Endocrinology, Vol 115, 741-747, Copyright © 1984 by Endocrine Society

ARTICLES

In vitro progesterone and testosterone production by the rat placenta during pregnancy

DW Matt and GJ MacDonald

In vitro placental production of progesterone, testosterone, 20 alpha- hydroxy-4-pregen-3-one, and 17 beta-estradiol (E2) was investigated throughout pregnancy in the rat by RIA. Incubations of minced placental preparations with the steroidogenic enzyme inhibitors aminogluthethimide phosphate [2-(p-aminophenyl)2-ethyl-glutarimide phosphate] and cyanoketone (2 alpha-cyano-4,4,17 beta-trimethyl-17 beta- hydroxy-5-androsten-3-one resulted in a dose-related inhibition of progesterone and testosterone production. Progesterone production (picograms per mg tissue) from 2-h incubations of minced placental preparations was low on day 10 of pregnancy (day 1 = morning sperm are found in vaginal washings), peaked on day 12 (mean +/- SE, 281 +/- 32), decreased on day 14 (183 +/- 20), and returned to low levels (less than 80 pg/mg tissue X 2 h) from day 16 to term. Testosterone production (picograms per mg tissue/2 h) was not detectable on day 10, progressively increased to a peak of 46 +/- 7 on day 18, and decreased to term. Production of 20 alpha-hydroxy-4-pregnen-3-one or E2 was negligible in these minced placental preparations. Addition of androstenedione to placental incubates did not result in E2 production. Total steroid production per placenta was calculated as a function of the average placental weight for a given day. Total placental progesterone production was low on day 10 and rose to high levels (greater than 12 ng/placenta X 2 h) from day 12 to term. Total testosterone production progressively increased to a peak of 19 +/- 3 ng/placenta X 12 h on day 18 and decreased to term. These results demonstrate that throughout pregnancy, the rat placenta is an active steroidogenic tissue.

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