Deletion of the androgen receptor in adipose tissue in male mice elevates retinol binding protein 4 and reveals independent effects on visceral fat mass and on glucose homeostasis

Cell-specific functions of androgen receptor in skeletal muscles

Androgens play a vital role not only in promoting the development of male sexual characteristics but also in exerting diverse physiological effects, including the regulation of skeletal muscle growth and function. Given that the effects of androgens are mediated through androgen receptor (AR) binding, an understanding of AR functionality is crucial for comprehending the mechanisms of androgen action on skeletal muscles. Drawing from insights gained using conditional knockout mouse models facilitated by Cre/loxP technology, we review the cell-specific functions of AR in skeletal muscles. We focus on three specific cell populations expressing AR within skeletal muscles: skeletal muscle cells, responsible for muscle contraction; satellite cells, which are essential stem cells contributing to the growth and regeneration of skeletal muscles; and mesenchymal progenitors, situated in interstitial areas and playing a crucial role in muscle homeostasis. Furthermore, the indirect effects of androgens on skeletal muscle through extra-muscle tissue are essential, especially for the regulation of skeletal muscle mass. The regulation of genes by AR varies across different cell types and contexts, including homeostasis, regeneration and hypertrophy of skeletal muscles. The varied mechanisms orchestrated by AR collectively influence the physiology of skeletal muscles.

Influence of Adipokines on Metabolic Dysfunction and Aging

Currently, 30% of the global population is overweight or obese, with projections from the World Obesity Federation suggesting that this figure will surpass 50% by 2035. Adipose tissue dysfunction, a primary characteristic of obesity, is closely associated with an increased risk of metabolic abnormalities, such as hypertension, hyperglycemia, and dyslipidemia, collectively termed metabolic syndrome. In particular, visceral fat accretion is considered as a hallmark of aging and is strongly linked to higher mortality rates in humans. Adipokines, bioactive peptides secreted by adipose tissue, play crucial roles in regulating appetite, satiety, adiposity, and metabolic balance, thereby rendering them key players in alleviating metabolic diseases and potentially extending health span. In this review, we elucidated the role of adipokines in the development of obesity and related metabolic disorders while also exploring the potential of certain adipokines as candidates for longevity interventions.

Identification and characterization of structural variants related to meat quality in pigs using chromosome-level genome assemblies

BACKGROUND

Many studies have been performed to identify various genomic loci and genes associated with the meat quality in pigs. However, the full genetic architecture of the trait still remains unclear in part because of the lack of accurate identification of related structural variations (SVs) which resulted from the shortage of target breeds, the limitations of sequencing data, and the incompleteness of genome assemblies. The recent generation of a new pig breed with superior meat quality, called Nanchukmacdon, and its chromosome-level genome assembly (the NCMD assembly) has provided new opportunities.

RESULTS

By applying assembly-based SV calling approaches to various genome assemblies of pigs including Nanchukmacdon, the impact of SVs on meat quality was investigated. Especially, by checking the commonality of SVs with other pig breeds, a total of 13,819 Nanchukmacdon-specific SVs (NSVs) were identified, which have a potential effect on the unique meat quality of Nanchukmacdon. The regulatory potentials of NSVs for the expression of nearby genes were further examined using transcriptome- and epigenome-based analyses in different tissues.

CONCLUSIONS

Whole-genome comparisons based on chromosome-level genome assemblies have led to the discovery of SVs affecting meat quality in pigs, and their regulatory potentials were analyzed. The identified NSVs will provide new insights regarding genetic architectures underlying the meat quality in pigs. Finally, this study confirms the utility of chromosome-level genome assemblies and multi-omics analysis to enhance the understanding of unique phenotypes.

Profiling of Skeletal Muscle and Adipose Tissue Depots in Men with Advanced Prostate Cancer Receiving Different Forms of Androgen Deprivation Therapy

Background

Androgen deprivation therapy (ADT) is a common treatment modality for men with prostate cancer. Increases in adipose tissue mass and decreases in skeletal muscle mass are known on-target adverse effects of standard ADT. The effects of newer agents such as abiraterone acetate (ABI) and enzalutamide (ENZA) on body composition and how these compare with standard luteinizing hormone-releasing hormone agonists (aLHRHs) are unclear.

Objective

To assess the effects of different forms of androgen deprivation therapy on body composition in men with prostate cancer.

Design setting and participants

Using a retrospective design, 229 patients receiving aLHRHs alone (n = 120) or in combination with ABI (n = 53) or ENZA (n = 56) were studied.

Outcome measurements and statistical analysis

Muscle, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were assessed at baseline, 6 mo, and 18 mo after initiating therapy using a cross-sectional densitometry analysis performed on standard of care computed tomography images. Response trajectories for all treatment groups were calculated via a two-way analysis of variance post hoc test, for both within-group and between-group differences.

Results and limitations

Treatment with aLHRHs, ABI, and ENZA was associated with a median muscle volume loss of -1.4%, -4.8%, and -5.5% at 6 mo, and -7.1%, -8.1%, and -8.3% at 18 mo, respectively. Therapy with aLHRHs was associated with minimal changes in VAT (0.3% at 6 mo and -0.1% at 18 mo). ABI therapy was associated with significant increases in VAT at 6 mo (4.9%) but not at 18 mo (0.5%), and ENZA therapy was associated with significant decreases in VAT (-4.6% at 6 mo and -5.4% at 18 mo). With respect to SAT, treatment with aLHRHs was associated with increases over time (8.6% at 6 mo and 4.7% at 18 mo), ABI was associated with decreases over time (-3.6% at 6 mo and -6.8% at 18 mo), and ENZA had no clear effects (1.7% at 6 mo and 3.3% at 18 mo).

Conclusions

ADT regimens cause significant short-term losses in muscle mass, with the most rapid effects occurring with ABI and ENZA. The three regimens have disparate effects on SAT and VAT, suggesting distinct roles of androgens in these tissues.

Patient summary

Androgen deprivation therapy alters body composition in men with prostate cancer. Abiraterone and enzalutamide are associated with losses in muscle mass compared with luteinizing hormone-releasing hormone agonists. These treatments impact subcutaneous and visceral fat mass, suggesting distinct roles of androgens in these tissues.

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.

Advances in mitochondria-centered mechanism behind the roles of androgens and androgen receptor in the regulation of glucose and lipid metabolism

An increasing number of studies have reported that androgens and androgen receptors (AR) play important roles in the regulation of glucose and lipid metabolism. Impaired glucose and lipid metabolism and the development of obesity-related diseases have been found in either hypogonadal men or male rodents with androgen deficiency. Exogenous androgens supplementation can effectively improve these disorders, but the mechanism by which androgens regulate glucose and lipid metabolism has not been fully elucidated. Mitochondria, as powerhouses within cells, are key organelles influencing glucose and lipid metabolism. Evidence from both pre-clinical and clinical studies has reported that the regulation of glucose and lipid metabolism by androgens/AR is strongly associated with the impact on the content and function of mitochondria, but few studies have systematically reported the regulatory effect and the molecular mechanism. In this paper, we review the effect of androgens/AR on mitochondrial content, morphology, quality control system, and function, with emphases on molecular mechanisms. Additionally, we discuss the sex-dimorphic effect of androgens on mitochondria. This paper provides a theoretical basis for shedding light on the influence and mechanism of androgens on glucose and lipid metabolism and highlights the mitochondria-based explanation for the sex-dimorphic effect of androgens on glucose and lipid metabolism.

Contribution of local regeneration of glucocorticoids to tissue steroid pools

11β-Hydroxysteroid dehydrogenase 1 (11βHSD1) is a drug target to attenuate adverse effects of chronic glucocorticoid excess. It catalyses intracellular regeneration of active glucocorticoids in tissues including brain, liver and adipose tissue (coupled to hexose-6-phosphate dehydrogenase, H6PDH). 11βHSD1 activity in individual tissues is thought to contribute significantly to glucocorticoid levels at those sites, but its local contribution vs glucocorticoid delivery via the circulation is unknown. Here, we hypothesised that hepatic 11βHSD1 would contribute significantly to the circulating pool. This was studied in mice with Cre-mediated disruption of Hsd11b1 in liver (Alac-Cre) vs adipose tissue (aP2-Cre) or whole-body disruption of H6pdh. Regeneration of [9,12,12-2H3]-cortisol (d3F) from [9,12,12-2H3]-cortisone (d3E), measuring 11βHSD1 reductase activity was assessed at steady state following infusion of [9,11,12,12-2H4]-cortisol (d4F) in male mice. Concentrations of steroids in plasma and amounts in liver, adipose tissue and brain were measured using mass spectrometry interfaced with matrix-assisted laser desorption ionisation or liquid chromatography. Amounts of d3F were higher in liver, compared with brain and adipose tissue. Rates of appearance of d3F were ~6-fold slower in H6pdh-/- mice, showing the importance for whole-body 11βHSD1 reductase activity. Disruption of liver 11βHSD1 reduced the amounts of d3F in liver (by ~36%), without changes elsewhere. In contrast disruption of 11βHSD1 in adipose tissue reduced rates of appearance of circulating d3F (by ~67%) and also reduced regenerated of d3F in liver and brain (both by ~30%). Thus, the contribution of hepatic 11βHSD1 to circulating glucocorticoid levels and amounts in other tissues is less than that of adipose tissue.

Dihydrotestosterone, and Not Testosterone, Enhances the LPS-Induced Inflammatory Cytokine Gene Expression in Human Adipocytes

BACKGROUND

The development of obesity-related complications lies in the low-grade inflammatory state consequent to adipocyte dysfunction. The direct involvement of sex hormones in adipose tissue inflammation has been previously suggested, but the evidence is scarce. In this study, we evaluated the effects of sex steroids on the in-vitroexpression of inflammatory mediators in human-derived adipocytes before and after lipopolysaccharide (LPS) exposure.

METHODS

Human adipocytes were differentiated from the vascular stromal fraction of adipose tissue samples of subjects undergoing abdominoplasty. We evaluated MCP-1, IL-1β, IL-6, and TNF-α gene expression in the presence of the main sex steroids, testosterone (T), and 17β-estradiol (E). Furthermore, we analyzed the effects of adipocytes exposure to the non-aromatizable androgen dihydrotestosterone (DHT), together with the effects of adipocytes pre-incubation with the aromatase inhibitor anastrozole alone (A), and in combination with T (A/T) before incubation with LPS.

RESULTS

DHT, but not T, significantly enhanced the LPSinduction of MCP-1, IL-1β, IL-6, and TNF-α. Intriguingly, the exposure of adipocytes with A/T dramatically increased the LPS-induced expression of all considered inflammatory cytokines, even more than a hundred-fold.

CONCLUSIONS

DHT and A/T dramatically enhance LPS-induced inflammatory cytokine expression in human-derived adipocytes. These results confirm the involvement of sex hormones in adipose tissue inflammation, suggesting a specific role for non-aromatizable androgens as the amplificatory sex hormones of the inflammatory response.

The effect of Xuezhikang capsule on gene expression profile in brown adipose tissue of obese spontaneously hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Obesity is a critical threat to global health, and brown adipose tissue (BAT) is a potential target for the treatment of obesity and comorbidities. Xuezhikang Capsule (XZK), an extract of red yeast rice, has remarkable clinical efficacy and is widely used for the treatment of hyperlipidemia and coronary heart disease. However, its modulatory effect on BAT remains unknown.

AIM OF THIS STUDY

The aim of this study was to investigate the protective mechanism of XZK in the obese spontaneously hypertensive rat (SHR) model by evaluating the regulatory effect of XZK on the BAT gene profile through transcriptome sequencing.

MATERIALS AND METHODS

The SHRs were randomly divided into four groups: the standard chow diet (STD) group, the STD supplemented with 126 mg/kg of XZK group, the high-fat diet (HFD) group, and the HFD supplemented with 126 mg/kg of XZK group. All SHRs were fed for 18 weeks. The metabolic phenotypes, including body weight, fat mass, oral glucose tolerance test (OGTT), and serum glucose and lipid levels, was evaluated, and hematoxylin and eosin staining (H&E) staining was performed to evaluate the adipose tissue histopathological phenotype. Transcriptome sequencing was performed to determine the mechanism by which XZK improves the metabolic phenotype and the expression of key differential expression genes was verified by real-time quantitative polymerase chain reaction (qRT-PCR).

RESULTS

XZK inhibited HFD-induced weight gain and adipose tissue remodeling in SHRs and prevented hypertrophy of epididymal adipocytes and maintained the brown fat phenotype. XZK intervention also improved glucose and lipid metabolism in SHRs, as suggested by a reduction in serum triglyceride (TG), low-density cholesterol (LDL-C), and fasting blood glucose (FBG) levels as well as increasing in serum high-density cholesterol (HDL-C) levels. Transcriptome sequencing analysis confirmed the regulatory effect of XZK on the gene expression profile of BAT, and the expression patterns of 45 genes were reversed by the XZK intervention. Additionally, the results of the transcriptome analysis of 10 genes that are important for brown fat function were in line with the results of qRT-PCR.

CONCLUSIONS

XZK protected SHRs from HFD-induced obesity, inhibited fat accumulation and improved glucolipid metabolism. Additionally, the protective effect of XZK on the overall metabolism of obese SHRs might partly be related to its regulatory effect on the BAT gene expression profile. These findings might provide novel therapeutic strategies for obesity-related metabolic diseases in traditional Chinese medicine (TCM).

Male Sex Hormones, Metabolic Syndrome, and Aquaporins: A Triad of Players in Male (in)Fertility

Infertility is becoming a chronic and emerging problem in the world. There is a resistant stigma that this health condition is mostly due to the female, although the literature supports that the responsibility for the onset of infertility is equally shared between both sexes in more or less equal proportions. Nevertheless, male sex hormones, particularly testosterone (T), are key players in male-related infertility. Indeed, hypogonadism, which is also characterized by changes in T levels, is one of the most common causes of male infertility and its incidence has been interconnected to the increased prevalence of metabolic diseases. Recent data also highlight the role of aquaporin (AQP)-mediated water and solute diffusion and the metabolic homeostasis in testicular cells suggesting a strong correlation between AQPs function, metabolism of testicular cells, and infertility. Indeed, recent studies showed that both metabolic and sexual hormone concentrations can change the expression pattern and function of AQPs. Herein, we review up-to-date information on the involvement of AQP-mediated function and permeability in men with metabolic syndrome and testosterone deficit, highlighting the putative mechanisms that show an interaction between sex hormones, AQPs, and metabolic syndrome that may contribute to male infertility.

High androgen concentrations in follicular fluid of polycystic ovary syndrome women

BACKGROUND

According to current definitions of Polycystic Ovary Syndrome (PCOS), hyperandrogenism is considered as a key element in the pathogenesis of this common endocrinopathy. However, until now, studies about ovarian androgen profile in women are very rare. Our aim was then to characterise the expression profile of the androgens in follicular fluid of 30 PCOS patients, and compare it to those of 47 Control women and 29 women with only polycystic ovary morphology on ultrasounds (ECHO group).

METHODS

A retrospective, single-centre cohort study was performed. The intrafollicular concentrations of the key androgens were assessed and correlated with the intrafollicular levels of some adipokines of interest. Androgens were quantified by mass spectrophotometry combined with ultra-high-performance liquid chromatography, while adipokine concentrations were measured by ELISA assays.

RESULTS

In PCOS patients, the intrafollicular concentrations of the androgens synthesised by ovarian theca cells, i.e., 17OH-pregnenolone, dehydroepiandrosterone, Δ4-androstenedione and testosterone, were significantly higher than those of the androgens of adrenal origin, and positively correlated with the main PCOS clinical and biological features, as well as with the adipokines mostly expressed in the follicular fluid of PCOS patients, i.e. resistin, omentin, chemerin and apelin. Conversely, Control women showed the highest levels of 17OH-progesterone, deoxycorticosterone and 11-deoxycortisol. Confirming these results, apelin levels were negatively associated with pregnenolone and deoxycorticosterone concentrations, while visfatin levels, which were higher in the Control group, negatively correlated with the Δ4-androstenedione and testosterone ones.

CONCLUSIONS

PCOS is characterised by a selective increase in the intrafollicular levels of the androgens synthesised by theca cells, strengthening the hypothesis that ovarian hyperandrogenism plays a central role in its pathogenesis. Further, the significant correlation between the intrafollicular concentrations of the androgens and most of the adipokines of interest, including apelin, chemerin, resistin and omentin, confirms the existence of a close relationship between these two hormonal systems, which appear deeply involved in ovarian physiology and PCOS physiopathology.

Sus_circPAPPA2 Regulates Fat Deposition in Castrated Pigs through the miR-2366/GK Pathway

CircRNAs play an important role in fat deposition, and testosterone-deficient boars exhibit significantly increased fat deposition; however, the mechanism by which testosterone regulates fat deposition through circRNAs remains unclear. In this study, circRNA-seq of backfat and abdominal fat from castrated and intact full-sib Yorkshire pigs was performed. The GO and KEGG enrichment analyses revealed that the host genes of the dorsal DE circRNAs were mainly involved in fatty acid transport, while in abdominal tissues, these genes were mainly involved in adipogenesis and inflammation. The interaction among sus_circPAPPA2, ssc-miR-2366 and GK was verified by dual fluorescence experiments and in porcine preadipocytes. The overexpression of sus_circPAPPA2 significantly inhibited the differentiation of preadipocytes. The expression of sus_circPAPPA2 was increased after adding 100 nM of testosterone, and preadipocyte differentiation was significantly inhibited. Testosterone can affect preadipocyte differentiation by upregulating the expression of sus_circPAPPA2, sponging miR-2366 and regulating the expression of genes, such as GK. These results indicate that testosterone can regulate the expression of adipocyte differentiation- and lipid metabolism-related genes by regulating the expression of circRNA, and ceRNA networks are different in the testosterone regulation of adipose deposition in different parts. This study provides basic data enhancing the understanding of the interaction between the hormone environment and mir-2366/GK to regulate trait performance in pigs.

Maternal high-fat diet programs white and brown adipose tissue lipidome and transcriptome in offspring in a sex- and tissue-dependent manner in mice

OBJECTIVE

The prevalence of overweight and obesity among children has drastically increased during the last decades and maternal obesity has been demonstrated as one of the ultimate factors. Nutrition-stimulated transgenerational regulation of key metabolic genes is fundamental to the developmental origins of the metabolic syndrome. Fetal nutrition may differently influence female and male offspring.

METHODS

Mice dam were fed either a control diet or a high-fat diet (HFD) for 6-week prior mating and continued their respective diet during gestation and lactation. At weaning, female and male offspring were fed the HFD until sacrifice. White (WAT) and brown (BAT) adipose tissues were investigated in vivo by nuclear magnetic resonance at two different timepoints in life (midterm and endterm) and tissues were collected at endterm for lipidomic analysis and RNA sequencing. We explored the sex-dependent metabolic adaptation and gene programming changes by maternal HFD in visceral AT (VAT), subcutaneous AT (SAT) and BAT of offspring.

RESULTS

We show that the triglyceride profile varies between adipose depots, sexes and maternal diet. In female offspring, maternal HFD remodels the triglycerides profile in SAT and BAT, and increases thermogenesis and cell differentiation in BAT, which may prevent metabolic complication later in life. Male offspring exhibit whitening of BAT and hyperplasia in VAT when born from high-fat mothers, with impaired metabolic profile. Maternal HFD differentially programs gene expression in WAT and BAT of female and male offspring.

CONCLUSION

Maternal HFD modulates metabolic profile in offspring in a sex-dependent manner. A sex- and maternal diet-dependent gene programming exists in VAT, SAT, and BAT which may be key player in the sexual dimorphism in the metabolic adaptation later in life.

Age and Sex: Impact on adipose tissue metabolism and inflammation

Age associated chronic inflammation is a major contributor to diseases with advancing age. Adipose tissue function is at the nexus of processes contributing to age-related metabolic disease and mediating longevity. Hormonal fluctuations in aging potentially regulate age-associated visceral adiposity and metabolic dysfunction. Visceral adiposity in aging is linked to aberrant adipogenesis, insulin resistance, lipotoxicity and altered adipokine secretion. Age-related inflammatory phenomena depict sex differences in macrophage polarization, changes in T and B cell numbers, and types of dendritic cells. Sex differences are also observed in adipose tissue remodeling and cellular senescence suggesting a role for sex steroid hormones in the regulation of the adipose tissue microenvironment. It is crucial to investigate sex differences in aging clinical outcomes to identify and better understand physiology in at-risk individuals. Early interventions aimed at targets involved in adipose tissue adipogenesis, remodeling and inflammation in aging could facilitate a profound impact on health span and overcome age-related functional decline.

Retinol-Binding Protein-4-A Predictor of Insulin Resistance and the Severity of Coronary Artery Disease in Type 2 Diabetes Patients with Coronary Artery Disease

(1) Background: Insulin resistance (IR) is the fundamental cause of type 2 diabetes (T2D), which leads to endothelial dysfunction and alters systemic lipid metabolism. The changes in the endothelium and lipid metabolism result in atherosclerotic coronary artery disease (CAD). In insulin-resistant and atherosclerotic CAD states, serum cytokine retinol-binding protein-4 (RBP-4) levels are elevated. The adipocyte-specific deletion of glucose transporter 4 (GLUT4) results in higher RBP-4 expression and IR and atherosclerotic CAD progression. (2) Aim: This study aimed to investigate the association of RBP-4 and clinical factors with IR and the severity of CAD. (3) Methods: Patients were recruited from diabetes and cardiology clinics and divided into three subgroups, namely (i) T2D patients with CAD, (ii) T2D-only patients, and (iii) CAD-only patients. The severity of CAD was classified as either single-vessel disease (SVD), double-vessel disease (DVD), or triple-vessel disease (TVD). An enzyme-linked immunosorbent assay was conducted to assess the concentration of serum RBP-4. Univariate (preliminary analysis) and multivariate (secondary analysis) logistic regressions were applied to assess the associations of RBP-4 and clinical factors with IR and the severity of CAD. (4) Results: Serum RBP-4 levels were associated with IR and the severity of CAD in all the three groups (all p-values are less than 0.05). Specifically, serum RBP-4 levels were associated with IR (p = 0.030) and the severity of CAD (SVD vs. DVD, p = 0.044; SVD vs. TVD, p = 0.036) in T2D patients with CAD. The clinical factors fasting plasma glucose (FPG) and angiotensin-converting-enzyme inhibitor (ACEI) were also associated with both IR and the severity of CAD in T2D patients with CAD. (5) Conclusion: RBP-4, FPG, and ACEI are predictors of IR and severity of CAD in T2D patients with CAD.

Standardized Saw Palmetto Extract Directly and Indirectly Affects Testosterone Biosynthesis and Spermatogenesis

We investigated whether a standardized saw palmetto extract (SP, mixture of supercritical extract and ethanol extract at a ratio of 9.5 to 0.5) can relieve the symptoms of andropause, including metabolic syndrome, and decreases in muscle endurance and spermatogenesis, in old rats. Twenty-four-week-old male Sprague Dawley rats received oral supplementation of SP at 40, 80, and 160 mg/kg body weight (bw) for 4 weeks. We found that SP supplementation reduced body weight gain by decreasing visceral and epididymal fat weights and the levels of serum triglycerides, total cholesterol, and low-density lipoprotein/very low-density lipoprotein cholesterol. In addition, SP supplementation increased muscle endurance, sperm counts, and testosterone biosynthesis through hormonal regulation. In Leydig cells under hydrogen peroxide-induced oxidative stress, SP treatment directly induced testosterone biosynthesis by activating the mRNA expression of the genes encoding 17,20-desmolase and 3β-hydroxysteroid dehydrogenase 4. In conclusion, our results suggest that supplementation of SP may be useful for alleviating the symptoms of andropause via direct and indirect regulation of testosterone biosynthesis.

Exercise Training Promotes Sex-Specific Adaptations in Mouse Inguinal White Adipose Tissue

Recent studies demonstrate that adaptations to white adipose tissue (WAT) are important components of the beneficial effects of exercise training on metabolic health. Exercise training favorably alters the phenotype of subcutaneous inguinal WAT (iWAT) in male mice, including decreasing fat mass, improving mitochondrial function, inducing beiging, and stimulating the secretion of adipokines. In this study, we find that despite performing more voluntary wheel running compared with males, these adaptations do not occur in the iWAT of female mice. Consistent with sex-specific adaptations, we report that mRNA expression of androgen receptor coactivators is upregulated in iWAT from trained male mice and that testosterone treatment of primary adipocytes derived from the iWAT of male, but not female mice, phenocopies exercise-induced metabolic adaptations. Sex specificity also occurs in the secretome profile, as we identify cysteine-rich secretory protein 1 (Crisp1) as a novel adipokine that is only secreted from male iWAT in response to exercise. Crisp1 expression is upregulated by testosterone and functions to increase glucose and fatty acid uptake. Our finding that adaptations to iWAT with exercise training are dramatically greater in male mice has potential clinical implications for understanding the different metabolic response to exercise training in males and females and demonstrates the importance of investigating both sexes in studies of adipose tissue biology.

Mitochondria in Sex Hormone-Induced Disorder of Energy Metabolism in Males and Females

Androgens have a complex role in the regulation of insulin sensitivity in the pathogenesis of type 2 diabetes. In male subjects, a reduction in androgens increases the risk for insulin resistance, which is improved by androgen injections. However, in female subjects with polycystic ovary syndrome (PCOS), androgen excess becomes a risk factor for insulin resistance. The exact mechanism underlying the complex activities of androgens remains unknown. In this review, a hormone synergy-based view is proposed for understanding this complexity. Mitochondrial overactivation by substrate influx is a mechanism of insulin resistance in obesity. This concept may apply to the androgen-induced insulin resistance in PCOS. Androgens and estrogens both exhibit activities in the induction of mitochondrial oxidative phosphorylation. The two hormones may synergize in mitochondria to induce overproduction of ATP. ATP surplus in the pancreatic β-cells and α-cells causes excess secretion of insulin and glucagon, respectively, leading to peripheral insulin resistance in the early phase of type 2 diabetes. In the skeletal muscle and liver, the ATP surplus contributes to insulin resistance through suppression of AMPK and activation of mTOR. Consistent ATP surplus leads to mitochondrial dysfunction as a consequence of mitophagy inhibition, which provides a potential mechanism for mitochondrial dysfunction in β-cells and brown adipocytes in PCOS. The hormone synergy-based view provides a basis for the overactivation and dysfunction of mitochondria in PCOS-associated type 2 diabetes. The molecular mechanism for the synergy is discussed in this review with a focus on transcriptional regulation. This view suggests a unifying mechanism for the distinct metabolic roles of androgens in the control of insulin action in men with hypogonadism and women with PCOS.

Lack of AR in LepRb Cells Disrupts Ambulatory Activity and Neuroendocrine Axes in a Sex-Specific Manner in Mice

Disorders of androgen imbalance, such as hyperandrogenism in females or hypoandrogenism in males, increase risk of visceral adiposity, type 2 diabetes, and infertility. Androgens act upon androgen receptors (AR) which are expressed in many tissues. In the brain, AR are abundant in hypothalamic nuclei involved in regulation of reproduction and energy homeostasis, yet the role of androgens acting via AR in specific neuronal populations has not been fully elucidated. Leptin receptor (LepRb)-expressing neurons coexpress AR predominantly in hypothalamic arcuate and ventral premammillary nuclei (ARH and PMv, respectively), with low colocalization in other LepRb neuronal populations, and very low colocalization in the pituitary gland and gonads. Deletion of AR from LepRb-expressing cells (LepRbΔAR) has no effect on body weight, energy expenditure, and glucose homeostasis in male and female mice. However, LepRbΔAR female mice show increased body length later in life, whereas male LepRbΔAR mice show an increase in spontaneous ambulatory activity. LepRbΔAR mice display typical pubertal timing, estrous cycles, and fertility, but increased testosterone levels in males. Removal of sex steroid negative feedback action induced an exaggerated rise in luteinizing hormone in LepRbΔAR males and follicle-stimulating hormone in LepRbΔAR females. Our findings show that AR can directly affect a subset of ARH and PMv neurons in a sex-specific manner and demonstrate specific androgenic actions in the neuroendocrine hypothalamus.

Androgen Action in Adipose Tissue and the Brain are Key Mediators in the Development of PCOS Traits in a Mouse Model

Polycystic ovary syndrome (PCOS) is a complex disorder characterized by endocrine, reproductive, and metabolic abnormalities. Despite PCOS being the most common endocrinopathy affecting women of reproductive age, the etiology of PCOS is poorly understood, so there is no cure and symptomatic treatment is suboptimal. Hyperandrogenism is the most consistent feature observed in PCOS patients, and recently aberrant neuroendocrine signaling and adipose tissue function have been proposed as playing a role in the development of PCOS. To investigate the role of adipose tissue and the brain as key sites for androgen receptor (AR)-mediated development of PCOS, we combined a white and brown adipose and brain-specific AR knockout (AdBARKO) mouse model with a dihydrotestosterone (DHT)-induced mouse model of PCOS. As expected, in wildtype (WT) control females, DHT exposure induced the reproductive PCOS traits of cycle irregularity, ovulatory dysfunction, and reduced follicle health, whereas in AdBARKO females, DHT did not produce the reproductive features of PCOS. The metabolic PCOS characteristics of increased adiposity, adipocyte hypertrophy, and hepatic steatosis induced by DHT in WT females were not evident in DHT-treated AdBARKO females, which displayed normal white adipose tissue weight and no adipocyte hypertrophy or liver steatosis. Dihydrotestosterone treatment induced increased fasting glucose levels in both WT and AdBARKO females. These findings demonstrate that adipose tissue and the brain are key loci of androgen-mediated actions involved in the developmental origins of PCOS. These data support targeting adipocyte and neuroendocrine AR-driven pathways in the future development of novel therapeutic strategies for PCOS.

Altered circadian clock as a novel therapeutic target for constant darkness-induced insulin resistance and hyperandrogenism of polycystic ovary syndrome

The mechanisms underlying metabolic and reproductive dysfunction caused by arrhythmic circadian clock and their involvement in polycystic ovary syndrome (PCOS) are not understood. Here, we addressed this issue using rats with constant light or darkness exposure for 8 weeks and human leukocytes and serum of PCOS and non-PCOS patients. Additionally, we utilized HepG2 cells and KGN cells to verify the molecular mechanisms. The arrhythmic expressions of circadian clock genes due to constant darkness induced the metabolic and reproductive hallmarks of PCOS in rats. After exposure to constant darkness, decreased brain and muscle ARNT-like protein 1 (BMAL1) promoted insulin resistance via glucose transporter 4 (GLUT4), and decreased period (PER) 1 and PER2 promoted androgen excess via insulin-like growth factor-binding protein 4 (IGFBP4) and sex hormone binding globulin (SHBG) in the liver. Hyperinsulinemia and hyperandrogenism shared a bidirectional link promoting aberrant expression of circadian genes and inducing apoptosis of ovarian granulosa cells. Notably, the altered expressions of circadian clock genes in darkness-treated rats matched those of PCOS patients. Furthermore, melatonin treatment relieved the hyperinsulinemia and hyperandrogenism of darkness-treated rats via BMAL1, PER1, and PER2. Restoring normal light/dark exposure for 2 weeks reversed these conditions via BMAL1. In conclusion, our findings elucidated the critical function of circadian clock genes, especially BMAL1, PER1, and PER2 in PCOS, which might aid the development of feasible preventive and therapeutic strategies for PCOS in women with biorhythm disorder.

Circulating Adipokine Levels in Nonobese Women With Polycystic Ovary Syndrome and in Nonobese Control Women: A Systematic Review and Meta-Analysis

Levels of circulating adipokines in nonobese polycystic ovary syndrome (PCOS) patients have been reported in many studies. However, the results are inconsistent. The aim of this meta-analysis is to assess whether the levels of circulating adipokines are changed in nonobese PCOS relative to nonobese healthy controls. To identify eligible studies, a literature research was performed in the PubMed, Embase, and Web of Science databases without restricting by region, journal, or language. A total of 81 studies met the eligibility criteria. The meta-analysis showed that the circulating level of adiponectin (standardized mean difference [SMD]: -0.95; 95% CI: -1.36 to -0.53) was significantly decreased in nonobese PCOS patients. In contrast, the circulating levels of chemerin (SMD: 1.13; 95% CI: 0.08 to 2.18), leptin (SMD: 0.47; 95% CI: 0.13 to 0.81), resistin (SMD: 0.45; 95% CI: 0.03 to 0.88), and visfatin (SMD: 1.38; 95% CI: 0.68 to 2.09) were significantly increased in nonobese PCOS patients. There were no significant changes in the circulating levels of apelin (SMD: 0.32; 95% CI: -1.34 to 1.99), irisin (SMD: 1.01; 95% CI: -0.68 to 2.70), omentin (SMD: -0.37; 95% CI: -1.05 to 0.31), or vaspin (SMD: 0.09; 95% CI: -0.14 to 0.32). Thus, scientific evidence suggests that the circulating adipokine levels are altered in nonobese PCOS patients compared to nonobese healthy controls. Therefore, independent of the degree of obesity, dysregulated circulating adipokine levels might play important roles in the occurrence and development of PCOS.

The Role of Diet and Weight Loss in Improving Secondary Hypogonadism in Men with Obesity with or without Type 2 Diabetes Mellitus

Despite growing recognition of the issue, obesity represents one of the most common public health problems, and its rates are still increasing globally. Among the number of comorbidities and complications associated with obesity, hypogonadism is listed, and this disorder, although frequently neglected, is characterized by a relevant impact on both quality of life and life expectancy. It is generally accepted that hypogonadism secondary to obesity is functional since it is reversible following weight loss. This review summarizes all current research examining the bidirectional relationship between excess body weight and low testosterone levels. Specifically, it evaluates the role that diet, with or without physical activity, plays in improving body weight and hypogonadism in adult and elderly men with obesity, with or without type 2 diabetes mellitus.

Obesity and male hypogonadism: Tales of a vicious cycle

Obesity prevalence, particularly in children and young adults, is perilously increasing worldwide foreseeing serious negative health impacts in the future to come. Obesity is linked to impaired male gonadal function and is currently a major cause of hypogonadism. Besides signs and symptoms directly derived from decreased circulating testosterone levels, males with obesity also present poor fertility outcomes, further evidencing the parallelism between obesity and male reproductive function. In addition, males with androgen deficiency also exhibit increased fat accumulation and reduced muscle and mineral bone mass. Thus, compelling evidence highlights a vicious cycle where male hypogonadism can lead to increased adiposity, while obesity can be a cause for male hypogonadism. On the opposite direction, sustained weight loss can attain amelioration of male gonadal function. In this scenario, a thorough evaluation of gonadal function in men with obesity is crucial to dissect the causes from the consequences in order to target clinical interventions towards maximized improvement of reproductive health. This review will address the causes and consequences of the bidirectional relationship between obesity and hypogonadism, highlighting the implicit male reproductive repercussions.

Sex hormones, aging and cardiometabolic syndrome

It is well documented that the metabolic syndrome predisposes patients to increased cardiovascular risk. Emerging data indicates that cardiovascular risk conferred by metabolic syndrome is highly dependent on sex and sex hormone status throughout the lifetime. Both male and female sex hormones, as well as sex chromosomes themselves, contribute to the development of obesity and intervene in the control of insulin homeostasis and blood pressure. Furthermore, men and women develop age-associated cardiometabolic risk in a sex-specific fashion in association with changes in these sex hormonal levels. Therefore, the current notion of the metabolic syndrome as a sex-independent diagnosis is antiquated, and novel studies and clinical trials utilizing these known sex differences in the development of metabolic dysregulation and cardiometabolic risk are warranted.

Androgen receptor deficiency in monocytes/macrophages does not alter adiposity or glucose homeostasis in male mice

Androgen deprivation in men leads to increased adiposity, but the mechanisms underlying androgen regulation of fat mass have not been fully defined. Androgen receptor (AR) is expressed in monocytes/macrophages, which are resident in key metabolic tissues and influence energy metabolism in surrounding cells. Male mice bearing a cell-specific knockout of the AR in monocytes/macrophages (M-ARKO) were generated to determine whether selective loss of androgen signaling in these cells would lead to altered body composition. Wild-type (WT) and M-ARKO mice (12–22 weeks of age, n = 12 per group) were maintained on a regular chow diet for 8 weeks and then switched to a high-fat diet for 8 additional weeks. At baseline and on both the regular chow and high-fat diets, no differences in lean mass or fat mass were observed between groups. Consistent with the absence of differential body weight or adiposity, no differences in food intake (3.0 ± 0.5 g per day for WT mice vs 2.8 ± 0.4 g per day for M-ARKO mice) or total energy expenditure (0.6 ± 0.1 Kcal h⁻¹ for WT mice vs 0.5 ± 0.1 Kcal h⁻¹ for M-ARKO mice) were evident between groups during high-fat feeding. Liver weight was greater in M-ARKO than that in WT mice (1.5 ± 0.1 g vs 1.3 ± 0.0 g, respectively, P = 0.02). Finally, M-ARKO mice did not exhibit impairments in glucose tolerance or insulin sensitivity relative to WT mice at any study time point. In aggregate, these findings suggest that AR signaling specifically in monocytes/macrophages does not contribute to the regulation of systemic energy balance, adiposity, or insulin sensitivity in male mice.

Randomized controlled trials - mechanistic studies of testosterone and the cardiovascular system

Testosterone deficiency is common in men with cardiovascular disease (CVD), and randomized placebo-controlled trials (RCTs) have reported beneficial effects of testosterone therapy on exercise-induced cardiac ischemia in chronic stable angina, functional exercise capacity, maximum oxygen consumption during exercise (VO_2max) and muscle strength in chronic heart failure (CHF), shortening of the Q-T interval, and improvement of some cardiovascular risk factors. Testosterone deficiency is associated with an adverse CV risk profile and mortality. Clinical and scientific studies have provided mechanistic evidence to support and explain the findings of the RCTs. Testosterone is a rapid-onset arterial vasodilator within the coronary circulation and other vascular beds including the pulmonary vasculature and can reduce the overall peripheral systemic vascular resistance. Evidence has demonstrated that testosterone mediates this effect on vascular reactivity through calcium channel blockade (L-calcium channel) and stimulates potassium channel opening by direct nongenomic mechanisms. Testosterone also stimulates repolarization of cardiac myocytes by stimulating the ultra-rapid potassium channel-operated current. Testosterone improves cardiac output, functional exercise capacity, VO_2max and vagally mediated arterial baroreceptor cardiac reflex sensitivity in CHF, and other mechanisms. Independent of the benefit of testosterone on cardiac function, testosterone substitution may also increase skeletal muscle glucose metabolism and enhance muscular strength, both factors that could contribute to the improvement in functional exercise capacity may include improved glucose metabolism and muscle strength. Testosterone improves metabolic CV risk factors including body composition, insulin resistance, and hypercholesterolemia by improving both glucose utilization and lipid metabolism by a combination of genomic and nongenomic actions of glucose uptake and utilization expression of the insulin receptor, glucose transporters, and expression on regulatory enzymes of key metabolic pathways. The effect on high-density lipoprotein-cholesterol (HDL-C) differs between studies in that it has been found to fall, rise, or have no change in levels. Testosterone replacement can suppress the levels of circulating pro-inflammatory cytokines and stimulate the production of interleukin-10 (IL-10) which has anti-inflammatory and anti-atherogenic actions in men with CVD. No effect on C-reactive protein has been detected. No adverse effects on clotting factors have been detected. RCTs have not clearly demonstrated any significant evidence that testosterone improves or adversely affects the surrogate markers of atherosclerosis such as reduction in carotid intima thickness or coronary calcium deposition. Any effect of testosterone on prevention or amelioration of atherosclerosis is likely to occur over years as shown in statin therapy trials and not months as used in testosterone RCTs. The weight of evidence from long-term epidemiological studies supports a protective effect as evidenced by a reduction in major adverse CV events (MACEs) and mortality in studies which have treated men with testosterone deficiency. No RCT where testosterone has been replaced to the normal healthy range has reported a significant benefit or adverse effect on MACE nor has any recent meta-analysis.

Association between Green Tea Consumption and Risk of Stroke in Middle-Aged and Older Korean Men: The Health Examinees (HEXA) Study

Green tea consumption is known to have varying effects on health and disease. The aim of this study was to investigate the association between green tea consumption and risk of stroke in Korean adult men. Data were obtained from the Health Examinees (HEXA) Study, which included 50,439 subjects aged 40 years and older. Information regarding dietary intake was collected from semi-quantified food frequency questionnaires consisting of 106 items. Green tea consumption was categorized as none, <1 cup/d, 1 to <3 cups/d, and ≥3 cups/d. Binary logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) to examine a possible association between green tea consumption and risk of stroke by controlling for potential confounders. Subgroup analyses by age, body mass index, hypertension, diabetes mellitus, smoking status, and alcohol consumption were also performed. Compared with green tea non-drinkers, individuals that consumed 1 to <3 cups/d or ≥3 cups/d of green tea had multivariable adjusted OR (CI) of stroke of 0.75 (0.59~0.97) and 0.62 (0.39~0.98), respectively, after adjusting for age and various confounders. In the subgroup analyses, an inverse association between green tea consumption and risk of stroke was identified among younger, non-hypertensive, and non-diabetic men. Higher consumption of green tea was inversely associated with stroke risk in middle-aged and older Korean men.

Reproductive Endocrinology of Nonalcoholic Fatty Liver Disease

The liver and the reproductive system interact in a multifaceted bidirectional fashion. Sex steroid signaling influences hepatic endobiotic and xenobiotic metabolism and contributes to the pathogenesis of functional and structural disorders of the liver. In turn, liver function affects the reproductive axis via modulating sex steroid metabolism and transport to tissues via sex hormone-binding globulin (SHBG). The liver senses the body's metabolic status and adapts its energy homeostasis in a sex-dependent fashion, a dimorphism signaled by the sex steroid milieu and possibly related to the metabolic costs of reproduction. Sex steroids impact the pathogenesis of nonalcoholic fatty liver disease, including development of hepatic steatosis, fibrosis, and carcinogenesis. Preclinical studies in male rodents demonstrate that androgens protect against hepatic steatosis and insulin resistance both via androgen receptor signaling and, following aromatization to estradiol, estrogen receptor signaling, through regulating genes involved in hepatic lipogenesis and glucose metabolism. In female rodents in contrast to males, androgens promote hepatic steatosis and dysglycemia, whereas estradiol is similarly protective against liver disease. In men, hepatic steatosis is associated with modest reductions in circulating testosterone, in part consequent to a reduction in circulating SHBG. Testosterone treatment has not been demonstrated to improve hepatic steatosis in randomized controlled clinical trials. Consistent with sex-dimorphic preclinical findings, androgens promote hepatic steatosis and dysglycemia in women, whereas endogenous estradiol appears protective in both men and women. In both sexes, androgens promote hepatic fibrosis and the development of hepatocellular carcinoma, whereas estradiol is protective.

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.

Metabolic Effects of Testosterone Hormone Therapy in Normal and Orchiectomized Male Rats: From Indirect Calorimetry to Lipolytic Enzymes

BACKGROUND AND AIM

Changes in total energy expenditure (TEE) and substrate metabolism may help explain the metabolic actions of testosterone (T). This study measured respiratory quotient (RQ), TEE, ghrelin, insulin, and key lipolysis enzyme concentrations in relation to body weight (wt) and food intake (FI) in both normal and bilaterally orchiectomized rats with/without T treatment.

METHODS

In total, thirty-two male Wistar rats (300-400 g) were divided into four groups (n = 8/group), including (a) sham-operated and vehicle-injected group (Sham), (b) T-treated sham group (T-Sham) for which sham-operated rats were injected with IM testosterone undecanoate (100 mg/kg, for one week), (c) orchiectomy and vehicle-injected group (Orch), and (d) T-replaced orchiectomy group (T-Orch). After one week, FI and wt were automatically recorded, indirect calorimetry parameters were measured, and blood samples were collected to measure T, ghrelin, insulin, growth hormone (GH), glucose, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), free fatty acids (FFA), and lipid profiles.

RESULTS

Orchiectomy decreased ghrelin, GH, and insulin levels, increased TEE and RQ, and lowered FI and wt. The T-Orch group exhibited increased levels of ghrelin (3-fold), insulin, GH, blood levels of lipolysis products, TEE, and FI in addition to reduced glucose levels (P < 0.05). This group demonstrated no significant changes in wt. In the T-Sham group, T increased ghrelin and insulin levels (P < 0.05) with strong positive correlations (r = 0.663 and 0.644, respectively, P < 0.05), increased ATGL levels, RQ toward carbohydrate utilization ranges, and TEE, and reduced HSL levels (P < 0.05) with insignificant changes in FI or wt.

CONCLUSIONS

T administration in orchiectomized rats significantly increased orexigenic mediators such as ghrelin and insulin without inducing any significant changes in wt. The mechanism for this finding might be the increased TEE and the stimulation of lipolysis through the ATGL enzyme. The associated rise of GH might help in interference with accumulation of lipid in adipose tissue. Apart from the effect on GH, T-Sham showed similar effects of T supplementation.

Prevalence of metabolic syndrome and non-alcoholic fatty liver disease in a cohort of italian patients with spinal-bulbar muscular atrophy

Spinal-bulbar muscular atrophy (SBMA), is an X-linked motor neuron disease caused by a CAG-repeat expansion in the first exon of the androgen receptor gene (AR) on chromosome X. In SBMA, non-neural clinical phenotype includes disorders of glucose and lipid metabolism. We investigated the prevalence of metabolic syndrome (MS), insulin resistance (IR) and non alcoholic fatty liver disease (NAFLD) in a group of SBMA patients. Forty-seven consecutive patients genetically diagnosed with SBMA underwent biochemical analyses. In 24 patients abdominal sonography examination was performed. Twenty-three (49%) patients had fasting glucose above reference values and 31 (66%) patients had a homeostatic model assessment (HOMA-IR) ≥ 2.6. High levels of total cholesterol were found in 24 (51%) patients, of LDL-cholesterol in 18 (38%) and of triglycerides in 18 (38%). HDL-cholesterol was decreased in 36 (77%) patients. Twenty-four (55%) subjects had 3 or more criteria of MS. A positive correlation (r = 0.52; p < 0.01) was observed between HOMA-IR and AR-CAG repeat length. AST and ALT were above the reference values respectively in 29 (62%) and 18 (38%) patients. At ultrasound examination increased liver echogenicity was found in 22 patients (92 %). In one patient liver cirrhosis was diagnosed. Liver/kidney ratio of grey-scale intensity, a semi-quantitative parameter of severity of steatosis, strongly correlated with BMI (r = 0.68; p < 0.005). Our study shows a high prevalence of IR, MS and NAFLD in SBMA patients, conditions that increase the cardiovascular risk and can lead to serious liver damage, warranting pharmacological and non-pharmacological treatment.

Olive Oil Nutraceuticals in the Prevention and Management of Diabetes: From Molecules to Lifestyle

Lifestyle is the primary prevention of diabetes, especially type-2 diabetes (T2D). Nutritional intake of olive oil (OO), the key Mediterranean diet component has been associated with the prevention and management of many chronic diseases including T2D. Several OO bioactive compounds such as monounsaturated fatty acids, and key biophenols including hydroxytyrosol and oleuropein, have been associated with preventing inflammation and cytokine-induced oxidative damage, glucose lowering, reducing carbohydrate absorption, and increasing insulin sensitivity and related gene expression. However, research into the interaction of OO nutraceuticals with lifestyle components, especially physical activity, is lacking. Promising postprandial effects have been reported when OO or other similar monounsaturated fatty acids were the main dietary fat compared with other diets. Animal studies have shown a potential anabolic effect of oleuropein. Such effects could be further potentiated via exercise, especially strength training, which is an essential exercise prescription for individuals with T2D. There is also an evidence from in vitro, animal, and limited human studies for a dual preventative role of OO biophenols in diabetes and cancer, especially that they share similar risk factors. Putative antioxidative and anti-inflammatory mechanisms and associated gene expressions resulting from OO biophenols have produced paradoxical results, making suggested inferences from dual prevention T2D and cancer outcomes difficult. Well-designed human interventions and clinical trials are needed to decipher such a potential dual anticancer and antidiabetic effects of OO nutraceuticals. Exercise combined with OO consumption, individually or as part of a healthy diet is likely to induce reciprocal action for T2D prevention outcomes.

Androgen and estrogen actions on male physical activity: a story beyond muscle

Physical inactivity is a pandemic that contributes to several chronic diseases and poses a significant burden on health care systems worldwide. The search for effective strategies to combat sedentary behavior has led to an intensification of the research efforts to unravel the biological substrate controlling activity. A wide body of preclinical evidence makes a strong case for sex steroids regulating physical activity in both genders, albeit the mechanisms implicated remain unclear. The beneficial effects of androgens on muscle as well as on other peripheral functions might play a role in favoring adaptation to exercise. Alternatively or in addition, sex steroids could act on specific brain circuitries to boost physical activity. This review critically discusses the evidence supporting a role for androgens and estrogens stimulating male physical activity, with special emphasis on the possible role of peripheral and/or central mechanisms. Finally, the potential translation of these findings to humans is briefly discussed.

Role of androgens in energy metabolism affecting on body composition, metabolic syndrome, type 2 diabetes, cardiovascular disease, and longevity: lessons from a meta-analysis and rodent studies

Testosterone is a sex hormone produced by testicular Leydig cells in males. Blood testosterone concentrations increase at three time-periods in male life-fetal, neonatal (which can be separated into newborn and infant periods), and pubertal stages. After peaking in the early 20s, the blood bioactive testosterone level declines by 1-2% each year. It is increasingly apparent that a low testosterone level impairs general physical and mental health in men. Here, this review summarizes recent systematic reviews and meta-analyses of epidemiological studies in males (including cross-sectional, longitudinal, and androgen deprivation studies, and randomized controlled testosterone replacement trials) in relation to testosterone and obesity,  body composition, metabolic syndrome, type 2 diabetes, cardiovascular disease, and longevity. Furthermore, underlying mechanisms are discussed using data from rodent studies involving castration or androgen receptor knockout. This review provides an update understanding of the role of testosterone in energy metabolism. Abbreviations AR: androgen receptor; CV: cardiovascular; FDA: US Food and Drug Administration; HFD: high-fat diet; KO: knockout; MetS: metabolic syndrome; RCT: randomized controlled trial; SHBG: sex hormone binding globulin; SRMA: systematic review and meta-analysis; TRT: testosterone replacement therapy; T2DM:type 2 diabetes mellitus.

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.

Genetic variants in sex hormone pathways and the risk of type 2 diabetes among African American, Hispanic American, and European American postmenopausal women in the US

BACKGROUND

Sex hormones are implicated in the development of diabetes. However, whether genetic variations in sex hormone pathways (SHPs) contribute to the risk of type 2 diabetes mellitus (T2DM) remains to be determined. This study investigated associations between genetic variations in all candidate genes in SHPs and T2DM risk among a cohort of women participating in the Women's Health Initiative (WHI).

METHODS

Single nucleotide polymorphisms (SNPs) located within 30 kb upstream and downstream of SHP genes were comprehensively examined in 8180 African American, 3498 Hispanic American, and 3147 European American women in the WHI. In addition, whether significant SNPs would be replicated in independent populations was examined.

RESULTS

After adjusting for age, region, and ancestry estimates and correcting for multiple testing, seven SNPs were significantly associated with the risk of T2DM among Hispanic American women were identified in the progesterone receptor (PGR) gene, with rs948516 showing the greatest significance (odds ratio 0.67; 95% confidence interval 0.57-0.78; P = 8.8 × 10^-7 ; false discovery rate, Q = 7.8 × 10^-4 ). These findings were not replicated in other ethnic groups in the WHI or in sex-combined analyses in replication studies.

CONCLUSION

Significant signals were identified implicating the PGR gene in T2DM development in Hispanic American women in the WHI, which are consistent with genome-wide association studies findings linking PGR to glucose homeostasis. Nevertheless, the PGR SNPs-T2DM association was not statistically significant in other ethnic populations. Further studies, especially sex-specific analyses, are needed to confirm the findings and clarify the role of SHPs in T2DM.

Low-protein diet in puberty impairs testosterone output and energy metabolism in male rats

We examined the long-term effects of protein restriction during puberty on the function of hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes in male rats. Male Wistar rats from the age of 30 to 60 days were fed a low-protein diet (4%, LP). A normal-protein diet (20.5%) was reintroduced to rats from the age of 60 to 120 days. Control rats were fed a normal-protein diet throughout life (NP). Rats of 60 or 120 days old were killed. Food consumption, body weight, visceral fat deposits, lipid profile, glycemia, insulinemia, corticosteronemia, adrenocorticotropic hormone (ACTH), testosteronemia and leptinemia were evaluated. Glucose-insulin homeostasis, pancreatic-islet insulinotropic response, testosterone production and hypothalamic protein expression of the androgen receptor (AR), glucocorticoid receptor (GR) and leptin signaling pathway were also determined. LP rats were hypophagic, leaner, hypoglycemic, hypoinsulinemic and hypoleptinemic at the age of 60 days (P < 0.05). These rats exhibited hyperactivity of the HPA axis, hypoactivity of the HPG axis and a weak insulinotropic response (P < 0.01). LP rats at the age of 120 days were hyperphagic and exhibited higher visceral fat accumulation, hyperleptinemia and dyslipidemia; lower blood ACTH, testosterone and testosterone release; and reduced hypothalamic expression of AR, GR and SOCS3, with a higher pSTAT3/STAT3 ratio (P < 0.05). Glucose-insulin homeostasis was disrupted and associated with hyperglycemia, hyperinsulinemia and increased insulinotropic response of the pancreatic islets. The cholinergic and glucose pancreatic-islet responses were small in 60-day-old LP rats but increased in 120-day-old LP rats. The hyperactivity of the HPA axis and the suppression of the HPG axis caused by protein restriction at puberty contributed to energy and metabolic disorders as long-term consequences.

The androgen receptor in bone marrow progenitor cells negatively regulates fat mass

It is well established that testosterone negatively regulates fat mass in humans and mice; however, the mechanism by which testosterone exerts these effects is poorly understood. We and others have shown that deletion of the androgen receptor (AR) in male mice results in a phenotype that mimics the three key clinical aspects of hypogonadism in human males; increased fat mass and decreased bone and muscle mass. We now show that replacement of the Ar gene specifically in mesenchymal progenitor cells (PCs) residing in the bone marrow of Global-ARKO mice, in the absence of the AR in all other tissues (PC-AR Gene Replacements), completely attenuates their increased fat accumulation. Inguinal subcutaneous white adipose tissue and intra-abdominal retroperitoneal visceral adipose tissue depots in PC-AR Gene Replacement mice were 50-80% lower than wild-type (WT) and 75-90% lower than Global-ARKO controls at 12 weeks of age. The marked decrease in subcutaneous and visceral fat mass in PC-AR Gene Replacements was associated with an increase in the number of small adipocytes and a healthier metabolic profile compared to WT controls, characterised by normal serum leptin and elevated serum adiponectin levels. Euglycaemic/hyperinsulinaemic clamp studies reveal that the PC-AR Gene Replacement mice have improved whole-body insulin sensitivity with higher glucose infusion rates compared to WT mice and increased glucose uptake into subcutaneous and intra-abdominal fat. In conclusion, these data provide the first evidence for an action of androgens via the AR in mesenchymal bone marrow PCs to negatively regulate fat mass and improve metabolic function.

ABCC1 confers tissue-specific sensitivity to cortisol versus corticosterone: A rationale for safer glucocorticoid replacement therapy

The aim of treatment in congenital adrenal hyperplasia is to suppress excess adrenal androgens while achieving physiological glucocorticoid replacement. However, current glucocorticoid replacement regimes are inadequate because doses sufficient to suppress excess androgens almost invariably induce adverse metabolic effects. Although both cortisol and corticosterone are glucocorticoids that circulate in human plasma, any physiological role for corticosterone has been neglected. In the brain, the adenosine 5'-triphosphate-binding cassette transporter ABCB1 exports cortisol but not corticosterone. Conversely, ABCC1 exports corticosterone but not cortisol. We show that ABCC1, but not ABCB1, is expressed in human adipose and that ABCC1 inhibition increases intracellular corticosterone, but not cortisol, and induces glucocorticoid-responsive gene transcription in human adipocytes. Both C57Bl/6 mice treated with the ABCC1 inhibitor probenecid and FVB mice with deletion of Abcc1 accumulated more corticosterone than cortisol in adipose after adrenalectomy and corticosteroid infusion. This accumulation was sufficient to increase glucocorticoid-responsive adipose transcript expression. In human adipose tissue, tissue corticosterone concentrations were consistently low, and ABCC1 mRNA was up-regulated in obesity. To test the hypothesis that corticosterone effectively suppresses adrenocorticotropic hormone (ACTH) without the metabolic adverse effects of cortisol, we infused cortisol or corticosterone in patients with Addison's disease. ACTH suppression was similar, but subcutaneous adipose transcripts of glucocorticoid-responsive genes were higher after infusion with cortisol rather than with corticosterone. These data indicate that corticosterone may be a metabolically favorable alternative to cortisol for glucocorticoid replacement therapy when ACTH suppression is desirable, as in congenital adrenal hyperplasia, and justify development of a pharmaceutical preparation.

Nonalcoholic fatty liver disease in spinal and bulbar muscular atrophy

Objective:

To determine the prevalence and features of fatty liver disease in spinal and bulbar muscular atrophy (SBMA).

Methods:

Two groups of participants with SBMA were evaluated. In the first group, 22 participants with SBMA underwent laboratory analysis and liver imaging. In the second group, 14 participants with SBMA were compared to 13 female carriers and 23 controls. Liver biopsies were done in 4 participants with SBMA.

Results:

Evidence of fatty liver disease was detected by magnetic resonance spectroscopy in all participants with SBMA in the first group, with an average dome intrahepatic triacylglycerol of 27% (range 6%–66%, ref ≤5.5%). Liver dome magnetic resonance spectroscopy measurements were significantly increased in participants with SBMA in the second group relative to age- and sex-matched controls, with average disease and male control measurements of 17% and 3%, respectively. Liver biopsies were consistent with simple steatosis in 2 participants and nonalcoholic steatohepatitis in 2 others.

Conclusions:

We observed evidence of nonalcoholic liver disease in nearly all of the participants with SBMA evaluated. These observations expand the phenotypic spectrum of the disease and provide a potential biomarker that can be monitored in future studies.

Circulating sex steroids coregulate adipose tissue immune cell populations in healthy men

Male hypogonadism results in changes in body composition characterized by increases in fat mass. Resident immune cells influence energy metabolism in adipose tissue and could promote increased adiposity through paracrine effects. We hypothesized that manipulation of circulating sex steroid levels in healthy men would alter adipose tissue immune cell populations. Subjects (n = 44 men, 19-55 yr of age) received 4 wk of treatment with the gonadotropin-releasing hormone receptor antagonist acyline with daily administration of 1) placebo gel, 2) 1.25 g testosterone gel (1.62%), 3) 5 g testosterone gel, or 4) 5 g testosterone gel with an aromatase inhibitor. Subcutaneous adipose tissue biopsies were performed at baseline and end-of-treatment, and adipose tissue immune cells, gene expression, and intra-adipose estrogen levels were quantified. Change in serum total testosterone level correlated inversely with change in the number of CD3⁺ (β = -0.36, P = 0.04), CD4⁺ (β = -0.34, P = 0.04), and CD8⁺ (β = -0.33, P = 0.05) T cells within adipose tissue. Change in serum 17β-estradiol level correlated inversely with change in the number of adipose tissue macrophages (ATMs) (β = -0.34, P = 0.05). A negative association also was found between change in serum testosterone and change in CD11c⁺ ATMs (β = -0.41, P = 0.01). Overall, sex steroid deprivation was associated with increases in adipose tissue T cells and ATMs. No associations were found between changes in serum sex steroid levels and changes in adipose tissue gene expression. Circulating sex steroid levels may regulate adipose tissue immune cell populations. These exploratory findings highlight a possible novel mechanism that could contribute to increased metabolic risk in hypogonadal men.

Impact of polyunsaturated and saturated fat overfeeding on the DNA-methylation pattern in human adipose tissue: a randomized controlled trial

Background: Dietary fat composition can affect ectopic lipid accumulation and, thereby, insulin resistance. Diets that are high in saturated fatty acids (SFAs) or polyunsaturated fatty acids (PUFAs) have different metabolic responses.Objective: We investigated whether the epigenome of human adipose tissue is affected differently by dietary fat composition and general overfeeding in a randomized trial.Design: We studied the effects of 7 wk of excessive SFA (n = 17) or PUFA (n = 14) intake (+750 kcal/d) on the DNA methylation of ∼450,000 sites in human subcutaneous adipose tissue. Both diets resulted in similar body weight increases. We also combined the data from the 2 groups to examine the overall effect of overfeeding on the DNA methylation in adipose tissue.Results: The DNA methylation of 4875 Cytosine-phosphate-guanine (CpG) sites was affected differently between the 2 diets. Furthermore, both the SFA and PUFA diets increased the mean degree of DNA methylation in adipose tissue, particularly in promoter regions. However, although the mean methylation was changed in 1797 genes [e.g., alpha-ketoglutarate dependent dioxygenase (FTO), interleukin 6 (IL6), insulin receptor (INSR), neuronal growth regulator 1 (NEGR1), and proopiomelanocortin (POMC)] by PUFAs, only 125 genes [e.g., adiponectin, C1Q and collagen domain containing (ADIPOQ)] were changed by SFA overfeeding. In addition, the SFA diet significantly altered the expression of 28 transcripts [e.g., acyl-CoA oxidase 1 (ACOX1) and FAT atypical cadherin 1 (FAT1)], whereas the PUFA diet did not significantly affect gene expression. When the data from the 2 diet groups were combined, the mean methylation of 1444 genes, including fatty acid binding protein 1 (FABP1), fatty acid binding protein 2 (FABP2), melanocortin 2 receptor (MC2R), MC3R, PPARG coactivator 1 α (PPARGC1A), and tumor necrosis factor (TNF), was changed in adipose tissue by overfeeding. Moreover, the baseline DNA methylation of 12 CpG sites that was annotated to 9 genes [e.g., mitogen-activated protein kinase 7 (MAPK7), melanin concentrating hormone receptor 1 (MCHR1), and splicing factor SWAP homolog (SFRS8)] was associated with the degree of weight increase in response to extra energy intake.Conclusions: SFA overfeeding and PUFA overfeeding induce distinct epigenetic changes in human adipose tissue. In addition, we present data that suggest that baseline DNA methylation can predict weight increase in response to overfeeding in humans. This trial was registered at clinicaltrials.gov as NCT01427140.

Gonadotropin-releasing hormone receptor (Gnrhr) gene knock out: Normal growth and development of sensory, motor and spatial orientation behavior but altered metabolism in neonatal and prepubertal mice

Gonadotropin-releasing hormone (GnRH) is important in the control of reproduction, but its actions in non-reproductive processes are less well known. In this study we examined the effect of disrupting the GnRH receptor in mice to determine if growth, metabolism or behaviors that are not associated with reproduction were affected. To minimize the effects of other hormones such as FSH, LH and sex steroids, the neonatal-prepubertal period of 2 to 28 days of age was selected. The study shows that regardless of sex or phenotype in the Gnrhr gene knockout line, there was no significant difference in the daily development of motor control, sensory detection or spatial orientation among the wildtype, heterozygous or null mice. This included a series of behavioral tests for touch, vision, hearing, spatial orientation, locomotory behavior and muscle strength. Neither the daily body weight nor the final weight on day 28 of the kidney, liver and thymus relative to body weight varied significantly in any group. However by day 28, metabolic changes in the GnRH null females compared with wildtype females showed a significant reduction in inguinal fat pad weight normalized to body weight; this was accompanied by an increase in glucose compared with wildtype females shown by Student-Newman-Keuls Multiple Comparison test and Student's unpaired t tests. Our studies show that the GnRH-GnRHR system is not essential for growth or motor/sensory/orientation behavior during the first month of life prior to puberty onset. The lack of the GnRH-GnRHR axis, however, did affect females resulting in reduced subcutaneous inguinal fat pad weight and increased glucose with possible insulin resistance; the loss of the normal rise of estradiol at postnatal days 15-28 may account for the altered metabolism in the prepubertal female pups.

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.

Estrogens and Androgens in Skeletal Physiology and Pathophysiology

Estrogens and androgens influence the growth and maintenance of the mammalian skeleton and are responsible for its sexual dimorphism. Estrogen deficiency at menopause or loss of both estrogens and androgens in elderly men contribute to the development of osteoporosis, one of the most common and impactful metabolic diseases of old age. In the last 20 years, basic and clinical research advances, genetic insights from humans and rodents, and newer imaging technologies have changed considerably the landscape of our understanding of bone biology as well as the relationship between sex steroids and the physiology and pathophysiology of bone metabolism. Together with the appreciation of the side effects of estrogen-related therapies on breast cancer and cardiovascular diseases, these advances have also drastically altered the treatment of osteoporosis. In this article, we provide a comprehensive review of the molecular and cellular mechanisms of action of estrogens and androgens on bone, their influences on skeletal homeostasis during growth and adulthood, the pathogenetic mechanisms of the adverse effects of their deficiency on the female and male skeleton, as well as the role of natural and synthetic estrogenic or androgenic compounds in the pharmacotherapy of osteoporosis. We highlight latest advances on the crosstalk between hormonal and mechanical signals, the relevance of the antioxidant properties of estrogens and androgens, the difference of their cellular targets in different bone envelopes, the role of estrogen deficiency in male osteoporosis, and the contribution of estrogen or androgen deficiency to the monomorphic effects of aging on skeletal involution.

Estrogens and Androgens in Skeletal Physiology and Pathophysiology

Estrogens and androgens influence the growth and maintenance of the mammalian skeleton and are responsible for its sexual dimorphism. Estrogen deficiency at menopause or loss of both estrogens and androgens in elderly men contribute to the development of osteoporosis, one of the most common and impactful metabolic diseases of old age. In the last 20 years, basic and clinical research advances, genetic insights from humans and rodents, and newer imaging technologies have changed considerably the landscape of our understanding of bone biology as well as the relationship between sex steroids and the physiology and pathophysiology of bone metabolism. Together with the appreciation of the side effects of estrogen-related therapies on breast cancer and cardiovascular diseases, these advances have also drastically altered the treatment of osteoporosis. In this article, we provide a comprehensive review of the molecular and cellular mechanisms of action of estrogens and androgens on bone, their influences on skeletal homeostasis during growth and adulthood, the pathogenetic mechanisms of the adverse effects of their deficiency on the female and male skeleton, as well as the role of natural and synthetic estrogenic or androgenic compounds in the pharmacotherapy of osteoporosis. We highlight latest advances on the crosstalk between hormonal and mechanical signals, the relevance of the antioxidant properties of estrogens and androgens, the difference of their cellular targets in different bone envelopes, the role of estrogen deficiency in male osteoporosis, and the contribution of estrogen or androgen deficiency to the monomorphic effects of aging on skeletal involution.

Testosterone differentially regulates targets of lipid and glucose metabolism in liver, muscle and adipose tissues of the testicular feminised mouse

Testosterone deficiency is commonly associated with obesity, metabolic syndrome, type 2 diabetes and their clinical consequences-hepatic steatosis and atherosclerosis. The testicular feminised mouse (non-functional androgen receptor and low testosterone) develops fatty liver and aortic lipid streaks on a high-fat diet, whereas androgen-replete XY littermate controls do not. Testosterone treatment ameliorates these effects, although the underlying mechanisms remain unknown. We compared the influence of testosterone on the expression of regulatory targets of glucose, cholesterol and lipid metabolism in muscle, liver, abdominal subcutaneous and visceral adipose tissue. Testicular feminised mice displayed significantly reduced GLUT4 in muscle and glycolytic enzymes in muscle, liver and abdominal subcutaneous but not visceral adipose tissue. Lipoprotein lipase required for fatty acid uptake was only reduced in subcutaneous adipose tissue; enzymes of fatty acid synthesis were increased in liver and subcutaneous tissue. Stearoyl-CoA desaturase-1 that catalyses oleic acid synthesis and is associated with insulin resistance was increased in visceral adipose tissue and cholesterol efflux components (ABCA1, apoE) were decreased in subcutaneous and liver tissue. Master regulator nuclear receptors involved in metabolism-Liver X receptor expression was suppressed in all tissues except visceral adipose tissue, whereas PPARγ was lower in abdominal subcutaneous and visceral adipose tissue and PPARα only in abdominal subcutaneous. Testosterone treatment improved the expression (androgen receptor independent) of some targets but not all. These exploratory data suggest that androgen deficiency may reduce the buffering capability for glucose uptake and utilisation in abdominal subcutaneous and muscle and fatty acids in abdominal subcutaneous. This would lead to an overspill and uptake of excess glucose and triglycerides into visceral adipose tissue, liver and arterial walls.

Hypogonadism alters cecal and fecal microbiota in male mice

Low testosterone levels increase the risk for cardiovascular disease in men and lead to shorter life spans. Our recent study showed that androgen deprivation via castration altered fecal microbiota and exacerbated risk factors for cardiovascular disease, including obesity, impaired fasting glucose, excess hepatic triglyceride accumulation, and thigh muscle weight loss only in high-fat diet (HFD)-fed male mice. However, when mice were administered antibiotics that disrupted the gut microbiota, castration did not increase cardiovascular risks or decrease the ratio of dried feces to food intake. Here, we show that changes in cecal microbiota (e.g., an increased Firmicutes/Bacteroidetes ratio and number of Lactobacillus species) were consistent with changes in feces and that there was a decreased cecal content secondary to castration in HFD mice. Castration increased rectal body temperature and plasma adiponectin, irrespective of diet. Changes in the gut microbiome may provide novel insight into hypogonadism-induced cardiovascular diseases.