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Differential localization of placental extracellular superoxide dismutase as pregnancy progresses
K A Boggess1, H H Kay, J D Crapo
1Departments of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA.
Objective:
The aim of this study was to determine placental localization and activity of extracellular superoxide dismutase, a nitric oxide modulator, during early gestation and to correlate these characteristics with fetal vascular development.
Study Design:
First-trimester (n = 10) and second-trimester (n = 10) villi were obtained at elective pregnancy termination. Extracellular superoxide dismutase was localized by means of an immunoperoxidase method. Activity was measured by determining the inhibition of cytochrome c reduction at pH 10 and messenger ribonucleic acid expression by in situ hybridization.
Results:
Extracellular superoxide dismutase was intracellular within villous trophoblasts until 17 weeks' gestation, when it relocated to the villous extracellular matrix. Activities were similar between first- and second-trimester villi. In situ hybridization confirmed extracellular superoxide dismutase messenger ribonucleic acid within trophoblasts throughout gestation.
Conclusion:
Extracellular superoxide dismutase is produced by trophoblasts early in pregnancy, but it remains intracellular until 17 weeks' gestation, which may be related to fetal vascular development.