Neuroactive pregnanolone isomers during pregnancy.
The pregnanolone isomers (PI) allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one), pregnanolone (3alpha-hydroxy-5beta-pregnan-20-one), isopregnanolone (3beta-hydroxy-5alpha-pregnan-20-one), epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one), progesterone, and estradiol were measured in 138 pregnant women. The sampling was carried out from the first through the 10th month of pregnancy. Gas chromatography-mass spectrometry analysis and RIA were used for the measurement of steroid levels. The ratios of individual PI were similar to those found previously around parturition: about 25:10:7:1 for allopregnanolone, pregnanolone, isopregnanolone, and epipregnanolone, respectively. All the PI showed a significant increase during pregnancy, which was more pronounced in the 3alpha-steroids. The results indicated changing ratios between 3alpha- and 3beta-PI and between 5alpha- and 5beta-PI throughout pregnancy. The constant allopregnanolone/isopregnanolone ratio found through pregnancy weakened the hypothesis of the role of isopregnanolone in the onset of parturition. The ratio of estradiol (stimulating uterine activity) to 5alpha-PI and epipregnanolone exhibited significant changes during pregnancy in favor of estradiol up to the sixth or seventh month, in contrast to the constant estradiol/pregnanolone ratio. A pregnancy-stabilizing role of pregnanolone, counterbalancing the stimulating effect of estradiol on the onset of parturition, was suggested.
Parízek
Antonín
A
Department of Gynecology and Obstetrics, First Medical Faculty, Charles University, Prague 1, Czech Republic.
Hill
Martin
M
Kancheva
Radmila
R
Havlíková
Helena
H
Kancheva
Lyudmila
L
Cindr
Josef
J
Pasková
Andrea
A
Pouzar
Vladimír
V
Cerny
Ivan
I
Drbohlav
Pavel
P
Hájek
Zdenek
Z
Stárka
Luboslav
L
D004958:Estradiol / Q000097:blood; D005260:Female; D005865:Gestational Age; D006801:Humans; D007536:Isomerism; D007743:Labor, Obstetric / Q000097:blood; D011247:Pregnancy / Q000097:blood*; D011280:Pregnanolone / Q000097:blood*; D011374:Progesterone / Q000097:blood
D011374:Progesterone; D004958:Estradiol; D011280:Pregnanolone