Steroid metabolizing enzymes in pluripotential progenitor central nervous system cells: effect of differentiation and maturation

A novel in vitro system which allows extensive culturing of multipotential stem cells from mouse brain has made it possible to test whether enzymes that metabolize androgens and progestagens are present in undifferentiated central nervous system progenitor cells. Embryonic day 14 striatal cells were grown in the presence of either 20 ng/ml of epidermal growth factor (which prevents cell differentiation), or 2% fetal bovine serum (facilitating differentiation). Differentiation was complete by 35 days in vitro when the cell population comprised 86 +/- 2.0% astrocytes, 6 +/- 0.7% neurons 1.6 +/- 0.5% oligodendrocytes and 6.4 +/- 0.5% undifferentiated cells. No changes in the proportions of cell type were observed thereafter (38 and 45 days in vitro). 5 alpha-Reductive conversion (by 5 alpha-reductase) of testosterone and progesterone into dihydrotestosterone and dihydroprogesterone, and subsequent 3-alpha hydroxylation (by 3 alpha-hydroxysteroid dehydrogenase) to 3 alpha-diol and tetrahydroprogesterone were assayed in the cultures at 35, 38 and 45 days in vitro. Undifferentiated epidermal growth factor-treated cells (controls) formed about 10 times more dihydroprogesterone than dihydrotestosterone. Conversions of dihydrotestosterone and dihydroprogesterone, respectively, into 3 alpha-diol and tetrahydroprogesterone were very similar. In the fetal bovine serum-treated differentiating cells, 5 alpha-reductase converting progesterone increased at 38 days in vitro, and remained similarly elevated at 42 days in vitro (4 times). However, the conversion of testosterone into dihydrotestosterone remained at control levels up to 42 days in vitro when an increase was observed. 3 alpha-Hydroxysteroid dehydrogenase activity converting dihydroprogesterone but not dihydrotestosterone was increased at 38 and 42 days in vitro. These results show that undifferentiated central nervous system cells possess androgen and progestagen metabolizing enzymes which are strongly influenced by the cellular differentiation/maturation process.