Document Detail

Circulating levels of pregnanolone isomers during the third trimester of human pregnancy.
MedLine Citation:
PMID:  17583491     Owner:  NLM     Status:  MEDLINE    
This study addresses the question of whether changes in the biosynthesis and metabolism of neuroactive pregnanolone isomers (PIs) might participate in the timing of parturition in humans. The time profiles of unconjugated allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one, P3alpha5alpha), pregnanolone (3alpha-hydroxy-5beta-pregnan-20-one, P3alpha5beta), isopregnanolone (3beta-hydroxy-5alpha-pregnan-20-one, P3beta5alpha) and epipregnanolone (3beta-hydroxy-5beta-pregnan-20-one, P3beta5beta), pregnenolone, their polar conjugates, progesterone, 5alpha-dihydroprogesterone (P5alpha), and 5beta-dihydroprogesterone (P5beta) were monitored in the plasma of 30 healthy women during the third trimester of pregnancy, at 1-week intervals from the 30th week of gestation using GC-MS. Changes in the steroid levels were evaluated by two-way ANOVA with gestational age and subject as independent factors. The mean concentrations of free PIs ranged from 2 to 50 nmol/L, while the mean levels of their polar conjugates were 40-100 x higher. The ratio of 5alpha-PIs to progesterone significantly but inconspicuously culminated in the 35th week. The decelerating biosynthesis of free 5beta-PIs from the 31st week and their escalating sulfation was found from the 30th week. The changes were particularly evident in the second most abundant PI pregnanolone that may, like the allopregnanolone, sustain the pregnancy via attenuation of hypothalamic GABA(A)-receptors and prevent uterine contractility via binding to nuclear pregnane X receptor.
Martin Hill; David Cibula; Helena Havlíková; Lyudmila Kancheva; Tomás Fait; Radmila Kancheva; Antonín Parízek; Luboslav Stárka
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-05-16
Journal Detail:
Title:  The Journal of steroid biochemistry and molecular biology     Volume:  105     ISSN:  0960-0760     ISO Abbreviation:  J. Steroid Biochem. Mol. Biol.     Publication Date:    2007 Jun-Jul
Date Detail:
Created Date:  2007-08-13     Completed Date:  2007-11-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9015483     Medline TA:  J Steroid Biochem Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  166-75     Citation Subset:  IM    
Institute of Endocrinology, Národní trída 8, CZ 116 94 Prague 1, Czech Republic.
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MeSH Terms
Gas Chromatography-Mass Spectrometry
Pregnancy Trimester, Third
Pregnanolone / blood*
Reg. No./Substance:

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