Adrenal androgens and the menopausal transition

DREAM On, DREAM Off: A Review of the Estrogen Paradox in Luminal A Breast Cancers

It is generally assumed that all estrogen-receptor-positive (ER+) breast cancers proliferate in response to estrogen and, therefore, examples of the estrogen-induced regression of ER+ cancers are paradoxical. This review re-examines the estrogen regression paradox for the Luminal A subtype of ER+ breast cancers. The proliferative response to estrogen is shown to depend on the level of ER. Mechanistically, a window of opportunity study of pre-operative estradiol suggested that with higher levels of ER, estradiol could activate the DREAM-MMB (Dimerization partner, Retinoblastoma-like proteins, E2F4, and MuvB-MYB-MuvB) pathway to decrease proliferation. The response of breast epithelium and the incidence of breast cancers during hormonal variations that occur during the menstrual cycle and at the menopausal transition, respectively, suggest that a single hormone, either estrogen, progesterone or androgen, could activate the DREAM pathway, leading to reversible cell cycle arrest. Conversely, the presence of two hormones could switch the DREAM-MMB complex to a pro-proliferative pathway. Using publicly available data, we examine the gene expression changes after aromatase inhibitors and ICI 182,780 to provide support for the hypothesis. This review suggests that it might be possible to integrate all current hormonal therapies for Luminal A tumors within a single theoretical schema.

Sex-associated microRNAs potentially implicated in sporadic Alzheimer's disease (sAD)

BACKGROUND

The onset and pathology of sporadic Alzheimer's disease (sAD) seem to be affected by both sex and genetic mechanisms. Evidence supports that the high prevalence of sAD in women, worldwide, may be attributed to an interplay among aging, sex, and lifestyle, influenced by genetics, metabolic changes, and hormones. Interestingly, epigenetic mechanisms such as microRNAs (miRNAs), known as master regulators of gene expression, may contribute to this observed sexual dimorphism in sAD.

OBJECTIVES

To investigate the potential impact of sex-associated miRNAs on processes manifesting sAD pathology, as described by the Tau-driven Adverse Outcome Pathway (AOP) leading to memory loss.

METHODS

Using publicly available human miRNA datasets, sex-biased miRNAs, defined as differentially expressed by sex in tissues possibly affected by sAD pathology, were collected. In addition, sex hormone-related miRNAs were also retrieved from the literature. The compiled sex-biased and sex hormone-related miRNAs were further plugged into the dysregulated processes of the Tau-driven AOP for memory loss.

RESULTS

Several miRNAs, previously identified as sex-associated, were implicated in dysregulated processes associated with the manifestation of sAD pathology. Importantly, the described pathology processes were not confined to a particular sex. A mechanistic-based approach utilizing miRNAs was adopted in order to elucidate the link between sex and biological processes potentially involved in the development of memory loss.

CONCLUSIONS

The identification of sex-associated miRNAs involved in the early processes manifesting memory loss may shed light to the complex molecular mechanisms underlying sAD pathogenesis in a sex-specific manner.

Sex Hormones and Cardiovascular Disease in Relation to Menopause

Natural menopause is defined as the cessation of menstruation among women who have not undergone hysterectomy or bilateral oophorectomy. The implications of menopause management are particularly important with the aging of the population and increasing awareness of the importance of midlife risk upon longevity. Our understanding of the relationships between reproductive milestones and cardiovascular disease continues to evolve particularly regarding shared determinants of health.

Dehydroepiandrosterone sulfate (DHEAS) in excreta is a good indicator of serum DHEAS in Japanese macaques (Macaca fuscata)

We developed a microplate enzyme immunoassay (EIA) to measure dehydroepiandrosterone sulfate (DHEAS) in the blood, urine, and feces of Japanese macaques and evaluated the relationship between serum DHEAS and excreta DHEAS. Our DHEAS EIA using heterological DHEA derivatives conjugated with enzyme was highly sensitive, and linearities and recoveries for all matrices of Japanese macaques were reliable. For the biological evaluation of the metabolism of DHEAS in Japanese macaques, dissolved DHEAS was injected into the subjects, and consecutively collected serum, urine, and fecal samples were analyzed. The peaks of serum DHEAS were observed 6 h after the administration, while those of urine and feces were observed after 24 h. The fluctuation of those in urine and feces were significantly correlated with serum DHEAS levels. In addition, we measured pregnanediol-glucuronide (PdG), and estrone-conjugate (E₁C) in urine and fecal samples to investigate the effects of administrated DHEAS on these progesterone and estrogen metabolites. The peak of PdG was observed 24 h after administration, then declined sharply. The concentration of E₁C increased 1 week after administration in two out of three subjects. Our results suggest that measuring urinary and fecal DHEAS with our EIA provides a non-invasive alternative to assessing DHEAS levels in the serum of Japanese macaques.

PPI-Induced Changes in Plasma Metabolite Levels Influence Total Hip Bone Mineral Density in a UK Cohort

Proton pump inhibitors (PPIs) are among the most used drugs in the UK. PPI use has been associated with decreased bone mineral density (BMD) and increased fracture risk, although these results have been inconsistent. We hypothesized that PPI could modulate BMD by altering gut and/or host systemic metabolic environments. Using data from more than 5000 British male and female individuals, we confirmed that PPI use is associated with decreased lumbar spine and total hip BMD. This effect was not mediated through the gut microbiome. We suggest here that PPI use may influence total hip BMD, both directly and indirectly, via plasma metabolites involved in the sex hormone pathway. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Sex steroids and sex steroid-binding globulin levels amongst middle-aged and elderly men and women from general population

BACKGROUND AND AIMS

Availability of age- and sex-specific reference values for sex steroids and sex steroid-binding globulin (SHBG) levels allows for appropriate interpretation of research findings and their clinical applications. We report the sex-specific distribution and reference levels of sex steroids, including total estradiol, total testosterone and (calculated) free androgen index (cFAI), SHBG and other androgens dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS) and androstenedione across age.

METHODS

Using data from 3291 participants from the prospective population-based Rotterdam Study (2006-2008), we visualised the distribution of sex steroids and SHBG levels by calculating and depicting the 5th, 25th, 50th, 75th and 95th percentiles per year and per age-year across 5-year age bands to provide reference value ranges in men and women. Total estradiol and SHBG were measured using automated immunoassay and androgens using liquid chromatography-mass spectrometry (LC-MS/MS).

RESULT

Mean age was 56.8 (range 45.6-79.9) years in men and 56.9 (range 45.7-79.9) years in women. Amongst men, total estradiol and SHBG showed an increasing trend from 45 years onwards. In women, total estradiol and SHBG showed a decreasing trend from 45 years until the age of 60. From 60 years onwards, SHBG showed an increasing trend. For total testosterone, a clear declining trend was observed amongst men but not women. Other androgens showed a similar decreasing trend in both sexes from 45 years onwards.

DISCUSSION AND CONCLUSION

Our study underlines sex-specific trends in sex steroids and SHBG levels with ageing. This warrants taking into account sex- and age-specific reference values for sex steroids and SHBG when investigating their impact on health outcomes to prevent controversial results and allow for their appropriate clinical application.

Do Women Need Androgens Like a Fish Needs a Bicycle? A Review of the Literature and Clinical Guidelines

Biopotent androgens such as testosterone circulate in low levels in women. However, androgen precursors, such as dehyroepiandrosterone, are among the most abundant hormones produced in both men and women. While testosterone exerts obvious phenotypic effects in men and is essential for male sexual function, considerable debate and controversy abounds over the role of androgens in women and whether androgens exert an analogous role in women as they do in men. This piece reviews androgen economy in women and the clinical case for and against androgen treatment for women for specific indications.

The implications of the purinergic signaling throughout pregnancy

Purinergic signaling is a necessary mechanism to trigger or even amplify cell communication. Its ligands, notably adenosine triphosphate (ATP) and adenosine, modulate specific membrane-bound receptors in virtually all human cells. Regardless of the stage of the pregnancy, cellular communication between maternal, placental, and fetal cells is the paramount mechanism to sustain its optimal status. In this review, we describe the crucial role of purinergic signaling on the regulation of the maternal-fetal trophic exchanges, immune control, and endocrine exchanges throughout pregnancy. The nature of the modulation of both ATP and adenosine on the embryo-maternal interface, going through placental invasion until birth delivery depends on the general maternal-fetal health state and consequently on the selective activation of their specific receptors. In addition, an increasing number of studies have been demonstrating the pivotal role of ATP and adenosine in modulating deleterious effects of suboptimal conditions of pregnancy. Here, we discuss the role of purinergic signaling on the balance that coordinates the embryo-maternal exchanges and a promising therapeutic venue in the context of pregnancy disorders.

Growth Hormone/Insulin Growth Factor Axis in Sex Steroid Associated Disorders and Related Cancers

To date, almost all solid malignancies have implicated insulin-like growth factor (IGF) signalling as a driver of tumour growth. However, the remarkable level of crosstalk between sex hormones, the IGF-1 receptor (IGF-1R) and its ligands IGF-1 and 2 in endocrine driven cancers is incompletely understood. Similar to the sex steroids, IGF signalling is essential in normal development as well as growth and tissue homoeostasis, and undergoes a steady decline with advancing age and increasing visceral adiposity. Interestingly, IGF-1 has been found to play a compensatory role for both estrogen receptor (ER) and androgen receptor (AR) by augmenting hormonal responses in the absence of, or where low levels of ligand are present. Furthermore, experimental, and epidemiological evidence supports a role for dysregulated IGF signalling in breast and prostate cancers. Insulin-like growth factor binding protein (IGFBP) molecules can regulate the bioavailability of IGF-1 and are frequently expressed in these hormonally regulated tissues. The link between age-related disease and the role of IGF-1 in the process of ageing and longevity has gained much attention over the last few decades, spurring the development of numerous IGF targeted therapies that have, to date, failed to deliver on their therapeutic potential. This review will provide an overview of the sexually dimorphic nature of IGF signalling in humans and how this is impacted by the reduction in sex steroids in mid-life. It will also explore the latest links with metabolic syndromes, hormonal imbalances associated with ageing and targeting of IGF signalling in endocrine-related tumour growth with an emphasis on post-menopausal breast cancer and the impact of the steroidal milieu.

Relationship between bone density of paranasal sinuses and adrenal steroids pattern in women during menopausal transition

The course of menopause transition (MT) is associated with peculiarities of alterations occurring in a woman’s body, in particular, in the structure of bone tissue. Considering that bones of the paranasal sinuses (BPNSs) play a natural defense role against the spread of dental infection, their structure is important in dentistry. However, no information was found pertaining to changes of BPNSs during MT – a time when dental maladies increase in many women.

The aim of our study was to collate density of BPNSs with status of adrenal steroids in women during MT, since the pattern of their changes determines the course of MT.

Cross-sectional associations were examined between bone density of PNSs assessed by Spiral Computed Tomography and Serum content of testosterone (T), sex hormone binding globulin (SHBG), free androgen index (FAI), insulin, dehydroepiandrosterone sulfate (DHEAS), Adione, and Adiol in 113 women of perimenopausal age (age range from 45 to 55 years) who had already experienced premenopausal menstrual decline (amenorrhea less than 2 years).

Strong positive (r = 0.73) correlation between minimal bone density of maxillary sinus in women with level of DHEAS was detected. It is important to note, that the correlation between minimal density of the lower wall of frontal sinus is a weak positive (0.3). Therefore, it can be suggested that bone tissue of the maxillary sinus is more sensitive to changes in DHEAS.

The study showed that the level of male steroids, in particular DHEAS, affected the state of bone tissue in participants older than 50 years of age.

Is menopause still evolving? Evidence from a longitudinal study of multiethnic populations and its relevance to women's health

Background

To reflect on the impact of changing patterns of delayed marriage and reproduction and to seek evidence as to whether menopause is still evolving, characteristics of the menopause transition were investigated within and between ethnic populations in this study.

Methods

A cross-sectional analysis was conducted using data on 747 middle-aged women obtained from the Study of Women’s Health Across the Nation (SWAN) from 1996 to 2008. The ethnic groups included: Afro-American, Chinese, Japanese, Caucasian, and Hispanic. Perimenopause age and duration, menopause age, and hormonal indicators of menopause were examined across five ethnicities.

Results

We found a similar window of menopause age within populations, but no significant difference in perimenopause and menopause age between populations. The rate of increase of follicle-stimulating hormone and testosterone differed significantly in Hispanics and African-Americans during the menopause transition period.

Conclusions

The broad window of variation in age at menopause within the population and the absence of significant differences between populations, in combination with population variation in menopause symptoms, suggest that menopause is a relatively recently evolved and still evolving trait. Under the mate choice theory of menopause, menopause is the result of the accumulation of infertility mutations in older women due to men’s preference for younger mates. We propose a shifting mate choice-shifting menopause model which posits that, as the age of mate choice/marriage shifts to older ages, so will the age at menopause, and that menopause is a transient phase of female fertility; it can de-evolve, be delayed, if not disappear completely. Integrated longitudinal menopausal studies linked with genomics and hormonal studies on diverse ethnic populations can provide valuable information bearing on women’s health and personalized medicine.

Steroid receptors and vertebrate evolution

Considering that life on earth evolved about 3.7 billion years ago, vertebrates are young, appearing in the fossil record during the Cambrian explosion about 542 to 515 million years ago. Results from sequence analyses of genomes from bacteria, yeast, plants, invertebrates and vertebrates indicate that receptors for adrenal steroids (aldosterone, cortisol), and sex steroids (estrogen, progesterone, testosterone) also are young, with an estrogen receptor and a 3-ketosteroid receptor first appearing in basal chordates (cephalochordates: amphioxus), which are close ancestors of vertebrates. Duplication and divergence of the 3-ketosteroid receptor yielded an ancestral progesterone receptor and an ancestral corticoid receptor, the common ancestor of the glucocorticoid and mineralocorticoid receptors, in jawless vertebrates (cyclostomes: lampreys, hagfish). This was followed by evolution of an androgen receptor, distinct glucocorticoid and mineralocorticoid receptors and estrogen receptor-α and -β in cartilaginous fishes (Chondrichthyes: sharks). Further evolution of mineralocorticoid signaling occurred with the evolution of aldosterone synthase in lungfish, a forerunner of terrestrial vertebrates. Adrenal and sex steroid receptors are not found in echinoderms and hemichordates, which are ancestors in the lineage of cephalochordates and vertebrates. The evolution of steroid receptors at key nodes in the evolution of vertebrates, in which steroid receptors act as master switches to regulate differentiation, development, reproduction, immune responses, electrolyte homeostasis and stress responses, suggests an important role for steroid receptors in the evolutionary success of vertebrates, considering that the human genome contains about 22,000 genes, which is not much larger than genomes of invertebrates, such as Caenorhabditis elegans (~18,000 genes) and Drosophila (~14,000 genes).

The promiscuous estrogen receptor: Evolution of physiological estrogens and response to phytochemicals and endocrine disruptors

Many actions of estradiol (E2), the principal physiological estrogen in vertebrates, are mediated by estrogen receptor-α (ERα) and ERβ. An important physiological feature of vertebrate ERs is their promiscuous response to several physiological steroids, including estradiol (E2), Δ⁵-androstenediol, 5α-androstanediol, and 27-hydroxycholesterol. A novel structural characteristic of Δ⁵-androstenediol, 5α-androstanediol, and 27-hydroxycholesterol is the presence of a C19 methyl group, which precludes the presence of an aromatic A ring with a C3 phenolic group that is a defining property of E2. The structural diversity of these estrogens can explain the response of the ER to synthetic chemicals such as bisphenol A and DDT, which disrupt estrogen physiology in vertebrates, and the estrogenic activity of a variety of plant-derived chemicals such as genistein, coumestrol, and resveratrol. Diversity in the A ring of physiological estrogens also expands potential structures of industrial chemicals that can act as endocrine disruptors. Compared to E2, synthesis of 27-hydroxycholesterol and Δ⁵-androstenediol is simpler, leading us, based on parsimony, to propose that one or both of these steroids or a related metabolite was a physiological estrogen early in the evolution of the ER, with E2 assuming this role later as the canonical estrogen. In addition to the well-studied role of the ER in reproductive physiology, the ER also is an important transcription factor in non-reproductive tissues such as the cardiovascular system, kidney, bone, and brain. Some of these ER actions in non-reproductive tissues appeared early in vertebrate evolution, long before the emergence of mammals.

Testosterone and Cardiovascular Health

There is an ongoing debate in the medical community regarding the effects of testosterone on cardiovascular (CV) health. For decades, there has been conflicting evidence regarding the association of endogenous testosterone levels and CV disease (CVD) events that has resulted in much debate and confusion among health care providers and patients alike. Testosterone therapy has become increasingly widespread, and after the emergence of studies that reported increased CVD events in patients receiving testosterone therapy, the US Food and Drug Administration (FDA) released a warning statement about testosterone and its potential risk regarding CV health. Some of these studies were later found to be critically flawed, and some experts, including the American Association of Clinical Endocrinologists and an expert panel regarding testosterone deficiency and its treatment, reported that some of the FDA statements regarding testosterone therapy were lacking scientific evidence. This article summarizes the current evidence regarding the relationship between testosterone (endogenous and supplemental) and CV health. A literature review was conducted via search using PubMed and specific journal databases, including the New England Journal of Medicine and the Journal of the American College of Cardiology. Key search terms included testosterone and cardiovascular health, coronary artery disease, heart failure, androgen deprivation therapy, intima-media thickness, and adrenal androgens. Initial study selection was limited to publications within the past 10 years (January 1, 2007, through December 31, 2016); however, key publications outside of this time frame were selected if they provided important quantitative data or historical perspectives for the review of this topic. The search was further supplemented by reviewing references in selected articles.

The relation among steroid hormone levels, lipid profile and menopausal symptom severity

INTRODUCTION

Many postmenopausal women experience hot flashes, night sweats, non-specific emotional and psychological distresses. Our aim was to investigate the relation among steroid hormone levels, lipid profile and menopausal symptom severity using the menopause rating scale (MRS).

METHODS

A cross-sectional study was performed at our outpatient clinic with natural postmenopausal women. A total of 444 women were included in this study. The basic characteristics of the study population, such as age, gravidity, parity, time to menopause onset and body mass index (BMI) were recorded. Venous blood samples were collected from subjects after overnight fasting. The levels of high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, total cholesterol, triglyceride (TG), fasting plasma glucose, C-reactive protein, thyroid-stimulating hormone (TSH), cortisol, estradiol (E2), progesterone, testosterone and dehydroepiandrostenedione sulfate (DHEA-S) were analyzed. The MRS questionnaire validated for the Turkish population was used to assess the menopausal symptoms.

RESULTS

There was a statistically significant difference between mild and severe total symptom scores for TG, and elevated TG levels were observed in the severe group (p = 0.04). Elevated testosterone levels were observed with severe psychological symptom and total symptom scores. There were significant differences in progesterone level in psychological, urogenital, and total scores and lower levels were seen in severe symptom groups. There was a significant negative correlation between urogenital symptom scores and progesterone levels (p < 0.001).

DISCUSSION

Elevated levels of testosterone were related to severe psychological symptom and total menopausal symptom scores. A decrease in progesterone levels was related to high psychological, urogenital and total menopausal symptom scores. Elevated TG levels were also related to the total severe symptom scores.

Changes in androstenedione, dehydroepiandrosterone, testosterone, estradiol, and estrone over the menopausal transition

Background

Previous reports have noted that dehydroepiandrosterone-sulfate (DHEAS) increases prior to the final menstrual period (FMP) and remains stable beyond the FMP. How DHEAS concentrations correspond with other sex hormones across the menopausal transition (MT) including androstenedione (A4), testosterone (T), estrone (E1), and estradiol (E2) is not known. Our objective was to examine how DHEAS, A4, T, E1, and E2 changed across the MT by White vs. African-American (AA) race/ethnicity.

Methods

We conducted a longitudinal observational analysis of a subgroup of women from the Study of Women’s Health Across the Nation observed over 4 visits prior to and 4 visits after the FMP (n = 110 women over 9 years for 990 observations). The main outcome measures were DHEAS, A4, T, E1, and E2.

Results

Compared to the decline in E2 concentrations, androgen concentrations declined minimally over the MT. T (β 9.180, p < 0.0001) and E1 (β 11.365, p < 0.0001) were higher in Whites than in AAs, while elevations in DHEAS (β 28.80, p = 0.061) and A4 (β 0.2556, p = 0.052) were borderline. Log-transformed E2 was similar between Whites and AAs (β 0.0764, p = 0.272). Body mass index (BMI) was not significantly associated with concentrations of androgens or E1 over time.

Conclusion

This report suggests that the declines in E2 during the 4 years before and after the FMP are accompanied by minimal changes in DHEAS, A4, T, and E1. There are modest differences between Whites and AAs and minimal differences by BMI.

Distribution of Salivary Testosterone in Men and Women in a British General Population-Based Sample: The Third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

Introduction:

Measurement of salivary testosterone (Sal-T) to assess androgen status offers important potential advantages in epidemiological research. The utility of the method depends on the interpretation of the results against robustly determined population distributions, which are currently lacking.

Aim:

To determine age-specific Sal-T population distributions for men and women.

Methods:

Morning saliva samples were obtained from participants in the third National Survey of Sexual Attitudes and Lifestyles, a probability sample survey of the British general population. Sal-T was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Linear and quantile regression analyses were used to determine the age-specific 2.5th and 97.5th percentiles for the general population (1675 men and 2453 women) and the population with health exclusions (1145 men and 1276 women).

Results:

In the general population, the mean Sal-T level in men decreased from 322.6 pmol/L at 18 years of age to 153.9 pmol/L at 69 years of age. In women, the decrease in the geometric mean Sal-T level was from 39.8 pmol/L at 18 years of age to 19.5 pmol/L at 74 years of age. The annual decrease varied with age, with an average of 1.0% to 1.4% in men and 1.3% to 1.5% in women. For women, the 2.5th percentile fell below the detection limit (<6.5 pmol/L) from age 52 years onward. The mean Sal-T level was approximately 6 times greater in men than in women, and this remained constant over the age range. The Sal-T level was lowest for men and highest for women in the summer. The results were similar for the general population with exclusions.

Conclusions:

To our knowledge, this is the first study to describe the sex- and age-specific distributions for Sal-T in a large representative population using a specific and sensitive LC-MS/MS technique. The present data can inform future population research by facilitating the interpretation of Sal-T results as a marker of androgen status.

Naturally Occurring Changes in Estradiol Concentrations in the Menopause Transition Predict Morning Cortisol and Negative Mood in Perimenopausal Depression

Risk of depression increases considerably during the menopause transition (or perimenopause) - the 5-6 years surrounding the last menstrual period. While the mechanisms underlying this increased risk are unknown, we have hypothesized that excessive estradiol (E2) fluctuation, which accompanies the perimenopause, may be implicated. We have furthermore proposed that dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis may underlie E2 fluctuation's effect on mood. This study examined the relationship between weekly changes in salivary E2, salivary cortisol levels and weekly mood in 30 perimenopausal women recruited to achieve equal numbers of women with current depression, past depression, and no history of depression. Greater weekly increases in E2 were associated with increased cortisol among past and currently depressed women; greater E2 increases were also associated with negative mood among currently depressed women. These findings provide evidence that HPA axis dysregulation, correlated with E2 fluctuation, may be implicated in the pathophysiology of perimenopausal depression.

Conditions and possible mechanisms of VCD-induced ovarian failure

Perimenopause is an important period in women's lives, in which they experience a series of physiological changes. Current animal models of perimenopause fail to adequately replicate this particular stage in female life, while current in vitro models are too simplistic and cannot account for systemic effects. Neither the naturally-ageing animal model, nor the ovariectomised animal model, mimic the natural transitional process that is the menopause. In vivo and in vitro studies have confirmed that the occupational chemical, 4-vinylcyclohexene diepoxide (VCD), can cause selective destruction of the ovarian primordial and primary follicles of rats and mice by accelerating the apoptotic process, which successfully mimics the perimenopausal state in women. However, it is the in vivo VCD-induced rodent perimenopausal models that are currently the most widely used in research, rather than any of the available in vitro models. Studies on the mechanisms involved have found that VCD induces ovotoxicity via interference with the c-kit/kit ligand and apoptotic signalling pathways, among others. Overall, the VCD-induced perimenopausal animal models have provided some insight into female perimenopause, but they are far from ideal models of the human situation.

Trajectories and phenotypes with estrogen exposures across the lifespan: What does Goldilocks have to do with it?

This article is part of a Special Issue "Estradiol and cognition". Estrogens impact the organization and activation of the mammalian brain in both sexes, with sex-specific critical windows. Throughout the female lifespan estrogens activate brain substrates previously organized by estrogens, and estrogens can induce non-transient brain and behavior changes into adulthood. Therefore, from early life through the transition to reproductive senescence and beyond, estrogens are potent modulators of the brain and behavior. Organizational, reorganizational, and activational hormone events likely impact the trajectory of brain profiles during aging. A "brain profile," or quantitative brain measurement for research purposes, is typically a snapshot in time, but in life a brain profile is anything but static--it is in flux, variable, and dynamic. Akin to this, the only thing continuous and consistent about hormone exposures across a female's lifespan is that they are noncontinuous and inconsistent, building and rebuilding on past exposures to create a present brain and behavioral landscape. Thus, hormone variation is especially rich in females, and is likely the destiny for maximal responsiveness in the female brain. The magnitude and direction of estrogenic effects on the brain and its functions depend on a myriad of factors; a "Goldilocks" phenomenon exists for estrogens, whereby if the timing, dose, and regimen for an individual are just right, markedly efficacious effects present. Data indicate that exogenously-administered estrogens can bestow beneficial cognitive effects in some circumstances, especially when initiated in a window of opportunity such as the menopause transition. Could it be that the age-related reduction in efficacy of estrogens reflects the closure of a late-in-life critical window occurring around the menopause transition? Information from classic and contemporary works studying organizational/activational estrogen actions, in combination with acknowledging the tendency for maximal responsiveness to cyclicity, will elucidate ways to extend sensitivity and efficacy into post-menopause.

The different role of sex hormones on female cardiovascular physiology and function: not only oestrogens

Human response to different physiologic stimuli and cardiovascular (CV) adaptation to various pathologies seem to be gender specific. Sex-steroid hormones have been postulated as the major contributors towards these sex-related differences. This review will discuss current evidence on gender differences in CV function and remodelling, and will present the different role of the principal sex-steroid hormones on female heart. Starting from a review of sex hormones synthesis, receptors and CV signalling, we will summarize the current knowledge concerning the role of sex hormones on the regulation of our daily activities throughout the life, via the modulation of autonomic nervous system, excitation-contraction coupling pathway and ion channels activity. Many unresolved questions remain even if oestrogen effects on myocardial remodelling and function have been extensively studied. So this work will focus attention also on the controversial and complex relationship existing between androgens, progesterone and female heart.

The menopause and aging, a comparative perspective

The neuroendocrinology of menopause is reviewed from a comparative perspective, with emphasis on laboratory rodent models. These changes are compared by the 2011 STRAW criteria (Stages of Reproductive Aging Workshop). Ovarian cell loss begins prenatally in all mammals studied, with exponential depletion of primary follicles and oocytes in association with loss of fecundity by midlife. Rodents and humans also share progressively increasing irregularity in ovulatory cycles and increasing fetal aneuploidy as oocyte depletion become imminent. Hypothalamic impairments of the estrogen-induced surge of pituitary gonadotrophins (luteinizing hormone, LH; follicle stimulating hormone, FSH) are prominent in middle-aged rodents, but sporadic in peri-menopausal women. In aging rodents, hypothalamic impairments of the LH surge have been experimentally associated with prolonged phases of sustained estradiol (E2) and very low progesterone (P4) ('unopposed estradiol'). Although peri-menopausal women also show hyper-estrogenic cycles, there is no indication for irreversible hypothalamic desensitization by E2. Ongoing cognitive assessments in clinical trials of estrogen therapy with and without P4 or other progestins may further inform about possible persisting effects of unopposed estrogens.This article is part of a Special Issue entitled 'Menopause'.

Testosterone increases circulating dehydroepiandrosterone sulfate levels in the male rhesus macaque

The adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are two of the most abundant hormones in the human circulation. Furthermore, they are released in a circadian pattern and show a marked age-associated decline. Adult levels of DHEA and DHEAS are significantly higher in males than in females, but the reason for this sexual dimorphism is unclear. In the present study, we administered supplementary androgens [DHEA, testosterone and 5α-dihydrotestosterone (DHT)] to aged male rhesus macaques (Macaca mulatta). While this paradigm increased circulating DHEAS immediately after DHEA administration, an increase was also observed following either testosterone or DHT administration, resulting in hormonal profiles resembling levels observed in young males in terms of both amplitude and circadian pattern. This stimulatory effect was limited to DHEAS, as an increase in circulating cortisol was not observed. Taken together, these data demonstrate an influence of the hypothalamo-pituitary-testicular axis on adrenal function in males, possibly by sensitizing the zona reticularis to the stimulating action of adrenocorticopic hormone. This represents a plausible mechanism to explain sex differences in circulating DHEA and DHEAS levels, and may have important implications in the development of hormone therapies designed for elderly men and women.

What are the physiological estrogens?

Estradiol (E2) is the principal physiological estrogen in mammals. E2 and its active metabolites, estrone and estriol have a characteristic phenolic A ring, unlike progesterone, testosterone, cortisol and aldosterone, which have an A ring containing a C3-ketone, a Δ(4) bond and a C19 methyl group. Crystal structures of E2 in the estrogen receptor (ER) confirm the importance of the A ring in stabilizing E2 in the ER. However, other steroids, including Δ(5)-androstenediol, 5α-androstanediol and 27-hydroxycholesterol, which have a saturated A ring containing a 3β-hydroxyl and a C19 methyl group, also mediate physiological responses through binding to estrogen receptor-α (ERα) and ERβ. Moreover, selective estrogen response modulators (SERMs) with diverse structures also regulate transcription of ERα and ERβ. Our understanding of the physiological responses mediated by these "alternative" estrogens is in its infancy. Further studies of the role of these steroids and SERMs in regulating responses mediated by ERα and ERβ a variety of tissues, during different stages of development, are likely to uncover additional estrogenic activities.

The ageing cortical synapse: hallmarks and implications for cognitive decline

Normal ageing is associated with impairments in cognitive function, including memory. These impairments are linked, not to a loss of neurons in the forebrain, but to specific and relatively subtle synaptic alterations in the hippocampus and prefrontal cortex. Here, we review studies that have shed light on the cellular and synaptic changes observed in these brain structures during ageing that can be directly related to cognitive decline in young and aged animals. We also discuss the influence of the hormonal status on these age-related alterations and recent progress in the development of therapeutic strategies to limit the impact of ageing on memory and cognition in humans.