Nineteen healthy young women, non-smokers and of normal weight, used a
combined oral contraceptive, consisting of 20 mug ethinylestradiol an
d 150 mug desogestrel, for 9 cycles and were investigated before start
ing oral contraceptive use, and during the 3rd, 6th and 9th cycle. In
all cases, the antioxidant erythrocyte enzyme activities, superoxide-d
ismutase (SOD), catalase (CAT) and glutathione-peroxidase (GSH-Px), we
re determined. Pyruvate-kinase (PK) activity was also considered as a
predictable index of the age and constancy of the erythrocyte populati
on. A steady, significant increase in GSH-Px and CAT enzyme activities
was found. No significant variations were found in SOD and PK enzyme
levels. These findings clearly suggest that the use of combined oral c
ontraceptives leads to an increase in antioxidant defenses. The specif
ic physiological and biochemical mechanisms of this response merit fur
ther investigation.