The androgen receptor confers protection against diet-induced atherosclerosis, obesity, and dyslipidemia in female mice

FSH Is Responsible for Androgen Deprivation Therapy-Associated Atherosclerosis in Mice by Exaggerating Endothelial Inflammation and Monocyte Adhesion

BACKGROUND

Androgen deprivation therapy (ADT) is the mainstay treatment for advanced prostate cancer. But ADTs with orchiectomy and gonadotropin-releasing hormone (GnRH) agonist are associated with increased risk of cardiovascular diseases, which appears less significant with GnRH antagonist. The difference of follicle-stimulating hormone (FSH) in ADT modalities is hypothesized to be responsible for ADT-associated cardiovascular diseases.

METHODS

We administered orchiectomy, GnRH agonist, or GnRH antagonist in male ApoE-/- mice fed with Western diet and manipulated FSH levels by testosterone and FSH supplementation or FSH antibody to investigate the role of FSH elevation on atherosclerosis. By combining lipidomics, in vitro study, and intraluminal FSHR (FSH receptor) inhibition, we delineated the effects of FSH on endothelium and monocytes and the underlying mechanisms.

RESULTS

Orchiectomy and GnRH agonist, but not GnRH antagonist, induced long- or short-term FSH elevation and significantly accelerated atherogenesis. In orchiectomized and testosterone-supplemented mice, FSH exposure increased atherosclerosis. In GnRH agonist-treated mice, blocking of short FSH surge by anti-FSHβ antibody greatly alleviated endothelial inflammation and delayed atherogenesis. In GnRH antagonist-treated mice, FSH supplementation aggravated atherogenesis. Mechanistically, FSH, synergizing with TNF-α (tumor necrosis factor alpha), exacerbated endothelial inflammation by elevating VCAM-1 (vascular cell adhesion protein 1) expression through the cAMP/PKA (protein kinase A)/CREB (cAMP response element-binding protein)/c-Jun and PI3K (phosphatidylinositol 3 kinase)/AKT (protein kinase B)/GSK-3β (glycogen synthase kinase 3 beta)/GATA-6 (GATA-binding protein 6) pathways. In monocytes, FSH upregulated CD29 (cluster of differentiation 29) expression via the PI3K/AKT/GSK-3β/SP1 (specificity protein 1) pathway and promoted monocyte-endothelial adhesion both in vitro and in vivo. Importantly, FSHR knockdown by shRNA in endothelium of carotid arteries markedly reduced GnRH agonist-induced endothelial inflammation and atherosclerosis in mice.

CONCLUSIONS

FSH is responsible for ADT-associated atherosclerosis by exaggerating endothelial inflammation and promoting monocyte-endothelial adhesion.

FKBP51-Hsp90 Interaction-Deficient Mice Exhibit Altered Endocrine Stress Response and Sex Differences Under High-Fat Diet

FK506-binding protein 51 kDa (FKBP51), encoded by Fkbp5 gene, gained considerable attention as an important regulator of several aspects of human biology including stress response, metabolic dysfunction, inflammation, and age-dependent neurodegeneration. Its catalytic peptidyl-prolyl isomerase (PPIase) activity is mediated by the N-terminal FK506-binding (FK1) domain, whereas the C-terminal tetratricopeptide motif (TPR) domain is responsible for FKBP51 interaction with molecular chaperone heat shock protein 90 (Hsp90). To understand FKBP51-related biology, several mouse models have been created. These include Fkbp5 complete and conditional knockouts, overexpression, and humanized models. To dissect the role of FKBP51-Hsp90 interaction in FKBP51 biology, we have created an interaction-deficient mouse (Fkbp5TPRmut) by introducing two-point mutations in the TPR domain of FKBP51. FKBP51-Hsp90 interaction-deficient mice are viable, fertile and show Mendelian inheritance. Intracellular association of FKBP51 with Hsp90 is significantly reduced in homozygous mutants compared to wild-type animals. No behavioral differences between genotypes were seen at 2 months of age, however, sex-dependent differences were detected in Y-maze and fear conditioning tests at the age of 12 months. Moreover, we have found a significant reduction in plasma levels of corticosterone and adrenocorticotropic hormone in Fkbp5TPRmut mice after acute stress. In contrast to Fkbp5 knockout mice, females of Fkbp5TPRmut showed increased body weight gain under high-fat diet treatment. Our data confirm the importance of FKBP51-Hsp90 interactions for stress-related endocrine signaling. Also, Fkbp5TPRmut mice can serve as a useful in vivo tool to discriminate between Hsp90-dependent and independent functions of FKBP51.

An overview on androgen-mediated actions in skeletal muscle and adipose tissue

Androgens are a class of steroid hormones primarily associated with male sexual development and physiology, but exert pleiotropic effects in either sex. They have a crucial role in various physiological processes, including the regulation of skeletal muscle and adipose tissue homeostasis. The effects of androgens are mainly mediated through the androgen receptor (AR), a ligand-activated nuclear receptor expressed in both tissues. In skeletal muscle, androgens via AR exert a multitude of effects, ranging from increased muscle mass and strength, to the regulation of muscle fiber type composition, contraction and metabolic functions. In adipose tissue, androgens influence several processes including proliferation, fat distribution, and metabolism but they display depot-specific and organism-specific effects which differ in certain context. This review further explores the potential mechanisms underlying androgen-AR signaling in skeletal muscle and adipose tissue. Understanding the roles of androgens and their receptor in skeletal muscle and adipose tissue is essential for elucidating their contributions to physiological processes, disease conditions, and potential therapeutic interventions.

Androgen action on myogenesis throughout the lifespan; comparison with neurogenesis

Androgens' pleiotropic actions in promoting sex differences present not only a challenge to providing a comprehensive account of their function, but also an opportunity to gain insights by comparing androgenic actions across organ systems. Although often overlooked by neuroscientists, skeletal muscle is another androgen-responsive organ system which shares with the nervous system properties of electrochemical excitability, behavioral relevance, and remarkable capacity for adaptive plasticity. Here we review androgenic regulation of mitogenic plasticity in skeletal muscle with the goal of identifying areas of interest to those researching androgenic mechanisms mediating sexual differentiation of neurogenesis. We use an organizational-activational framework to relate broad areas of similarity and difference between androgen effects on mitogenesis in muscle and brain throughout the lifespan, from early organogenesis, through pubertal organization, adult activation, and aging. The focus of the review is androgenic regulation of muscle-specific stem cells (satellite cells), which share with neural stem cells essential functions in development, plasticity, and repair, albeit with distinct, muscle-specific features. Also considered are areas of paracrine and endocrine interaction between androgen action on muscle and nervous system, including mediation of neural plasticity of innervating and distal neural populations by muscle-produced trophic factors.

Sexual Dimorphism in Cardiometabolic Diseases: The Role of AMPK

Cardiovascular diseases (CVDs) are the leading cause of mortality and disability among both males and females. The risk of cardiovascular diseases is heightened by the presence of a risk factor cluster of metabolic syndrome, covering obesity and obesity-related cardiometabolic risk factors such as hypertension, glucose, and lipid metabolism dysregulation primarily. Sex hormones contribute to metabolic regulation and make women and men susceptible to obesity development in a different manner, which necessitates sex-specific management. Identifying crucial factors that protect the cardiovascular system is essential to enhance primary and secondary prevention of cardiovascular diseases and should be explicitly studied from the perspective of sex differences. It seems that AMP-dependent protein kinase (AMPK) may be such a factor since it has the protective role of AMPK in the cardiovascular system, has anti-diabetic properties, and is regulated by sex hormones. Those findings highlight the potential cardiometabolic benefits of AMPK, making it an essential factor to consider. Here, we review information about the cross-talk between AMPK and sex hormones as a critical point in cardiometabolic disease development and progression and a target for therapeutic intervention in human disease.

Cardiovascular and metabolic actions of the androgens: Is testosterone a Janus-faced molecule?

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide and in the Western world, one-third of all deaths are attributed to CVD. A conspicuous characteristic of this healthcare epidemic is that most CVD is higher in men than in age-matched premenopausal women, yet reasons for these obvious sex differences remain poorly understood. Driven by clinical case and epidemiological studies and supported by animal experiments, a strong dogma emerged early on that testosterone (TES) exerts deleterious effects on cardiovascular health and exacerbates development of CVD and metabolic dysfunctions in men. In this review, earlier and more recent clinical and experimental animal evidence of cardiovascular and metabolic effects of androgens are discussed. The more recent evidence overwhelmingly suggests that it is progressive, age-dependent declines in TES levels in men that exacerbate CVD and metabolic dysfunctions, while TES exerts beneficial systemic hypotensive effects and protects against metabolic syndrome (MetS) and type2 diabetes mellitus (T2DM). Recent findings reveal existence of bi-directional modulation of glucose and fat homeostasis by TES in females vs males, such that age-dependent declines in TES levels in males and abnormal increases in normally low TES levels in females both result in similar dysfunction in glucose and fat homeostasis, resulting in development of MetS and T2DM, central risk factors for development of CVD, in men as well as women. These findings suggest that the long-held view that TES is detrimental to male health should be discarded in favor of the view that, at least in men, TES is beneficial to cardiovascular and metabolic health.

Gender Differences in Cardiovascular Health: Hormonal Effects on Cardiovascular Risk and Management

Cardiovascular disease is the number one cause of death worldwide both in men and women. Significant differences however exist in the age of onset, type of cardiovascular disease (CVD), and treatment response among the genders. These differences are due to both gender societal effects and biological differences from the influence of the hormonal and metabolic milieu in the two sexes.Estrogens are the main female hormone. They impact signaling in almost every body organ and thus affect cardiovascular risk factors. These result in differential expression of CVD. The differential effect of treatment modalities is only recently being evaluated.Research is ongoing regarding the pathophysiology of these differences. Our current level of knowledge is described in this chapter.

The Hepatoprotective and Hepatotoxic Roles of Sex and Sex-Related Hormones

Most liver diseases, including acute liver injury, drug-induced liver injury, viral hepatitis, metabolic liver diseases, and end-stage liver diseases, are strongly linked with hormonal influences. Thus, delineating the clinical manifestation and underlying mechanisms of the “sexual dimorphism” is critical for providing hints for the prevention, management, and treatment of those diseases. Whether the sex hormones (androgen, estrogen, and progesterone) and sex-related hormones (gonadotrophin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, and prolactin) play protective or toxic roles in the liver depends on the biological sex, disease stage, precipitating factor, and even the psychiatric status. Lifestyle factors, such as obesity, alcohol drinking, and smoking, also drastically affect the involving mechanisms of those hormones in liver diseases. Hormones deliver their hepatic regulatory signals primarily via classical and non-classical receptors in different liver cell types. Exogenous sex/sex-related hormone therapy may serve as a novel strategy for metabolic liver disease, cirrhosis, and liver cancer. However, the undesired hormone-induced liver injury should be carefully studied in pre-clinical models and monitored in clinical applications. This issue is particularly important for menopause females with hormone replacement therapy (HRT) and transgender populations who want to receive gender-affirming hormone therapy (GAHT). In conclusion, basic and clinical studies are warranted to depict the detailed hepatoprotective and hepatotoxic mechanisms of sex/sex-related hormones in liver disease. Prolactin holds a promising perspective in treating metabolic and advanced liver diseases.

The hypothalamus for whole-body physiology: from metabolism to aging

Obesity and aging are two important epidemic factors for metabolic syndrome and many other health issues, which contribute to devastating diseases such as cardiovascular diseases, stroke and cancers. The brain plays a central role in controlling metabolic physiology in that it integrates information from other metabolic organs, sends regulatory projections and orchestrates the whole-body function. Emerging studies suggest that brain dysfunction in sensing various internal cues or processing external cues may have profound effects on metabolic and other physiological functions. This review highlights brain dysfunction linked to genetic mutations, sex, brain inflammation, microbiota, stress as causes for whole-body pathophysiology, arguing brain dysfunction as a root cause for the epidemic of aging and obesity-related disorders. We also speculate key issues that need to be addressed on how to reveal relevant brain dysfunction that underlines the development of these disorders and diseases in order to develop new treatment strategies against these health problems.

Obesity I: Overview and molecular and biochemical mechanisms

Obesity is a chronic, relapsing condition characterized by excess body fat. Its prevalence has increased globally since the 1970s, and the number of obese and overweight people is now greater than those underweight. Obesity is a multifactorial condition, and as such, many components contribute to its development and pathogenesis. This is the first of three companion reviews that consider obesity. This review focuses on the genetics, viruses, insulin resistance, inflammation, gut microbiome, and circadian rhythms that promote obesity, along with hormones, growth factors, and organs and tissues that control its development. It shows that the regulation of energy balance (intake vs. expenditure) relies on the interplay of a variety of hormones from adipose tissue, gastrointestinal tract, pancreas, liver, and brain. It details how integrating central neurotransmitters and peripheral metabolic signals (e.g., leptin, insulin, ghrelin, peptide YY_3-36) is essential for controlling energy homeostasis and feeding behavior. It describes the distinct types of adipocytes and how fat cell development is controlled by hormones and growth factors acting via a variety of receptors, including peroxisome proliferator-activated receptor-gamma, retinoid X, insulin, estrogen, androgen, glucocorticoid, thyroid hormone, liver X, constitutive androstane, pregnane X, farnesoid, and aryl hydrocarbon receptors. Finally, it demonstrates that obesity likely has origins in utero. Understanding these biochemical drivers of adiposity and metabolic dysfunction throughout the life cycle lends plausibility and credence to the "obesogen hypothesis" (i.e., the importance of environmental chemicals that disrupt these receptors to promote adiposity or alter metabolism), elucidated more fully in the two companion reviews.

Assessment of androgen receptor, IGF-IR and insulin receptor expression in male patients with severe peripheral artery disease

Background

Peripheral artery disease (PAD) of the lower limbs is a common condition that can affect quality of life. Androgen receptor (AR) can exert sex-specific effects on metabolic system, endothelial function and vascular tone. IGF-I receptor (IGF-IR) and insulin receptor (IR) may also be involved in the aforementioned functions. The aim of this study was to evaluate AR, IGF-IR and IR expression in the arterial vessel walls of PAD patients.

Results

This is a cross-sectional study examining 30 males with PAD undergoing open surgery procedures. Mean age was 75.9 ± 8.8y. All patients belonged to Rutherford stage 4–6. Median expression levels of IR, IGF-IR and AR significantly decreased from stage 4–6 (p < 0.05).

Significance

The study evidenced a progressive decrease of IR, IGF-IR and AR expression as the severity of disease increased. Altered levels of IR, IGF-IR and AR following PAD may be useful for the clinical evaluation of these patients.

White, brown, and bone marrow adipose tissue behavior in DHEA-induced PCOS mice

METHODS

Thirty-one female C57BL/6J mice were divided into four groups: two were treated with subcutaneous dehydroepiandrosterone (DHEA) implants and divided into normal and hypercaloric diet (HFD). Two were control and divided into normal and HFD. Presence of insulin resistance, growth, and adipocyte markers expression of white and brown adipose tissues and growth and inflammatory cytokines expression of bone marrow adipose tissue were evaluated.

RESULTS

Hypercaloric diet groups presented higher total weight gain and huge growth in all fat sites, except bone marrow. They also demonstrated greater expression of adipocyte markers in sites of white adipose tissue. DHEA + HFD group showed more insulin intolerance than all other groups. DHEA shows to abrogate AdipoQ expression in all fatty tissues.

CONCLUSIONS

DHEA alone does not influence adipose tissue growth, but contributes to increased insulin resistance and influences the expression of adipokines. Proximal MAT showed different behavior from the other fat depot.

Sex Hormone-Binding Globulin Is Associated with Obesity and Dyslipidemia in Prepubertal Children

Sex hormone-binding globulin (SHBG) is associated with age, sex, and puberty. The association of SHBG with various diseases has been suggested nowadays, however, the relationships in prepubertal children have not been sufficiently investigated. This study analyzed the relationship of SHBG with body mass index (BMI) and plasma lipid levels in prepubertal children. We evaluated the association of SHBG with BMI among the 693 prepubertal children subdivided into normal, overweight, and obese groups, with plasma lipid levels among the children subdivided into normal and dyslipidemia groups. The obese and overweight group had lower SHBG levels than the normal BMI group in both sexes. The dyslipidemia group included subjects with low high-density lipoprotein cholesterol (HDL-C), high triglycerides (TG), or a high atherogenic index of plasma (AIP); this group had lower SHBG than the normal lipid group. SHBG was positively correlated with HDL-C, and negatively correlated with TG and AIP. After adjusting for BMI, SHBG was positively correlated with HDL-C and negatively correlated with TG and AIP in all groups. In conclusion, SHBG levels are closely correlated with BMI in prepubertal children. SHBG may play a meaningful role in the decrease in HDL-C and increase in TG during prepubertal age.

Impact of Short-Term Isoflavone Intervention in Polycystic Ovary Syndrome (PCOS) Patients on Microbiota Composition and Metagenomics

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 5-20% of women of reproductive age worldwide and is associated with disorders of glucose metabolism. Hormone and metabolic signaling may be influenced by phytoestrogens, such as isoflavones. Their endocrine effects may modify symptom penetrance in PCOS. Equol is one of the most active isoflavone metabolites, produced by intestinal bacteria, and acts as a selective estrogen receptor modulator.

METHOD

In this interventional study of clinical and biochemical characterization, urine isoflavone levels were measured in PCOS and control women before and three days after a defined isoflavone intervention via soy milk. In this interventional study, bacterial equol production was evaluated using the log(equol: daidzein ratio) and microbiome, metabolic, and predicted metagenome analyses were performed.

RESULTS

After isoflavone intervention, predicted stool metagenomic pathways, microbial alpha diversity, and glucose homeostasis in PCOS improved resembling the profile of the control group at baseline. In the whole cohort, larger equol production was associated with lower androgen as well as fertility markers.

CONCLUSION

The dynamics in our metabolic, microbiome, and predicted metagenomic profiles underline the importance of external phytohormones on PCOS characteristics and a potential therapeutic approach or prebiotic in the future.

Addition of fish oil to atherogenic high fat diet inhibited atherogenesis while olive oil did not, in LDL receptor KO mice

BACKGROUND AND AIMS

Mediterranean diet has been associated with decreased cardiovascular morbidity and mortality. Both fish and olive oil are key components of this diet. Therefore, we compared their effects on nonalcoholic fatty liver disease (NAFLD) and atherogenesis in a mouse model, fed a high fat diet.

METHODS AND RESULTS

Forty nine, female LDL receptor knockout (LDLR KO) mice were allocated into 3 groups and fed an atherogenic high fat (HF) diet for 9 weeks. The HF group was fed a high fat diet alone. A HF + OO group was fed a HF diet with added olive oil (60 ml/kg feed), and the third group (HF + FO) was fed a HF diet with added fish oil (60 ml/kg feed). Both additions of fish and olive oil, significantly decreased plasma cholesterol elevation compared to HF diet. Nevertheless, only fish oil addition reduced significantly atherosclerotic lesion area by 51% compared to HF group. Liver levels of eicosapentenoic (EPA) and docosahexaenoic (DHA) acids were several folds higher in HF + FO group than in HF and HF + OO groups. Liver levels of oleic acid were higher in HF + OO compared to the other groups. Moreover, Fish oil addition significantly decreased NAFLD scores related to steatosis and inflammation and lowered the expression of the inflammatory genes interleukin 6 (IL6) and monocyte chemoattractant protein 1 (MCP1).

CONCLUSION

These results suggest that fish oil addition on top of an atherogenic, HF diet, is beneficial, while olive oil is not, in its effect on plaque formation and NAFLD in LDLR KO mice.

Combined network pharmacology and virtual reverse pharmacology approaches for identification of potential targets to treat vascular dementia

Dementia is a major cause of disability and dependency among older people. If the lives of people with dementia are to be improved, research and its translation into druggable target are crucial. Ancient systems of healthcare (Ayurveda, Siddha, Unani and Sowa-Rigpa) have been used from centuries for the treatment vascular diseases and dementia. This traditional knowledge can be transformed into novel targets through robust interplay of network pharmacology (NetP) with reverse pharmacology (RevP), without ignoring cutting edge biomedical data. This work demonstrates interaction between recent and traditional data, and aimed at selection of most promising targets for guiding wet lab validations. PROTEOME, DisGeNE, DISEASES and DrugBank databases were used for selection of genes associated with pathogenesis and treatment of vascular dementia (VaD). The selection of new potential drug targets was made by methods of NetP (DIAMOnD algorithm, enrichment analysis of KEGG pathways and biological processes of Gene Ontology) and manual expert analysis. The structures of 1976 phytomolecules from the 573 Indian medicinal plants traditionally used for the treatment of dementia and vascular diseases were used for computational estimation of their interactions with new predicted VaD-related drug targets by RevP approach based on PASS (Prediction of Activity Spectra for Substances) software. We found 147 known genes associated with vascular dementia based on the analysis of the databases with gene-disease associations. Six hundred novel targets were selected by NetP methods based on 147 gene associations. The analysis of the predicted interactions between 1976 phytomolecules and 600 NetP predicted targets leaded to the selection of 10 potential drug targets for the treatment of VaD. The translational value of these targets is discussed herewith. Twenty four drugs interacting with 10 selected targets were identified from DrugBank. These drugs have not been yet studied for the treatment of VaD and may be investigated in this field for their repositioning. The relation between inhibition of two selected targets (GSK-3, PTP1B) and the treatment of VaD was confirmed by the experimental studies on animals and reported separately in our recent publications.

Estrogen withdrawal and replacement differentially target liver and adipose tissues in female mice fed a high-fat high-sucrose diet: impact of a chronic exposure to a low-dose pollutant mixture☆

Postmenopausal women may be at particular risk when exposed to chemicals especially endocrine disruptors because of hormonal deficit. To get more insight, ovariectomized C57Bl6/J mice fed a high-fat high-sucrose diet were chronically exposed from 5 to 20 weeks of age to a low-dose mixture of chemicals with one dioxin, one polychlorobiphenyl, one phthalate and bisphenol A. Part of the mice received as well E2 implants to explore the potential estrogenic dependency of the metabolic alterations. With this model, estrogen loss resulted in glucose but not lipid metabolism impairment, and E2 replacement normalized the enhanced body and fat pad weight, and the glucose intolerance and insulin resistance linked to ovariectomy. It also altered cholesterol metabolism in the liver concurrently with enhanced estrogen receptor Esr1 mRNA level. In addition, fat depots responded differently to estrogen withdrawal (e.g., selective mRNA enhancement of adipogenesis markers in subcutaneous and of inflammation in visceral fat pads) and replacement challenges. Importantly, the pollutant mixture impacted lipid deposition and mRNA expression of several genes related to lipid metabolism but not Esr1 in the liver. Adiponectin levels were altered as well. In addition, the mRNA abundance of the various estrogen receptors was regionally impacted in fat tissues. Besides, xenobiotic processing genes did not change in response to the pollutant mixture in the liver. The present findings bring new light on estrogen-dependent metabolic alterations with regards to situations of loss of estrogens as observed after menopause.

Hyperandrogenic origins of polycystic ovary syndrome - implications for pathophysiology and therapy

INTRODUCTION

Polycystic ovary syndrome (PCOS) diagnosis comprises combinations of female hyperandrogenism, menstrual irregularity and polycystic ovaries. While it is a familial and highly prevalent endocrine disorder, progress towards a cure is hindered by absence of a definitive pathogenic mechanism and lack of an animal model of naturally occurring PCOS.

AREAS COVERED

These include an overview of PCOS and its potential etiology, and an examination of insights gained into its pathogenic origins. Animal models derived from experimentally-induced hyperandrogenism during gestation, or from naturally-occurring PCOS-like traits, most reliably demonstrate reproductive, neuroendocrine and metabolic pathogenesis.

EXPERT OPINION

Genetic studies, while identifying at least 17 PCOS risk genes, account for <10% of women with PCOS. A number of PCOS risk genes involve regulation of gonadotropin secretion or action, suggesting a reproductive neuroendocrine basis for PCOS pathogenesis. Consistent with this notion, a number of animal models employing fetal androgen excess demonstrate epigenetic induction of PCOS-like traits, including reproductive neuroendocrine and metabolic dysfunction. Monkey models are most comprehensive, while mouse models provide molecular insight, including identifying the androgen receptor, particularly in neurons, as mediating androgen-induced PCOS-like programming. Naturally-occurring female hyperandrogenism is also demonstrated in monkeys. Animal models are poised to delineate molecular gateways to PCOS pathogenesis.

Mechanisms for Sex Differences in Energy Homeostasis

Sex differences exist in the regulation of energy homeostasis. Better understanding of the underlying mechanisms for sexual dimorphism in energy balance may facilitate development of gender-specific therapies for human diseases, e.g. obesity. Multiple organs, including the brain, liver, fat and muscle, play important roles in the regulations of feeding behavior, energy expenditure and physical activity, which therefore contribute to the maintenance of energy balance. It has been increasingly appreciated that this multi-organ system is under different regulations in male vs. female animals. Much of effort has been focused on roles of sex hormones (including androgens, estrogens and progesterone) and sex chromosomes in this sex-specific regulation of energy balance. Emerging evidence also indicates that other factors (not sex hormones/receptors and not encoded by the sex chromosomes) exist to regulate energy homeostasis differentially in males vs. females. In this review, we summarize factors and signals that have been shown to regulate energy homeostasis in a sexually dimorphic fashion and propose a framework where these factors and signals may be integrated to mediate sex differences in energy homeostasis.

Prevalence and treatment of central hypogonadism and hypoandrogenism in women with hypopituitarism

PURPOSE

Women with hypopituitarism have increased morbidity and mortality, and hypogonadism has been suggested to be a contributing mechanism. The purpose of this study was to investigate the prevalence of central hypogonadism and hypoandrogenism in women with hypopituitarism at a single Swedish center.

METHODS

All consecutive women (n = 184) who commenced growth hormone (GH) replacement therapy at Sahlgrenska University Hospital in Gothenburg between 1995 and 2015 were included. In accordance with the Endocrine Society Clinical Practice Guidelines, strict criteria, based on menstrual history combined with laboratory measurements, were used to define central hypogonadism. Hypoandrogenism was defined as subnormal levels of dehydroepiandrosterone sulfate and/or androstenedione.

RESULTS

Central hypogonadism was present in 78% of the women, in 75% of those ≤ 52 years and in 82% of those > 52 years of age. Hypoandrogenism was found in 61% of all the women and in 92% of those with adrenocorticotropic hormone (ACTH) deficiency. The estrogen substitution rate in hypogonadal women ≤ 52 years was lower than the hormonal substitution rate in the other pituitary hormone axes (74% versus 100%, P < 0.001). The use of estrogen substitution tended to decrease between 2000 and 2016. Few women received androgen treatment.

CONCLUSIONS

In this first study of hypogonadism in women with hypopituitarism, using stringent diagnostic criteria for hypogonadism, the prevalence of central hypogonadism and low androgen levels was high and estrogen substitution was insufficient. Further studies are needed to elucidate the importance of hypogonadism and insufficient sex steroid replacement for the increased morbidity in hypopituitary women.

Sex differences in endothelial function important to vascular health and overall cardiovascular disease risk across the lifespan

Diseases of the cardiovascular system are the leading cause of morbidity and mortality in men and women in developed countries, and cardiovascular disease (CVD) is becoming more prevalent in developing countries. The prevalence of atherosclerotic CVD in men is greater than in women until menopause, when the prevalence of CVD increases in women until it exceeds that of men. Endothelial function is a barometer of vascular health and a predictor of atherosclerosis that may provide insights into sex differences in CVD as well as how and why the CVD risk drastically changes with menopause. Studies of sex differences in endothelial function are conflicting, with some studies showing earlier decrements in endothelial function in men compared with women, whereas others show similar age-related declines between the sexes. Because the increase in CVD risk coincides with menopause, it is generally thought that female hormones, estrogens in particular, are cardioprotective. Moreover, it is often proposed that androgens are detrimental. In truth, the relationships are more complex. This review first addresses female and male sex hormones and their receptors and how these interact with the cardiovascular system, particularly the endothelium, in healthy young women and men. Second, we address sex differences in sex steroid receptor-independent mechanisms controlling endothelial function, focusing on vascular endothelin and the renin-angiotensin systems, in healthy young women and men. Finally, we discuss sex differences in age-associated endothelial dysfunction, focusing on the role of attenuated circulating sex hormones in these effects.

Sex differences in lipid and lipoprotein metabolism

BACKGROUND

Endogenous sex hormones are important for metabolic health in men and women. Before menopause, women are protected from atherosclerotic cardiovascular disease (ASCVD) relative to men. Women have fewer cardiovascular complications of obesity compared to men with obesity. Endogenous estrogens have been proposed as a mechanism that lessens ASCVD risk, as risk of glucose and lipid abnormalities increases when endogenous estrogens decline with menopause. While baseline risk is higher in males than females, endogenously produced androgens are also protective against fatty liver, diabetes and ASCVD, as risk goes up with androgen deprivation and with the decline in androgens with age.

SCOPE OF REVIEW

In this review, we discuss evidence of how endogenous sex hormones and hormone treatment approaches impact fatty acid, triglyceride, and cholesterol metabolism to influence metabolic and cardiovascular risk. We also discuss potential reasons for why treatment strategies with estrogens and androgens in older individuals fail to fully recapitulate the effects of endogenous sex hormones.

MAJOR CONCLUSIONS

The pathways that confer ASCVD protection for women are of potential therapeutic relevance. Despite protection relative to men, ASCVD is still the major cause of mortality in women. Additionally, diabetic women have similar ASCVD risk as diabetic men, suggesting that the presence of diabetes may offset the protective cardiovascular effects of being female through unknown mechanisms.

Mouse models of peripheral metabolic disease

Metabolic disease risk is driven by defects in the function of cells that regulate energy homeostasis, as well as altered communication between the different tissues or organs that these cells occupy. Thus, it is desirable to use model organisms to understand the contribution of different cells, tissues and organs to metabolism. Mice are widely used for metabolic research, since well-characterised mouse strains (in terms of their genotype and phenotype) allow comparative studies and human disease modelling. Such research involves strains containing spontaneous mutations that lead to obesity and diabetes, surgically- and chemically-induced models, those that are secondary to caloric excess, genetic mutants created by transgenesis and gene knockout technologies, and peripheral models generated by Cre-Lox or CRISPR/Cas9 approaches. Focussing on obesity and type 2 diabetes as relevant metabolic diseases, we systematically review each of these models, discussing their use, limitations, and future potential.

The impact of androgen actions in neurons on metabolic health and disease

The male hormone testosterone exerts different effects on glucose and energy homeostasis in males and females. Testosterone deficiency predisposes males to visceral obesity, insulin resistance and type 2 diabetes. However, testosterone excess predisposes females to similar metabolic dysfunction. Here, we review the effects of testosterone actions in the central nervous system on metabolic function in males and females. In particular, we highlight changes within the hypothalamus that control glucose and energy homeostasis. We distinguish the organizational effects of testosterone in the programming of neural circuitry during development from the activational effects of testosterone during adulthood. Finally, we explore potential sites where androgen might be acting to impact metabolism within the central nervous system.

The role of androgen receptors in atherosclerosis

Male disadvantage in cardiovascular health is well recognised. However, the influence of androgens on atherosclerosis, one of the major causes of many life-threatening cardiovascular events, is not well understood. With the dramatic increase in clinical prescription of testosterone in the past decade, concerns about the cardiovascular side-effects of androgen supplementation or androgen deprivation therapy are increasing. Potential atheroprotective effects of testosterone could be secondary to (aromatase-mediated) conversion into oestradiol or, alternatively, to direct activation of androgen receptors (AR). Recent development of animal models with cell-specific AR knockout has indicated a complex role for androgen action in atherosclerosis. Most studies suggest androgens are atheroprotective but the precise role of AR remains unclear. Increased use of AR knockout models should clarify the role of AR in atherogenesis and, thus, lead to exploitation of this pathway as a therapeutic target.

Sex differences in the effects of androgens acting in the central nervous system on metabolism

One of the most sexually dimorphic aspects of metabolic regulation is the bidirectional modulation of glucose and energy homeostasis by testosterone in males and females. Testosterone deficiency predisposes men to metabolic dysfunction, with excess adiposity, insulin resistance, and type 2 diabetes, whereas androgen excess predisposes women to insulin resistance, adiposity, and type 2 diabetes. This review discusses how testosterone acts in the central nervous system, and especially the hypothalamus, to promote metabolic homeostasis or dysfunction in a sexually dimorphic manner. We compare the organizational actions of testosterone, which program the hypothalamic control of metabolic homeostasis during development, and the activational actions of testosterone, which affect metabolic function after puberty. We also discuss how the metabolic effect of testosterone is centrally mediated via the androgen receptor.

Chronic exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces an obesogenic effect in C57BL/6J mice fed a high fat diet

Contaminant involvement in the pathophysiology of obesity is widely recognized. It has been shown that low dose and chronic exposure to endocrine disruptor compounds (EDCs) potentiated diet- induced obesity. High and acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a persistent organic pollutant (POP) and an EDC with anti-estrogenic property, causes wasting syndrome . However at lower doses, the TCDD metabolic effects remain poorly understood. We investigated the obesogenic effect during chronic exposure of TCDD at 1μg/kg body weight (bw)/week in adult C57BL/6J mice fed with a high fat diet (HFD) and exposed from 10 to 42 weeks old to TCDD or equal volume of vehicle by intragastric gavage. Under these conditions, TCDD was obesogenic in adult mice (7% in males and 8% in females), which was linked to fat mass. A sex effect was observed in the fat mass distribution in adipose tissue and in the hepatic triglyceride content evolution. In visceral fat pad weight, we observed a decrease (11%) in males and an increase (14%) in females. The hepatic triglyceride content increase (41%) in females only. TCDD failed to induce any change in plasma parameters regarding glucose and lipid homeostasis. Messenger ribonucleic acid (mRNA) levels involved in adipose tissue and hepatic metabolism, inflammation, xenobiotic metabolism and endocrine disruption were differently regulated between males and females. In conclusion, these results provide new evidence that dioxin, a POP and EDC can be obesogenic for adult mice with multi-organ effects.

The effects of chronic testosterone administration on body weight, food intake, and adipose tissue are changed by estrogen treatment in female rats

In females, estrogens play pivotal roles in preventing excess body weight (BW) gain. On the other hand, the roles of androgens in female BW, appetite, and energy metabolism have not been fully examined. We hypothesized that androgens' effects on food intake (FI) and BW regulation change according to the estrogens' levels. To evaluate this hypothesis, the effects of chronic testosterone administration in ovariectomized (OVX) female rats with or without estradiol supplementation were examined in this study. Chronic testosterone administration decreased BW, FI, white adipose tissue (WAT) weight, and adipocyte size in OVX rats, whereas it increased BW, WAT weight, and adipocyte size in OVX with estradiol-administered rats. In addition, chronic testosterone administration increased hypothalamic CYP19a1 mRNA levels in OVX rats, whereas it did not alter CYP19a1 mRNA levels in OVX with estradiol-administered rats, indicating that conversion of testosterone to estrogens in the hypothalamus may be activated in testosterone-administered OVX rats. Furthermore, chronic testosterone administration decreased hypothalamic TNF-α mRNA levels in OVX rats, whereas it increased hypothalamic IL-1β mRNA levels in OVX with estradiol-administered rats. On the other hand, IL-1β and TNF-α mRNA levels in visceral and subcutaneous WAT and liver were not changed by chronic testosterone administration in both groups. These data indicate that the effects of chronic testosterone administration on BW, FI, WAT weight, and adipocyte size were changed by estradiol treatment in female rats. Testosterone has facilitative effects on BW gain, FI, and adiposity under the estradiol-supplemented condition, whereas it has inhibitory effects in the non-supplemented condition. Differences in the responses of hypothalamic factors, such as aromatase and inflammatory cytokines, to testosterone might underlie these opposite effects.

Androgen inhibits key atherosclerotic processes by directly activating ADTRP transcription

Low androgen levels are associated with an increased risk of coronary artery disease (CAD), thrombosis and myocardial infarction (MI), suggesting that androgen has a protective role. However, little is known about the underlying molecular mechanism. Our genome-wide association study identified the ADTRP gene encoding the androgen-dependent TFPI regulating protein as a susceptibility gene for CAD and MI. The expression level of ADTRP was regulated by androgen, but the molecular mechanism is unknown. In this study, we identified the molecular mechanism by which androgen regulates ADTRP expression and tested the hypothesis that androgen plays a protective role in cardiovascular disease by activating ADTRP expression. Luciferase assays with an ADTRP promoter luciferase reporter revealed that androgen regulated ADTRP transcription in a dose- and time-dependent manner, and the effect was abolished by three different androgen inhibitors, including pyrvinium pamoate, bicalutamide, and cyproterone acetate. Chromatin-immunoprecipitation showed that the androgen receptor bound to a half androgen response element (ARE, TGTTCT) located at +324bp from the ADTRP transcription start site. The ARE is required for concentration-dependent transcriptional activation of ADTRP. HL-60 monocyte adhesion to EAhy926 endothelial cells (ECs) and transmigration across the EC layer, the two processes critical to development of CAD and MI, were inhibited by androgen, but the effect was rescued by ADTRP siRNA and exacerbated by overexpression of ADTRP and its downstream genes PIK3R3 and MIA3. These data suggest that one molecular mechanism by which androgen confers protection against CAD is stimulation of ADTRP expression.

Neuroendocrine androgen action is a key extraovarian mediator in the development of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a complex hormonal disorder characterized by reproductive, endocrine, and metabolic abnormalities. As the origins of PCOS remain unknown, mechanism-based treatments are not feasible and current management relies on treatment of symptoms. Hyperandrogenism is the most consistent PCOS characteristic; however, it is unclear whether androgen excess, which is treatable, is a cause or a consequence of PCOS. As androgens mediate their actions via the androgen receptor (AR), we combined a mouse model of dihydrotestosterone (DHT)-induced PCOS with global and cell-specific AR-resistant (ARKO) mice to investigate the locus of androgen actions that mediate the development of the PCOS phenotype. Global loss of the AR reveals that AR signaling is required for all DHT-induced features of PCOS. Neuron-specific AR signaling was required for the development of dysfunctional ovulation, classic polycystic ovaries, reduced large antral follicle health, and several metabolic traits including obesity and dyslipidemia. In addition, ovariectomized ARKO hosts with wild-type ovary transplants displayed normal estrous cycles and corpora lutea, despite DHT treatment, implying extraovarian and not intraovarian AR actions are key loci of androgen action in generating the PCOS phenotype. These findings provide strong evidence that neuroendocrine genomic AR signaling is an important extraovarian mediator in the development of PCOS traits. Thus, targeting AR-driven mechanisms that initiate PCOS is a promising strategy for the development of novel treatments for PCOS.

MECHANISMS IN ENDOCRINOLOGY: Nutrition as a mediator of oxidative stress in metabolic and reproductive disorders in women

Nutrition can generate oxidative stress and trigger a cascade of molecular events that can disrupt oxidative and hormonal balance. Nutrient ingestion promotes a major inflammatory and oxidative response at the cellular level in the postprandial state, altering the metabolic state of tissues. A domino of unfavorable metabolic changes is orchestrated in the main metabolic organs, including adipose tissue, skeletal muscle, liver and pancreas, where subclinical inflammation, endothelial dysfunction, mitochondrial deregulation and impaired insulin response and secretion take place. Simultaneously, in reproductive tissues, nutrition-induced oxidative stress can potentially violate delicate oxidative balance that is mandatory to secure normal reproductive function. Taken all the above into account, nutrition and its accompanying postprandial oxidative stress, in the unique context of female hormonal background, can potentially compromise normal metabolic and reproductive functions in women and may act as an active mediator of various metabolic and reproductive disorders.

The role of sex steroids in white adipose tissue adipocyte function

With the increasing knowledge that gender influences normal physiology, much biomedical research has begun to focus on the differential effects of sex on tissue function. Sexual dimorphism in mammals is due to the combined effects of both genetic and hormonal factors. Hormonal factors are mutable particularly in females in whom the estrous cycle dominates the hormonal milieu. Given the severity of the obesity epidemic and the fact that there are differences in the obesity rates in men and women, the role of sex in white adipose tissue function is being recognized as increasingly important. Although sex differences in white adipose tissue distribution are well established, the mechanisms affecting differential function of adipocytes within white adipose tissue in males and females remain largely understudied and poorly understood. One of the largest differences in the endocrine environment in males and females is the concentration of circulating androgens and estrogens. This review examines the effects of androgens and estrogens on lipolysis/lipogenesis, adipocyte differentiation, insulin sensitivity and adipokine production in adipocytes from white adipose tissue with a specific emphasis on the sexual dimorphism of adipocyte function in white adipose tissue during both health and disease.

Metabolic dysfunction in female mice with disruption of 5α-reductase 1

5α-Reductases irreversibly catalyse A-ring reduction of pregnene steroids, including glucocorticoids and androgens. Genetic disruption of 5α-reductase 1 in male mice impairs glucocorticoid clearance and predisposes to glucose intolerance and hepatic steatosis upon metabolic challenge. However, it is unclear whether this is driven by changes in androgen and/or glucocorticoid action. Female mice with transgenic disruption of 5α-reductase 1 (5αR1-KO) were studied, representing a 'low androgen' state. Glucocorticoid clearance and stress responses were studied in mice aged 6 months. Metabolism was assessed in mice on normal chow (aged 6 and 12 m) and also in a separate cohort following 1-month high-fat diet (aged 3 m). Female 5αR1-KO mice had adrenal suppression (44% lower AUC corticosterone after stress), and upon corticosterone infusion, accumulated hepatic glucocorticoids (~27% increased corticosterone). Female 5αR1-KO mice aged 6 m fed normal chow demonstrated insulin resistance (~35% increased area under curve (AUC) for insulin upon glucose tolerance testing) and hepatic steatosis (~33% increased hepatic triglycerides) compared with controls. This progressed to obesity (~12% increased body weight) and sustained insulin resistance (~38% increased AUC insulin) by age 12 m. Hepatic transcript profiles supported impaired lipid β-oxidation and increased triglyceride storage. Female 5αR1-KO mice were also predisposed to develop high-fat diet-induced insulin resistance. Exaggerated predisposition to metabolic disorders in female mice, compared with that seen in male mice, after disruption of 5αR1 suggests phenotypic changes may be underpinned by altered metabolism of glucocorticoids rather than androgens.

The Role of Sex and Sex Hormones in Regulating Obesity-Induced Inflammation

Metabolic and non-metabolic complications due to obesity are becoming more prevalent, yet our understanding of the mechanisms driving these is not. This is due to individual risk factor variability making it difficult to predict disease outcomes such as diabetes and insulin resistance. Gender is a critical factor in obesity outcomes with women having more adiposity but reduced metabolic complications compared to men. The role of immune system activation during obesity is an emerging field that links adiposity to metabolic syndrome. Furthermore, evidence from animal models suggests that sex differences exist in immune responses and, therefore, could be a possible mechanism leading to sex differences in metabolic disease. While there is still much to learn in the area of sex-differences research, this chapter will review the current knowledge and literature detailing the role of sex and sex hormones on adiposity and metabolically induced inflammation in obesity.

Study on material base and action mechanism of compound Danshen dripping pills for treatment of atherosclerosis based on modularity analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been widely used in China and its surrounding countries in clinical treatments for centuries-long time. However, due to the complexity of TCM constituents, both action mechanism and material base of TCM remain nearly unknown.

AIM OF THE STUDY

The present study was designed to uncover the action mechanism and material base of TCM in a low-cost manner.

MATERIALS AND METHODS

Compound Danshen dripping pills (DSP) is a widely used TCM for treatment of atherosclerosis, and was researched here to demonstrate the effectiveness of our method. We constructed a heterogeneous network for DSP, identified the significant network module, and analyzed the primary pharmacological units by performing GO and pathways enrichment analysis.

RESULTS

Two significant network modules were identified from the heterogeneous network of DSP, and three compounds out of four hub nodes in the network were found to intervene in the process of atherosclerosis. Moreover, 13 out of 20 enriched pathways that were ranked in top 10 corresponding to both the two pharmacological units were found to be involved in the process of atherosclerosis.

CONCLUSIONS

Quercetin, luteolin and apigenin may be the main active compounds which modulate the signaling pathways, such as metabolism of xenobiotics by cytochrome P450, retinol metabolism, etc. The present method helps reveal the action mechanism and material base of DSP for treatment of atherosclerosis.

Sexually dimorphic myeloid inflammatory and metabolic responses to diet-induced obesity

It is well known in clinical and animal studies that women and men have different disease risk as well as different disease physiology. Women of reproductive age are protected from metabolic and cardiovascular disease compared with postmenopausal women and men. Most murine studies are skewed toward the use of male mice to study obesity-induced metabolic dysfunction because of similar protection in female mice. We have investigated dietary obesity in a mouse model and have directly compared inflammatory responses in males and females. In this review we will summarize what is known about sex differences in diet-induced inflammation and will summarize our data on this topic. It is clear that sex differences in high-fat diet-induced inflammatory activation are due to cell intrinsic differences in hematopoietic responses to obesogenic cues, but further research is needed to understand what leads to sexually dimorphic responses.

The direction of cross affects [corrected] obesity after puberty in male but not female offspring

Background

We investigated parent-of-origin and allele-specific expression effects on obesity and hepatic gene expression in reciprocal crosses between the Berlin Fat Mouse Inbred line (BFMI) and C57Bl/6NCrl (B6N).

Results

We found that F1-males with a BFMI mother developed 1.8 times more fat mass on a high fat diet at 10 weeks than F1-males of a BFMI father. The phenotype was detectable from six weeks on and was preserved after cross-fostering. RNA-seq data of liver provided evidence for higher biosynthesis and elongation of fatty acids (p = 0.00635) in obese male offspring of a BFMI mother versus lean offspring of a BFMI father. Furthermore, fatty acid degradation (p = 0.00198) and the peroxisome pathway were impaired (p = 0.00094). The circadian rhythm was affected as well (p = 0.00087). Among the highest up-regulated protein coding genes in obese males were Acot4 (1.82 fold, p = 0.022), Cyp4a10 (1.35 fold, p = 0.026) and Cyp4a14 (1.32 fold, p = 0.012), which hydroxylize fatty acids and which are known to be increased in liver steatosis. Obese males showed lower expression of the genetically imprinted and paternally expressed 3 (Peg3) gene (0.31 fold, p = 0.046) and higher expression of the androgen receptor (Ar) gene (2.38 fold, p = 0.068). Allelic imbalance was found for expression of ATP-binding cassette transporter gene Abca8b. Several of the differentially expressed genes contain estrogen response elements.

Conclusions

Parent-of-origin effects during gametogenesis and/or fetal development in an obese mother epigenetically modify the transcription of genes that lead to enhanced fatty acid synthesis and impair β-oxidation in the liver of male, but not female F1 offspring. Down-regulation of Peg3 could contribute to trigger this metabolic setting. At puberty, higher amounts of the androgen receptor and altered access to estrogen response elements in affected genes are likely responsible for male specific expression of genes that were epigenetically triggered. A suggestive lack of estrogen binding motifs was found for highly down-regulated genes in adult hepatocytes of obese F1 males (p = 0.074).

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2164-2) contains supplementary material, which is available to authorized users.