CORTICOSTERONE BINDING BY RAT BRAIN CYTOSOL¹

Abstract

Abstract Significant quantities of corticosterone were associated with macromolecules of the brain cytosol following intrathecal administration of [ 3 H]corticosterone to adrenalectomized rats. Fifteen times more steroid was found associated with proteins from adrenalectomized rats than from control animals or adrenalectomized animals pretreated with corticosterone. Pretreatment of adrenalectomized rats with 11‐dehydrocorticosterone, Cortisol and cortisone decreased the amount of [ 3 H]corticosterone found associated with protein, whereas progesterone, oestradiol and testosterone did not interfere with the association of [ 3 H]corticosterone with macromolecules of the cytosol. Further evidence for protein‐steroid interaction was obtained by incubating [ 3 H]corticosterone (B), [ 3 H]cortisol (F), or 11‐[ 3 H]deoxycortisol (S) with brain cytosols. The degree of binding was in the order B > F > S.