5α-reductase 1 and 2 expression and activity in human ovarian follicles, stroma and corpus luteum as compared to neonatal foreskin

Abstract 5α-Reductase is the steroidogenic enzyme which reduces testosterone to 5α-dihydrotestosterone. In the human two different enzymes have been described, 5α-reductase 1 and 2. The present investigations were undertaken to determine whether 5α-reductase 1 and 2 were expressed in the human ovary, and to determine the relative activity of the two enzymes in various ovarian tissues. The ovary apparently expressed mRNA for only 5α-reductase 1, whereas the foreskin expressed both 5α-reductase 1 and 2. We compared the 5α-reductase activity at both pH 5.5 (optimum for 5α-reductase 2 activity) and 8.0 (optimum for 5α-reductase 1 activity). 5α-reductase activity of foreskin at pH 5.5 was 3900 times higher than small follicles, 1500 times higher than ovarian stroma, and 240 times higher than corpora lutea (all P P P P P P P P