The effects of physiological changes in estrogens and androgens on the erythrocyte antioxidant superoxide dismutase, catalase and glutathione peroxidase enzyme activities during the menstrual cycle were investigated in healthy eumenorrheic women. Blood samples were taken on alternate days from twelve normally cyclic women (age range: 20 to 27 years; mean age: 24·1 years) from the first day of one menstrual cycle until the first day of the subsequent one. Plasma was analyzed for FSH, LH, estradiol, progesterone, testosterone, free testosterone and androstenedione concentrations. Erythrocyte superoxide dismutase, catalase and glutathione peroxidase activities were evaluated on the same days and cycle length was standardized on the basis of the preovulatory estradiol peak. Significant cyclic phase-related changes were observed in glutathione peroxidase (P<0·05), with higher glutathione peroxidase activity levels from the late follicular to the early luteal phase compared with those found in the early follicular phase (P<0·001 and P<0·002 respectively). A significant positive correlation was observed between mean estradiol and glutathione peroxidase cycle-related variations (r=0·80, P<0·001), whereas no significant cycle phase-dependent changes were seen in superoxide dismutase and catalase. No effect of progesterone and androgens on the erythrocyte antioxidant enzyme system was documented. The findings indicate that physiological ovarian estradiol production during the menstrual cycle may have an important role in regulating erythrocyte glutathione peroxidase activity.

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After birth, host defences must be recruited to manage the transition from an almost sterile to a normal environment. The present study was undertaken to evaluate the relationship between cytokine plasma levels and phagocyte burst in mothers and neonates during the peripartal period. Plasma levels of interleukin (IL)-1 IL-6, tumour necrosis factor (TNF)-α interferon (IFN)-γ and granulocyte-macrophage colony-stimulating factor (GM-CSF) and whole blood superoxide anion (^●O₂) generation were evaluated in 27 healthy mothers, 16 undergoing vaginal delivery (VD) and 11 elective caesarean section (ECS) and in their babies. Blood specimens were taken from the mothers at the beginning of labour, during labour, immediately after delivery and 4 days later in the VD group, and before anaesthesia, immediately after delivery and 4 days later in the ECS group; neonatal samples were taken at birth (cord blood) and 4 days later. After delivery by VD, these mothers had higher plasma levels of IL-1β, IL-6, IFN-γ and higher ^●O₂ generation than those delivered by ECS. IL-6 plasma levels and ^●O₂ generation were higher in babies born by VD than in those born by ECS. A statistically significant correlation between IL·6 plasma levels and ^●O₂ release was observed in cord blood of babies born by VD (r = 0.69; p < 0.006). The study demonstrates that labour plays an important role in modulating host defences in the newborn.

Our findings support the hypothesis that oestrogens are responsible for the sex-related differences in glutathione peroxidase activity. The hypothesis generated from the present study can be tested directly in experimental models involving specific bone marrow cells by analysis of specific glutathione peroxidase transcriptional changes.

The findings support the hypothesis that physiological ovarian E2 production during the menstrual cycle may play an important role in regulating erythrocyte glutathione peroxidase activity.