Selenium and malondialdehyde content and glutathione peroxidase activity in maternal and umbilical cord blood and amniotic fluid

Placenta tissue may be a major source of lipid peroxidation products in pre gnancy. It was proven that placental peroxidation activity increases with g estation. Selenium (Se), as an essential constituent of glutathione peroxid ase (GSH-Px), takes part in the reduction of hydrogen peroxides and lipid p eroxides. Malondialdehyde (MDA) is a major breakdown product split off from lipid peroxides. In this study, Se and MDA content and GSH-Px activity wer e measured in blood and plasma taken from 20 apparently healthy nonpregnant women between 19 and 38 yr of age and from 115 unselected pregnant women b etween 17 and 45 yr of age (35 in the first trimester, 22 in the second tri mester, 38 in the third trimester, and 20 within 2 d of delivery). Samples of umbilical cord blood and amniotic fluid were taken from women in the sec ond and third trimesters and at delivery. The Se content was measured by at omic absorption spectrometry (AAS), plasma MDA concentration by thiobarbitu ric acid reaction, and Se-dependent GSH-Px spectrometrically. Blood and pla sma Se contents of nonpregnant women were below those considered adequate, indicating low selenium intake. In comparison to nonpregnant women, pregnan t women had significantly decreased whole-blood and plasma Se levels in the second and third trimesters and at delivery. The significant drop of whole -blood SeGSH-Px activity was observed in the first trimester of pregnancy a nd its lower activity was maintained until delivery. A significant drop in plasma SeGSH-Px activity occurred in the second trimester and attained the minimal level at delivery. The Se level and SeGSH-Px activity in maternal a nd umbilical cord blood were at similar levels. Amniotic-fluid SeGSH-Px act ivity was nondetectable or exceptionally low and its Se content remained un changed during pregnancy. Plasma levels of MDA were significantly decreased in the second and third trimesters and at delivery. The fetal blood plasma at birth had a lower MDA level compared to the levels of MDA of their moth ers at delivery. A low, but significant inverse correlation existed between blood SeGSH-Px activity and plasma MDA content and between plasma Se and p lasma MDA contents during pregnancy A significant decrease of Se and SeGSH- Px activities (antioxidant enzyme) in both blood and plasma suggests a poss ible drop in total antioxidant status during pregnancy. Elevated MDA plasma levels might be the result of increased lipid peroxidation in placental ti ssue during pregnancy.