Simultaneously reduced gene expression of cortisol-activating and cortisol-inactivating enzymes in placentas of small-for-gestational-age neonates

OBJECTIVE: The enzyme 11 beta- hydroxysteroid dehydrogenase type 2 (11 beta HSD2) converts cortisol into cortisone. Reduced placental activity of 11 beta 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 11 beta- 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 11 beta-HSD1 and 11 beta-HSD2 messenger ribonucleic acid (mRNA) was determined using reverse transcription-polymerase chain reaction. RESULTS: Placental mRNA expression of 11 beta-HSD1 and 11 beta-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 11 beta-HSD2 and 11 beta-HSD1 gene expression is reduced. Adapted levels of 11 beta-HSD1 might result in a counterregulatory mechanism limiting transplacental passage of elevated cortisol levels.