pregnenolone

Pregnenolone is an unsaturated hydroxy steroid ketone with the chemical formula C₂₁H₃₂O₂. It is formed through the oxidation of steroids, such as cholesterol.1

In the biosynthesis of steroid hormones, cholesterol serves as the primary precursor. The process begins with the conversion of cholesterol into pregnenolone within the mitochondria. This conversion is facilitated by a cleavage enzyme and is stimulated by hormones like corticotropin (ACTH) or angiotensin in the adrenal glands, and follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the ovaries and testes.23

Once formed, pregnenolone moves to the endoplasmic reticulum, where it is enzymatically converted into progesterone. Progesterone can then be further transformed into specific steroid hormones, including androgens and estrogens in the ovaries and testes, and mineralocorticoids and glucocorticoids in the adrenal cortex. Pregnenolone itself yields progesterone upon dehydrogenation.31