The Site of Secretion of Androstenedione in Non-Pregnant Women

SUMMARY The site of secretion of androstenedione in women was investigated by measuring the concentration of androstenedione in peripheral and ovarian venous plasma by radioimmunoassay at different stages of the menstrual cycle. The concentration in peripheral plasma rose from 1·45 ± 0·11 ( s.e.m. ) ng/ml on day 1 to a peak on the 7 days around mid-cycle (2·29 ± 0·08) before declining gradually during the luteal phase. The concentration of androstenedione in plasma draining ovaries containing the pre-ovulatory follicle or a corpus luteum (33·2 ± 9·0) was significantly higher than in plasma draining the contralateral ovary (10·1 ± 1·6, P < 0·001). In women in whom ovulation was induced with gonadotrophins the concentration of androstenedione in peripheral plasma rose from 1·42 ± 0·21 before treatment to reach maximum levels (2·5–4·5 ng/ml) in the luteal phase. There was a significant ( P < 0·001) correlation between the concentration of androstenedione and oestradiol-17β in peripheral ( r = 0·50) and ovarian ( r = 0·79) venous plasma. These findings indicate that all three cellular compartments in the ovary secrete significant amounts of androstenedione in women during their reproductive life.