Dehydroepiandrosterone placental transformations

CYB5A, yielding dehydroepiandrosterone (DHEA), which enters the circulation as DHEA sulfate (DHEAS), a substrate for P450 3A7 in the fetal liver below dashed line in box). In the plaeenta, steroid sulfatase removes the sulfate from 16a-hydroxyDHEAS, and 3PHSD1 oxidizes and isomerizes 16a-hydroxyDHEA, to yield 16a-hydroxyandrostenedione. Placental P450aro and 17PHSD1 catalyze the final transformations to 16a-hydroxyestrone and estriol, respectively. 

Figure 18 outline.s the transformations of dehydroepiandrosterone and dehydrocpiandrost( rone sulfate in the fetal and placental compartments. 

Pic. 13. Transformations of dehydroepiandrostwone and dehydroepiandrosterone sulfate in the fetal and placental compartments. (I) Only a little conversion of DIIA into indro.stenedionc occurs in fetid testis. (2) Limited interconversion. DHA-S dehydro-cpiandrosterone sulfate DIIA dehydroepiandrc terone.

Fig. 18. Schematic representation of the principal transformations of the Cu and Cl steroids and their conjugates in the fetal and placental compartments. Aj-P pregnenolone P progesterone ITd-IlO-Aj-P iTa-hydroxyprcgnenolone 17a-HO-P 17a-hydroxyprogesterone DTI A dehydroepiandrosterone AND androstenedione 17/J-.D1I-DHA androstenediol-lTp DIIA-S dehydroepiandrosterone sxilfate Ida-IIO-DHA 16a-hydroxydchydrocpiandrosterone 16 -1I0-D1IA-S 16a-hydroxydehydroepi-androstcrono sulfate androstenetriol-S androstenetriol sulfate E estriol Kj-S estriol sulfate T testosterone Ej estradiol Kj-S estradiol sulfate E[ estrone E -S estione sulfate.

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