[Various mechanisms of the participation of the hypophysis and somatotropin in the hormonal regulation of the level of specific estrogen-binding protein in the rat liver].

A study was made of the role of the hypophysis and STH in the regulation of the level of specific estrogen-binding protein (SEBP) and estrogen receptors (ER) in the rat liver, in the expression of the SEPB-determining effect of androgens (A) and the regulating action of estrogens (E) on the SEPB level. The SEPB and ER content was determined by quantitative methods permitting the differential testing of one E-binding protein from another. Hypophysectomy of males caused a decrease in the SEPB and ER levels. STH administration increased the SEPB and ER levels in the liver of the hypophysectomized males but did not influence the level of these proteins in intact animals. Hypophysectomy of intact and ovariectomized females blocked the SEPB-determining action of A even at early time after operation. Estrogens (E) were capable of producing an inhibitory effect on the SEPB level at early time after hypophysectomy of males. The efficacy of E action after hypophysectomy decreased in parallel with a decrease in the ER content in the liver. The administration of STH to hypophysectomized males resulted in an increase in the ER level and a subsequent reduction of SEPB negative reaction to E. It was concluded that hypophysial factors could produce a direct, sensitizing and permissive for sex steroids action on the SEPB level.