Evidence that a non-steroidal factor from corpus luteum of pregnant sheep inhibits aromatase activity of ovarian follicles in vitro.
Porcine and ovine follicular tissues were used to investigate, in vitro, the effect of charcoal-treated aqueous extract from ovine corpora lutea of pregnancy on aromatase activity as determined by the conversion of [3H]testosterone to oestradiol by follicular walls and measurement of 3H2O release. Extract (500 micrograms protein) prepared from corpora lutea of day 112 of pregnancy but not extract (500 micrograms) prepared from ovine fetal cotyledonary tissue obtained at a similar time significantly decreased (P < 0.02) aromatase activity of pig follicles in the absence of FSH. These results demonstrate that a non-steroidal factor in the corpora lutea of late pregnancy directly inhibits aromatase activity. When the effects of different doses (300, 600 or 1200 micrograms) of luteal extract from corpora lutea of day 100 of pregnancy on aromatase activity of pig follicles were studied, the dose by treatment (presence or absence of FSH) interaction was not significant. Luteal extract dose at 300 micrograms did not affect aromatase activity but a significant decrease in activity occurred at 600 micrograms of luteal extract (600 versus 300 micrograms, P < 0.02). There was no further significant increase in the inhibitory effect with 1200 micrograms luteal extract. When the effects of 600 micrograms luteal extract from corpora lutea of days 15, 75 or 100 of pregnancy on aromatase activity of pig follicles were studied, a significant (P < 0.05) stage of pregnancy effect was detected, but the stage of pregnancy by treatment (presence or absence of FSH) interaction was not significant. No effect was noted with day 15 or day 75 luteal extract.(ABSTRACT TRUNCATED AT 250 WORDS)
al-Gubory
K H
KH
INRA Station de Physiologie animale, Unité d'Endocrinologie de l'Embryon, Jouy-en-Josas, France.
Driancourt
M A
MA
Antoine
M
M
Martal
J
J
Neimer
N
N
D000818:Animals; D001141:Aromatase / Q000378:metabolism; D047072:Aromatase Inhibitors; D003338:Corpus Luteum / Q000378:metabolism*; D046508:Culture Techniques; D005260:Female; D006080:Ovarian Follicle / Q000201:enzymology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*; D013552:Swine
D047072:Aromatase Inhibitors; D001141:Aromatase