Steroid-receptor complexes and their interaction with the rat liver nuclei during ontogenesis

Steroid-receptor complexes (SRCs) (glucocorticoids, estrogens and progestins) are isolated from rat liver and purified 1500-2000-fold. Both the initial cytosol complexes and those purified 2000-fold were characterized by gel filtration on Sephadex G-100 and DEAE-cellulose chromatography. The purified rat liver SRCs were used for binding to the isolated liver nuclei from rats of different ages (1.5, 6, 12, 24 months). Binding of progestin and estrogen-receptor complexes from rat liver to homological nuclei of 1.5-month-old rats is maximum, no distinct differences being found in the case of glucocorticoid-receptor complexes. SRC binding to the nuclei progressively declines with age, reaching its minimum by 24 months. The revealed differences in SRC binding by the nuclei of animals of different ages seem to be the basis of the hormone-induced changes in the organism functioning at various stages of ontogenesis.