Effects of 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one on steroidogenesis in gonads of rat fetuses.

1. The effect of 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one (4-MA) on the fetal rat steroidogenesis was examined. 18- and 20-day-old fetal ovaries were incubated in the presence of dcAMP (1 mM) and spironolactone (10 mM) and progesterone production was assessed with and without 4-MA (0.01-50 microM). 2. High concentrations of 4-MA significantly decreased the production of progesterone. 3. Similar inhibition of the testosterone synthesis was observed in 16-day-old fetal testes explanted either in the control medium (M199) or in the presence of LH (100 ng/ml) when treated with 4-MA. The effect was rapidly reversible in both gonads.