Role of Neuroglobin in the Neuroprotective Actions of Estradiol and Estrogenic Compounds

Estradiol exerts neuroprotective actions that are mediated by the regulation of a variety of signaling pathways and homeostatic molecules. Among these is neuroglobin, which is upregulated by estradiol and translocated to the mitochondria to sustain neuronal and glial cell adaptation to injury. In this paper, we will discuss the role of neuroglobin in the neuroprotective mechanisms elicited by estradiol acting on neurons, astrocytes and microglia. We will also consider the role of neuroglobin in the neuroprotective actions of clinically relevant synthetic steroids, such as tibolone. Finally, the possible contribution of the estrogenic regulation of neuroglobin to the generation of sex differences in brain pathology and the potential application of neuroglobin as therapy against neurological diseases will be examined.

Pathological Maintenance and Evolution of Breast Cancer: The Convergence of Irreversible Biological Actions of ER Alpha

Estrogen receptor alpha (ERα) is a modulator of breast cancer maintenance and evolution. Hence, analysis of underlying mechanisms by which ERα operates is of importance for the improvement of the hormonal therapy of the disease. This review focuses on the irreversible character of the mechanism of action of ERα, which also concerns other members of the steroid hormones receptors family. ERα moves in permanence between targets localized especially at the chromatin level to accomplish gene transcriptions imposed by the estrogenic ligands and specific antagonists. Receptor association as at the plasma membrane, where it interacts with other recruitment sites, extends its regulatory potency to growth factors and related peptides through activation of signal transductions pathways. If the latter procedure is suitable for the transcriptions in which the receptor operates as a coregulator of another transcription factor, it is of marginal influence with regard to the direct estrogenic regulation procedure, especially in the context of the present review. Irreversibility of the successive steps of the underlying transcription cycle guarantees maintenance of homeostasis and evolution according to vital necessities. To justify this statement, reported data are essentially described in a holistic view rather than in the context of exhaustive analysis of a molecular event contributing to a specific function as well as in a complementary perspective to elaborate new therapeutic approaches with antagonistic potencies against those tumors promoting ERα properties.

Influence of Estrogens on Uterine Vascular Adaptation in Normal and Preeclamptic Pregnancies

During pregnancy, the maternal cardiovascular system undergoes significant changes, including increased heart rate, cardiac output, plasma volume, and uteroplacental blood flow (UPBF) that are required for a successful pregnancy outcome. The increased UPBF is secondary to profound circumferential growth that extends from the downstream small spiral arteries to the upstream conduit main uterine artery. Although some of the mechanisms underlying uterine vascular remodeling are, in part, known, the factors that drive the remodeling are less clear. That higher circulating levels of estrogens are positively correlated with gestational uterine vascular remodeling suggests their involvement in this process. Estrogens binding to the estrogen receptors expressed in cytotrophoblast cells and in the uterine artery wall stimulate an outward hypertrophic remodeling of uterine vasculature. In preeclampsia, generally lower concentrations of estrogens limit the proper uterine remodeling, thereby reducing UPBF increases and restricting the growth of the fetus. This review aims to report estrogenic regulation of the maternal uterine circulatory adaptation in physiological and pathological pregnancy that favors vasodilation, and to consider the underlying molecular mechanisms by which estrogens regulate uteroplacental hemodynamics.

Estrogenic Regulation of Synaptic Health and Cognition in Aging Rhesus Monkeys

A compelling case can be made for estrogen’s role in maintaining synaptic health in the context of cognitive aging. This chapter first reviews clinical literature pertinent to estrogenic actions on cognition in menopausal women. Next, the authors provide a comprehensive summary of recent investigations in aging rhesus monkeys, which have emerged as a particularly powerful model for the study of synaptic and cognitive effects of both natural and surgical menopause. In particular, we focus on hippocampal and dorsolateral prefrontal cortex neurons and circuits that degenerate in normal aging and Alzheimer’s disease. The responsiveness of these brain regions to estrogen and implications for their related memory systems are discussed. Finally, the chapter highlights work that needs to be done to more fully understand the molecular basis for the complex interplay between menopause, aging, and vulnerability to Alzheimer’s disease in higher cognitive function and synaptic health.

Estrogenic Regulation of Hippocampal Neurogenesis Throughout the Lifespan

Neurogenesis in the hippocampus exists across a number of species, including humans. Steroid hormones, such as estrogens, modulate neurogenesis dependent on age, reproductive experience and sex. Findings are discussed in the chapter with reference to how neurogenesis in the hippocampus is related to learning and memory. Natural fluctuations in ovarian hormones or removal of ovaries modulate neurogenesis in the short term but not in the long term. Maternal experience has long-lasting effects on neurogenesis in the hippocampus. Acute estrogens increase proliferation in adult female rodents, but influence survival of new neurons dependent on a number of factors including sex, cognitive training, type of estrogen, and whether or not cells were produced under estrogens. This chapter outlines findings indicating that estrogens can be strong modulators of adult hippocampal neurogenesis, which may have implications for disorders involving hippocampal dysfunction that target women.