11b-Hydroxysteroid Dehydrogenase and Glucocorticoid Receptor Messenger RNA Expression in Porcine Placentae: Effects of Stage of Gestation, Breed, and Uterine Environment1

Glucocorticoids are known to influence many aspects of prenatal development. Three important regulators of glucocorticoid actions at the cellular level are the enzymes 11b-hydroxysteroid dehydrogenase type 1 (11bHSD-1), 11b-hydroxysteroid dehydrogenase type 2 (11bHSD-2), and glucocorticoid receptors (GR). The present study was conducted to determine the presence of these regulators in porcine placentae during early gestation (Days 24–40; term 5 114 days) and to examine the influence of breed and uterine environment. Three pig models differing in uterine environment as reflected by embryonic survival from Days 24 to 40 were used: intact white cross-bred gilts (WC-INT); white cross-bred gilts that had been unilaterally hysterectomized-ovariectomized before puberty (WC-UHO); and intact Meishan gilts (ME). Porcine-specific partial cDNAs for 11bHSD-1 and 11bHSD-2 and a cRNA for GRa were developed and used to produce 32P-labeled probes for Northern blot analyses. The 11bHSD dehydrogenase activity was measured in vitro at saturating concentrations of substrate and coenzyme. At Day 24 of gestation, 11bHSD-2 mRNA, dehydrogenase activity, and GR mRNA were present, but 11bHSD-1 mRNA was absent. All three mRNAs and dehydrogenase activity increased (P , 0.01) by Day 40. On Day 30, placental 11bHSD-2 mRNA was decreased (P 5 0.03) by 47% in WC-UHO versus WC-INT. Placental 11bHSD dehydrogenase activity was 2-fold greater (P , 0.01) in ME versus WC-INT on Day 24 of gestation. These results demonstrate, to our knowledge for the first time, the presence of 11bHSD-1, 11bHSD-2, and GR mRNA as well as 11bHSD dehydrogenase activity in the porcine placenta during early pregnancy. Moreover, a role for glucocorticoids in porcine embryonic development is suggested. conceptus, cortisol, developmental biology, embryo, glucocorticoid receptor