Estrogens and neuroprotection.

In recent years, we have become increasingly aware that estrogen is a gonadal hormone that exerts diverse non-reproductive actions on multiple organs and in multiple physiological systems. Amongst these, estrogen has profound effects on plasticity and cell survival of the adult brain. Over the past 100 years, the lifespan of women has increased to >80 years, but the age of the menopause has remained fixed. Women are therefore living an ever-increasing proportion of their lives in a hypoestrogenic, postmenopausal state, which could contribute to an increased risk of cognitive dysfunction and a variety of neurodegenerative diseases. Recent experiments emphasize the importance of apoptosis as a mechanism of cell death after brain injury induced by global ischemia, and indicate that estrogen treatment has a neuroprotective effect by attenuating expression of selective markers of apoptosis.