Stimulation of mammalian erythropoiesis by 5beta-H steroid metabolites

The effects of a number of steroid compounds on erythropoiesis in normal and polycythemic mice were examined. Of the steroids that stimulated erythropoiesis, the hormone testosterone and certain 5beta-H C(19) and C(21) nonhormonal metabolites were the most effective. Anti-erythropoietin abolished the erythropoiesis-stimulating effects of testosterone but not those exerted by the 5beta-H steroid, 11-ketopregnanolone. Similarly, testosterone but not 11-ketopregnanolone evoked the production of erythropoiesis-stimulating factor in rats. It is concluded that two mechanisms underlie the stimulating actions of steroids on erythropoiesis; one through the production of erythropoietin and the second involving a more direct influence on the blood-forming tissues. The 5beta-H steroid metabolites are postulated to act on erythropoiesis via the latter mechanism.