Table of Contents
ISRN Endocrinology
Volume 2013, Article ID 814690, 16 pages
http://dx.doi.org/10.1155/2013/814690
Review Article

Estrogen Signaling and the Aging Brain: Context-Dependent Considerations for Postmenopausal Hormone Therapy

Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, 2160 S First Avenue, Maywood, IL 60153, USA

Received 12 April 2013; Accepted 21 May 2013

Academic Editors: F. Escobar-Jimenez, H. Galbo, E. Hajduch, M. Hiriart, H.-Q. Qu, and H. Ueshiba

Copyright © 2013 Natasha N. Mott and Toni R. Pak. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Recent clinical studies have spurred rigorous debate about the benefits of hormone therapy (HT) for postmenopausal women. Controversy first emerged based on a sharp increase in the risk of cardiovascular disease in participants of the Women’s Health Initiative (WHI) studies, suggesting that decades of empirical research in animal models was not necessarily applicable to humans. However, a reexamination of the data from the WHI studies suggests that the timing of HT might be a critical factor and that advanced age and/or length of estrogen deprivation might alter the body's ability to respond to estrogens. Dichotomous estrogenic effects are mediated primarily by the actions of two high-affinity estrogen receptors alpha and beta (ERα & ERβ). The expression of the ERs can be overlapping or distinct, dependent upon brain region, sex, age, and exposure to hormone, and, during the time of menopause, there may be changes in receptor expression profiles, post-translational modifications, and protein:protein interactions that could lead to a completely different environment for E2 to exert its effects. In this review, factors affecting estrogen-signaling processes will be discussed with particular attention paid to the expression and transcriptional actions of ERβ in brain regions that regulate cognition and affect.