Oxidative Challenge and Glucose-6-Phosphate Dehydrogenase Activity of Preterm and Term Neonatal Red Blood Cells

Abstract

Background: Recent studies suggest that a low antioxidant level in preterm infants may predispose them to increased oxidative stress and results in hyperbilirubinemia, whereas glucose-6-phosphate dehydrogenase (G6PD) activity was found to be higher in preterm infants than in term infants. Objectives: To evaluate (1) the oxidative effect of α-naphthol on preterm and term red blood cells, and (2) the relationship between G6PD activity and the gestational age of these infants. Methods: G6PD activities were determined in preterm and term infants by a standard diagnostic method. Whole blood samples were incubated with α-naphthol for 2 h and their pre- and post-challenged reduced glutathione (GSH) levels were quantified. Results: The mean G6PD activity in preterm infants (n = 113; 13.52 ± 0.19 U/g Hb; gestational age 30.67 ± 0.28 weeks) was significantly higher than that in term infants (n = 100; 12.36 ± 0.16 U/g Hb; gestational age 39.82 ± 0.14 weeks; p < 0.001). A significantly negative correlation was demonstrated between gestational age and G6PD activity (r = –0.34, p < 0.001). GSH levels of preterm and term subjects were similar at baseline, but were significantly decreased upon challenge with α-naphthol (p < 0.001). The percentage reduction in GSH levels was similar in the various gestational age groups. Conclusions: Our data show that G6PD activities had a negative correlation with gestational age of G6PD-normal infants. The similar response of preterm and term erythrocytes to an α-naphthol challenge indicates the manifestation of an active anti-oxidative pathway mediated by cellular GSH.