Endogenous antioxidant defences in plasma and erythrocytes of pregnant women during different trimesters of pregnancy

Abstract

Background: To assess the antioxidant capacity of pregnant women in Ogun State, Nigeria.

Methods: The activities of total superoxide dismutase (total SOD), manganese superoxide dismutase (Mn-SOD), catalase (CAT), glutathione transferase(GST), aminolevulinic acid dehydratase (ALAD), and the concentrations of glutathione (GSH), were determined in the plasma and red blood cells of non-pregnant (n=20), normal healthy pregnant women during different trimesters of pregnancy (n=90), and pregnant women with pre-eclampsia (n=7).

Results: A 2-fold increase in erythrocyte CAT activity was observed in the pregnant women (p<0.05), while CAT activity in the pre-eclamptic women was not significantly different from control (p0.05). A 3-fold increase in plasma Mn-SOD was observed in the pregnant women including those with pre-eclampsia (p<0.05). ALAD activities in the first, second and third trimesters of pregnancy were 35, 51 and 55% of control, respectively (p<0.05), while in the women with pre-eclampsia it was 31% of control (p<0.05). Total SOD also decreased significantly in the erythrocytes of the pre-eclamptic women (p<0.05). Other antioxidants (GST and GSH) were not affected.

Conclusions: Results suggest that oxidative stress is higher in pregnancy than in non-pregnant state. Our findings also suggest that while plasma Mn-SOD might play a significant role in detoxifying the superoxide anions produced in the placenta, the decomposition of hydrogen peroxide in erythrocytes is mainly due to CAT activity. Whether inhibition of ALAD contributes to the etiology of pre-eclampsia remains to be elucidated.