OVARIAN AND SERUM CONCENTRATIONS OF ANDROGEN THROUGHOUT PREGNANCY IN THE RAT

Levels of serum and ovarian androgen were studied throughout pregnancy in the rat. Serum androgen decreased by more than 50% from Day 5-8 of pregnancy and with minor fluctuations remained essentially unchanged at ~0.4 ng/ml until days 11 or 12. A drastic rise then occurred in serum androgen which reached values of 3±1 ng/ml on Day 17. After Day 18 the serum concentration of androgen decreased steadily, but on Day 22 the levels were still 0.9±0.2 ng/ml. The ovarian concentration of androgen remained relatively constant from Days 7 through 21 of pregnancy, between 20-45 pg/mg wet tissue. However, the concentration rose to over 200 pg/mg of ovarian tissue on Day 22; at this time the nonluteal tissue of the ovary contained ~5 times more androgen than did the corpora lutea. Prior to Day 21 of pregnancy, the concentration of androgen was similar in luteal and nonluteal tissues. These results suggest that the high level of androgen found in the serum in the second half of pregnancy is from nonovarian origin and that the significant increase in ovarian androgen at the end of pregnancy is from nonluteal sources.