Objective: The enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) converts cortisol into cortisone. Reduced placental activity of 11beta-HSD2 in small-for-gestational-age (SGA) neonates results in fetal cortisol excess. In the present study, we examined the yet unknown gene expression of 11beta-HSD1, which primarily synthesizes cortisol in SGA placenta.
Study design: In placentas taken from 24 women with normal-weight newborns and 16 women with SGA neonates, expression of 11beta-HSD1 and 11beta-HSD2 messenger ribonucleic acid (mRNA) was determined using reverse transcription-polymerase chain reaction.
Results: Placental mRNA expression of 11beta-HSD1 and 11beta-HSD2 was significantly reduced in the SGA group (P = .006 and P < .0001). Both enzymes showed a significant correlation to birthweight SD score and placental weight. Also, levels of both enzymes were significantly correlated.
Conclusion: In placental tissue of SGA neonates 11beta-HSD2 and 11beta-HSD1 gene expression is reduced. Adapted levels of 11beta-HSD1 might result in a counterregulatory mechanism limiting transplacental passage of elevated cortisol levels.