Minireview: Neuroprotective effects of estrogen - New insights into mechanisms of action

An accumulating body of evidence dearly establishes that estradiol is a pot ent neuroprotective and neurotrophic factor in the adult: it influences mem ory and cognition, decreases the risk and delays the onset of neurological diseases such as Alzheimer's disease, and attenuates the extent of cell dea th that results from brain injuries such as cerebrovascular stroke and neur otrauma. Thus, estradiol appears to act at two levels: 1) it decreases the risk of disease or injury; and/or 2) it decreases the extent of injury incu rred by suppressing the neurotoxic stimulus itself or increasing the resili ence of the brain to a given injury. During the past century, the average l ife span of women has increased dramatically, whereas the time of the menop ause has remained essentially constant. Thus, more women will live a larger fraction of their lives in a postmenopausal, hypoestrogenic state than eve r before. Clearly, it is critical for us understand the circumstances under which estradiol exerts protective actions and the cellular and molecular m echanisms that underlie these novel, nonreproductive actions.