17Beta-estradiol and anti-estrogen ICI:compound 182,780 regulate expression of lipoprotein lipase and hormone-sensitive lipase in isolated subcutaneous abdominal adipocytes

Sex-specific regulation of miR-22 and ERα in white adipose tissue of obese dam's female offspring impairs the early postnatal development of functional beige adipocytes in mice

During inguinal adipose tissue (iWAT) ontogenesis, beige adipocytes spontaneously appear between postnatal 10 (P10) and P20 and their ablation impairs iWAT browning capacity in adulthood. Since maternal obesity has deleterious effects on offspring iWAT function, we aimed to investigate its effect in spontaneous iWAT browning in offspring. Female C57BL/6 J mice were fed a control or obesogenic diet six weeks before mating. Male and female offspring were euthanized at P10 and P20 or weaned at P21 and fed chow diet until P60. At P50, mice were treated with saline or CL316,243, a β3-adrenoceptor agonist, for ten days. Maternal obesity induced insulin resistance at P60, and CL316,243 treatment effectively restored insulin sensitivity in male but not female offspring. This discrepancy occurred due to female offspring severe browning impairment. During development, the spontaneous iWAT browning and sympathetic nerve branching at P20 were severely impaired in female obese dam's offspring but occurred normally in males. Additionally, maternal obesity increased miR-22 expression in the iWAT of male and female offspring during development. ERα, a target and regulator of miR-22, was concomitantly upregulated in the male's iWAT. Next, we evaluated miR-22 knockout (KO) offspring at P10 and P20. The miR-22 deficiency does not affect spontaneous iWAT browning in females and, surprisingly, anticipates iWAT browning in males. In conclusion, maternal obesity impairs functional iWAT development in the offspring in a sex-specific way that seems to be driven by miR-22 levels and ERα signaling. This impacts adult browning capacity and glucose homeostasis, especially in female offspring.

Using new indices to predict metabolism dysfunction-associated fatty liver disease (MAFLD): analysis of the national health and nutrition examination survey database

BACKGROUND

Metabolism dysfunction-associated fatty liver disease (MAFLD), is the most common chronic liver disease. Few MAFLD predictions are simple and accurate. We examined the predictive performance of the albumin-to-glutamyl transpeptidase ratio (AGTR), plasma atherogenicity index (AIP), and serum uric acid to high-density lipoprotein cholesterol ratio (UHR) for MAFLD to design practical, inexpensive, and reliable models.

METHODS

The National Health and Nutrition Examination Survey (NHANES) 2007-2016 cycle dataset, which contained 12,654 participants, was filtered and randomly separated into internal validation and training sets. This study examined the relationships of the AGTR and AIP with MAFLD using binary multifactor logistic regression. We then created a MAFLD predictive model using the training dataset and validated the predictive model performance with the 2017-2018 NHANES and internal datasets.

RESULTS

In the total population, the predictive ability (AUC) of the AIP, AGTR, UHR, and the combination of all three for MAFLD showed in the following order: 0.749, 0.773, 0.728 and 0.824. Further subgroup analysis showed that the AGTR (AUC1 = 0.796; AUC2 = 0.690) and the combination of the three measures (AUC1 = 0.863; AUC2 = 0.766) better predicted MAFLD in nondiabetic patients. Joint prediction outperformed the individual measures in predicting MAFLD in the subgroups. Additionally, the model better predicted female MAFLD. Adding waist circumference and or BMI to this model improves predictive performance.

CONCLUSION

Our study showed that the AGTR, AIP, and UHR had strong MAFLD predictive value, and their combination can increase MAFLD predictive performance. They also performed better in females.

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.

Pubertal glyphosate-based herbicide exposure aggravates high-fat diet-induced obesity in female mice

Glyphosate-based herbicides (GBH) are the most widely used pesticides globally. Studies have indicated that they may increase the risk of various organic dysfunctions. Herein, we verified whether exposure to GBH during puberty increases the susceptibility of male and female mice to obesity when they are fed a high-fat diet (HFD) in adulthood. From the 4th-7th weeks of age, male and female C57Bl/6 mice received water (CTL group) or 50 mg GBH /kg body weight (BW; GBH group). From the 8th-21st weeks of age, the mice were fed a standard diet or a HFD. It was found that pubertal GBH exposure exacerbated BW gains and hyperphagia induced by HFD, but only in female GBH-HFD mice. These female mice also exhibited high accumulation of perigonadal and subcutaneous fat, as well as reduced lean body mass. Both male and female GBH-HFD displayed hypertrophic white adipocytes. However, only in females, pubertal GBH exposure aggravated HFD-induced fat accumulation in brown adipocytes. Furthermore, GBH increased plasma cortisol levels by 80% in GBH-HFD males, and 180% in GBH-HFD females. In conclusion, pubertal GBH exposure aggravated HFD-induced obesity, particularly in adult female mice. This study provides novel evidence that GBH misprograms lipid metabolism, accelerating the development of obesity when individuals are challenged by a second metabolic stressor, such as an obesogenic diet.

GPER/PKA-Dependent Enhancement of Hormone-Sensitive Lipase Phosphorylation in 3T3-L1 Adipocytes by Piceatannol

We previously reported that piceatannol (PIC) had an anti-obesity effect only in ovariectomized (OVX) postmenopausal obesity mice. PIC was found to induce the phosphorylation of hormone-sensitive lipase (pHSL) in OVX mice. To elucidate the mechanism by which PIC activates HSL, we investigated the effect of PIC using 3T3-L1 adipocytes. PIC induced HSL phosphorylation at Ser563 in 3T3-L1 cells, as in vivo experiments showed. pHSL (Ser563) is believed to be activated through the β-adrenergic receptor (β-AR) and protein kinase A (PKA) pathways; however, the addition of a selective inhibitor of β-AR did not inhibit the effect of PIC. The addition of a PKA inhibitor with PIC blocked pHSL (Ser563), suggesting that the effects are mediated by PKA in a different pathway than β-AR. The addition of G15, a selective inhibitor of the G protein-coupled estrogen receptor (GPER), reduced the activation of HSL by PIC. Furthermore, PIC inhibited insulin signaling and did not induce pHSL (Ser565), which represents its inactive form. These results suggest that PIC acts as a phytoestrogen and phosphorylates HSL through a novel pathway that activates GPER and its downstream PKA, which may be one of the inhibitory actions of PIC on fat accumulation in estrogen deficiency.

Estrogens in Adipose Tissue Physiology and Obesity-Related Dysfunction

Menopause-related decline in estrogen levels is accompanied by a change in adipose tissue distribution from a gynoid to an android and an increased prevalence of obesity in women. These unfavorable phenomena can be partially restored by hormone replacement therapy, suggesting a significant role for estrogen in the regulation of adipocytes' function. Indeed, preclinical studies proved the involvement of these hormones in adipose tissue development, metabolism, and inflammatory activity. However, the relationship between estrogen and obesity is bidirectional. On the one hand-their deficiency leads to excessive fat accumulation and impairs adipocyte function, on the other-adipose tissue of obese individuals is characterized by altered expression of estrogen receptors and key enzymes involved in their synthesis. This narrative review aims to summarize the role of estrogen in adipose tissue development, physiology, and in obesity-related dysfunction. Firstly, the estrogen classification, synthesis, and modes of action are presented. Next, their role in regulating adipogenesis and adipose tissue activity in health and the course of obesity is described. Finally, the potential therapeutic applications of estrogen and its derivates in obesity treatment are discussed.

Chronotype and Sleep Quality in Obesity: How Do They Change After Menopause?

PURPOSE OF REVIEW

This review primarily provides an overview of the current evidence on chronotype (which reflects an individual's preference for the timing of sleeping, eating, and activity in a 24-h period) and sleep quality changes in obesity in postmenopausal women. It also explores possible nutritional strategies to manage these changes in this phase of a woman's life.

RECENT FINDINGS

Menopause is a life stage frequently associated with sleep disturbances and changes in circadian rhythms. Sleep disturbances are one of the main symptoms of menopause and are caused by several factors such as hormonal changes, obesity, and melatonin reduction. In addition, the chronotype also changes following menopause. Nutritional strategies are essential because they could help manage menopausal sleep disturbances and circadian misalignment, particularly by tackling obesity and overweight. In the management of postmenopausal women, especially those experiencing obesity, careful assessment of sleep disturbances and chronotype and subsequent development of the most appropriate treatment, including nutritional management, should be part of the treatment routine.

Changes in adipose tissue microRNA expression across the menstrual cycle in regularly menstruating females: a pilot study

Cyclical changes in hormone profiles across the menstrual cycle are associated with alterations in metabolic control. MicroRNAs (miRNAs) contribute to regulating metabolic control, including adipose tissue metabolism. How fluctuations in hormonal profiles across the menstrual cycle affect adipose tissue miRNA expression remains unknown. Eleven healthy, regularly menstruating females underwent four sampling visits across their menstrual cycle. Subcutaneous abdominal adipose tissue and venous blood samples were collected at each sampling visit. Luteinizing hormone (LH) tests, calendar counting, and serum hormone concentrations were used to determine menstrual cycle phases: early-follicular (EF), late-follicular (LF), postovulatory (PO), and midluteal (ML). Serum follicle-stimulating hormone, LH, estrogen, progesterone, and testosterone were determined using multiplex magnetic bead panels and enzyme-linked immunosorbent assays. Global adipose tissue miRNA expression levels were determined via microarray in a subset of participants (n = 8) and 17 candidate miRNAs were validated by RT-qPCR in the whole cohort (n = 11). Global analysis of adipose tissue miRNA expression identified 33 miRNAs significantly altered across the menstrual cycle; however, no significant differences remained after correcting for multiple testing (P > 0.05). RT-qPCR analysis of candidate miRNAs revealed miR-497-5p expression was significantly altered across the menstrual cycle ([Formula: see text] = 0.18, P = 0.03); however, post hoc tests did not reveal any significant differences between menstrual cycle phases (P > 0.05). miR-30c-5p was associated with testosterone concentration (R² = 0.13, P = 0.033). These pilot data indicate differences in adipose tissue miRNAs in healthy women across the menstrual cycle and a weak association with ovarian hormones. Further research in larger sample sizes is required to confirm regulation of miRNA expression across the menstrual cycle.

A practical nutritional guide for the management of sleep disturbances in menopause

Sleep disturbances (SD) represent one of the main symptoms of menopause and they are caused by several factors. Hormonal changes such as the reduction of oestrogen levels and the consequent vasomotor symptoms (VMS) along with psychiatric disorders such as depression and anxiety could contribute to the onset of SD. Furthermore, obesity per sè or through the obstructive sleep apnoea (OSA) could blunt sleep. Moreover, in menopause is usual a reduction in melatonin, that could contribute to SD. Nutritional strategies are paramount because they could contribute to manage menopause-related SD, in particular tackling obesity and overweight. Furthermore, some foods, such as soy, fish, whole grains, vegetables and fruit could decrease symptoms like depression and VMS, correlated with SD in postmenopausal women. Therefore, the aim of this review is to provide an overview of the current evidence on SD in menopause and to provide nutritional strategies for managing SD in this context.

The follicular fluid metabolome differs according to the endometriosis phenotype

RESEARCH QUESTION

Is there a follicular fluid-specific metabolic profile in deep infiltrating endometriosis (DIE) depending on the presence of an associated ovarian endometrioma (OMA) that could lead to the identification of biomarkers for diagnosis and prognosis of the disease?

DESIGN

In this prospective cohort study, proton nuclear magnetic resonance (¹H-NMR) experiments were carried out on 50 follicular fluid samples from patients presenting with DIE, associated or not associated with an OMA, and 29 follicular fluid samples from patients with infertility caused by a tubal obstruction.

RESULTS

Concentrations of glucose, citrate, creatine and amino acids such as tyrosine and alanine were lower in women with DIE than control participants, whereas concentrations of lactate, pyruvate, lipids and ketone bodies were higher. Metabolic analysis revealed enhanced concentrations of glycerol and ketone bodies in patients with OMA, indicative of an activation of lipolysis followed by beta-oxidation. Concentrations of lactate and pyruvate were increased in patients without OMA, whereas the concentration of glucose was decreased, highlighting activation of the anaerobic glycolysis pathway. Differences in concentrations of amino acids such as threonine and glutamine were also statistically relevant in discriminating between the presence or absence of OMA.

CONCLUSIONS

Results indicate a mitochondrial dysregulation in endometriosis phenotypes, with a modified balance between anaerobic glycolysis and beta-oxidation in OMA phenotypes that could affect the fertility of women with endometriosis. As the composition of the follicular fluid has been shown to be correlated with oocyte development and outcome of implantation after fertilization, these findings may help explain the high level of infertility in these patients.

Gonad metabolomics and blood biochemical analysis reveal differences associated with testicular oocytes in wild largemouth bass (Micropterus salmoides)

Adverse reproductive effects associated with gonadal intersex among freshwater fish could hold considerable implications for population sustainability. Presence of testicular oocytes (TO) is the most common form of intersex and is widespread among centrarchids (sunfishes) of North America and other freshwater teleosts. Placing TO within the toxicological context of adverse outcome pathways (AOPs) to assess ecological risk is a priority for ecotoxicologists due to the association of TO with harmful chemical exposure and adverse reproductive effects in some cases. However, key event relationships between EDC exposure, incidence of TO, and apical outcomes have yet to be fully elucidated - in part due to a lack of knowledge of relationships between intersex gonad physiology and fish health. Understanding the physiological status of intersex fish is critical to assess ecological risk, understand mechanisms of induction, and to establish biomarkers of intersex in fish. In the present study, features of gonad metabolite profiles associated with TO in largemouth bass (LMB, Micropterus salmoides) from an impoundment in Georgia (USA) were determined using GC-MS-based metabolomics. Clinical blood biochemical screens were used to evaluate markers of fish health associated with TO. Results suggest that physiological changes in energy expenditure as well as relatively 'feminized' gonad lipid and protein metabolism may be related to the occurrence of TO in male LMB, and highlight the need to understand relationships between intersex and physical stressors such as elevated temperature and hypoxia. These results provide novel insight to AOPs associated with TO and identify candidate analytes for biomarker discovery.

Endometriosis phenotypes are associated with specific serum metabolic profiles determined by proton-nuclear magnetic resonance

RESEARCH QUESTION

What is the correlation between serum metabolic profile and endometriosis phenotype?

DESIGN

A pilot study nestled in a prospective cohort study at a university hospital, including 46 patients with painful endometriosis who underwent surgery and 21 controls who did not have macroscopic endometriotic lesions. Endometriosis was strictly classified into two groups of 23 patients each: endometrioma (OMA) and deep infiltrating endometriosis (DIE). Serum samples were collected before surgery for metabolomic profiling based on proton-nuclear magnetic resonance spectroscopy in combination with statistical approaches. Comparative identification of the metabolites in the serum from endometriosis patients and from controls was carried out, including an analysis according to endometriosis phenotype.

RESULTS

The serum metabolic profiles of the endometriosis patients revealed significantly lower concentrations of several amino acids compared with the controls, whereas the concentrations of free fatty acids and ketone bodies were significantly higher. The OMA and the DIE phenotypes each had a specific metabolic profile, with higher concentrations of two ketone bodies in the OMA group, and higher concentrations of free fatty acids and lipids in the DIE group.

CONCLUSION

Proton-nuclear magnetic resonance-based metabolomics of serum samples were found to have ample potential for identifying metabolic changes associated with endometriosis phenotypes. This information may improve our understanding of the pathogenesis of endometriosis.

Myocardium Metabolism in Physiological and Pathophysiological States: Implications of Epicardial Adipose Tissue and Potential Therapeutic Targets

The main energy substrate of adult cardiomyocytes for their contractility are the fatty acids. Its metabolism generates high ATP levels at the expense of high oxygen consumption in the mitochondria. Under low oxygen supply, they can get energy from other substrates, mainly glucose, lactate, ketone bodies, etc., but the mitochondrial dysfunction, in pathological conditions, reduces the oxidative metabolism. In consequence, fatty acids are stored into epicardial fat and its accumulation provokes inflammation, insulin resistance, and oxidative stress, which enhance the myocardium dysfunction. Some therapies focused on improvement the fatty acids entry into mitochondria have failed to demonstrate benefits on cardiovascular disorders. Oppositely, those therapies with effects on epicardial fat volume and inflammation might improve the oxidative metabolism of myocardium and might reduce the cardiovascular disease progression. This review aims at explain (a) the energy substrate adaptation of myocardium in physiological conditions, (b) the reduction of oxidative metabolism in pathological conditions and consequences on epicardial fat accumulation and insulin resistance, and (c) the reduction of cardiovascular outcomes after regulation by some therapies.

Sex differences on adipose tissue remodeling: from molecular mechanisms to therapeutic interventions

Sexual dimorphism greatly influences adipose tissue remodeling, which is characterized by changes in the activity, number, and/or size of adipocytes in response to distinct stimuli, including lifestyle and anti-obesity drugs. This sex dependence seems to be due to the anatomical and endocrine disparities between men and women. At the molecular level, sex hormones are believed to mediate such differences and involve estrogen and androgen receptor-induced gene expression. The signaling pathways that regulate adipose tissue metabolism and function include peroxisome proliferator-activated receptor gamma, uncoupling protein 1 (UCP1), 5' adenosine monophosphate-activated protein kinase (AMPK), and mitochondrial oxidative phosphorylation (OXPHOS), among other molecular players. Sex hormone-related pathways also interplay with adrenergic signaling, probably the most well-characterized molecular mechanism implicated in the remodeling of white adipose tissue. This review overviews and integrates the signaling pathways behind sexual dimorphism in adipose tissue remodeling, hoping to increase the knowledge on the pathogenesis of diseases, such as obesity and related comorbidities, and consequently, to drive future studies to investigate the regulation of this tissue homeostasis, either in men or women.

Obesity: a neuroimmunometabolic perspective

Neuroimmunology and immunometabolism are burgeoning topics of study, but the intersection of these two fields is scarcely considered. This interplay is particularly prevalent within adipose tissue, where immune cells and the sympathetic nervous system (SNS) have an important role in metabolic homeostasis and pathology, namely in obesity. In the present Review, we first outline the established reciprocal adipose-SNS relationship comprising the neuroendocrine loop facilitated primarily by adipose tissue-derived leptin and SNS-derived noradrenaline. Next, we review the extensive crosstalk between adipocytes and resident innate immune cells as well as the changes that occur in these secretory and signalling pathways in obesity. Finally, we discuss the effect of SNS adrenergic signalling in immune cells and conclude with exciting new research demonstrating an immutable role for SNS-resident macrophages in modulating SNS-adipose crosstalk. We posit that the latter point constitutes the existence of a new field - neuroimmunometabolism.

Role of Complement and Complement-Related Adipokines in Regulation of Energy Metabolism and Fat Storage

Adipose tissue releases many cytokines and inflammatory factors described as adipokines. In obesity, adipokines released from expanding adipose tissue are implicated in disease progression and metabolic dysfunction. However, mechanisms controlling the progression of adiposity and metabolic complications are not fully understood. It has been suggested that expanding fat mass and sustained release of inflammatory adipokines in adipose tissue lead to hypoxia, oxidative stress, apoptosis, and cellular damage. These changes trigger an immune response involving infiltration of adipose tissue with immune cells, complement activation and generation of factors involved in opsonization and clearance of damaged cells. Abundant evidence now indicates that adipose tissue is an active secretory source of complement and complement-related adipokines that, in addition to their inflammatory role, contribute to the regulation of metabolic function. This article highlights advances in knowledge regarding the role of these adipokines in energy regulation of adipose tissue through modulating lipogenic and lipolytic pathways. Several adipokines will be discussed including adipsin, Factor H, properdin, C3a, Acylation-Stimulating Protein, C1q/TNF-related proteins, and response gene to complement-32 (RGC-32). Interactions between these factors will be described considering their immune-metabolic roles in the adipose tissue microenvironment and their potential contribution to progression of adiposity and metabolic dysfunction. The differential expression and the role of complement factors in gender-related fat partitioning will also be addressed. Identifying lipogenic adipokines and their specific autocrine/paracrine roles may provide means for adipose-tissue-targeted therapeutic interventions that may disrupt the vicious circle of adiposity and disease progression. © 2019 American Physiological Society. Compr Physiol 9:1411-1429, 2019.

The Cooccurrence of Obesity, Osteoporosis, and Sarcopenia in the Ovariectomized Rat: A Study for Modeling Osteosarcopenic Obesity in Rodents

Background

Obesity, osteoporosis, and sarcopenia may individually occur due to age-related gradual alterations in body composition. This study investigates the cooccurrence of these age-related diseases in female animals with low levels of ovarian hormone in the absence of complex multifactorial process of chronological aging.

Methods

Thirty-six 5- and 10-month-old female rats were chosen to model pre- and postmenopausal women, respectively. Rats were divided into three treatment groups in each age category—sham, ovariectomized (ovx), and ovx + E₂ (17β-estradiol, 10 μg/kg)—and were pair-fed. Volunteer wheel running activity, body composition, bone microstructure, serum C-telopeptides of type I collagen, bone specific alkaline phosphatase, E₂, and gastrocnemius and soleus muscles were analyzed.

Results

The cooccurrence of osteoporosis, sarcopenia, and obesity was observed in the older ovx rats associated with a significant (p < 0.05) increased fat mass (30%), bone loss (9.6%), decreased normalized muscle mass-to-body-weight ratio (10.5%), and a significant decrease in physical activity (57%). The ratio of tibial bone mineral density to combined muscle mass was significantly decreased in both ovx age categories.

Conclusion

Ovariectomized rat could be used as an experimental model to examine the effect of loss of ovarian hormones, while controlling for energy intake and expenditure, to conduct obesity and body composition translational research in females without the confounding effect of genetic background.

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 Body Weight Regulation in Men

Our understanding of the metabolic roles of sex steroids in men has evolved substantially over recent decades. Whereas testosterone once was believed to contribute to metabolic risk in men, the importance of adequate androgen exposure for the maintenance of metabolic health has been demonstrated unequivocally. A growing body of evidence now also supports a critical role for estrogens in metabolic regulation in men. Recent data from clinical intervention studies indicate that estradiol may be a stronger determinant of adiposity than testosterone in men, and even short-term estradiol deprivation contributes to fat mass accrual. The following chapter will outline findings to date regarding the mechanisms, whereby estrogens contribute to the regulation of body weight and adiposity in men. It will present emergent clinical data as well as preclinical findings that reveal mechanistic insights into estrogen-mediated regulation of body composition. Findings in both males and females will be reviewed, to draw comparisons and to highlight knowledge gaps regarding estrogen action specifically in males. Finally, the clinical relevance of estrogen exposure in men will be discussed, particularly in the context of a rising global prevalence of obesity and expanding clinical use of sex steroid-based therapies in men.

Lipoprotein lipase and lipid profiles in plasma and placenta from normal pregnancies compared with patients with intrahepatic cholestasis of pregnancy

OBJECTIVE

To analyse lipoprotein lipase (LPL) expression and lipid levels in placenta and plasma of patients with intrahepatic cholestasis of pregnancy (ICP) and normal pregnancies.

METHODS

This prospective study included 30 patients with ICP and 30 gestational-age-matched pregnancies without any complications. Enzyme-linked immunosorbent assays were used to investigate plasma LPL levels from 28 weeks of gestation, at 4-weekly intervals, to 38 weeks of gestation, and data were assessed longitudinally. Immunohistochemistry, Western blotting and real-time polymerase chain reaction were used to detect placental LPL expression and activity. Placental triglyceride and total cholesterol levels were also analysed. The clinical data related to ICP and lipid profiles were collected retrospectively.

RESULTS

Plasma LPL concentration increased with gestational age in both groups, but the increase was limited in the ICP group. Immunohistochemistry revealed LPL staining mainly in syncytiotrophoblasts, and 3,3'-diamino-benzidine tetrahydrochloride wt% was lower in ICP placenta compared with normal placenta (p<0.01). LPL protein and mRNA expression in ICP placenta were significantly lower than in normal placenta (p<0.01). LPL activity was not significantly different in both groups. Correlation analysis indicated that the plasma LPL level was negatively associated with the corresponding concentration of total bile acid (r=-0.57) in the ICP group.

CONCLUSION

Reduced LPL expression in placenta, limited increase in LPL level in maternal plasma, and abnormal lipid profiles were found in patients with ICP. LPL was possibly related to ICP by participating abnormal lipid metabolism.

Updated survey of the steroid-converting enzymes in human adipose tissues

Over the past decade, adipose tissues have been increasingly known for their endocrine properties, that is, their ability to secrete a number of adipocytokines that may exert local and/or systemic effects. In addition, adipose tissues have long been recognized as significant sites for steroid hormone transformation and action. We hereby provide an updated survey of the many steroid-converting enzymes that may be detected in human adipose tissues, their activities and potential roles. In addition to the now well-established role of aromatase and 11β-hydroxysteroid dehydrogenase (HSD) type 1, many enzymes have been reported in adipocyte cell lines, isolated mature cells and/or preadipocytes. These include 11β-HSD type 2, 17β-HSDs, 3β-HSD, 5α-reductases, sulfatases and glucuronosyltransferases. Some of these enzymes are postulated to bear relevance for adipose tissue physiology and perhaps for the pathophysiology of obesity. This elaborate set of steroid-converting enzymes in the cell types of adipose tissue deserves further scientific attention. Our work on 20α-HSD (AKR1C1), 3α-HSD type 3 (AKR1C2) and 17β-HSD type 5 (AKR1C3) allowed us to clarify the relevance of these enzymes for some aspects of adipose tissue function. For example, down-regulation of AKR1C2 expression in preadipocytes seems to potentiate the inhibitory action of dihydrotestosterone on adipogenesis in this model. Many additional studies are warranted to assess the impact of intra-adipose steroid hormone conversions on adipose tissue functions and chronic conditions such as obesity, diabetes and cancer.

Cross-sectional associations of acylation stimulating protein (ASP) and adipose tissue gene expression with estradiol and progesterone in pre- and postmenopausal women

OBJECTIVE

Sex steroid hormones play an important regulatory role in fat metabolism and obesity. We hypothesized involvement of interactions between ovarian hormones with acylation stimulating protein (ASP).

DESIGN, PATIENTS AND MEASUREMENTS

In 392 women with wide age (18-69 years) and body size (BMI: 17 to 90 kg/m(2) ) ranges, fasting plasma levels of ASP, ovarian hormones, glucose, adiponectin and lipids/apolipoproteins were assessed, along with determination of metabolic syndrome (MS) features. Gene expression of C3 (ASP precursor) and related receptors C5L2, C3aR and C5aR in subcutaneous and omental adipose tissues was measured in a subset.

RESULTS

Acylation stimulating protein correlated negatively with concentrations of estradiol (P < 0·0001), adiponectin (P < 0·001) and apolipoprotein A1 (P < 0·001) and positively with apolipoprotein B levels (P < 0·001), systolic blood pressure (P < 0·001), waist circumference (P < 0·001), and triglyceride concentrations (P < 0·01). In age-matched groups of lean, overweight, metabolically healthy obese (MHO) and obese with metabolic syndrome (MSO), there was a stepwise increase in ASP levels (P < 0·001) while concentrations of adiponectin (P < 0·0001) and estradiol (P < 0·001) but not those of progesterone decreased. Progesterone but not estradiol levels correlated positively with C3 gene expression in omental adipose tissue (P < 0·05) and negatively with C5L2 expression in both omental (P < 0·01) and subcutaneous (P < 0·05) adipose tissues.

CONCLUSION

Our results are consistent with the concept that sex hormones differentially influence circulating ASP and adipose tissue gene expression of its related proteins in a depot-specific manner. ASP may play a role in the regulation of regional fat metabolism through interactions with sex hormones in women.

Estrogen signaling in metabolic inflammation

There is extensive evidence supporting the interference of inflammatory activation with metabolism. Obesity, mainly visceral obesity, is associated with a low-grade inflammatory state, triggered by metabolic surplus where specialized metabolic cells such as adipocytes activate cellular stress initiating and sustaining the inflammatory program. The increasing prevalence of obesity, resulting in increased cardiometabolic risk and precipitating illness such as cardiovascular disease, type 2 diabetes, fatty liver, cirrhosis, and certain types of cancer, constitutes a good example of this association. The metabolic actions of estrogens have been studied extensively and there is also accumulating evidence that estrogens influence immune processes. However, the connection between these two fields of estrogen actions has been underacknowledged since little attention has been drawn towards the possible action of estrogens on the modulation of metabolism through their anti-inflammatory properties. In the present paper, we summarize knowledge on the modification inflammatory processes by estrogens with impact on metabolism and highlight major research questions on the field. Understanding the regulation of metabolic inflammation by estrogens may provide the basis for the development of therapeutic strategies to the management of metabolic dysfunctions.

Sex-dependent expression of caveolin 1 in response to sex steroid hormones is closely associated with development of obesity in rats

Caveolin-1 (CAV1) is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD) and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2) and androgen (dihydrotestosterone, DHT) had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL) and uncoupling protein 1 (UCP1) in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1.

Interaction of the endocrine system with inflammation: a function of energy and volume regulation

During acute systemic infectious disease, precisely regulated release of energy-rich substrates (glucose, free fatty acids, and amino acids) and auxiliary elements such as calcium/phosphorus from storage sites (fat tissue, muscle, liver, and bone) are highly important because these factors are needed by an energy-consuming immune system in a situation with little or no food/water intake (sickness behavior). This positively selected program for short-lived infectious diseases is similarly applied during chronic inflammatory diseases. This review presents the interaction of hormones and inflammation by focusing on energy storage/expenditure and volume regulation. Energy storage hormones are represented by insulin (glucose/lipid storage and growth-related processes), insulin-like growth factor-1 (IGF-1) (muscle and bone growth), androgens (muscle and bone growth), vitamin D (bone growth), and osteocalcin (bone growth, support of insulin, and testosterone). Energy expenditure hormones are represented by cortisol (breakdown of liver glycogen/adipose tissue triglycerides/muscle protein, and gluconeogenesis; water retention), noradrenaline/adrenaline (breakdown of liver glycogen/adipose tissue triglycerides, and gluconeogenesis; water retention), growth hormone (glucogenic, lipolytic; has also growth-related aspects; water retention), thyroid gland hormones (increase metabolic effects of adrenaline/noradrenaline), and angiotensin II (induce insulin resistance and retain water). In chronic inflammatory diseases, a preponderance of energy expenditure pathways is switched on, leading to typical hormonal changes such as insulin/IGF-1 resistance, hypoandrogenemia, hypovitaminosis D, mild hypercortisolemia, and increased activity of the sympathetic nervous system and the renin-angiotensin-aldosterone system. Though necessary during acute inflammation in the context of systemic infection or trauma, these long-standing changes contribute to increased mortality in chronic inflammatory diseases.

The role of estrogen in adipose tissue metabolism: insights into glucose homeostasis regulation

Adipose tissue is an organ with active endocrine function involved in the regulation of energy balance and glucose homeostasis via multiple metabolic signaling pathways targeting the brain, liver, skeletal muscle, pancreas, and other organs. There is increasing evidence demonstrating that the female sex hormone, estrogen, regulates adipose development and improves systemic glucose homeostasis in both males and females. The underlying mechanism linking estrogenic regulation in adipose tissue and systemic glucose metabolism has not been fully elucidated, but is thought to include interactions of estrogen receptor signaling events involving lipolytic and/or lipogenic enzyme activity, free fatty acid metabolism, and adipocytokine production. Thus, understanding the effects of estrogen replacement on adipose tissue biology and metabolism is important in determining the risk of developing obesity-related metabolic disorders in patients undergoing treatment for sex hormone deficiency. In this report, we review literature regarding the role of estrogens and their corresponding receptors in the control of adipose metabolism and glucose homeostasis in both rodents and humans. We also discuss the effects of selective estrogen receptor modulators on glucose metabolism.

Gender differences in skeletal muscle substrate metabolism - molecular mechanisms and insulin sensitivity

It has become increasingly apparent that substrate metabolism is subject to gender-specific regulation, and the aim of this review is to outline the available evidence of molecular gender differences in glucose and lipid metabolism of skeletal muscle. Female sex has been suggested to have a favorable effect on glucose homeostasis, and the available evidence from hyperinsulinemic-euglycemic clamp studies is summarized to delineate whether there is a gender difference in whole-body insulin sensitivity and in particular insulin-stimulated glucose uptake of skeletal muscle. Whether an eventual higher insulin sensitivity of female skeletal muscle can be related to gender-specific regulation of molecular metabolism will be topic for discussion. Gender differences in muscle fiber type distribution and substrate availability to and in skeletal muscle are highly relevant for substrate metabolism in men and women. In particular, the molecular machinery for glucose and fatty acid oxidative and storage capacities in skeletal muscle and its implications for substrate utilization during metabolic situations of daily living are discussed, emphasizing their relevance for substrate choice in the fed and fasted state, and during periods of physical activity and recovery. Together, handling of carbohydrate and lipids and regulation of their utilization in skeletal muscle have implications for whole-body glucose homeostasis in men and women. 17-β estradiol is the most important female sex hormone, and the identification of estradiol receptors in skeletal muscle has opened for a role in regulation of substrate metabolism. Also, higher levels of circulating adipokines as adiponectin and leptin in women and their implications for muscle metabolism will be considered.

17β-Estradiol and estradiol fatty acyl esters and estrogen-converting enzyme expression in adipose tissue in obese men and women

CONTEXT

Obesity is associated with increased circulating 17β-estradiol (E₂), but less is known about E₂ concentrations in adipose tissue. In addition to E₂, adipose tissue synthesizes E₂ fatty acyl esters (E₂-FAE).

OBJECTIVE

The aim was to compare estrogen concentrations and expression of estrogen-converting enzymes in adipose tissue between severely obese men and women.

DESIGN AND SETTING

Tissue samples were obtained during elective surgery in University Central Hospital in the years 2008 through 2011.

PATIENTS

We studied 14 men and 22 premenopausal women undergoing bariatric surgery and 10 control women operated for nonmalignant reasons.

INTERVENTIONS

Paired samples were taken from abdominal sc and visceral adipose tissue and serum and analyzed for E₂ and E₂-FAE by fluoroimmunoassay and liquid chromatography-tandem mass spectrometry. mRNA expression of genes was analyzed by quantitative PCR.

RESULTS

Compared with men, E₂ levels in sc adipose tissue in obese women were higher, along with higher relative mRNA expression of steroid sulfatase and 17β-hydroxysteroid dehydrogenases 1, 7, and 12. In men, E₂-FAE concentrations in adipose tissue were similar to E₂ but in women significantly lower compared with E₂. Adipose tissue E₂-FAE and serum E₂-FAE levels correlated positively in obese subjects. Serum E₂ did not significantly correlate with E₂ concentration or mRNA expression of genes in adipose tissue in obese men or women.

CONCLUSIONS

The production of E₂ by the large adipose mass was not reflected by increased circulating E₂ concentrations in severely obese men or women. However, adipose tissue may contribute to concentrations of serum E₂-FAE.

G protein-coupled estrogen receptor-selective ligands modulate endometrial tumor growth

Endometrial carcinoma is the most common cancer of the female reproductive tract. GPER/GPR30 is a 7-transmembrane spanning G protein-coupled receptor that has been identified as the third estrogen receptor, in addition to ERα and ERβ. High GPER expression is predictive of poor survival in endometrial and ovarian cancer, but despite this, the estrogen-mediated signaling pathways and specific estrogen receptors involved in endometrial cancer remain unclear. Here, employing ERα-negative Hec50 endometrial cancer cells, we demonstrate that GPER mediates estrogen-stimulated activation of ERK and PI3K via matrix metalloproteinase activation and subsequent transactivation of the EGFR and that ER-targeted therapeutic agents (4-hydroxytamoxifen, ICI182,780/fulvestrant, and Raloxifene), the phytoestrogen genistein, and the “ERα-selective” agonist propylpyrazole triol also function as GPER agonists. Furthermore, xenograft tumors of Hec50 cells yield enhanced growth with G-1 and estrogen, the latter being inhibited by GPER-selective pharmacologic antagonism with G36. These results have important implications with respect to the use of putatively ER-selective ligands and particularly for the widespread long-term use of “ER-targeted” therapeutics. Moreover, our findings shed light on the potential mechanisms of SERM/SERD side effects reported in many clinical studies. Finally, our results provide the first demonstration that pharmacological inhibition of GPER activity in vivo prevents estrogen-mediated tumor growth.

Ovarian cycle-specific regulation of adipose tissue lipid storage by testosterone in female nonhuman primates

Previous studies in rodents and humans suggest that hyperandrogenemia causes white adipose tissue (WAT) dysfunction in females, although the underlying mechanisms are poorly understood. In light of the differences in the length of the ovarian cycle between humans and rodents, we used a nonhuman primate model to elucidate the effects of chronic hyperandrogenemia on WAT function in vivo. Female rhesus macaques implanted with testosterone capsules developed insulin resistance and altered leptin secretion on a high-fat, Western-style diet. In control visceral WAT, lipolysis and hormone-sensitive lipase expression were upregulated during the luteal phase compared with the early follicular (menses) phase of the ovarian cycle. Hyperandrogenemia attenuated elevated lipolysis and hormone-sensitive lipase activity in visceral WAT during the luteal phase but not during menses. Under control conditions, insulin-stimulated Akt and Erk activation and fatty acid uptake in WAT were not significantly affected by the ovarian cycle. In contrast, testosterone treatment preferentially increased fatty acid uptake and insulin signaling at menses. The fatty acid synthase and glucose transporter-4 genes were upregulated by testosterone during the luteal phase. In summary, this study reveals ovarian stage-specific fluctuations in adipocyte lipolysis and suggests that male sex hormones increase and female sex hormones decrease lipid storage in female WAT.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

G protein-coupled estrogen receptor in energy homeostasis and obesity pathogenesis

Obesity and its related metabolic diseases have reached a pandemic level worldwide. There are sex differences in the prevalence of obesity and its related metabolic diseases, with men being more vulnerable than women; however, the prevalence of these disorders increases dramatically in women after menopause, suggesting that sex steroid hormone estrogens play key protective roles against development of obesity and metabolic diseases. Estrogens are important regulators of several aspects of metabolism, including body weight and body fat, caloric intake and energy expenditure, and glucose and lipid metabolism in both males and females. Estrogens act in complex ways on their nuclear estrogen receptors (ERs) ERα and ERβ and transmembrane ERs such as G protein-coupled estrogen receptor. Genetic tools, such as different lines of knockout mouse models, and pharmacological agents, such as selective agonists and antagonists, are available to study function and signaling mechanisms of ERs. We provide an overview of the evidence for the physiological and cellular actions of ERs in estrogen-dependent processes in the context of energy homeostasis and body fat regulation and discuss its pathology that leads to obesity and related metabolic states.

Role of nuclear receptors in lipid dysfunction and obesity-related diseases

This article is a report on a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics and held at the Experimental Biology 12 meeting in San Diego, CA. The presentations discussed the roles of a number of nuclear receptors in regulating glucose and lipid homeostasis, the pathophysiology of obesity-related disease states, and the promise associated with targeting their activities to treat these diseases. While many of these receptors (in particular, constitutive androstane receptor and pregnane X receptor) and their target enzymes have been thought of as regulators of drug and xenobiotic metabolism, this symposium highlighted the advances made in our understanding of the endogenous functions of these receptors. Similarly, as we gain a better understanding of the mechanisms underlying bile acid signaling pathways in the regulation of body weight and glucose homeostasis, we see the importance of using complementary approaches to elucidate this fascinating network of pathways. The observation that some receptors, like the farnesoid X receptor, can function in a tissue-specific manner via well defined mechanisms has important clinical implications, particularly in the treatment of liver diseases. Finally, the novel findings that agents that selectively activate estrogen receptor β can effectively inhibit weight gain in a high-fat diet model of obesity identifies a new role for this member of the steroid superfamily. Taken together, the significant findings reported during this symposium illustrate the promise associated with targeting a number of nuclear receptors for the development of new therapies to treat obesity and other metabolic disorders.

In utero and neonate exposure to nonylphenol develops hyperadrenalism and metabolic syndrome later in life. I. First generation rats (F(1))

Nonylphenol (NP) is an endocrine disruptor (ENDR). It is a chemical associated with the production and degradation of nonylphenol ethoxylates (NPE). NPE is widely used as nonionic surfactants. Previously, we observed that NP increased the production of corticosterone and aldosterone from zona fasciculata-reticularis, and zona glomerulosa cells, respectively. By the "fetal origins adult diseases" (Barker hypothesis), we examined the possible impact of NP exposure during developmental (in utero and neonatal) period with focus on disturbed adrenal function and related hyperadrenal syndrome, i.e. Cushings syndrome/metabolic syndrome. In this study, female rats drink NP water during pregnancy and lactation conferred F(1) generation: (1) increase the corticosterone, aldosterone concentration in plasma; (2) increase 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity in liver and adipose tissue; (3) increase aldosterone synthase activity in adrenal for adult offspring. Furthermore, it can increase body weight, adrenocorticotropin (ACTH) concentration in plasma, 11β-HSD1 protein expression in liver, steroidogenic acute regulatory (StAR) protein expression and 11β-hydroxylase activity in adrenal for male adult offspring. In summary, NP exposure during developmental period bestowed F(1) generation with hyperadrenalism and its consequence of metabolic syndrome.

Fatty Acid Oxidation and Cardiovascular Risk during Menopause: A Mitochondrial Connection?

Menopause is a consequence of the normal aging process in women. This fact implies that the physiological and biochemical alterations resulting from menopause often blur with those from the aging process. It is thought that menopause in women presents a higher risk for cardiovascular disease although the precise mechanism is still under discussion. The postmenopause lipid profile is clearly altered, which can present a risk factor for cardiovascular disease. Due to the role of mitochondria in fatty acid oxidation, alterations of the lipid profile in the menopausal women will also influence mitochondrial fatty acid oxidation fluxes in several organs. In this paper, we propose that alterations of mitochondrial bioenergetics in the heart, consequence from normal aging and/or from the menopausal process, result in decreased fatty acid oxidation and accumulation of fatty acid intermediates in the cardiomyocyte cytosol, resulting in lipotoxicity and increasing the cardiovascular risk in the menopausal women.

Estrogen sulfotransferase inhibits adipocyte differentiation

The estrogen sulfotransferase (EST) is a phase II drug-metabolizing enzyme known to catalyze the sulfoconjugation of estrogens. EST is highly expressed in the white adipose tissue of male mice, but the role of EST in the development and function of adipocytes remains largely unknown. In this report, we showed that EST played an important role in adipocyte differentiation. EST was highly expressed in 3T3-L1 preadipocytes and primary mouse preadipocytes. The expression of EST was dramatically reduced in differentiated 3T3-L1 cells and mature primary adipocytes. Overexpression of EST in 3T3-L1 cells prevented adipocyte differentiation. In contrast, preadipocytes isolated from EST knockout (EST-/-) mice exhibited enhanced differentiation. The inhibitory effect of EST on adipogenesis likely resulted from the sustained activation of ERK1/2 MAPK and inhibition of insulin signaling, leading to a failure of switch from clonal expansion to differentiation. The enzymatic activity of EST was required for the inhibitory effect of EST on adipogenesis, because an enzyme-dead EST mutant failed to inhibit adipocyte differentiation. In vivo, overexpression of EST in the adipose tissue of female transgenic mice resulted in smaller adipocyte size. Taken together, our results suggest that EST functions as a negative regulator of adipogenesis.

Acylation stimulating protein: a female lipogenic factor?

Acylation stimulating protein (ASP) is a potent lipogenic factor produced from adipocytes. Plasma ASP levels were shown to increase in obesity, diabetes mellitus type II and dyslipidemia, and decrease after weight loss and fasting. Growing evidence suggests that ASP may significantly contribute to subcutaneous fat storage in females. In vitro, ASP stimulated triglyceride synthesis to a larger extent in subcutaneous compared with omental adipocytes. The ASP receptor binding affinity to plasma membranes prepared from adipose tissue showed higher binding affinity to plasma membranes from female adipose tissue compared with male adipose tissue, and was more pronounced to subcutaneous compared with omental plasma membranes. Human studies demonstrated that postprandial triglyceride clearance predicted by ASP levels was more efficient in women than in men. In mice, postprandial triglyceride clearance, with intraperitoneal ASP administration, was faster in females compared with males. The ASP deficient mice were resistant to weight gain and had reduced fat mass that was more pronounced in females. Recent findings in humans and mice point to a significant association between progesterone and ASP variations in females. In this review, we highlight findings, to date, linking ASP to physiological and hormonal alterations that may contribute to subcutaneous fat distribution typical to females.

Metabolic impact of estrogen signalling through ERalpha and ERbeta

Estrogens, acting on both estrogen receptors alpha (ERalpha) and beta (ERbeta) are recognized as important regulators of glucose homeostasis and lipid metabolism. ERs belong to the family of nuclear hormone receptors which mainly act as ligand activated transcription factors. Both ERs are expressed in metabolic tissue such as adipose tissue, skeletal muscle, liver and pancreas, as well as in the central nervous system. Expression pattern of both ERs differ between species, sexes, and specific tissues. The present review will focus on the key effects of ERs on glucose- and lipid metabolism. It appears that ERalpha mainly mediates beneficial metabolic effects of estrogens such as anti-lipogenesis, improvement of insulin sensitivity and glucose tolerance, and reduction of body weight/fat mass. In contrast, ERbeta activation seems to be detrimental for the maintenance of regular glucose and lipid homeostasis. Metabolic actions of both receptors in relevant tissues will be discussed.

Impact of walking on adipose tissue lipoprotein lipase activity and expression in pre- and postmenopausal women

OBJECTIVE

The aim of this study was to examine regional variation in adipose tissue lipoprotein lipase (AT-LPL) activity and expression in pre-and postmenopausal women, before and after training, once differences in chronological age or obesity degree are taken into account.

METHODS

Sixteen late pre- and 14 early postmenopausal (49 +/- 2 vs. 52 +/- 2 years; p < 0.001) moderately obese women (body mass index 29-35 kg/m(2)) were subjected to a 16-week walking program (3 sessions/week of 45 min at 60% heart rate reserve). Abdominal and femoral AT-LPL activity and expression, fasting lipid-lipoprotein profile, body composition, and cardiorespiratory fitness (CRF) were measured before and after our intervention. Statistical analyses were performed using covariance analysis for age differences.

RESULTS

AT-LPL activity and expression, lipid-lipoprotein metabolism, body fatness, and CRF were similar at baseline, irrespective of the group considered. Slight reductions in plasma cholesterol and high-density lipoprotein (HDL) cholesterol levels, fat mass and waist girth reductions, CRF increases as well as femoral AT-LPL activity and expression decreases after our intervention were comparable, regardless of menopausal status (0.0001 < p < 0.05).

CONCLUSIONS

Lipid storage is decreased in the femoral depot after walking, regardless of menopausal status. Reduction in AT-LPL activity or expression does not lead to a more deleterious lipid-lipoprotein profile, despite the modest decrease noted in HDL cholesterol concentrations.

Differential estrogenic 17beta-hydroxysteroid dehydrogenase activity and type 12 17beta-hydroxysteroid dehydrogenase expression levels in preadipocytes and differentiated adipocytes

Estradiol (E2) is produced locally in adipose tissue and could play an important role in fat distribution and accumulation, especially in women. It is well recognized that aromatase is expressed in adipose tissue; however the identity of its estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD) partner is not identified. To gain a better knowledge about the enzyme responsible for the conversion of estrone into estradiol, we determined the activity and expression levels of known estrogenic 17beta-HSDs, namely types 1, 7 and 12 17beta-HSD in preadipocytes before and after differentiation into mature adipocytes using an adipogenic media. Estrogenic 17beta-HSD activity was assessed using [(14)C]-labelled estrone, while mRNA expression levels of types 1, 7 and 12 17beta-HSD were quantified using real-time PCR and protein expression levels of type 12 17beta-HSD was determined using immunoblot analysis. The data indicate that there is a low conversion of E1 into E2 in preadipocytes; however this activity is increased approximately 5-fold (p<0.0001) in differentiated adipocytes. The increased estrogenic 17beta-HSD activity is consistent with the increase in protein expression levels of 17beta-HSD12.

Does oestrogen allow women to store fat more efficiently? A biological advantage for fertility and gestation

In normal healthy-weight humans, women have a higher percentage body fat than men, a difference that commences at puberty and continues throughout adult life, suggesting that the mechanism is related to sex steroids. The first half of pregnancy is also a stage of body fat gain in women. From an energy balance point, there is no explanation why women should be fatter than men, as the latter consume more calories proportionately. Moreover, women store fat in early pregnancy when caloric intake does not significantly change. The aim of this review is to focus on evidence supporting one mechanism that may account for these findings. That is, oestrogen reduces postprandial fatty acid oxidation leading to an increase in body fat which may account for the greater fat mass observed in women compared with men and the fat gain in early pregnancy. Therefore, female puberty and early pregnancy could be seen as states of efficient fat storage of energy in preparation for fertility, foetal development and lactation providing an obvious biological advantage. Further research into this mechanism of fat storage may provide further insights into the regulation of body fat.

Pathways of adipose tissue androgen metabolism in women: depot differences and modulation by adipogenesis

The objective was to examine pathways of androgen metabolism in abdominal adipose tissue in women. Abdominal subcutaneous (SC) and omental (OM) adipose tissue samples were surgically obtained in women. Total RNA was isolated from whole adipose tissue samples and from primary preadipocyte cultures before and after induction of differentiation. Expression levels of several steroid-converting enzyme transcripts were examined by real-time RT-PCR. Androgen conversion rates were also measured. We found higher expression levels in SC compared with OM adipose tissue for type 1 3beta-hydroxysteroid dehydrogenase (3beta-HSD-1; P < 0.05), for aldo-keto reductase 1C3 (AKR1C3; P < 0.0001), for AKR1C2 (P < 0.0001), and for the androgen receptor (P < 0.0001). 17beta-HSD-2 mRNA levels were lower in SC adipose tissue (P < 0.05). Induction of adipocyte differentiation led to significantly increased expression levels in SC cultures for AKR1C3 (4.7-fold, P < 0.01), 11-cis-retinol dehydrogenase (6.9-fold, P < 0.02), AKR1C2 (5.6-fold, P < 0.004), P-450 aromatase (5.7-fold, P < 0.02), steroid sulfatase (3.1-fold, P < 0.02), estrogen receptor-beta (11.8-fold, P < 0.01), and the androgen receptor (4.0-fold, P < 0.0005). Generally similar but nonsignificant trends were obtained in OM cultures. DHT inactivation rates increased with differentiation, this effect being mediated by dexamethasone alone, through a glucocorticoid receptor-dependent mechanism. In conclusion, higher mRNA levels of enzymes synthesizing and inactivating androgens are found in differentiated adipocytes, consistent with higher androgen-processing rates in these cells. Glucocorticoid-induced androgen inactivation may locally modulate the exposure of adipose cells to active androgens.

Adiponectin isoform distribution in women--relationship to female sex steroids and insulin sensitivity

Little is known about the associations between adiponectin and its oligomeric isoforms with female sex steroids, and the relevance of these relationships to insulin sensitivity in women. In a cross-sectional study of 32 healthy women (12 premenopausal, 10 postmenopausal, and 10 early pregnant), we investigated the correlations of total adiponectin and the high-, medium-, and low-molecular weight oligomers (HMW, MMW, and LMW, respectively) with estrogen, progesterone, adiposity, and insulin resistance. Fat mass and serum concentrations of estradiol, progesterone, insulin, glucose, and total and isoform adiponectin were measured. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Serum concentrations of total and HMW adiponectin were highest in postmenopausal women and lowest in pregnant women. Concentrations of the MMW and LMW isoforms were not significantly different between the 3 groups. Total adiponectin, HMW adiponectin, and MMW adiponectin were negatively associated with estradiol and progesterone; but no associations between the LMW isoform and female sex steroids were observed. Fat mass and HOMA-IR were highest in pregnant women and lowest in premenopausal women. The HOMA-IR was positively associated with fat mass, estradiol, and progesterone, and negatively associated with total, HMW, and MMW adiponectin. Multivariate stepwise regression analysis revealed that fat mass explained 34% of the variance in HOMA-IR and that total and isoform adiponectin contributed an additional 10% to 15%. In the multivariate linear regression analysis, there were significant interactions of estradiol and progesterone with adiponectin or fat mass in the associations with HOMA-IR. In conclusion, there are strong negative associations of serum adiponectin and some of its isoforms with estradiol and progesterone. Female sex steroids are likely to affect insulin sensitivity through modulation of adiponectin and body fat.