Submitted to: Life Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 2000
Publication Date: February 1, 2000
Citation: Klemcke, H.G. 2000. Dehydrogenase and oxoreductase activities of porcine placental 11beta-hydroxysteroid dehydrogenase. Life Sciences. 66(11):1045-1052. Interpretive Summary: Pig litter size at birth is reduced due to 30-50% mortality during gestation. In order to increase litter size, it is important to understand factors that limit litter size and those factors that are important for normal prenatal development. One such factor could be the steroid hormone cortisol. Optimal concentrations of cortisol may be beneficial to normal development, whereas excessive concentrations are known to limit growth an even cause fetal losses. One factor regulating the availability of cortisol to target tissues is the enzyme 11beta-hydroxysteroid dehydrogenase (11B-HSD) that interconverts biologically active cortisol and inactive cortisone. It has been suggested that placental 11B-HSD may protect fetuses from higher maternal cortisol concentrations. The current study was conducted to determine if both forms of 11B-HSD (oxidative, cortisol to cortisone; reductive, cortisone to cortisol) are present at day y75 of gestation (term = 114 days) in pig placentae. Both forms were found to be present, and 11B-HSD oxidative activity greatly exceeded reductive activity. Larger fetuses and placentae were associated with greater concentrations of placental 11B-HSD oxidative activity. These data suggest that porcine placental 11B-HSD oxidative activity helps to provide an optimal glucocorticoid environment that supports enhanced fetal and placental growth.
Technical Abstract: Dehydrogenase (cortisol to cortisone) and oxoreductase (cortisone to cortisol) activities of porcine placental 11beta-hydroxysteroid dehydrogenase (11B-HSD) were measured in tissue fragment cultures on day 75 of gestation. Dehydrogenase activity was over fivefold greater than oxoreductase activity (p < .001). There were positive linear associations (p < .01) between net dehydrogenase activity (dehydrogenase minus oxoreductase) and fetal weight, fetal length, and placental weight. These data indicate a predominance of placental 11B-HSD dehydrogenase activity at this gestational stage that would insure a net conversion of cortisol to cortisone as it traverses the placenta. The data further suggest that 11B-HSD activities may provide an optimal glucocorticoid environment that is supportive of enhanced fetal and placental growth.