[Effect of type III glucocorticoid receptors on binding of corticosterone by the type II glucocorticoid receptors].

Binding of 3H-corticosterone by the glucocorticoid receptors of the II and III types in liver and thymus cytosol was studied in adrenalectomized rat males. After thermoinactivation of the type II glucocorticoid receptors the rate of corticosterone binding with the only receptors of the III type was estimated at various periods of incubation. The rate of 3H-corticosterone association with the glucocorticoid receptors of the III type in liver and thymus cytosol was distinctly higher as compared with that of the III type receptors. The type III glucocorticoid receptors were shown to inhibit binding of corticosterone with the receptors of II type until their saturation with the hormone occurred. Physiological role of the type III glucocorticoid receptors in biological efficiency of glucocorticoids is discussed.