisone (10(-7) M) produces a time-dependent depletion of hydrocortisone-binding sites. This effect is glucocorticoid-specific, since glucocorticoid agonists cause depletion to the same extent as hydrocortisone. After withdrawal of the hormone from the incubation medium, cells are able to replenish their complement of receptor. The existence of this down-regulation process may represent a protective mechanism against the partial proliferative inhibitory action of glucocorticoids for bone marrow fibroblasts and also a stimulus for differentiation to adipocytes.