67 Relationships of circulating pregnanolone isomers and their polar conjugates to the status of sex, menstrual cycle, and pregnancy Radmila Kancheva, Martin Hill, David Cibula1, Helena Vcˇela´kova´, Lyudmila Kancheva, Jana Vrbı´kova´, Toma´sˇ Fait1, Antonı´nParˇ´ızek1 and Luboslav Sta´rka Institute of Endocrinology, Na´rodnı´trˇı´da 8, CZ 116 94 Prague 1, Czech Republic 1Department of Gynecology and Obstetrics, 1st Medical Faculty, Charles University, Apolina´rˇska´ 18, CZ 128 51 Prague 2, Czech Republic (Requests for offprints should be addressed to M Hill; Email:
[email protected]) Abstract Pregnanolone isomers (PIs) and their polar conjugates (PICs) found in P indicate the more intensive conjugation of 5a-PI modulate ionotropic receptors such as g-aminobutyric acid during pregnancy. This mechanism probably provides for the or pregnane X receptors. Besides, brain synthesis, PI elimination of neuroinhibitory P3a5a in the maternal penetrates the blood–brain barrier. We evaluated the compartment. Additionally, our result points to a limited physiological importance of PI respecting the status of sex, sulfation capacity for neuroinhibitory P3a5b in P. In contrast menstrual cycle, and pregnancy. Accordingly, circulating to the situation in M, F, and L where the P3a5bC is the most levels of allopregnanolone (P3a5a), isopregnanolone abundant PIC, and P3a5b is present in minor quantities (P3b5a), pregnanolone (P3a5b), epipregnanolone (P3b5b), compared with the P3a5a,P3a5b may acquire physiological their polar conjugates, and related steroids were measured in importance during pregnancy, contributing to the sustaining 15 men (M), 15 women in the follicular phase (F), 16 women thereof. On the other hand, the declining formation of in the luteal phase (L), and 30 women in the 36th week of P3a5b may participate in the initiation of parturition, given gestation (P) using GC–MS.