Increased biological oxidation and reduced anti-oxidant enzyme activity in pre-eclamptic placentae

Abstract

Oxidative stress occurs when cellular levels of reactive oxygen species exceed anti-oxidant capabilities and has been implicated in the pathogenesis of pre-eclampsia. In this study we have examined the tissue levels of endogenous anti-oxidant proteins (superoxide dismutase, glutathione peroxidase, thioredoxin reductase and thioredoxin) and the level of lipid and protein oxidation in placental samples from normal and pre-eclamptic pregnancies. Pre-eclamptic tissue homogenates demonstrated significantly increased levels of lipid peroxidation (20.68 ± 7.811 μM/mg protein versus 5.33 ± 4.03 μM/mg protein, P<0.001) and a trended increase in protein carbonyl concentration (248.1 ± 97.71 units/mg protein versus 209.7 ± 82.6 units/mg protein) when compared to controls. The levels and activities of the anti-oxidant proteins superoxide dismutase (2.48 ± 0.6 U/mg protein versus 2.02 ± 0.51 U/mg protein, P<0.02), thioredoxin reductase (19.25 ± 9.81 U/mg protein versus 13.02 ± 5.66 U/mg protein, P=0.02), thioredoxin (107.00 ± 18.11 ng/mg protein versus 91.12 ± 21.18 ng/mg protein, P=0.02) and glutathione peroxidase (17.33 ± 6.63 mmol/min/mg protein versus 11.50 ± 3.11 mmol/min/mg, P<0.02) were all found to be significantly reduced when comparing pre-eclamptic placental tissue homogenates to gestational age-matched control placentae from non-pre-eclamptic pregnancies. The results of this study demonstrate a decreased enzymatic anti-oxidant capacity and increased oxidation in placental tissue from pre-eclamptic women, which may contribute to the pathogenesis of this complex disorder. © 2004 Elsevier Ltd. All rights reserved.