Role of sex hormones in the modulation of cholangiocyte function

Figure 3 The biosynthesis of the sex hormones starts with the oxidation of the side chain of cholesterol, which is catalyzed by the enzyme cytochrome P450_scc to form pregnenolone. The next steps in the biosynthesis of testosterone can proceed via two different routes. Pregnenolone can be oxidised first by cytochrome P450_17a to 17a-hydroxypregnenolone. The enzyme 3β-HSD also can convert pregnenolone first into progesterone. Both pregnenolone and progesterone are accepted as substrate by the enzyme cytochrome P450_17a. In this way, after 3β-hydroxy-5-androstene-17-one (DHEA) synthesis, there is the testosterone and successively the estradiol formation.