5Alpha-dihydroprogesterone (5alpha-DHP) is the immediate precursor of 5alpha-pregnan-3alpha-ol-20-one, a potent anxiolytic/anesthetic agent in all vertebrate animals tested, including humans. The levels of 5alpha-DHP in the plasma of pregnant women are very high; and during the third trimester of pregnancy, the blood production rate of this steroid may exceed 100 mg/24 h. 5Alpha-DHP in maternal plasma, however, cannot be accounted for totally by the metabolism of maternal plasma progesterone. This study was conducted to evaluate the possibility that 5alpha-DHP is synthesized in placenta from 5alpha-pregnan-3alpha/beta-ol-20-ones delivered to the trophoblast via the fetal umbilical blood. In incubations of placental minces with radiolabelled 5alpha-pregnan-3alpha/beta-ol-20-ones, there is extensive epimerization and the intermediate, 5alpha-DHP, is the major product. In other incubations, 5alpha-pregnan-3beta-ol-20-one-sulfate was hydrolysed and the liberated 5alpha-pregnan-3beta-ol-20-one was converted to 5alpha-DHP by homogenates of placental tissue, but 5alpha-pregnan-3beta-ol-20-one-sulfate was not. The oxidation of 5alpha-pregnan-3alpha/beta-ol-20-ones was concentrated in microsome-enriched preparations of placental tissue and the apparent Kms for 5alpha-pregnan-3alpha-ol-20-one and 5alpha-pregnan-3beta-ol-20-one were 3.6 microM and 78 nM, respectively. The Vmaxs for 5alpha-DHP formation from 5alpha-pregnan-3alpha-ol-20-one and 5alpha-pregnan-3beta-ol-20-one were, respectively, 336 pmol/min/mg protein and 9.7 nmol/min/mg protein. These oxidation reactions were supported by both NAD+ and NADP+. We suggest that progesterone, which enters the umbilical circulation from its site of synthesis in the syncytiotrophoblast, is metabolized in the fetus to 5alpha-pregnan-3alpha/beta-ol-ones and to 5alpha-pregnan-3alpha/beta-yl-20-one sulfates. These metabolites of progesterone, 5alpha-pregnan-3alpha/beta-ol-20-one and 5alpha-pregnan-3beta-yl-20-one sulfate, formed in the fetus, serve as plasma-borne substrates for trophoblast formation of 5alpha-DHP. Because of the hemochorioendothelial nature of human placentation, 5alpha-DHP secreted from the trophoblast will preferentially enter the maternal compartment, thus constituting a maternal plasma progesterone-independent source of 5alpha-DHP.

5-alpha-Dihydroprogesterone↗

PubMedDate not supplied

Accumulation of interleukin-1beta and interleukin-6 in amniotic fluid: a sequela of labour at term and preterm.

From the finding of micro-organisms or inflammatory mediators, or both, in amniotic fluid (AF), it has been proposed that intrauterine infection is one cause of preterm labour (PTL, intact fetal membranes). This theory, however, remains unproved, i.e. the accumulation of micro-organisms and inflammatory mediators in AF after labour is in progress may be the consequence, not the cause, of labour both at term and preterm. This study was conducted to evaluate this possibility by a comparison of the concentrations of interleukin (IL)-1beta and IL-6 in AFs collected before and during PTL (<34 weeks gestation) with those in AFs collected at term (before labour and from the forebag and upper compartments of the amniotic sac during labour). The concentrations of IL-1beta and IL-6 in AF were also analysed as a function of the duration of labour (term or preterm) before fluid collection. In addition, studies were conducted to define the source of IL-1beta in AF. A total of 666 AFs were evaluated. IL-1beta was not detected (<50 pg/ml) in AFs collected before the onset of labour at any stage of gestation (n = 320), including 170 fluids obtained at term. During labour, IL-1beta was detected (>50 pg/ml) in 58 out of 106 (54.7%), 17 out of 64 (26.6%) and 60 out of 176 (34%) of AF samples obtained during PTL, term labour (upper compartment) and term labour (forebag) respectively. AF sampling, as well as labour and delivery, were completed in <18 h in all term pregnancies. However, labour (with cervical dilation) was in progress for >18 h before AF was collected in 39 out of 106 (37%) PTL pregnancies. The incidence of IL-1beta-positive samples among AFs collected before 18 h of PTL (23 out of 67; 34%) was indistinguishable from that in AFs collected during labour at term. However, in AFs collected after >18 h PTL, the incidence of IL-1beta-positive samples was 35 out of 39 (89.7%) The concentrations of IL-1beta (pg/ml; mean +/- SEM) in AFs collected during PTL (2680 +/- 730; n = 106) were greater than those in AFs collected from the upper compartment and forebag during term labour (436 +/- 244, n = 64; and 468 +/- 119, n = 176) respectively; this difference, however, was attributable to very high concentrations of IL-1beta in AFs in which PTL was in progress for >18 h before AF collection (6021 +/- 1832; n = 39). The concentrations of IL-6 in AF were correlated with those of IL-1beta (P < 0.001). We conclude that IL-1beta and IL-6 accumulate in AF in a similar proportion of pregnancies during the first 18 h of term and preterm labour. Therefore, the accumulation of these cytokines in AF cannot be taken as evidence for a role for infection in the pathogenesis of PTL.

Amniotic Fluid↗

PubMedDate not supplied

Effect of epidermal growth factor on ornithine decarboxylase activity in A431 cells.

Epidermal growth factor (EGF) stimulates mitogenesis in a number of cell lines; but in A431 cells, EGF causes inhibition of replication. To investigate the possibility that an alteration in the polyamine biosynthetic pathway could be associated with this unusual response of A431 cells to EGF, we evaluated the effect of EGF on ornithine decarboxylase activity. We also evaluated the action of inhibitors of ornithine decarboxylase (difluoromethyl ornithine and retinoic acid) on A431 cell replication. We found a significant stimulatory effect of EGF on ornithine decarboxylase activity and a significant inhibition of cell replication by ornithine decarboxylase inhibitors. These findings are suggestive that the paradoxical response of A431 cells to EGF stimulation is not due to an aberrant response in polyamine formation. Specifically, we found that A431 cells respond, like other cell types, to a growth factor (viz., EGF) with an increase in ODC activity. Moreover, in A431 cells ornithine decarboxylase activity is required for replication.

Carcinoma, Squamous Cell↗