Changes in the abundance of mRNA for type-I 3 beta-hydroxysteroid dehydrogenase/delta 5-->delta 4 isomerase in the human placenta and fetal membranes during pregnancy and labor.
A local decrease in progesterone synthesis in the placenta and fetal membranes has long been proposed as a possible mechanism in the control of human labor. We have examined whether changes occur in the abundance of mRNA for 3 beta-hydroxysteroid dehydrogenase/delta 5-->delta 4 isomerase (3 beta-HSD), the enzyme which catalyzes the conversion of pregnenolone to progesterone in human placenta and fetal membranes, by Northern blot analysis using a cDNA probe to human placental type-I 3 beta-HSD, the predominant isoenzyme in the placenta. The abundance of 3 beta-HSD mRNA (1.7-kb transcript) was about 10-fold greater in term placenta than in chorio-decidua, but undetectable in total RNA from amnion. There was no change in the abundance of 3 beta-HSD mRNA in either placenta or chorio-decidua obtained after elective cesarean section at term, after preterm labor, or after term or postterm vaginal delivery. We conclude that the abundance of 3 beta-HSD mRNA does not change in the placenta or fetal membranes with labor, consistent with the view that changes in 3 beta-HSD gene expression and decreased progesterone production are unlikely to effect intrauterine paracrine/autocrine regulatory mechanisms leading to term or preterm labor in women.
Riley
S C
SC
MRC Group in Fetal and Neonatal Health and Development, Lawson Research Institute, St Joseph's Health Centre, London, Ont., Canada.
Bassett
N S
NS
Berdusco
E T
ET
Yang
K
K
Leystra-Lantz
C
C
Luu-Thé
V
V
Labrie
F
F
Challis
J R
JR
D015152:Blotting, Northern; D002823:Chorion / Q000378:metabolism; D003656:Decidua / Q000378:metabolism; D005321:Extraembryonic Membranes / Q000201:enzymology*; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy / Q000378:metabolism*; D011284:Pregnenolone / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D011375:Progesterone Reductase / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013251:Steroid Isomerases / Q000235:genetics* / Q000378:metabolism
C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D011374:Progesterone; D011284:Pregnenolone; D011375:Progesterone Reductase; D013251:Steroid Isomerases