Neuroactive steroids, their precursors and polar conjugates during parturition and postpartum in maternal blood: 2. Time profiles of pregnanolone isomers

Time profiles of the pregnanolone isomers epipregnanolone (3 beta -hydroxy- 5 beta -pregnan-20-one), allopregnanolone (3 alpha -hydroxy-5 alpha -pregna n-20-one), pregnanolone (3 alpha -hydroxy-5 beta -pregnan-20-one), and isop regnanolone (3 beta -hydroxy-5 alpha -pregnan-20-one) were measured around parturition and in the postpartum period in the serum of 13 and three women with subarachnoidal and epidural analgesia, respectively. In addition, the levels of polar conjugates of all pregnanolone isomers were followed durin g parturition. GC/MS analysis was used for the measurement of steroid level s. 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 pr ofile of the conjugated/free steroid ratio exhibited a significant decrease within the first hour and the first day after delivery in all of the isome rs investigated. A decrease was also observed in the ratio of 3 alpha /3 be ta -isomers and 5 alpha /5 beta -isomers around parturition. The possible p hysiological consequences of the findings are indicated. (C) 2001 Elsevier Science Ltd. All rights reserved.