5-ALPHA-REDUCTASE-1 AND 5-ALPHA-REDUCTASE-2 EXPRESSION AND ACTIVITY IN HUMAN OVARIAN FOLLICLES, STROMA AND CORPUS-LUTEUM AS COMPARED TO NEONATAL FORESKIN

5 alpha-Reductase is the steroidogenic enzyme which reduces testostero ne to 5 alpha-dihydrotestosterone. In the human two different enzymes have been described, 5 alpha-reductase 1 and 2. The present investigat ions were undertaken to determine whether 5 alpha-reductase 1 and 2 we re expressed in the human ovary, and to determine the relative activit y of the two enzymes in various ovarian tissues. The ovary apparently expressed mRNA for only 5 alpha-reductase 1, whereas the foreskin expr essed both 5 alpha-reductase 1 and 2. We compared the 5 alpha-reductas e activity at both pH 5.5 (optimum for 5 alpha-reductase 2 activity) a nd 8.0 (optimum for 5 alpha-reductase 1 activity). 5 alpha-reductase a ctivity of foreskin at pH 5.5 was 3900 times higher than small follicl es, 1500 times higher than ovarian stroma, and 240 times higher than c orpora lutea (all P < 0.01). 5 alpha-reductase activity of corpora lut ea at pH 5.5 was 17-fold higher than that of follicles (P < 0.01) and 6.5-fold higher than that of ovarian stroma (P < 0.05). 5 alpha-Reduct ase activity of foreskin at pH 8.0 was 93 times higher than small foll icles, 51 times higher than corpora lutea, and 170 times higher than o varian stroma (all P < 0.01). The ratio of 5 alpha-reductase activity at pH 5.5 to that at pH 8.0 was higher in foreskin than in corpus lute um (P < 0.05), ovarian stroma (P < 0.01), or ovarian follicles (P < 0. 01). The ratio was lower in ovarian follicles than in stroma or corpus luteum (both P < 0.05). Copyright (C) 1996 Elsevier Science Ltd.