Effects of sex steroid hormones on regional fat depots as assessed by magnetic resonance imaging in transsexuals

The effects of gender-affirming hormone therapy on myocardial, hepatic, pancreatic lipid content, body fat distribution and other cardiometabolic risk factors: A magnetic resonance-based study in transgender individuals

Purpose

We aimed to assess the changes in body fat distribution, intraorgan lipid accumulation, and cardiometabolic risk factors after 6 months of gender-affirming hormone therapy (GAHT) in transgender men (TM) and transgender women (TW).

Methods

Conducted at the Medical University of Vienna between 2019 and 2022, the study included 15 TW and 20 TM. We conducted magnetic resonance imaging and spectroscopy to determine the visceral (VAT) and subcutaneous adipose tissue (SAT) amounts, the VAT/SAT ratio, and the intraorgan lipid content (liver, pancreas, myocardium), bloodwork, and an oral glucose tolerance test at baseline and after 6 months of GAHT.

Results

Pancreatic, hepatic, and intramyocardial lipid contents did not significantly change in either group after 6 months of GAHT. In TW, VAT/SAT ratio decreased significantly from baseline 0,930 (IQR 0,649-1,287) to 0,758 (IQR 0,424-0,900; p = 0,011) after 6 months of GAHT. The updated homeostatic model assessment for insulin sensitivity (HOMA2-%S) significantly decreased from 83,03 % (±31,11) to 64,27 % (±18,01; p = 0,047), indicating decreased insulin sensitivity, while the updated homeostatic model assessment for β-cell function (HOMA2-%β) increased (from 128,11 % (±35,80) to 156,80 % (±39,49); p = 0,020) in TW after 6 months of GAHT. In TM, there were no changes in glucose metabolism parameters except for an increase in HbA1c (5,1% (±0,3) vs 5,3% (±0,4), p = 0,001).

Conclusions

6 months of GAHT were not associated with statistically significant changes in myocardial, hepatic, or pancreatic lipid content. Short-term GAHT led to a marked body fat redistribution with a significant decrease in the VAT/SAT ratio in TW.

Body composition, exercise-related performance parameters and associated health factors of transgender women, cisgender women and cisgender men volleyball players

OBJECTIVE

The inclusion of transgender athletes in competitive sports has promoted significant dialogue and controversy among exercise-related professionals. The objective of this study was to investigate body composition, exercise-related performance parameters and associated health-related factors of transgender women (TW), cisgender women (CW) and cisgender men (CM) amateur volleyball players.

METHODS

This was a cross-sectional study comprising TW, CW and CM amateur volleyball players eligible with the following characteristics: 'gender incongruent' (for TW only); age between 18 and 35 years; body mass index (BMI) between 18.0 and 29.9 kg/m2; 'very active' according to the International Physical Activity Questionnaire, and engaged in regular volleyball training for at least 1 year. All participants were assessed for body composition, blood biomarkers, handgrip strength, countermovement jump height (CMJ), squat jump height (SQJ) and maximum oxygen consumption (V̇O2max).

RESULTS

69 amateur volleyball players were initially evaluated, but only 23 met the inclusion criteria and were included in the study (7 TW, 8 CW and 8 CM). Age (p=0.07) and BMI (p=0.26) were similar between groups. Estradiol (p=0.47), total testosterone (p=1.00) and haemoglobin (p=1.00) levels did not differ between TW and CW. However, analysis not adjusted by confounding variables showed that CM presented higher testosterone levels (p<0.001), haemoglobin levels (p=0.03), lean body mass (p=0.03), handgrip strength (p<0.001), CMJ (p<0.001), SQJ (p=0.012) and V̇O2max (mL/min) (p=0.001) compared with TW. When adjusted by confounding variables, all p values were <0.05, except for SQJ (p=0.062).

CONCLUSION

TW athletes displayed similar exercise performance and biomarkers compared with CW but lower results compared with CM.

Metabolic Features of Assigned Female at Birth Transgender People on Gender-Affirming Hormone Therapy: A Meta-analysis

Purpose

There is a paucity of data on the safety and efficacy of long-term testosterone (T)-based gender-affirming hormone therapy (GAHT) on anthropometric parameters, body composition, and glycolipid metabolism in assigned female at birth (AFAB) persons. The purpose of this study was to provide an updated meta-analysis on this topic.

Methods

We searched PubMed, Scopus, and Cochrane Library for relevant studies. Pre-/post-therapy changes in body mass index (BMI), waist-to-hip ratio (WHR), body composition, lipid glycemic/insulinemic profiles were combined as mean differences (MD) with 95% confidence interval (CI), using random-effect models.

Results

Thirty-nine studies (N=1949) were analyzed. At pooled estimates, GAHT was associated with significant decrease in fat mass (MD: -1.29 kg; 95% CI: -2.52 to -0.05; p=0.04) and increase in lean mass (4.12 kg; 95% CI: 3.07-5.16; p<0.00001), BMI (0.78 kg/m2; 95% CI: 0.50-1.07; p<0.00001), and WHR (0.02; 95%CI: 0.01-0.03; p=0.003) in the absence of heterogeneity (I 2=0%). T therapy was also accompanied by unfavorable effects on lipid profile, including increases in total cholesterol (4.95 mg/dL; 95% CI: 1.53-8.37; p=0.005), LDL (11.15 mg/dL; 95% CI: 7.57-14.74; p<0.00001), and triglycerides (9.49 mg/dL; 95% CI: 4.39-14.58; p=0.0003) and decrease in HDL concentration (-7.52 mg/dL; 95% CI: -9.38 to -5.67; p<0.00001). Finally, T therapy resulted in a significant decrease in blood glucose concentration (-2.06 mg/dL; 95% CI: -3.37 to -0.74; p=0.002), with no significant effects on homeostatic model assessment index of insulin resistance.

Conclusion

T-based GAHT in AFAB people is associated with androgenic changes in body composition and body fat distribution, accompanied by the acquisition of a more unfavorable cardiovascular lipid profile.

Adipokine secretion and lipolysis following gender-affirming treatment in transgender individuals

BACKGROUND

The organ-specific effects of gender-affirming sex hormone treatment (GAHT) in transgender women (TW) and transgender men (TM) are insufficiently explored. This study investigated the effects of GAHT on adipose tissue function.

METHODS

In a single-center interventional prospective study, 32 adults undergoing GAHT, 15 TW and 17 TM, were examined with anthropometry and abdominal subcutaneous adipose tissue biopsies obtained before initiation of treatment, 1 month after endogenous sex hormone inhibition and three and 11 months after initiated GAHT. Fat cell size, basal/stimulated lipolysis and cytokine secretion in adipose tissue were analyzed.

RESULTS

TW displayed an increase in complement component 3a and retinol-binding protein 4 (RBP4) secretion after sex hormone inhibition, which returned to baseline following estradiol treatment. No changes in lipolysis were seen in TW. TM showed downregulation of RBP4 after treatment, but no changes in basal lipolysis. In TM, the estrogen suppression led to higher noradrenaline stimulated (NA) lipolysis that was normalized following testosterone treatment. At 11 months, the ratio of NA/basal lipolysis was lower compared to baseline. There were no significant changes in fat cell size in either TW or TM.

CONCLUSION

In TW, gonadal hormone suppression results in transient changes in cytokines and in TM there are some changes in NA-stimulated lipolysis following testosterone treatment. However, despite the known metabolic effects of sex hormones, the overall effects of GAHT on adipose tissue function are small and likely have limited clinical relevance, but larger studies with longer follow-up are needed to confirm these findings.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02518009, Retrospectively registered 7 August 2015.

Disentangling the impact of gluteofemoral versus visceral fat accumulation on cardiometabolic health using sex-stratified Mendelian randomization

BACKGROUND AND AIMS

Individuals with a higher abdominal adipose tissue accumulation are at higher risk of developing cardiometabolic diseases. For a given body mass index (BMI), women typically present lower abdominal adipose tissue accumulation compared to men. Whether abdominal adiposity is a causal driver of cardiometabolic risk, or a mere marker of ectopic fat deposition is debated.

METHODS

We investigated the sex-specific and sex-combined impact of height and BMI-adjusted gluteofemoral adipose tissue (GFATadj) adjusted abdominal subcutaneous adipose tissue (ASATadj) and adjusted visceral adipose tissue (VATadj) on cardiometabolic traits and diseases using Mendelian randomization.

RESULTS

Leveraging genome-wide summary statistics on GFATadj, ASATadj and VATadj from 39,076 UK Biobank participants with full-body magnetic resonance imaging available, we found that GFATadj is associated with a more favourable cardiometabolic risk profile including lower low density lipoprotein (LDL) cholesterol, triglycerides, fasting glucose, fasting insulin, liver enzyme levels and blood pressure as well as higher high density lipoprotein (HDL) cholesterol levels. GFATadj also is negatively associated with ischemic stroke, coronary artery disease, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). ASATadj is not associated with cardiometabolic traits and diseases, whereas VATadj is associated with liver fat accumulation but not with NAFLD or other cardiometabolic traits or diseases. Although the absolute effect sizes of GFATadj on LDL cholesterol were more pronounced in women compared to men, most associations did not differ by sex.

CONCLUSIONS

The inability of subcutaneous fat depots to efficiently store energy substrates could be the causal factor underlying the association of visceral lipid deposition with cardiometabolic health.

The predictive significance of lipid accumulation products for future diabetes in a non-diabetic population from a gender perspective: an analysis using time-dependent receiver operating characteristics

Objective

The increasing prevalence of diabetes is strongly associated with visceral adipose tissue (VAT), and gender differences in VAT remarkably affect the risk of developing diabetes. This study aimed to assess the predictive significance of lipid accumulation products (LAP) for the future onset of diabetes from a gender perspective.

Methods

A total of 8,430 male and 7,034 female non-diabetic participants in the NAGALA (NAfld in the Gifu Area, Longitudinal Analysis) program were included. The ability of LAP to assess the risk of future new-onset diabetes in both genders was analyzed using multivariate Cox regression. Subgroup analysis was conducted to explore the impact of potential modifiers on the association between LAP and diabetes. Additionally, time-dependent receiver operator characteristics (ROC) curves were used to assess the predictive power of LAP in both genders for new-onset diabetes over the next 2-12 years.

Results

Over an average follow-up of 6.13 years (maximum 13.14 years), 373 participants developed diabetes. Multivariate Cox regression analysis showed a significant gender difference in the association between LAP and future diabetes risk (P-interaction<0.05): the risk of diabetes associated with LAP was greater in females than males [hazard ratios (HRs) per standard deviation (SD) increase: male 1.20 (1.10, 1.30) vs female 1.35 (1.11, 1.64)]. Subgroup analysis revealed no significant modifying effect of factors such as age, body mass index (BMI), smoking history, drinking history, exercise habits, and fatty liver on the risk of diabetes associated with LAP (All P-interaction <0.05). Time-dependent ROC analysis showed that LAP had greater accuracy in predicting diabetes events occurring within the next 2-12 years in females than males with more consistent predictive thresholds in females.

Conclusions

This study highlighted a significant gender difference in the association between LAP and future diabetes risk. The risk of diabetes associated with LAP was greater in females than in males. Furthermore, LAP showed superior predictive ability for diabetes at different time points in the future in females and had more consistent and stable predictive thresholds in females, particularly in the medium and long term.

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

Characterising body composition and bone health in transgender individuals receiving gender-affirming hormone therapy

BACKGROUND

Gender-affirming hormone therapy (GAHT) is prescribed to produce secondary sex characteristics aligning external anatomy with gender identity to mitigate gender dysphoria. Transgender women are generally treated with oestrogens and anti-androgens, whereas transgender men are treated with testosterone. The objective of this narrative review was to characterise the influence of GAHT on body composition and bone health in the transgender population to help address weight concerns and chronic disease risk.

METHODS

Studies were extracted from PubMed and Scopus and limited to only those utilising imaging technologies for precise adipose tissue, lean mass, and bone mineral density (BMD) quantification.

RESULTS

Although methodologies differed across the 20 investigations that qualified for inclusion, clear relationships emerged. Specifically, among transgender women, most studies supported associations between oestrogen therapy and decreases in lean mass and increases in both, fat mass and body mass index (BMI). Within transgender men, all studies reported associations between testosterone therapy and increases in lean mass, and although not as consistent, increases in BMI and decreases in fat mass. No consistent changes in BMD noted for either group.

CONCLUSIONS

Additional research is needed to appropriately assess and evaluate the implications of these body composition changes over time (beyond 1 year) in larger, more diverse groups across all BMI categories. Future studies should also seek to evaluate nutrient intake, energy expenditure and other important lifestyle habits to diminish health disparities within this vulnerable population. Policies are needed to help integrate registered dietitians into the routine care of transgender individuals.

Transwoman Elite Athletes: Their Extra Percentage Relative to Female Physiology

There is increasing debate as to whether transwoman athletes should be included in the elite female competition. Most elite sports are divided into male and female divisions because of the greater athletic performance displayed by males. Without the sex division, females would have little chance of winning because males are faster, stronger, and have greater endurance capacity. Male physiology underpins their better athletic performance including increased muscle mass and strength, stronger bones, different skeletal structure, better adapted cardiorespiratory systems, and early developmental effects on brain networks that wires males to be inherently more competitive and aggressive. Testosterone secreted before birth, postnatally, and then after puberty is the major factor that drives these physiological sex differences, and as adults, testosterone levels are ten to fifteen times higher in males than females. The non-overlapping ranges of testosterone between the sexes has led sports regulators, such as the International Olympic Committee, to use 10 nmol/L testosterone as a sole physiological parameter to divide the male and female sporting divisions. Using testosterone levels as a basis for separating female and male elite athletes is arguably flawed. Male physiology cannot be reformatted by estrogen therapy in transwoman athletes because testosterone has driven permanent effects through early life exposure. This descriptive critical review discusses the inherent male physiological advantages that lead to superior athletic performance and then addresses how estrogen therapy fails to create a female-like physiology in the male. Ultimately, the former male physiology of transwoman athletes provides them with a physiological advantage over the cis-female athlete.

The 2D:4D index is associated with the development of excess body weight in adults, but not with the rate of weight loss following bariatric surgery

2D:4D finger length ratio is a proxy of prenatal sex hormone exposure. Prenatal testosterone decreases and prenatal estrogens increase this index. In the current study we investigated whether the 2D:4D index, as a marker of the prenatal hormonal environment, is associated with the development of overweight and obesity in adults, and whether is it correlated with the rate of weight loss in patients after bariatric surgery. We tested 125 adults with obesity (BMI ≥ 30.0 kg/m²), 125 adults with overweight (BMI 25.0–29.9 kg/m²) and 153 persons with normal body weight (BMI < 25 kg/m²) of both sexes. We have found that the development of excessive body weight in men and women, and fat accumulation in the upper arms, thighs and lower legs in women with obesity (but not men) are associated with increased prenatal estrogen exposure. This relationship indicates a new area of activity in the field of obesity prevention. Moreover, it seems that the 2D:4D index (especially of the right hand) may be a useful factor in early prediction of the risk of developing excessive body weight in humans. The rate of weight loss after bariatric surgery is independent of prenatal exposure to sex hormones.

Gender Affirming Body Contouring and Physical Transformation in Transgender Individuals

There is a subset of transgender individuals, who after having undergone gender affirming surgeries want body contouring so that the overall body shape is congruent to the body image. Hormonal therapy can bring about a considerable change in the physical transformation. However, there is an increase in requests for specific body contouring procedures because of increased awareness in the society.

There are significant differences between the skeletal as well as soft tissue characteristics of male and female body. Body contouring in transgender individuals can be achieved by altering the skeletal structure or the overlying soft tissues or combining both. In this article, we discuss body contouring as an adjunct to gender affirming surgeries, in both male to female and female to male transgender individuals.

Body Fat Distribution and Associated Risk of Cardiovascular Disease in Adults With Cerebral Palsy

Objective: Fat distribution has increasingly been acknowledged as a more significant health parameter than general obesity, in terms of the risk of cardiovascular disease (CVD). We aimed to investigate the regional fat distribution pattern and general body fat characteristics of adults with cerebral palsy (CP), and we explored the risk of CVD in this population. Methods: People aged ≥20 years who were diagnosed with CP were recruited between February 2014 and November 2014. The subjects underwent a structured interview, laboratory studies, and physical examination. The amount and distribution of fat were determined directly by dual-energy X-ray absorptiometry. Laboratory analysis was performed to measure total cholesterol and triglyceride, high-density lipoprotein (HDL), low-density lipoprotein, and fasting plasma glucose levels. The Framingham risk score (FRS) was used to present the 10-year risk for having CVD, and predictors such as sex, age, total cholesterol, HDL, systolic blood pressure, treatment for hypertension, and smoking status were used to calculate the FRS. Results: Ninety-nine adults (58 men, mean age 41.77 ± 8.95 years) with CP were included. The participants consisted of all five levels of the Gross Motor Function Classification System. The mean body mass index (BMI) was 22.52 ± 4.58 kg/m². According to BMI criteria, 54.9% were overweight and 27.3% were obese. The fat mass index criteria revealed 10.1% excess fat and 7.6% obesity. In univariable regression analysis, age, the timing of physical function deterioration, and android fat percentage were associated with the FRS (p <0.001, p <0.001, and p = 0.007, respectively). In multiple regression analysis, the FRS was associated with age and android fat percentage, based on the following formula: " FRS= - 18 . 549 + 0 . 410  ∗  Age + 0 . 577  ∗  Android percent fat  ( % )   ( R 2 =0 . 528 ) ' '                                                                                                                                          ( p < 0.001 ) . Conclusions: Body fat distribution in the android area is significantly associated with future CVD risk in adults with CP.

Sex differences in white adipose tissue expansion: emerging molecular mechanisms

The escalating prevalence of individuals becoming overweight and obese is a rapidly rising global health problem, placing an enormous burden on health and economic systems worldwide. Whilst obesity has well described lifestyle drivers, there is also a significant and poorly understood component that is regulated by genetics. Furthermore, there is clear evidence for sexual dimorphism in obesity, where overall risk, degree, subtype and potential complications arising from obesity all differ between males and females. The molecular mechanisms that dictate these sex differences remain mostly uncharacterised. Many studies have demonstrated that this dimorphism is unable to be solely explained by changes in hormones and their nuclear receptors alone, and instead manifests from coordinated and highly regulated gene networks, both during development and throughout life. As we acquire more knowledge in this area from approaches such as large-scale genomic association studies, the more we appreciate the true complexity and heterogeneity of obesity. Nevertheless, over the past two decades, researchers have made enormous progress in this field, and some consistent and robust mechanisms continue to be established. In this review, we will discuss some of the proposed mechanisms underlying sexual dimorphism in obesity, and discuss some of the key regulators that influence this phenomenon.

Association of body-shape phenotypes with imaging measures of body composition in the UK Biobank cohort: relevance to colon cancer risk

Background

Body mass index (BMI), waist and hip circumference are strongly correlated and do not reflect body composition. A Body Shape Index (ABSI) and Hip Index (HI) define waist and hip size among individuals with the same weight and height and would thus reflect body density. We examined differences in body composition between body-shape phenotypes defined with ABSI and HI and used this information to propose explanations for associations between body-shape phenotypes and colon cancer risk.

Methods

We used data from the UK Biobank Resource for 15,520 men, 16,548 women with dual-emission X-ray absorptiometry (DXA) measurements; 3997 men, 4402 women with magnetic resonance imaging (MRI) measurements; 200,289 men, 230,326 women followed-up for colon cancer. We defined body-shape phenotypes as: large-ABSI-small-HI (“apple”), small-ABSI-large-HI (“pear”), small-ABSI-small-HI (“slim”), large-ABSI-large-HI (“wide”). We evaluated differences in body composition in linear models and associations with colon cancer risk in Cox proportional hazards models adjusted for confounders and explored heterogeneity by BMI.

Results

Among individuals with the same height and weight, visceral adipose tissue (VAT) was lowest for “pear” and highest for “apple”, while abdominal subcutaneous adipose tissue (ASAT) was lowest for “slim” and highest for “wide” phenotype. In the gynoid region, differences between “apple” and “pear” phenotypes were accounted for mainly by fat mass in women but by lean mass in men. In men, lean mass was inversely associated with waist size, while the pattern of gynoid fat resembled ASAT in women. Lean and fat mass were higher for higher BMI, but not hand grip strength. Compared to normal weight “pear”, the risk of colon cancer in men (1029 cases) was higher for “apple” phenotype for normal weight (hazard ratio HR = 1.77; 95% confidence interval: 1.16–2.69) and comparably for overweight and obese, higher for “wide” phenotype for overweight (HR = 1.60; 1.14–2.24) and comparably for obese, but higher for “slim” phenotype only for obese (HR = 1.98; 1.35–2.88). Associations with colon cancer risk in women (889 cases) were weaker.

Conclusions

ABSI-by-HI body-shape phenotypes provide information for body composition. Colon cancer risk in men appears related to ASAT quantity for “slim” and “wide” but to factors determining VAT accumulation for “apple” phenotype.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08820-6.

Cardiopulmonary fitness but not muscular fitness associated with visceral adipose tissue mass

PURPOSE

The purpose of this study is to identify the association between physical fitness (cardiopulmonary and musculoskeletal) and the distribution of abdominal fat in overweight and obese adults.

METHODS

Of the total 102 overweight and obese participants, 99 participants completed all measurements. Cardiopulmonary fitness was assessed by maximal oxygen consumption test and muscular fitness was assessed using 10 repetition max. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography (CT) at the level of lumbar spine 4-5.

RESULTS

Cardiopulmonary fitness was inversely associated with both VAT and SAT, while muscular fitness only inversely associated with SAT. Multiple linear regression analyses indicated that gender, age, and cardiopulmonary fitness, but not muscular fitness, were associated with VAT, and age, cardiopulmonary fitness, and muscular fitness were significantly associated with SAT.

CONCLUSIONS

Cardiopulmonary fitness is more closely related to both VAT and SAT while muscular fitness is related with SAT.

Sex and Gender Differences in Clinical Pharmacology: Implications for Transgender Medicine

The transgender adult population is growing globally, but clinical pharmacology has lagged behind other areas of transgender medicine. Medical care for transgender adults may include long‐term testosterone or estrogen treatment to align secondary sex characteristics with gender identity. Clinicians often use drug–drug interaction data from the general adult population to predict medication disposition or safety among transgender adults. However, this approach does not address the complex pharmacodynamic effects of hormone therapy in transgender adults. In this review, we critically examine sex‐related and gender‐related differences in clinical pharmacology and apply these data to discuss current gaps in transgender medicine.

A Review of Hand Feminization and Masculinization Techniques in Gender Affirming Therapy

INTRODUCTION

Anatomical characteristics that are incongruent with an individual's gender identity can cause significant gender dysphoria. Hands exhibit prominent dimorphic sexual features, but despite their visibility, there are limited studies examining gender affirming procedures for the hands. This review is intended to cover the anatomical features that define masculine and feminine hands, the surgical and non-surgical approaches for feminization and masculinization of the hand, and to adapt established aesthetic hand techniques for gender affirming care.

METHODS

The authors performed a comprehensive database search of PubMed, Embase OVID and SCOPUS to identify articles on the characterization of masculine or feminine hands, hand treatments related to gender affirmation, and articles related to techniques for hand masculinization and feminization in the non-transgender population.

RESULTS

From 656 possibly relevant articles, 42 met the inclusion criteria for the current literature search. There is currently no medical literature specifically exploring the surgical or non-surgical options for hand gender affirmation. The available techniques for gender affirming procedures discussed in this paper are appropriated from those more commonly used for hand rejuvenation.

CONCLUSION

There is a dearth of literature addressing the options for transgender individuals seeking gender affirming procedures of the hand. Though established procedures used for hand rejuvenation may be utilized in gender affirming care, further study is required to determine relative salience of various hand features to gender dysphoria in transgender patients of various identities, as well as development of novel techniques to meet these needs.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. .

Sex and Gender Differences in Clinical Pharmacology: Implications for Transgender Medicine

The transgender adult population is growing globally, but clinical pharmacology has lagged behind other areas of transgender medicine. Medical care for transgender adults may include long-term testosterone or estrogen treatment to align secondary sex characteristics with gender identity. Clinicians often use drug-drug interaction data from the general adult population to predict medication disposition or safety among transgender adults. However, this approach does not address the complex pharmacodynamic effects of hormone therapy in transgender adults. In this review, we critically examine sex-related and gender-related differences in clinical pharmacology and apply these data to discuss current gaps in transgender medicine.

How does hormone transition in transgender women change body composition, muscle strength and haemoglobin? Systematic review with a focus on the implications for sport participation

Objectives

We systemically reviewed the literature to assess how long-term testosterone suppressing gender-affirming hormone therapy influenced lean body mass (LBM), muscular area, muscular strength and haemoglobin (Hgb)/haematocrit (HCT).

Design

Systematic review.

Data sources

Four databases (BioMed Central, PubMed, Scopus and Web of Science) were searched in April 2020 for papers from 1999 to 2020.

Eligibility criteria for selecting studies

Eligible studies were those that measured at least one of the variables of interest, included transwomen and were written in English.

Results

Twenty-four studies were identified and reviewed. Transwomen experienced significant decreases in all parameters measured, with different time courses noted. After 4 months of hormone therapy, transwomen have Hgb/HCT levels equivalent to those of cisgender women. After 12 months of hormone therapy, significant decreases in measures of strength, LBM and muscle area are observed. The effects of longer duration therapy (36 months) in eliciting further decrements in these measures are unclear due to paucity of data. Notwithstanding, values for strength, LBM and muscle area in transwomen remain above those of cisgender women, even after 36 months of hormone therapy.

Conclusion

In transwomen, hormone therapy rapidly reduces Hgb to levels seen in cisgender women. In contrast, hormone therapy decreases strength, LBM and muscle area, yet values remain above that observed in cisgender women, even after 36 months. These findings suggest that strength may be well preserved in transwomen during the first 3 years of hormone therapy.

Transgender Women in the Female Category of Sport: Perspectives on Testosterone Suppression and Performance Advantage

Males enjoy physical performance advantages over females within competitive sport. The sex-based segregation into male and female sporting categories does not account for transgender persons who experience incongruence between their biological sex and their experienced gender identity. Accordingly, the International Olympic Committee (IOC) determined criteria by which a transgender woman may be eligible to compete in the female category, requiring total serum testosterone levels to be suppressed below 10 nmol/L for at least 12 months prior to and during competition. Whether this regulation removes the male performance advantage has not been scrutinized. Here, we review how differences in biological characteristics between biological males and females affect sporting performance and assess whether evidence exists to support the assumption that testosterone suppression in transgender women removes the male performance advantage and thus delivers fair and safe competition. We report that the performance gap between males and females becomes significant at puberty and often amounts to 10-50% depending on sport. The performance gap is more pronounced in sporting activities relying on muscle mass and explosive strength, particularly in the upper body. Longitudinal studies examining the effects of testosterone suppression on muscle mass and strength in transgender women consistently show very modest changes, where the loss of lean body mass, muscle area and strength typically amounts to approximately 5% after 12 months of treatment. Thus, the muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed. Sports organizations should consider this evidence when reassessing current policies regarding participation of transgender women in the female category of sport.

Sex differences in the association of sphingolipids with age in Dutch and South-Asian Surinamese living in Amsterdam, the Netherlands

BACKGROUND

Men have a higher risk for cardiovascular disease (CVD) early in life, while women have a higher risk later in life. The sex-related differences in CVD risk, especially by age, could be related to sphingolipid metabolism. We compared plasma sphingolipid concentrations and its increase by age in men and women.

METHODS

Plasma concentrations of 13 types of sphingolipids were measured by liquid chromatography-tandem mass spectrometry in a random subsample of 328 men and 372 women of Dutch and South-Asian Surinamese ethnic origin, participating in the HELIUS study. Sphingolipid concentrations were compared between men and women by age group (18-39, 40-55, and 56-70 years). Multiple linear regression was used to determine sex differences in age trends in sphingolipids stratified by ethnicity. Analyses were performed without adjustment and adjusted for body mass index (BMI) and waist circumference.

RESULTS

At age 18-39 years, sphingolipid concentrations were lower in women than those in men, but at age 56-70 years this was reversed. At higher age, women showed higher concentrations than men. In line, we observed a more rapid increase of sphingolipid concentrations by age in women than in men. The observed sex differences were not explained by BMI or waist circumference. Patterns of sex differences were similar across ethnic groups, although the strength of associations differed.

CONCLUSIONS

Mean sphingolipid concentrations increase more rapidly with age in women than in men. Therefore, plasma lipid concentrations of sphingolipids, although lower in women than in men at younger age, are higher in women than in men at older age.

Sexual dimorphism in cardiometabolic health: the role of adipose tissue, muscle and liver

Obesity is associated with many adverse health effects, such as an increased cardiometabolic risk. Despite higher adiposity for a given BMI, premenopausal women are at lower risk of cardiometabolic disease than men of the same age. This cardiometabolic advantage in women seems to disappear after the menopause or when type 2 diabetes mellitus develops. Sexual dimorphism in substrate supply and utilization, deposition of excess lipids and mobilization of stored lipids in various key metabolic organs (such as adipose tissue, skeletal muscle and the liver) are associated with differences in tissue-specific insulin sensitivity and cardiometabolic risk profiles between men and women. Moreover, lifestyle-related factors and epigenetic and genetic mechanisms seem to affect metabolic complications and disease risk in a sex-specific manner. This Review provides insight into sexual dimorphism in adipose tissue distribution, adipose tissue, skeletal muscle and liver substrate metabolism and tissue-specific insulin sensitivity in humans, as well as the underlying mechanisms, and addresses the effect of these sex differences on cardiometabolic health. Additionally, this Review highlights the implications of sexual dimorphism in the pathophysiology of obesity-related cardiometabolic risk for the development of sex-specific prevention and treatment strategies.

Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators

OBJECTIVE

To examine the effect of gender affirming hormones on athletic performance among transwomen and transmen.

METHODS

We reviewed fitness test results and medical records of 29 transmen and 46 transwomen who started gender affirming hormones while in the United States Air Force. We compared pre- and post-hormone fitness test results of the transwomen and transmen with the average performance of all women and men under the age of 30 in the Air Force between 2004 and 2014. We also measured the rate of hormone associated changes in body composition and athletic performance.

RESULTS

Participants were 26.2 years old (SD 5.5). Prior to gender affirming hormones, transwomen performed 31% more push-ups and 15% more sit-ups in 1 min and ran 1.5 miles 21% faster than their female counterparts. After 2 years of taking feminising hormones, the push-up and sit-up differences disappeared but transwomen were still 12% faster. Prior to gender affirming hormones, transmen performed 43% fewer push-ups and ran 1.5 miles 15% slower than their male counterparts. After 1 year of taking masculinising hormones, there was no longer a difference in push-ups or run times, and the number of sit-ups performed in 1 min by transmen exceeded the average performance of their male counterparts.

SUMMARY

The 15-31% athletic advantage that transwomen displayed over their female counterparts prior to starting gender affirming hormones declined with feminising therapy. However, transwomen still had a 9% faster mean run speed after the 1 year period of testosterone suppression that is recommended by World Athletics for inclusion in women's events.

Sex differences in human adipose tissue gene expression and genetic regulation involve adipogenesis

Sex differences in adipose tissue distribution and function are associated with sex differences in cardiometabolic disease. While many studies have revealed sex differences in adipocyte cell signaling and physiology, there is a relative dearth of information regarding sex differences in transcript abundance and regulation. We investigated sex differences in subcutaneous adipose tissue transcriptional regulation using omic-scale data from ∼3000 geographically and ethnically diverse human samples. We identified 162 genes with robust sex differences in expression. Differentially expressed genes were implicated in oxidative phosphorylation and adipogenesis. We further determined that sex differences in gene expression levels could be related to sex differences in the genetics of gene expression regulation. Our analyses revealed sex-specific genetic associations, and this finding was replicated in a study of 98 inbred mouse strains. The genes under genetic regulation in human and mouse were enriched for oxidative phosphorylation and adipogenesis. Enrichment analysis showed that the associated genetic loci resided within binding motifs for adipogenic transcription factors (e.g., PPARG and EGR1). We demonstrated that sex differences in gene expression could be influenced by sex differences in genetic regulation for six genes (e.g., FADS1 and MAP1B). These genes exhibited dynamic expression patterns during adipogenesis and robust expression in mature human adipocytes. Our results support a role for adipogenesis-related genes in subcutaneous adipose tissue sex differences in the genetic and environmental regulation of gene expression.

Obesity in African-Americans: The role of physiology

The disproportionate obesity in African American (AA) women has a physiologic basis and can be explained by the interactive effects of insulin secretion, insulin clearance, insulin sensitivity and the glycaemic load of the diet. This review will present data supporting a physiologic basis for obesity propensity in obesity-prone AA women that resides in their unique metabolic/endocrine phenotype: high beta-cell responsiveness, low hepatic insulin extraction and relatively high insulin sensitivity, which together result in a high exposure of tissues and organs to insulin. When combined with a high-glycaemic (HG) diet (that stimulates insulin secretion), this underlying propensity to obesity becomes manifest, as ingested calories are diverted from energy production to storage. Our data indicate that both weight loss and weight loss maintenance are optimized with low-glycaemic (LG) vs HG diet in AA. Whether greater obesity in AA is mechanistically related to their greater prevalence of type 2 diabetes is debatable. This review provides data indicating that obesity is not strongly related to insulin resistance in AA. Rather, insulin resistance in AA is associated with relatively low adipose tissue in the leg, consistent with a genetic predisposition to impaired lipid storage. Greater bioenergetic efficiency has been reported in AA and, via resultant oxidative damage, could plausibly contribute to insulin resistance. In summary, it is proposed here that a subset of AA women are predisposed to obesity due to a specific metabolic/endocrine phenotype. However, greater diabetes risk in AA has an independent aetiology based on impaired lipid storage and mitochondrial efficiency/oxidative stress.

Sex Differences in Adipose Tissue Function

Regional adipose tissue distribution differs between men and women. Differences in the accumulation of adipose tissue as well as the regulation of secretion of a number of products from adipose tissue are under the control of sex steroids, which act through a wide variety of mechanisms, both direct and indirect, to tailor metabolism to the unique needs of each sex. A fuller understanding of sex-based differences in adipose tissue function may help with tailored strategies for disease prevention and treatment and provide insights into fundamental differences in the processes that regulate nutrient homeostasis and body weight.

Clinical impact of visceral-to-subcutaneous fat ratio in patients with acute aortic dissection

Background

Obesity has increased worldwide. Although the visceral-to-subcutaneous fat ratio (VS ratio) is an established risk factor for cardiovascular disease, its clinical impact on the long-term prognosis of patients with acute aortic dissection (AAD) remains unclear.

Materials and methods

This retrospective study included 111 patients with AAD admitted to our hospital from 2013 to 2016. Patients who died during hospitalization, and those diagnosed with Marfan’s syndrome were excluded. Visceral and subcutaneous fat accumulation (VFA, SFA) at umbilical level were calculated on a dedicated workstation. Major Adverse Cardiovascular and Cerebrovascular Events (MACCE) and worsening renal function (WRF) at 3 years were evaluated.

Results

Patient characteristics were as below: age, 73 ± 13; male, 55%; Stanford type A, 53%. Average VFA, SFA, and VS ratio on admission were 98 (52–145) cm², 141 (90–185) cm², and 0.75 (0.47–0.97), respectively. VFA was higher in male than in female (male, 134 [84–179] cm²; female, 71 [46–99] cm²; p < 0.001), whereas SFA was similar (male, 141 [91–174] cm²: female, 134 [90–205] cm²; p = 0.687). VS ratio was also higher in male (male, 0.88 [0.75–1.17]; female, 0.49 [0.39–0.65]; p < 0.001). Both MACCE and WRF at 3 years were observed in 17 (15%) and 32 (29%) patients, respectively. Multivariate Cox regression analysis demonstrated that VS ratio tended to be associated with the 3-year MACCE (HR for an increase of 0.5 unit, 1.49; 95% CI, 0.99–2.24; p = 0.056). This result persisted in male (HR for an increase of 0.5 unit, 1.54; 95% CI, 0.96–2.48; p = 0.073) but not female. The VS ratio was not related to the 3-year WRF.

Conclusion

The VS ratio tends to be associated with the 3-year MACCE in patients with AAD. This finding is inconclusive owing to a small sample and low incidence of adverse events. Further studies with larger samples are needed to confirm the clinical significance of VS ratio.

Prohibitin: A hypothetical target for sex-based new therapeutics for metabolic and immune diseases

IMPACT STATEMENT

Traditional sex-related biases in research are now obsolete, and it is important to identify the sex of humans, animals, and even cells in research protocols, due to the role of sex as a fundamental facet of biology, predisposition to disease, and response to therapy. Genetic sex, epigenetics and hormonal regulations, generate sex-dimorphisms. Recent investigations acknowledge sex differences in metabolic and immune health as well as chronic diseases. Prohibitin, an evolutionarily conserved molecule, has pleotropic functions in mitochondrial housekeeping, plasma membrane signaling, and nuclear genetic transcription. Studies in adipocytes, macrophages, and transgenic mice indicate that prohibitin interacts with sex steroids and plays a role in mediating sex differences in adipose tissues and immune cell types. Prohibitin may, depending on context, modulate predisposition to chronic metabolic diseases and malignancy and, because of these attributes, could be a target for sex-based therapies of metabolic and immune-related diseases as well as cancer.

Risk analysis of systemic levels of estrogen and adipokines as well as estrogen receptors from PBMCs in childbearing and perimenopausal women with obesity

PURPOSE

We aimed to evaluate the clinical value of systemic levels of estrogen and adipokines as well as estrogen receptors from peripheral blood mononuclear cells (PBMCs) in childbearing and perimenopausal women with obesity.

SUBJECTS AND METHODS

We observed 292 women, including 160 perimenopausal women (80 with obesity and 80 without obesity) and 132 women of childbearing age (67 with obesity and 65 without obesity). Body parameters, such as body mass index and waist circumference, were measured. Fat distribution was evaluated using a computerized tomography scanner. The levels of serum estrogen, leptin, visfatin, and adiponectin were measured using an enzyme-linked immunosorbent assay. The expression of circulating ERs was evaluated by Western blot analysis.

RESULTS

Perimenopausal women and childbearing women with obesity exhibited lower levels of estrogen and adiponectin, in addition to a distribution of visceral fat with higher levels of leptin and visfatin. These findings reflect the current data of menopausal women, which confirms the reliability of this experimental system. However, the expression of ERα in peripheral blood was significantly enhanced in women with obesity of both childbearing and perimenopausal age. This result is contrary to the common understanding of adipose tissue, namely that ERα is protective. The expression of ERβ in the women without obesity of both childbearing and perimenopausal age was higher than in women with obesity, which coincides with the results of a previous study on adipose tissue.

CONCLUSION

Our data fundamentally contradicts the utility of circulating ERα and ERα/ERβ evaluations in obesity studies. Because estrogen exerts pleiotropic effects on multiple tissues in the body through differential regulation of ERs, although the expression of ERβ coincides with the results of a previous study on adipose tissue, the expression levels of ERs in blood cannot be used as a diagnostic of informative tool for obesity in women.

A new approach to study the sex differences in adipose tissue

Obesity is one of the most invaliding and preventable diseases in the United States. Growing evidence suggests that there are sex differences in obesity in human and experimental animals. However, the specific mechanisms of this disease are unknown. Consequently, there is any particular treatment according to the sex/gender at this time. During the last decade, we observe a rise in the study of adipocyte and the possible mechanisms involved in the different roles of the fat. Furthermore, the effect of sex steroids on the adipocyte is one of the fields that need elucidation. Supporting evidence suggests that sex steroids play an essential role not only in the fat distribution, but also, in its metabolism, proliferation, and function. Thus, using in vitro and in vivo studies will contribute to our fight against this critical health public problem encompassing both sexes. In the present review, we discuss some of the recent advances in the adipocytes and the effect of the sex steroids on the adipose tissue. Also, we propose a new alternative to study the role of sex steroids on adipocyte biology through human adipose-derived stem cells.

Alterations in Body Uneasiness, Eating Attitudes, and Psychopathology Before and After Cross-Sex Hormonal Treatment in Patients with Female-to-Male Gender Dysphoria

Body dissatisfaction plays an important role in the development of psychiatric problems such as eating disorders as well as gender dysphoria (GD). Cross-sex hormonal treatment (CHT) alleviates the dissatisfaction by making various changes in the body. We examined the alteration of body uneasiness, eating attitudes and behaviors, and psychological symptoms longitudinally in Turkish participants with female-to-male gender dysphoria (FtM GD) after CHT. Thirty-seven participants with FtM GD and 40 female controls were asked to complete the Body Uneasiness Test to explore different areas of body-related psychopathology, the Eating Attitudes Test to assess eating disturbances, and the Symptom Checklist-90 Revised to measure psychological state, both before CHT and after 6 months of CHT administration. The baseline mean body weight, BMI scores, body uneasiness scores, and general psychopathological symptoms of participants with FtM GD were significantly higher than female controls, whereas baseline eating attitudes and behaviors were not significantly different. Over time, FtM GD participants' mean body weight and BMI scores increased, body uneasiness and general psychopathological symptoms decreased, and eating attitudes and behaviors had not changed at 24th weeks following CHT administration compared to baseline. CHT may have a positive impact on body uneasiness and general psychopathological symptoms in participants with FtM GD. However, CHT does not have an impact on eating attitudes and behaviors.

Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance

Elite athletic competitions have separate male and female events due to men's physical advantages in strength, speed, and endurance so that a protected female category with objective entry criteria is required. Prior to puberty, there is no sex difference in circulating testosterone concentrations or athletic performance, but from puberty onward a clear sex difference in athletic performance emerges as circulating testosterone concentrations rise in men because testes produce 30 times more testosterone than before puberty with circulating testosterone exceeding 15-fold that of women at any age. There is a wide sex difference in circulating testosterone concentrations and a reproducible dose-response relationship between circulating testosterone and muscle mass and strength as well as circulating hemoglobin in both men and women. These dichotomies largely account for the sex differences in muscle mass and strength and circulating hemoglobin levels that result in at least an 8% to 12% ergogenic advantage in men. Suppression of elevated circulating testosterone of hyperandrogenic athletes results in negative effects on performance, which are reversed when suppression ceases. Based on the nonoverlapping, bimodal distribution of circulating testosterone concentration (measured by liquid chromatography-mass spectrometry)-and making an allowance for women with mild hyperandrogenism, notably women with polycystic ovary syndrome (who are overrepresented in elite athletics)-the appropriate eligibility criterion for female athletic events should be a circulating testosterone of <5.0 nmol/L. This would include all women other than those with untreated hyperandrogenic disorders of sexual development and noncompliant male-to-female transgender as well as testosterone-treated female-to-male transgender or androgen dopers.

Adipocytes ESR1 Expression, Body Fat and Response to Testosterone Therapy in Hypogonadal Men Vary According to Estradiol Levels

Estradiol (E2), mainly produced from Testosterone (T) in men, promotes visceral lipolysis. However, high visceral fat and hyperestrogenemia are features of obese hypogonadal (HG) men. Our study objectives are to evaluate relationships between circulating E2 and: (1) fat mass; (2) Estrogen Receptor α (ESR1) expression in subcutaneous adipose tissue; (3) changes in body fat after 6 months (M) of T therapy in HG men.

HYPOTHESES

(1) existence of a range of circulating E2 associated with better body composition; (2) serum E2 determines tissue E2 sensitivity which affects response to T therapy. Men 40⁻74 years old, T < 300 (ng/dL), given T-cypionate for 6 months. Subjects were divided into 4-E2 categories: (1) <10.0; (2) 10.0⁻15.9; (3) 16.0⁻19.9; (4) ≥20.0 (pg/mL). Body composition (DXA), fat biopsies (liposuction), gene expression (qPCR), serum E2 and T (LC/MS), at baseline and 6 months. We enrolled 105 men; 90 completed the study. Group 2 had lower total and truncal fat mass (p < 0.01) but higher % lean mass (p < 0.001). ESR1 mRNA was the highest in group 1 (p = 0.01). At 6 months, group 1 had higher reduction in total (p = 0.03) and truncal (p = 0.01) fat. In conclusion, serum E2 = 10⁻15.9 (pg/mL) is associated with the best body composition profile in HG men; however, those with E2 < 10 (pg/mL) had the best response (greater fat loss) to T replacement possibly because of greater E2 sensitivity.

Female rats are more susceptible to metabolic effects of dehydroepiandrosterone treatment

Dehydroepiandrosterone (DHEA) is a steroid hormone that presents several effects on metabolism; however, most of the studies have been performed on male animals, while few authors have investigated possible sex differences regarding the metabolic effects of DHEA. Therefore, the aim of this study was to evaluate the effect of different doses of DHEA on metabolic parameters of male and ovariectomized female Wistar rats. Sex differences were found in the metabolism of distinct substrates and in relation to the effect of DHEA. In respect to the glucose metabolism in the liver, the conversion of glucose to CO₂ and the synthesis of lipids from glucose were 53% and 33% higher, respectively, in males. Also, DHEA decreased hepatic lipogenesis only in females. Regarding the hepatic glycogen synthesis pathway, females presented 73% higher synthesis than males, and the effect of DHEA was observed only in females, where it decreased this parameter. In the adipose tissue, glucose uptake was 208% higher in females and DHEA decreased this parameter. In the muscle, glucose uptake was 168% higher in females and no DHEA effect was observed. In summary, males and females present a different metabolic profile, with females being more susceptible to the metabolic effects of DHEA.

Sport and Transgender People: A Systematic Review of the Literature Relating to Sport Participation and Competitive Sport Policies

Background

Whether transgender people should be able to compete in sport in accordance with their gender identity is a widely contested question within the literature and among sport organisations, fellow competitors and spectators. Owing to concerns surrounding transgender people (especially transgender female individuals) having an athletic advantage, several sport organisations place restrictions on transgender competitors (e.g. must have undergone gender-confirming surgery). In addition, some transgender people who engage in sport, both competitively and for leisure, report discrimination and victimisation.

Objective

To the authors’ knowledge, there has been no systematic review of the literature pertaining to sport participation or competitive sport policies in transgender people. Therefore, this review aimed to address this gap in the literature.

Method

Eight research articles and 31 sport policies were reviewed.

Results

In relation to sport-related physical activity, this review found the lack of inclusive and comfortable environments to be the primary barrier to participation for transgender people. This review also found transgender people had a mostly negative experience in competitive sports because of the restrictions the sport’s policy placed on them. The majority of transgender competitive sport policies that were reviewed were not evidence based.

Conclusion

Currently, there is no direct or consistent research suggesting transgender female individuals (or male individuals) have an athletic advantage at any stage of their transition (e.g. cross-sex hormones, gender-confirming surgery) and, therefore, competitive sport policies that place restrictions on transgender people need to be considered and potentially revised.

Metabolic and functional changes in transgender individuals following cross-sex hormone treatment: Design and methods of the GEnder Dysphoria Treatment in Sweden (GETS) study

Background

Although the divergent male and female differentiation depends on key genes, many biological differences seen in men and women are driven by relative differences in estrogen and testosterone levels. Gender dysphoria denotes the distress that gender incongruence with the assigned sex at birth may cause. Gender-affirming treatment includes medical intervention such as inhibition of endogenous sex hormones and subsequent replacement with cross-sex hormones. The aim of this study is to investigate consequences of an altered sex hormone profile on different tissues and metabolic risk factors. By studying subjects undergoing gender-affirming medical intervention with sex hormones, we have the unique opportunity to distinguish between genetic and hormonal effects.

Methods

The study is a single center observational cohort study conducted in Stockholm, Sweden. The subjects are examined at four time points; before initiation of treatment, after endogenous sex hormone inhibition, and three and eleven months following sex hormone treatment. Examinations include blood samples, skeletal muscle-, adipose- and skin tissue biopsies, arteriography, echocardiography, carotid Doppler examination, whole body MRI, CT of muscle and measurements of muscle strength.

Results

The primary outcome measure is transcriptomic and epigenomic changes in skeletal muscle. Secondary outcome measures include transcriptomic and epigenomic changes associated with metabolism in adipose and skin, muscle strength, fat cell size and ability to release fatty acids from adipose tissue, cardiovascular function, and body composition.

Conclusions

This study will provide novel information on the role of sex hormone treatment in skeletal muscle, adipose and skin, and its relation to cardiovascular and metabolic disease.

Fat Mass Follows a U-Shaped Distribution Based on Estradiol Levels in Postmenopausal Women

OBJECTIVE

Estradiol (E2) regulates adipose tissue resulting in increased fat mass (FM) with declining E2. However, increased visceral fat and hyperestrogenemia are features of obese individuals. It is possible that adipocytes in obese individuals are less sensitive to E2 resulting in higher FM. Our objective is to identify the range of serum E2 for which postmenopausal women have the lowest FM and best body composition.

METHODS

Cross-sectional data from 252 community-dwelling postmenopausal women, 42-90 years old. Subjects were stratified into categories of E2 (pg/ml): (1) ≤10.5; (2) 10.6-13.9; (3) 14.0-17.4; and (4) ≥17.5. Body composition by dual-energy X-ray absorptiometry. Serum E2 by radioimmunoassay. Between-group comparisons by analysis of covariance.

RESULTS

E2 linearly increased with increasing body weight and body mass index (r = 0.15 and p = 0.01 for both), but not with total FM (kg) or % FM (r = 0.07, p = 0.34 and r = -0.04, p = 0.56, respectively). However, total FM (kg) followed a U-shaped distribution and was significantly lower in group 3 (27.6 ± 10.6), compared with groups 1: (34.6 ± 12.5), 2: (34.0 ± 12.4), and 4: (37.0 ± 10.6), p = 0.005. % FM was also lowest in group 3. While fat-free mass (FFM, kg) increased with increasing E2 (p < 0.001), % FFM was highest in group 3.

CONCLUSION

In our population of postmenopausal women, FM followed a U-shaped distribution according to E2 levels. E2 between 14.0 and 17.4 pg/ml is associated with the best body composition, i.e., lowest total and % FM and highest % FFM. Given the role of E2 in regulating body fat, high FM at the high end of the E2 spectrum may suggest reduced E2 sensitivity in adipocytes among obese postmenopausal women.

CLINICAL TRIALS

ClinicalTrials.gov identifier: NCT00146107.

Daily Gene Expression Rhythms in Rat White Adipose Tissue Do Not Differ Between Subcutaneous and Intra-Abdominal Depots

White adipose tissue (WAT) is present in different depots throughout the body. Although all depots are exposed to systemic humoral signals, they are not functionally identical. Studies in clock gene knockout animals and in shift workers suggest that daily rhythmicity may play an important role in lipid metabolism. Differences in rhythmicity between fat depots might explain differences in depot function; therefore, we measured mRNA expression of clock genes and metabolic genes on a 3-h interval over a 24-h period in the subcutaneous inguinal depot and in the intra-abdominal perirenal, epididymal, and mesenteric depots of male Wistar rats. We analyzed rhythmicity using CircWave software. Additionally, we measured plasma concentrations of glucose, insulin, corticosterone, and leptin. The clock genes (Bmal1/Per2/Cry1/Cry2/RevErbα/DBP) showed robust daily gene expression rhythms, which did not vary between WAT depots. Metabolic gene expression rhythms (SREBP1c/PPARα/PPARγ/FAS/LPL/Glut4/HSL/CPT1b/leptin/visfatin/resistin) were more variable between depots. However, no distinct differences between intra-abdominal and subcutaneous rhythms were found. Concluding, specific fat depots are not associated with differences in clock gene expression rhythms and, therefore, do not provide a likely explanation for the differences in metabolic function between different fat depots.

MECHANISMS IN ENDOCRINOLOGY: The sexually dimorphic role of androgens in human metabolic disease

Female androgen excess and male androgen deficiency manifest with an overlapping adverse metabolic phenotype, including abdominal obesity, insulin resistance, type 2 diabetes mellitus, non-alcoholic fatty liver disease and an increased risk of cardiovascular disease. Here, we review the impact of androgens on metabolic target tissues in an attempt to unravel the complex mechanistic links with metabolic dysfunction; we also evaluate clinical studies examining the associations between metabolic disease and disorders of androgen metabolism in men and women. We conceptualise that an equilibrium between androgen effects on adipose tissue and skeletal muscle underpins the metabolic phenotype observed in female androgen excess and male androgen deficiency. Androgens induce adipose tissue dysfunction, with effects on lipid metabolism, insulin resistance and fat mass expansion, while anabolic effects on skeletal muscle may confer metabolic benefits. We hypothesise that serum androgen concentrations observed in female androgen excess and male hypogonadism are metabolically disadvantageous, promoting adipose and liver lipid accumulation, central fat mass expansion and insulin resistance.

Peri-muscular adipose tissue may play a unique role in determining insulin sensitivity/resistance in women with polycystic ovary syndrome

STUDY QUESTION

Do the determinants of insulin sensitivity/resistance differ in women with and without polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Peri-muscular thigh adipose tissue is uniquely associated with insulin sensitivity/resistance in women with PCOS, whereas adiponectin and thigh subcutaneous adipose are the main correlates of insulin sensitivity/resistance in women without PCOS.

WHAT IS KNOWN ALREADY

In subject populations without PCOS, insulin sensitivity/resistance is determined by body fat distribution and circulating concentrations of hormones and pro-inflammatory mediators. Specifically, visceral (intra-abdominal) adipose tissue mass is adversely associated with insulin sensitivity, whereas thigh subcutaneous adipose appears protective against metabolic disease. Adiponectin is an insulin-sensitizing hormone produced by healthy subcutaneous adipose that may mediate the protective effect of thigh subcutaneous adipose. Testosterone, which is elevated in PCOS, may have an adverse effect on insulin sensitivity/resistance.

STUDY DESIGN, SIZE, DURATION

Cross-sectional study of 30 women with PCOS and 38 women without PCOS; data were collected between 2007 and 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were group-matched for obesity, as reflected in BMI (Mean ± SD; PCOS: 31.8 ± 6.0 kg/m²; without PCOS: 31.5 ± 5.0 kg/m²). The whole-body insulin sensitivity index (WBISI) was assessed using a mixed-meal tolerance test; Homeostasis Model Assessment-Insulin resistance (HOMA-IR) was determined from fasting insulin and glucose values. Adipose tissue distribution was determined by computed tomography (CT) scan. Partial correlation analysis, adjusting for total fat mass, was used to identify correlates of WBISI and HOMA-IR within each group of women from measures of body composition, body fat distribution, reproductive-endocrine hormones and adipokines/cytokines. Stepwise multiple linear regression analysis was used to identify the variables that best predicted WBISI and HOMA-IR.

MAIN RESULTS AND THE ROLE OF CHANCE

Among women with PCOS, both WBISI and HOMA-IR were best predicted by peri-muscular adipose tissue cross-sectional area. Among women without PCOS, both WBISI and HOMA-IR were best predicted by adiponectin and thigh subcutaneous adipose tissue.

LIMITATIONS, REASONS FOR CAUTION

Small sample size, group matching for BMI and age, and the use of surrogate measures of insulin sensitivity/resistance.

WIDER IMPLICATIONS OF THE FINDINGS

Because insulin resistance is the root cause of obesity and comorbidities in PCOS, determining its cause could lead to potential therapies. Present results suggest that peri-muscular adipose tissue may play a unique role in determining insulin sensitivity/resistance in women with PCOS. Interventions such as restriction of dietary carbohydrates that have been shown to selectively reduce fatty infiltration of skeletal muscle may decrease the risk for type 2 diabetes in women with PCOS.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by National Institutes of Health grants R01HD054960, R01DK67538, P30DK56336, P60DK079626, M014RR00032 and UL1RR025777. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

NCT00726908.

The role of sex steroid hormones in the pathophysiology and treatment of sarcopenia

Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.

Sex hormones and macronutrient metabolism

The biological differences between males and females are determined by a different set of genes and by a different reactivity to environmental stimuli, including the diet, in general. These differences are further emphasized and driven by the exposure to a different hormone flux throughout the life.

These differences have not been taken into appropriate consideration by the scientific community. Nutritional sciences are not immune from this “bias” and when nutritional needs are concerned, females are considered only when pregnant, lactating or when their hormonal profile is returning back to “normal,” i.e., to the male-like profile.

The authors highlight some of the most evident differences in aspects of biology that are associated with nutrition.

This review presents and describes available data addressing differences and similarities of the “reference man” vs. the “reference woman” in term of metabolic activity and nutritional needs. According to this assumption, available evidences of sex-associated differences of specific biochemical pathways involved in substrate metabolism are reported and discussed. The modulation by sexual hormones affecting glucose, amino acid and protein metabolism and the metabolization of nutritional fats and the distribution of fat depots, is considered targeting a tentative starting up background for a gender concerned nutritional science.

Impaired estrogen receptor action in the pathogenesis of the metabolic syndrome

Considering the current trends in life expectancy, women in the modern era are challenged with facing menopausal symptoms as well as heightened disease risk associated with increasing adiposity and metabolic dysfunction for up to three decades of life. Treatment strategies to combat metabolic dysfunction and associated pathologies have been hampered by our lack of understanding regarding the biological underpinnings of these clinical conditions and our incomplete understanding of the effects of estrogens and the tissue-specific functions and molecular actions of its receptors. In this review we provide evidence supporting a critical and protective role for the estrogen receptor α specific form in the maintenance of metabolic homeostasis and insulin sensitivity. Studies identifying the ER-regulated pathways required for disease prevention will lay the important foundation for the rational design of targeted therapeutics to improve women's health while limiting complications that have plagued traditional hormone replacement interventions.

Effects of sex steroids on bones and muscles: Similarities, parallels, and putative interactions in health and disease

Estrogens and androgens influence the growth and maintenance of bones and muscles and are responsible for their sexual dimorphism. A decline in their circulating levels leads to loss of mass and functional integrity in both tissues. In the article, we highlight the similarities of the molecular and cellular mechanisms of action of sex steroids in the two tissues; the commonality of a critical role of mechanical forces on tissue mass and function; emerging evidence for an interplay between mechanical forces and hormonal and growth factor signals in both bones and muscles; as well as the current state of evidence for or against a cross-talk between muscles and bone. In addition, we review evidence for the parallels in the development of osteoporosis and sarcopenia with advancing age and the potential common mechanisms responsible for the age-dependent involution of these two tissues. Lastly, we discuss the striking difference in the availability of several drug therapies for the prevention and treatment of osteoporosis, as compared to none for sarcopenia. This article is part of a Special Issue entitled "Muscle Bone Interactions".