Oxidative damage and the pathogenesis of menopause related disturbances and diseases

Abstract

The postmenopausal phase of life is frequently associated in women with subjective symptoms (e.g. vasomotor) and real diseases (atherosclerosis with coronary ischemia, osteoporosis, Alzheimer-type neurodegeneration, urogenital dystrophy), which together determine the post-menopausal syndrome. Observations that oxidative damage by reactive oxygen/nitrogen species in experimental models can contribute to the pathogenesis of these disturbances stimulated research on the relationships between menopause, its endocrine deficiency, oxidative balance and the "wellness" in postmenopausal life. The connection among these events is probably due to the loss of protective actions exerted by estrogens during the fertile life. Most recent studies have revealed that estrogens exert an antioxidant action not by direct chemical neutralization of reactants as it was expected until recently but by modulating the expression of antioxidant enzymes that control levels of biological reducing agents. Also nutritional antioxidants apparently act by a similar mechanism. From this perspective it is conceivable that a cumulative control of body oxidant challenges and biological defenses could help in monitoring between "normal" and "pathological" menopause. However, as clinical studies failed to confirm this scenario in vivo, we have decided to review the existing literature to understand the causes of this discrepancy and whether this was due to methodologic reasons or to real failure of the basic hypothesis.