Erythropoietic activity of steroid metabolites in mice.

The per cent Fe(59) incorporation into circulating erythrocytes as an indicator for new hemoglobin production was used in the polycythemic exhypoxic mouse system to study the effects of certain steroid hormone metabolites on erythropiesis. Enhanced Fe(59) incorporation was observed after the administration of several metabolites with a 5beta-H configuration, while those with a 5alpha-H configuration had no stimulatory effect. The stimulatory effect in avian systems has been shown by others to be due to an increased activity of delta-aminolevulinic acid synthetase, the limiting enzyme in heme biosynthesis. These in vivo studies thus indicate that in this mouse system, as in previously reported studies with avian and human bone marrow cells, some steroid metabolites stimulate hemoglobin synthesis. The observation that the same structure-junction relationship exists in the currently described system as in the avian suggests that these steroids probably induce delta-aminolevulinic acid synthetase in the mouse. The erythropoietic action of these nonandrogenic steroid metabolites may prove to be clinically useful.