Superoxide dismutase as a regulatory switch in mammalian testicular steroidogenesis.

The delta 4-pathway of testosterone biosynthesis in leydig cells, widely believed to proceed through pregnenolone--greater than pregnenedione--greater than progesterone route catalyzed by 5 delta-3 beta-hydroxysteroid dehydrogenase and delta 5-delta 4-isomerase respectively is shown to pass through an alternate pathway mediated by superoxide dismutase and peroxidase. A built-in regulatory switch is incorporated in this route, with the superoxide dismutase inducible upon LH-stimulation of the leydig cells.