Differences in expression and activity of 11β-hydroxysteroid dehydrogenase type 1 and 2 in human placentas of term pregnancies according to birth weight and gender

BackgroundFetal exposure to maternal glucocorticoids may determine fetal growth and the programing of later disorders. Availability of the glucocorticoids in the placenta is regulated by the 11β-hydroxysteroid dehydrogenase (11β-HSDs) enzymes. To date, there are discrepancies with regard to cortisol (F) cord blood levels in fetuses with intrauterine growth retardation in different species.ObjectiveTo study the expression and activity of 11β-HSDs in placentas from full term small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) newborns, and cortisol cord blood concentration.MethodsTwenty-five placentas from AGA, 24 SGA and 25 LGA were collected.ResultsSGA newborns had significantly lower and LGA newborns had significantly higher birth weight, birth length, head circumference, and placental weight than AGA counterparts. We observed a direct correlation between placental weight and birth weight, birth length and head circumference, and higher cord F levels in SGA newborns. The 11β-HSD1 expression was similar among the SGA, AGA, and LGA placentas. However, within the placentas of SGA newborns, the 11β-HSD1 mRNA levels were significantly reduced in the chorionic plate compared with basal plate. An inverse correlation between cord F levels and activity of 11β-HSD1 in the chorionic plate of the SGA placentas was detected. The 11β-HSD2 activity was seven- to eightfold higher compared with 11β-HSD1 in the placentas, and there was a lower 11β-HSD2 activity in females' SGA placentas compared with the male SGA placentas.ConclusionWe observed a lower expression and activity of 11β-HSD1 in the chorionic plate of the SGA placentas, suggesting a possible compensatory mechanism to diminish the higher cortisol fetal concentrations observed in fetuses with intrauterine growth restriction.