17-Hydroxypregnenolone

17-Hydroxypregnenolone (also 17-OH-pregnenolone and 17α-hydroxypregnenolone), is a C21 steroid that is obtained by hydroxylation of pregnenolone at the C17α position. This step is performed by the mitochondrial cytochrome P450 enzyme 17α-hydroxylase (CYP17A1) that is present in the adrenal and gonads. Peak levels are reached in humans at the end of puberty and then decline. High levels are also achieved during pregnancy.

Prohormone

17-OH-pregnenolone is considered a prohormone in the formation of dehydroepiandrosterone (DHEA), itself a prohormone of the sex steroids.

This conversion is mediated by the enzyme 17,20 lyase. As such 17-OH-pregenolone represents an intermediary in the delta-5-pathway that leads from pregnenolone to DHEA. 17-hydroxypregneolone is also converted to 17-hydroxyprogesterone, a prohormone for glucocorticosteroids and androstenedione through the activity of 3-hydroxysteroid dehydrogenase.

Neurohormone

There is some evidence that 17-OH-pregnenolone may have activity as a neurosteroid.