Pregnanolone Isomers, Pregnenolone and Their Polar
Conjugates Around Parturition
J. KLAK1, M. HILL1,
A. PAŘÍZEK2, H. HAVLÍKOVÁ1, M.
BIČÍKOVÁ1, R. HAMPL1, T. FAIT3,
J. ŠULCOVÁ, V. POUZAR4, R. KANCHEVA1,
L. STÁRKA1
1Institute of Endocrinology, 2Clinics
of Gynecology and Obstetrics, First Faculty of Medicine,
3General Faculty Hospital, Charles University
and 4Institute of Organic Chemistry and
Biochemistry, Czech Academy of Sciences, Prague, Czech
Republic
Received April 9, 2002
Accepted June 5, 2002
Summary
The levels of
four pregnanolone isomers and their polar conjugates and
pregnenolone sulfate were measured in the plasma of 13 and 7
women at delivery with subarachnoidal and epidural analgesia,
respectively, and in corresponding samples of umbilical plasma
using a simple quadrupole GC/MS system with electron impact
ionization (pregnenolone isomers), RIA following HPLC separation
(pregnenolone) and specific RIA (pregnanolone sulfate). The
concentration of epipregnanolone (3b-hydroxy-5b-pregnan-20-one)
in both
maternal and umbilical plasma was much lower than that of other
pregnanolone isomers.
The
levels of 3b-hydroxy-pregnanolone
isomers were significantly higher in the umbilical plasma than
in the maternal, while the differences in 3a-hydroxy-isomers
were insignificant. The differences in conjugates were
insignificant with the exception of allopregnanolone, the levels
of which were lower in umbilical plasma. In
all the pregnanolone isomers, a significantly lower conjugated/unconjugated
steroid ratio was found in the umbilical plasma than in the
maternal plasma.
In addition, time profiles of the steroids were measured around
parturition and in the postpartum period in the maternal serum.
Similarly, the levels of polar conjugates of all pregnanolone
isomers were followed during parturition. Changes in
concentrations of free steroids exhibited a similar pattern,
with a fall primarily within the first hour after delivery. The
decrease in conjugated steroids was shifted to the interval
within the first hour and first day after delivery, and the
changes were more pronounced. The time profiles of the
conjugated/free steroid ratio exhibited a significant decrease
within the first hour and the first day after delivery in all of
the isomers investigated. A decrease was also observed in the
ratio of 3a/3b-
isomers and 5a/5b-
isomers around parturition. The possible physiological
consequences of the findings are indicated.
Key
words
Pregnanolone isomers • Pregnenolone • Maternal plasma •
Umbilical plasma • Parturition
Reprint
requests
Martin Hill, Institute of Endocrinology, Národní třída 8,
Prague, CZ 116 94, Czech Republic. Fax: +420-2-24905 325.
E-mail: mhill@endo.cz
|
