Atrial natriuretic factor regulates steroidogenic responsiveness and cyclic nucleotide levels in mouse Leydig cells in vitro.

The effects of synthetic atrial natriuretic factor (ANF) on the regulation of mouse Leydig cell steroidogenesis have been studied in vitro. ANF in nanomolar concentration increased testosterone production by more than 30-fold over basal levels. Concomitantly, cyclic guanosine monophosphate levels were increased 35-fold; cyclic adenosine monophosphate levels fell minimally (15-20%). ANF at low concentration (1 X 10(-11) M) inhibited testosterone production by luteinizing hormone-stimulated cells, while at higher concentration (greater than 2 X 10(-9) M) ANF stimulated steroidogenesis beyond the level attained by luteinizing hormone alone. These results indicate that ANF can exert stimulatory effects on testosterone steroidogenesis in vitro, and that the mechanism may involve an intracellular messenger other than cyclic adenosine monophosphate.