Oxidative Stress: The Role of Estrogen and Progesterone

The effect of estrogen and progesterone on oxidative status is not yet very clear, improvements and detrimental effects having been reported with the use of menopausal hormone therapy or hormonal contraceptives, respectively. In this study, we evaluated the role played by estrogen and progesterone separately, on the oxidative status of 32 women, 18 to 43 years old, by inducing high levels of estrogen and then adding high levels of progesterone. During a cycle of in vitro fertilization, blood samples were collected prior to gonadotrophin stimulation (low estradiol levels), on the day of oocyte retrieval (high levels of estrogen), and on the day of embryo transfer (high levels of estrogen and progesterone). Total blood levels of oxidants (FORT), antioxidants (FORD), and their ratio FORT/FORD were measured using a colorimetric method based on the Fenton reaction. Seven women measured their early morning body temperature at the same time points. FORT significantly decreased from the low- to the high-estrogen phase (p = 0.023) and increased from the high-estrogen to the high-estrogen-progesterone phase (p = 0.006). FORD showed an opposite but non-significant trend. The FORT/FORD ratio decreased from the low- to the high-estrogen phase (p = 0.0104) and increased from the high-estrogen to the high-estrogen -progesterone phase (p = 0.004). Body temperature (n = 7) decreased in the high-estrogen phase (p = 0.001) and increased from the high-estrogen to the high-estrogen-progesterone phase (p = 0.001). In the seven women, FORT (p = 0.009) and FORT/FORD (p = 0.0056) were linearly related to body temperature values. Our data show opposite effects of estrogen and progesterone on oxidative status. These effects seem to be related to the effect exerted on body temperature regulation.