Glucocorticoid and estrogen regulation of corticosteroid-binding globulin production by rat liver.

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Abstract
Rat liver can synthesize and secrete corticosteroid-binding globulin (CBG). Male rats were pretreated by adrenalectomy and/or glucocorticoid or estrogen administration and the rate of CBG production was measured in vitro. The production rates were assessed by the generation of specific corticosterone binding sites in both a liver-slice preparation and in an isolated perfused liver. The 2 techniques showed qualitatively similar results. The rate of CBG production and secretion was enhanced by adrenalectomy and inhibited by glucorticoid administration. Pretreatment of male rats with estradiol stimulated the rate of CBG production. The production rates were 20- to 40-fold higher in the perfused liver, demonstrating its superiority over the liver-slice system. The livers from intact rats secreted CBG binding sites at a rate of .apprx. 18 pmol/g liver per h, generating an estimated 20% of the total CBG content of a rat each day. The possible clinical implications of the therapeutic use of glucocorticoids that bind to CBG, yet inhibit CBG production, are discussed.