The role of estrogens in control of energy balance and glucose homeostasis

Sex-dependent Depot Differences in Adipose Tissue Development and Function; Role of Sex Steroids

Men and women are different in their fat mass and distribution pattern. The gynoid-type fat distribution, accumulation in lower-body, is considered to be protective while the android-type accumulation in upper-body, both in abdominal subcutaneous and visceral depots, is detrimental. Sex-dependent depot differences in adipose metabolic and endocrine functions are thought to contribute to the sexual disparity in fat distribution as well as its association with cardiometabolic risks. Although molecular details have not been completely elucidated, available evidence shows that sex steroid hormones are important factors governing sexual dimorphism in adipose tissue distribution and hence, risks for metabolic diseases. We will review sex-dependent heterogeneities in adipose tissue properties that can link their depot-specific biology to metabolic complications in men and women. In addition, we will also review how sex steroids regulate adipose tissue biology, both development and functional characteristics, with emphasis on their depot-dependent actions.

Association of smoking with prevalence of common diseases and metabolic abnormalities in community-dwelling Japanese individuals

Smoking is a significant risk factor for cardiovascular diseases (CVDs). Given that certain common pathologies, including hypertension, dyslipidemia and type 2 diabetes mellitus, are major risk factors for CVDs, the association of smoking with CVDs may be attributable, at least in part, to its effects on common diseases. The aim of the present study was to determine the association of smoking with the prevalence of common diseases and metabolic abnormalities in community-dwelling Japanese individuals. The study included 5,959 subjects (1,302 current smokers, 1,418 past smokers and 3,239 nonsmokers) recruited to the Inabe Health and Longevity Study, a longitudinal genetic epidemiological study of atherosclerotic, cardiovascular and metabolic diseases. Various metabolic parameters and prevalence of common diseases were compared between smokers and nonsmokers using multivariable regression or logistic regression analysis with adjustments for age. Analysis indicated significantly higher serum concentrations of triglycerides and lower concentrations of high-density lipoprotein (HDL)-cholesterol in current smokers compared with nonsmokers in men and women. Serum concentrations of creatinine and systolic blood pressure were significantly lower and estimated glomerular filtration rate was higher in male current smokers. In addition, body weight was higher in female current smokers. In multivariable logistic regression analysis, smoking was significantly associated with the prevalence of dyslipidemia [P=6.3×10^-10; odds ratio (OR), 1.81], hypertriglyceridemia (P=2.3×10^-20; OR, 2.39), hypo-HDL-cholesterolemia (P=2.0×10^-9; OR, 2.14), metabolic syndrome (P=0.0003; OR, 1.61) and chronic kidney disease (P=4.4×10^-15; OR, 0.54) in men, but not in women. The results indicated that smoking is significantly associated with various metabolic abnormalities and prevalence of common diseases in Japanese individuals, with certain sex differences, which may lead to accelerated development of CVDs.

Effects of a standard high-fat diet with or without multiple deficiencies on bone parameters in ovariectomized mature rat

The aim of this study was to determine the effects of a standard high fat diet (D12451) with or without vitamin D3, phosphorus, and calcium (i.e., high-fat diet [HFD] or high-fat deficient diet [HFDD]) on the bone parameters of ovariectomized female rats. Six-month-old of female Sprauge Dawley (SD) rats were randomly divided into six study groups: sham operation with standard chow diet (SSCD), sham operation with a HFD (SHFD), sham operation with a HFDD (SHFDD), ovariectomized (OVX), OVX with a HFD (OVX-HFD), and OVX with a HFDD (OVX-HFDD). A bilateral ovariectomy was administered to the OVX, OVX-HFD, and OVX-HFDD rats, while the SSCD, SHFD, and SHFDD rats were only given a laparotomy. Multiple analyses concerning the glucose and insulin tolerance, structure, bone strength, bone matrix, and mineralization of the rats were conducted in order to produce a detailed characterization of the effects of a HFD and a HFDD on postmenopausal osteoporotic rats. Seven months of HFD and HFDD feeding resulted in obesity and insulin resistance in female SD rats. A standard HFD increased the bone calcium content and bone strength of OVX rats. Conversely, the serum N-mid osteocalcin (N-MID-OT) and tartrate-resistant acid phosphatase (TRAP) levels in the OVX-HFDD group were increased, accompanied by a clear decrease in the bone mineral density (BMD), bone mineral content (BMC), bone calcium and bone strength, as well as reduced osteocalcin expression. A HFDD weakened the activity of the osteoblasts while aggravating bone loss and decreasing bone strength in ovariectomized rats, which may be due to the calcium, phosphorus and vitamin D3 deficiencies in the diet.

The effects of 17 alpha-estradiol to inhibit inflammation in vitro

Background

17 Alpha-estradiol (17 α-E2) is a natural, non-feminizing stereoisomer of 17 beta-estradiol (17 β-E2). Whereas much is known about the physiological effects of 17 β-E2, much less is known about 17 α-E2. For example, 17 β-E2 exerts anti-inflammatory effects in neurons and adipocytes through binding and activation of estrogen receptor alpha (ERα); however, if 17 α-E2 has similar effects on inflammation is currently unknown.

Methods

To begin to address this, we analyzed the ability of 17 α-E2 and 17 β-E2 to suppress lipopolysaccharide (LPS)-induced inflammation in vitro using embryonic fibroblast cells (MEF) from wild type and total body ERα (ERKO) male and female mice. Additionally, we further probed if there were sex differences with respect to the effects of E2s using primary pre-adipocyte cells from C57BL/6J male and female mice. Also, we probed mechanistically the effects of E2s in fully differentiated 3T3-L1 cells.

Results

Both E2s decreased LPS-induced markers of inflammation Tnf-α and Il-6, and increased the anti-inflammatory markers Il-4 and IL-6 receptor (Il-6ra) in MEF cells. To begin to understand the mechanisms by which both E2’s mediate their anti-inflammatory effects, we probed the role of ERα using two methods. First, we used MEF cells from ERKO mice and found reductions in ERα diminished the ability of 17 α-E2 to suppress Tnf-α in female but not in male cells, demonstrating a sexual dimorphism in regard to the role of ERα to mediate 17 α-E2’s effects. Second, we selectively reduced the expression of ERα in 3T3-L1 cells using siRNA and found reductions in ERα diminished the ability of both E2s to suppress Tnf-α and Il-6 expression. Lastly, to determine the mechanisms by which E2s reduce inflammation, we explored the role of NFκB-p65 and found both E2s decreased NFκB-p65 expression.

Conclusions

In conclusion, we demonstrate for the first time that 17 α-E2, as well as 17 β-E2, suppresses inflammation through their effects on ERα and NFκB-p65.

Electronic supplementary material

The online version of this article (10.1186/s13293-017-0151-9) contains supplementary material, which is available to authorized users.

Effect of Soy and Soy Isoflavones on Obesity-Related Anthropometric Measures: A Systematic Review and Meta-analysis of Randomized Controlled Clinical Trials

Soy may be a suitable food for anti-obesity efforts because of its high protein and isoflavone content. We conducted this meta-analysis to evaluate potential effects of soy and soy isoflavones on weight, waist circumference, and fat mass. PubMed, MEDLINE, Scopus, EMBASE, and Cochrane databases were searched. Twenty-four trials with soy and 17 trials with isoflavones passed the eligibility stage. According to the results, soy showed no overall statistically significant effect on weight, waist circumference, or fat mass, but a significant increasing effect on weight was observed in some circumstances: for instance, in obese subjects [mean difference (MD): 0.80 kg; 95% CI: 0.15, 1.45 kg; P = 0.02], with ingestions of ≥40 g soy protein/d (MD: 0.94 kg; 95% CI: 0.11, 1.77 kg; P = 0.03), with short-term applications (1-3 mo) (MD: 0.45 kg; 95% CI: 0.05, 0.86 kg; P = 0.03), and when soy was compared with meat (MD: 0.36 kg; 95% CI: 0.09, 0.64 kg; P = 0.03) and whey protein (MD: 1.53 kg; 95% CI: 0.10, 2.96 kg; P = 0.04). In contrast to the effects of soy on weight, soy significantly decreased waist circumference in older ages (MD: -0.36 cm; 95% CI: -0.71, -0.01 cm; P = 0.04), in women (MD: -0.32 cm; 95% CI: -0.57, -0.08 cm; P = 0.01), and at doses of <40 g soy protein/d (MD: -0.31 cm; 95% CI: -0.57, -0.05 cm; P = 0.02). Isoflavone studies, conducted only in women, showed that isoflavones may reduce body mass index (BMI; in kg/m2) (MD: -0.26; 95% CI: -0.55, 0.04; P = 0.085), especially in dosages <100 mg/d (MD: -0.48; 95% CI: -0.90, -0.06; P = 0.02) and in intervention periods of 2-6 mo (MD: -0.28; 95% CI: -0.56, 0.00; P = 0.053), but no effect was observed in higher doses or longer intervention periods. Also, a trend for reduced BMI after consumption of isoflavones was observed in Caucasians (MD: -0.35; 95% CI: -0.74, 0.04; P = 0.08). Overall, results showed that, although soy is the major source of isoflavones, soy and isoflavones may have different impacts on weight status.

Discriminative control by deprivation states and external cues in male and female rats

Previous research indicates that decisions about when to eat in response to food cues in the environment are based on interoceptive energy states (i.e., hunger and fullness) and learning about and remembering prior eating experiences. However, this animal model has exclusively been tested on male rodents. Despite evidence that women are more susceptible to obesity and cognitive disorders associated with excess weight (e.g., Alzheimer's disease) than men, the generality of these findings with males to females remains unknown. To address this gap, the current research investigated associative learning mechanisms involved in food intake control in females by training both males and females in a Pavlovian deprivation discrimination in which varying levels of food deprivation are trained with competitive external cues to signal reward. In Experiment 1, male and female rats showed similar performance in discriminating between 0 and 24h deprivation state/external cue compounds and in subsequent tests, confirming stimulus control by deprivation states. Experiment 2 assessed learning about more ecologically valid 0 and 4h deprivation states in competition with external cues in both males and females. With the low-level deprivation state parameters, females outperformed males in discriminative control by deprivation states, particularly on the contingency rewarded under satiation and not deprivation. While females showed an enhanced degree of energy state processing under some deprivation conditions, overall, these findings suggest similar mechanisms of learned appetitive control in both sexes.

Gender differences in glucose homeostasis and diabetes

Some aspects of glucose homeostasis are regulated differently in males and females. This review discusses the most fundamental gender differences in glucose homeostasis and diabetes. These include the prevalence of impaired fasting glucose and impaired glucose tolerance, the prevalence and incidence of type 2 and type 1 diabetes, and the sex-specific effects of testosterone and estrogen deficiency and excess. These gender-specific differences in glucose homeostasis represent a source of factors that should be studied to develop gender-based therapeutic avenues for diabetes.

Estradiol modulates neural response to conspecific and heterospecific song in female house sparrows: An in vivo positron emission tomography study

Although there is growing evidence that estradiol modulates female perception of male sexual signals, relatively little research has focused on female auditory processing. We used in vivo 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) imaging to examine the neuronal effects of estradiol and conspecific song in female house sparrows (Passer domesticus). We assessed brain glucose metabolism, a measure of neuronal activity, in females with empty implants, estradiol implants, and empty implants ~1 month after estradiol implant removal. Females were exposed to conspecific or heterospecific songs immediately prior to imaging. The activity of brain regions involved in auditory perception did not differ between females with empty implants exposed to conspecific vs. heterospecific song, but neuronal activity was significantly reduced in females with estradiol implants exposed to heterospecific song. Furthermore, our within-individual design revealed that changes in brain activity due to high estradiol were actually greater several weeks after peak hormone exposure. Overall, this study demonstrates that PET imaging is a powerful tool for assessing large-scale changes in brain activity in living songbirds, and suggests that after breeding is done, specific environmental and physiological cues are necessary for estradiol-stimulated females to lose the selectivity they display in neural response to conspecific song.

Sex Steroid Hormones Regulate Leptin Transcript Accumulation and Protein Secretion in 3T3-L1 Cells

Leptin is an adipokine produced by fat cells that regulates food consumption and metabolic activity. Sexual dimorphism in leptin and fat stores have been observed in humans and rodents with females having more leptin and greater levels of subcutaneous fat than males. One potential mechanism leading to this dimorphism is steroid hormone regulated synthesis of transcripts encoding leptin. Identification of direct regulatory mechanisms is difficult in animals or primary adipocytes due to these intertwined dimorphisms. We used well-characterized 3T3-L1 murine adipocytes to demonstrate that dihydrotestosterone (DHT) reduced Leptin (Lep) transcript abundance and cytosolic and secreted leptin protein. The magnitude of this effect was greatest on secreted leptin, which was decreased by DHT to 30% of the control. In contrast, 17β-estradiol significantly increased the abundance of transcripts encoding leptin and increased secreted leptin to 230% of the control. Treatment with estrogen and androgen receptor antagonists had opposite effects on Lep transcript abundance to steroid treatments, indicating that these transcriptional effects are mediated through the canonical steroid hormone signaling pathways. These results indicate that short-term treatments with steroid hormones are sufficient to alter both Lep transcript accumulation and leptin protein secretion, and may play a role in the sexual dimorphism of this adipokine.

Lack of Ovarian Secretions Reverts the Anabolic Action of Olanzapine in Female Rats

BACKGROUND

Olanzapine is an orexigenic antipsychotic drug associated with serious metabolic adverse effects in humans. Development of valid rodent models for antipsychotic-induced metabolic adverse effects is hampered by the fact that such effects occur in females only. Estradiol is a predominant female hormone that regulates energy balance. We hypothesized that the female-specific hyperphagia and weight gain induced by olanzapine in the rat are dependent on the presence of estrogens.

METHODS

Female sham-operated or ovariectomized rats were treated with a single injection of olanzapine depot formulation. Food intake, body weight, plasma lipids, lipogenic gene expression, energy expenditure, and thermogenic markers including brown adipose tissue uncoupling protein 1 protein levels were measured. Olanzapine was also administered to ovariectomized rats receiving estradiol replacement via the subcutaneous (peripheral) or intracerebroventricular route.

RESULTS

Orexigenic effects of olanzapine were lost in ovariectomized female rats. Ovariectomized rats treated with olanzapine had less pronounced weight gain than expected from their food intake. Accordingly, brown adipose tissue temperature and protein levels of uncoupling protein 1 were elevated. Replacement in ovariectomized rats with either peripherally or centrally administered estradiol reduced food intake and body weight. Cotreatment with olanzapine blocked the anorexigenic effect of peripheral, but not central estradiol.

CONCLUSIONS

Our results indicate that the ovarian hormone estradiol plays an important role in olanzapine-induced hyperphagia in female rats and pinpoint the complex effects of olanzapine on the balance between energy intake and thermogenesis.

Loss of ERα partially reverses the effects of maternal high-fat diet on energy homeostasis in female mice

Maternal high-fat diet (HFD) alters hypothalamic developmental programming and disrupts offspring energy homeostasis in rodents. 17β-estradiol (E2) also influences hypothalamic programming through estrogen receptor (ER) α. Therefore, we hypothesized that females lacking ERα would be more susceptible to maternal HFD. To address this question, heterozygous ERα knockout (WT/KO) dams were fed a control breeder chow diet (25% fat) or a semi-purified HFD (45% fat) 4 weeks prior to mating with WT/KO males or heterozygous males with an ERα DNA-binding domain mutation knocked in (WT/KI) to produce WT, ERα KO, or ERα KIKO females lacking ERE-dependent ERα signaling. Maternal HFD increased body weight in WT and KIKO, in part, due to increased adiposity and daytime carbohydrate utilization in WT and KIKO, while increasing nighttime fat utilization in KO. Maternal HFD also increased plasma leptin, IL-6, and MCP-1 in WT and increased arcuate expression of Kiss1 and Esr1 (ERα) and liver expression of G6pc and Pepck in WT and KIKO. Contrary to our hypothesis, these data suggest that loss of ERα signaling blocks the influence of maternal HFD on energy homeostasis, inflammation, and hypothalamic and liver gene expression and that restoration of ERE-independent ERα signaling partially reestablishes susceptibility to maternal HFD.

The Androgen Receptor Supports Tumor Progression After the Loss of Ovarian Function in a Preclinical Model of Obesity and Breast Cancer

The androgen receptor (AR) has context-dependent roles in breast cancer growth and progression. Overall, high tumor AR levels predict a favorable patient outcome, but several studies have established a tumor promotional role for AR, particularly in supporting the growth of estrogen receptor positive (ER-positive) breast cancers after endocrine therapy. Our previous studies have demonstrated that obesity promotes mammary tumor progression after ovariectomy (OVX) in a rat model of postmenopausal breast cancer. Here, we investigated a potential role for AR in obesity-associated post-OVX mammary tumor progression following ovarian estrogen loss. In this model, we found that obese but not lean rats had nuclear localized AR in tumors that progressed 3 weeks after OVX, compared to those that regressed. AR nuclear localization is consistent with activation of AR-dependent transcription. Longer-term studies (8 weeks post-OVX) showed that AR nuclear localization and expression were maintained in tumors that had progressed, but AR expression was nearly lost in tumors that were regressing. The anti-androgen enzalutamide effectively blocked tumor progression in obese rats by promoting tumor necrosis and also prevented the formation of new tumors after OVX. Neither circulating nor mammary adipose tissue levels of the AR ligand testosterone were elevated in obese compared to lean rats; however, IL-6, which we previously reported to be higher in plasma from obese versus lean rats, sensitized breast cancer cells to low levels of testosterone. Our study demonstrates that, in the context of obesity, AR plays a role in driving ER-positive mammary tumor progression in an environment of low estrogen availability, and that circulating factors unique to the obese host, including IL-6, may influence how cancer cells respond to steroid hormones.

Cafeteria diet differentially alters the expression of feeding-related genes through DNA methylation mechanisms in individual hypothalamic nuclei

We evaluated the effect of cafeteria diet (CAF) on the mRNA levels and DNA methylation state of feeding-related neuropeptides, and neurosteroidogenic enzymes in discrete hypothalamic nuclei. Besides, the expression of steroid hormone receptors was analyzed. Female rats fed with CAF from weaning increased their energy intake, body weight, and fat depots, but did not develop metabolic syndrome. The increase in energy intake was related to an orexigenic signal of paraventricular (PVN) and ventromedial (VMN) nuclei, given principally by upregulation of AgRP and NPY. This was mildly counteracted by the arcuate nucleus, with decreased AgRP expression and increased POMC and kisspeptin expression. CAF altered the transcription of neurosteroidogenic enzymes in PVN and VMN, and epigenetic mechanisms associated with differential promoter methylation were involved. The changes observed in the hypothalamic nuclei studied could add information about their differential role in food intake control and how their action is disrupted in obesity.

Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte

The metabolic syndrome (MetS) is defined as a cluster of 3 or more metabolic and cardiovascular risk factors and represents a serious problem for public health. Altered function of adipose tissue has a significant impact on whole-body metabolism and represents a key driver for the development of these metabolic derangements, collectively referred as to MetS. In particular, increased visceral and ectopic fat deposition play a major role in the development of insulin resistance and MetS. A large body of evidence demonstrates that aging and MetS share several metabolic alterations. Of importance, molecular pathways that regulate lifespan affect key processes of adipose tissue physiology, and transgenic mouse models with adipose-specific alterations in these pathways show derangements of adipose tissue and other metabolic features of MetS, which highlights a causal link between dysfunctional adipose tissue and deleterious effects on whole-body homeostasis. This review analyzes adipose tissue-specific dysfunctions, including metabolic alterations that are related to aging, that have a significant impact on the development of MetS.-Armani, A., Berry, A., Cirulli, F., Caprio, M. Molecular mechanisms underlying metabolic syndrome: the expanding role of the adipocyte.

Physiological and brain alterations produced by high-fat diet in male and female rats can be modulated by increased levels of estradiol during critical periods of development

BACKGROUND

Overnutrition due to a high-fat diet (HFD) can increase the vulnerability of the metabolic system to maladjustments. Estradiol has an inhibitory role on food intake and this hormone has demonstrated to be a crucial organizer during brain development.

OBJECTIVE

Our aim was to determine whether increased levels of estradiol in the early postnatal period modulate the alterations in metabolism and brain metabolic circuits produced by overnutrition.

METHODS

Twenty-four male and 24 female Wistar rats were submitted to a HFD (34.9% fat) or a control diet (5% fat) from gestational day 6. From postnatal (P) 6 to P13, both control and HFD groups were administered a s.c. injection of vehicle or estradiol benzoate (0.4 mg/kg), resulting in eight experimental groups (n = 6 in each group). Body weight, food intake and subcutaneous, visceral, and brown fat pads were measured. Agouti-related peptide, neuropeptide Y, orexin, and proopiomelanocortin (POMC) were analyzed by quantitative real-time polymerase chain reaction assay and plasma estradiol levels were measured by ELISA.

RESULTS

Males fed a HFD showed an increase in body weight and the amount of visceral and subcutaneous fat, which was coincident with an increase in the number of kilocalories ingested. Neonatal estradiol treatment restored the body weight and subcutaneous fat of HFD males to control levels. Hypothalamic POMC mRNA levels in HFD females were increased with respect to control females. This increase was reverted with estradiol treatment during development.

DISCUSSION

HFD and estradiol treatment have different effects on males and females. Overnutrition affects physiological parameters, such as body weight, visceral, and subcutaneous fat content, in males, while females present alterations in hypothalamic POMC mRNA levels. Hence, the increase in estradiol levels during a period that is critical for the programing of the feeding system can modulate some of the alterations produced by the continuous intake of high-fat content food.

Gold nanoparticle-based miR155 antagonist macrophage delivery restores the cardiac function in ovariectomized diabetic mouse model

Diabetic cardiomyopathy is a common disease in postmenopausal women, in whom the estrogen deficiency aggravates the pathology. In this study, we have found that estrogen deficiency due to ovariectomy aggravates the inflammation in the hearts of diabetic mice, as depicted by excessive proinflammatory type 1 macrophages (M1) over anti-inflammatory type 2 macrophages (M2). Accordingly, an additional increase of reactive oxygen species, cell apoptosis, cardiac hypertrophy, and fibrosis was observed in the hearts of ovariectomized diabetic mice, in comparison with the diabetes-only group. Significantly, miR155, a potent promoter of M1 polarization, was found to be additionally enhanced in the macrophages and hearts by ovariectomy. Tail vein injection of miR155-AuNP, in which thiol-modified antago-miR155 was covalently conjugated with gold nanoparticle (AuNP), preferentially delivered the nucleic acids into the macrophages via phagocytosis. Together with the increased M2 ratio and reduced inflammation, in vivo delivery of antago-miR155 reduced cell apoptosis and restored the cardiac function. The restoration efficacy of miR155-AuNP was much better than general macrophage depletion by clodrosome. In summary, we revealed that M1/M2 imbalance contributes to the aggravated cardiomyopathy in ovariectomized diabetic mice, and therapeutically reducing miR155 in macrophages by AuNP serves as a promising strategy in improving cardiac function.

Estrogens in Male Physiology

Estrogens have historically been associated with female reproduction, but work over the last two decades established that estrogens and their main nuclear receptors (ESR1 and ESR2) and G protein-coupled estrogen receptor (GPER) also regulate male reproductive and nonreproductive organs. 17β-Estradiol (E2) is measureable in blood of men and males of other species, but in rete testis fluids, E2 reaches concentrations normally found only in females and in some species nanomolar concentrations of estrone sulfate are found in semen. Aromatase, which converts androgens to estrogens, is expressed in Leydig cells, seminiferous epithelium, and other male organs. Early studies showed E2 binding in numerous male tissues, and ESR1 and ESR2 each show unique distributions and actions in males. Exogenous estrogen treatment produced male reproductive pathologies in laboratory animals and men, especially during development, and studies with transgenic mice with compromised estrogen signaling demonstrated an E2 role in normal male physiology. Efferent ductules and epididymal functions are dependent on estrogen signaling through ESR1, whose loss impaired ion transport and water reabsorption, resulting in abnormal sperm. Loss of ESR1 or aromatase also produces effects on nonreproductive targets such as brain, adipose, skeletal muscle, bone, cardiovascular, and immune tissues. Expression of GPER is extensive in male tracts, suggesting a possible role for E2 signaling through this receptor in male reproduction. Recent evidence also indicates that membrane ESR1 has critical roles in male reproduction. Thus estrogens are important physiological regulators in males, and future studies may reveal additional roles for estrogen signaling in various target tissues.

Protective regulation of the ACE2/ACE gene expression by estrogen in human atrial tissue from elderly men

Data from animal experiments and clinical investigations suggest that components of the renin-angiotensin system are markedly affected by sex hormones. However, whether estrogen affects human atrial myocardium has not been investigated yet. In this study, we determined the effects of estrogen on key components of atrial renin-angiotensin system: angiotensin-converting enzyme, responsible for generation of angiotensin II and angiotensin-converting enzyme 2, counteracting majority of AngII effects, and different renin-angiotensin system receptors, AT1R, AT2R, and MAS. First, the expression levels of estrogen receptors mRNA were determined in right atrial appendages obtained from patients undergoing heart surgery. The amounts of estrogen receptor α and estrogen receptor β mRNA were similar between women ( n = 14) and men ( n = 10). Atrial tissue slices (350 µm) were prepared from male donors which were exposed to estrogen (1-100 nM; n = 21) or stimulated at 4 Hz for 24 h in the presence or absence of 100 nM estrogen ( n = 16), respectively. The administration of estrogen did not change mRNA levels of estrogen receptors, but activated MAP kinases, Erk1/2. Furthermore, estrogen increased the amounts of angiotensin-converting enzyme 2-mRNA (1.89 ± 0.23; P < 0.05) but reduced that of angiotensin-converting enzyme-mRNA (0.78 ± 0.07, P < 0.05). In addition, the transcript levels of AT2R and MAS were upregulated by estrogen. Pacing of tissue slices significantly increased the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at both the mRNA and protein level. During pacing, administration of estrogen substantially lowered the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at the transcript (0.92 ± 0.21 vs. 2.12 ± 0.27 at 4 Hz) and protein level (0.94 ± 0.20 vs. 2.14 ± 0.3 at 4 Hz). Moreover, estrogen elicited anti-inflammatory and anti-oxidative effects on renin-angiotensin system-associated downstream effectors such as pro-oxidative LOX-1 and pro-inflammatory ICAM-1. An antagonist of estrogen receptor α reversed these anti-inflammatory and anti-oxidative effects of estrogen significantly. Overall, our results demonstrated that estrogen modifies the local renin-angiotensin system homeostasis and achieves protective effects in atrial myocardium from elderly men. Impact statement The present study demonstrates that estrogen affects the human atrial myocardium and mediates protective actions through estrogen receptors-(ER) dependent signaling. Estrogen substantially modulates the local RAS via downregulation of ACE and simultaneous upregulation of ACE2, AT2R and MAS expression levels. This is indicative of a shift of the classical RAS/ACE axis to the alternative, protective RAS/ACE2 axis. In support of this view, estrogen attenuated the expression of RAS-associated downstream effectors, LOX-1, and ICAM-1. A specific antagonist of ERα reversed the anti-inflammatory and anti-oxidative effects of estrogen in paced and non-paced atrial tissue slices. In summary, our data demonstrate the existence of protective effects of estrogen in atrial tissue from elderly men which are at least in part, mediated by the regulation of local RAS homeostasis.

Association of maternal weight with FADS and ELOVL genetic variants and fatty acid levels- The PREOBE follow-up

Single nucleotide polymorphisms (SNPs) in the genes encoding the fatty acid desaturase (FADS) and elongase (ELOVL) enzymes affect long-chain polyunsaturated fatty acid (LC-PUFA) production. We aimed to determine if these SNPs are associated with body mass index (BMI) or affect fatty acids (FAs) in pregnant women. Participants (n = 180) from the PREOBE cohort were grouped according to pre-pregnancy BMI: normal-weight (BMI = 18.5–24.9, n = 88) and overweight/obese (BMI≥25, n = 92). Plasma samples were analyzed at 24 weeks of gestation to measure FA levels in the phospholipid fraction. Selected SNPs were genotyped (7 in FADS1, 5 in FADS2, 3 in ELOVL2 and 2 in ELOVL5). Minor allele carriers of rs174545, rs174546, rs174548 and rs174553 (FADS1), and rs1535 and rs174583 (FADS2) were nominally associated with an increased risk of having a BMI≥25. Only for the normal-weight group, minor allele carriers of rs174537, rs174545, rs174546, and rs174553 (FADS1) were negatively associated with AA:DGLA index. Normal-weight women who were minor allele carriers of FADS SNPs had lower levels of AA, AA:DGLA and AA:LA indexes, and higher levels of DGLA, compared to major homozygotes. Among minor allele carriers of FADS2 and ELOVL2 SNPs, overweight/obese women showed higher DHA:EPA index than the normal-weight group; however, they did not present higher DHA concentrations than the normal-weight women. In conclusion, minor allele carriers of FADS SNPs have an increased risk of obesity. Maternal weight changes the effect of genotype on FA levels. Only in the normal-weight group, minor allele carriers of FADS SNPs displayed reduced enzymatic activity and FA levels. This suggests that women with a BMI≥25 are less affected by FADS genetic variants in this regard. In the presence of FADS2 and ELOVL2 SNPs, overweight/obese women showed higher n-3 LC-PUFA production indexes than women with normal weight, but this was not enough to obtain a higher n-3 LC-PUFA concentration.

A Guide for the Design of Pre-clinical Studies on Sex Differences in Metabolism

In animal models, the physiological systems involved in metabolic homeostasis exhibit a sex difference. Investigators often use male rodents because they show metabolic disease better than females. Thus, females are not used precisely because of an acknowledged sex difference that represents an opportunity to understand novel factors reducing metabolic disease more in one sex than the other. The National Institutes of Health (NIH) mandate to consider sex as a biological variable in preclinical research places new demands on investigators and peer reviewers who often lack expertise in model systems and experimental paradigms used in the study of sex differences. This Perspective discusses experimental design and interpretation in studies addressing the mechanisms of sex differences in metabolic homeostasis and disease, using animal models and cells. We also highlight current limitations in research tools and attitudes that threaten to delay progress in studies of sex differences in basic animal research.

The effects of oestrogens and their receptors on cardiometabolic health

Cardiovascular disease (CVD) is one of the leading causes of mortality in developed countries. The incidence of CVD is sexually dimorphic, and research has focused on the contribution of sex steroids to the development and progression of the cardiometabolic syndrome, which is defined as a clustering of interrelated risk factors that promote the development of atherosclerosis (which can lead to CVD) and type 2 diabetes mellitus. Data are inconclusive as to how sex steroids and their respective receptors increase or suppress the risk of developing the cardiometabolic syndrome and thus CVD. In this Review, we discuss the potential role, or roles, of sex hormones in cardiometabolic health by first focusing on the influence of oestrogens and their receptors on the risk of developing cardiometabolic syndrome and CVD. We also highlight what is known about testosterone and its potential role in protecting against the development of the cardiometabolic syndrome and CVD. Given the inconclusive nature of the data regarding the direct effects of each sex hormone, we advocate and highlight the importance of studying the relative levels and the ratio of sex hormones to each other, as well as the use of cross sex hormone therapy and its effect on cardiometabolic health.

Id1 Promotes Obesity by Suppressing Brown Adipose Thermogenesis and White Adipose Browning

Obesity results from increased energy intake or defects in energy expenditure. Brown adipose tissue (BAT) is specialized for energy expenditure, a process called adaptive thermogenesis. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) controls BAT-mediated thermogenesis by regulating the expression of Ucp1 Inhibitor of differentiation 1 (Id1) is a helix-loop-helix transcription factor that plays an important role in cell proliferation and differentiation. We demonstrate a novel function of Id1 in BAT thermogenesis and programming of beige adipocytes in white adipose tissue (WAT). We found that adipose tissue-specific overexpression of Id1 causes age-associated and high-fat diet-induced obesity in mice. Id1 suppresses BAT thermogenesis by binding to and suppressing PGC1α transcriptional activity. In WAT, Id1 is mainly localized in the stromal vascular fraction, where the adipose progenitor/precursors reside. Lack of Id1 increases beige gene and Ucp1 expression in the WAT in response to cold exposure. Furthermore, brown-like differentiation is increased in Id1-deficient mouse embryonic fibroblasts. At the molecular level, Id1 directly interacts with and suppresses Ebf2 transcriptional activity, leading to reduced expression of Prdm16, which determines beige/brown adipocyte cell fate. Overall, the study highlights the existence of novel regulatory mechanisms between Id1/PGC1α and Id1/Ebf2 in controlling brown fat metabolism, which has significant implications in the treatment of obesity and its associated diseases, such as diabetes.

Menopausal Hormone Therapy and Type 2 Diabetes Prevention: Evidence, Mechanisms, and Clinical Implications

Type 2 diabetes has reached epidemic proportions in the United States. Large, randomized controlled trials suggest that menopausal hormone therapy (MHT) delays the onset of type 2 diabetes in women. However, the mechanisms and clinical implications of this association are still a matter of controversy. This review provides an up-to-date analysis and integration of epidemiological, clinical, and basic studies, and proposes a mechanistic explanation for the effect of menopause and MHT on type 2 diabetes development and prevention. We discuss the beneficial effects of endogenous estradiol with respect to insulin secretion, insulin sensitivity, and glucose effectiveness; we also discuss energy expenditure and adipose distribution, both of which are affected by menopause and improved by MHT, which thereby decreases the incidence of type 2 diabetes. We reconcile differences among studies that investigated the effect of menopause and MHT formulations on type 2 diabetes. We argue that discrepancies arise from physiological differences in methods used to assess glucose homeostasis, ranging from clinical indices of insulin sensitivity to steady-state methods to assess insulin action. We also discuss the influence of the route of estrogen administration and the addition of progestogens. We conclude that, although MHT is neither approved nor appropriate for the prevention of type 2 diabetes due to its complex balance of risks and benefits, it should not be withheld from women with increased risk of type 2 diabetes who seek treatment for menopausal symptoms.

Overweight postmenopausal women with different plasma estradiol concentrations present with a similar pattern of energy expenditure and substrate oxidation rate before and after a fatty meal challenge

Menopause-related withdrawal of ovarian estrogens is associated with reduced energy metabolism and overall impairment of substrate oxidation. Estradiol's withdrawal after menopause is associated with a reduction in energy metabolism and impaired substrate oxidation, which contributes to weight gain and visceral fat accumulation. Here we aimed to investigate the association between plasma estradiol concentrations and energy expenditure (EE)/substrate oxidation in a group of overweight postmenopausal women before and after a fatty meal challenge. Women were divided into three groups according to their plasma estradiol concentrations (E2): group 1 - E₂ ≤ 39, group 2 - 40 ≤ E₂ ≤ 59, and group 3 - E₂ ≥ 60 pg/mL. VO₂ and VCO₂ volumes were collected following indirect calorimetry 5 h following a single lipid overload meal (1100 kcal, 72% of fat). For comparisons between groups and within the same group, a linear regression model with mixed effects was applied (P < 0.05). Forty-four women aged 55 ± 0.7 years-old, 8 ± 1.1 years following menopause, with a BMI of 30.5 ± 0.5 kg/m², and 41.9 ± 0.7% of body fat were enrolled the study. Plasma E2 concentrations were: group 1 - 30.4 ± 1.9, group 2 - 46.9 ± 1.5, and group 3 - 91.3 ± 12.0 pg/mL (P < 0.0001). EE at baseline and in the resting state was 1320 ± 24.3 kcal/d, and increased to 1440 ± 27.0 kcal/d 30 min following ingestion of the fatty meal (P < 0.0001), and rose again to an average of 1475 ± 30.3 kcal/d at the completion of experiment (P < 0.0001). Carbohydrate oxidation (Chox) was 0.155 ± 0.01 g/min at resting, maintained as 0.133 ± 0.00 g/min 30 min after ingestion of the fatty meal, and was 0.123 ± 0.01 g/min at the end of the testing period. Lipid oxidation (Lipox) was 0.041 ± 0.003 g/min at resting, increasing to 0.054 ± 0.003 g/min at 30 min (P = 0.01), and reaching 0.063 ± 0.003 g/min at the end of the experiment (P < 0.0001). There was no difference between groups for EE, Chox or Lipox. Our data suggest that EE and substrate oxidation were modulated following a lipid-meal challenge equally in all groups and this did not differ with plasma E2 concentrations.

SAK-HV Triggered a Short-period Lipid-lowering Biotherapy Based on the Energy Model of Liver Proliferation via a Novel Pathway

The accumulations of excess lipids within liver and serum are defined as non-alcoholic fatty liver disease (NAFLD) and hyperlipemia respectively. Both of them are components of metabolic syndrome that greatly threaten human health. Here, a recombinant fusion protein (SAK-HV) effectively treated NAFLD and hyperlipemia in high-fat-fed ApoE^-/- mice, quails and rats within just 14 days. Its triglyceride and cholesterol-lowering effects were significantly better than that of atorvastatin during the observation period. We explored the lipid-lowering mechanism of SAK-HV by the hepatic transcriptome analysis and serials of experiments both in vivo and in vitro. Unexpectedly, SAK-HV triggered a moderate energy and material-consuming liver proliferation to dramatically decrease the lipids from both serum and liver. We provided the first evidence that PGC-1α mediated the hepatic synthesis of female hormones during liver proliferation, and proposed the complement system-induced PGC-1α-estrogen axis via the novel STAT3-C/EBPβ-PGC-1α pathway in liver as a new energy model for liver proliferation. In this model, PGC-1α ignited and fueled hepatocyte activation as an “igniter”; PGC-1α-induced estrogen augmented the energy supply of PGC-1α as an “ignition amplifier”, then triggered the hepatocyte state transition from activation to proliferation as a “starter”, causing triglyceride and cholesterol-lowering effects via PPARα-mediated fatty acid oxidation and LDLr-mediated cholesterol uptake, respectively. Collectively, the SAK-HV-triggered distinctive lipid-lowering strategy based on the new energy model of liver proliferation has potential as a novel short-period biotherapy against NAFLD and hyperlipemia.

Tissue-specific effects of estrogen on glycerol channel aquaporin 7 expression in an ovariectomized mouse model of menopause

OBJECTIVE

Elevated fat mass and redistribution of body fat are commonly observed in postmenopausal women. Aquaporin 7 (AQP7), a unique glycerol permeable integral membrane protein, has been associated with the onset of obesity. We hypothesized that estrogen supplementation could counteract this fat accumulation and redistribution through tissue-specific modulation of AQP7.

METHODS

We measured fat depot weight, adipocyte size, and the expression of AQP7 and glycerol kinase (GK) in visceral and subcutaneous fat tissues of ovariectomized mice supplemented with or without 17β-estradiol.

RESULTS

Removal of the ovaries resulted in a significant decrease in AQP7 expression and an increase in GK expression in visceral adipocyte tissue; expression of AQP7 and GK in subcutaneous adipose tissue remained unaltered. Supplementation with estrogen significantly restored the visceral, but not subcutaneous, fat depot mass and adipocyte size to those of sham-operated mice. A marked increase in the expression of AQP7 and a reduction of GK were observed selectively in the visceral fat depots in estrogen-treated mice.

CONCLUSIONS

Our results suggest that estrogen has tissue-specific effects on AQP7 expression, and modulation of AQP7 by estrogen alters the balance of adipocyte metabolism between adipose tissue depots.

Risk of Diabetes After Hysterectomy With or Without Oophorectomy in Postmenopausal Women

The aim of this study was to determine the associations between hysterectomy, bilateral salpingo-oophorectomy (BSO), and incidence of diabetes in postmenopausal women participating in the Women's Health Initiative (WHI), a series of trials conducted in the United States, during the period 1993-1998. A total of 67,130 postmenopausal women aged 50-79 years were followed for a mean of 13.4 years. Among them, 7,430 cases of diabetes were diagnosed. Multivariable Cox proportional hazards models were used to assess the association between hysterectomy/oophorectomy status and diabetes incidence. Compared with women without hysterectomy, women with hysterectomy had a significantly higher risk of diabetes (hazard ratio = 1.13, 95% confidence interval: 1.06, 1.21). The increased risk of diabetes was similar for women with hysterectomy only and for women with hysterectomy with concomitant BSO. Compared with hysterectomy alone, hysterectomy with BSO was not associated with additional risk of diabetes after stratification by age at hysterectomy and hormone therapy status. In our large, prospective study, we observed that hysterectomy, regardless of oophorectomy status, was associated with increased risk of diabetes among postmenopausal women. However, our data did not support the hypothesis that early loss of ovarian estrogens is a risk factor for type 2 diabetes. The modest increased risk of diabetes associated with hysterectomy may be due to residual confounding, such as the reasons for hysterectomy.

ANRIL Promoter DNA Methylation: A Perinatal Marker for Later Adiposity

Experimental studies show a substantial contribution of early life environment to obesity risk through epigenetic processes. We examined inter-individual DNA methylation differences in human birth tissues associated with child's adiposity. We identified a novel association between the level of CpG methylation at birth within the promoter of the long non-coding RNA ANRIL (encoded at CDKN2A) and childhood adiposity at age 6-years. An association between ANRIL methylation and adiposity was also observed in three additional populations; in birth tissues from ethnically diverse neonates, in peripheral blood from adolescents, and in adipose tissue from adults. Additionally, CpG methylation was associated with ANRIL expression in vivo, and CpG mutagenesis in vitro inhibited ANRIL promoter activity. Furthermore, CpG methylation enhanced binding to an Estrogen Response Element within the ANRIL promoter. Our findings demonstrate that perinatal methylation at loci relevant to gene function may be a robust marker of later adiposity, providing substantial support for epigenetic processes in mediating long-term consequences of early life environment on human health.

Age- and menopause-related differences in subcutaneous adipose tissue estrogen receptor mRNA expression

OBJECTIVES

Changes in estrogen receptor (ER) expression likely underlie differential metabolic effects of estrogen in pre- and postmenopausal women. The aim of the current study was to determine whether ER gene expression in abdominal and femoral subcutaneous adipose tissue (SAT) was associated with age, menopause, or regional adiposity.

METHODS

We studied pre- and post-menopausal (n=23 and 22, respectively; age 35-65y) normal weight (mean±SD; BMI 23.7±2.5kg/m²) women with similar total fat mass. Abdominal and femoral SAT ERα (ESR1) and ERβ (ESR2) mRNA expression was determined by qPCR.

RESULTS

Total fat mass did not differ between pre- and postmenopausal women (22.7±5.3vs. 21.7±5.3kg). Compared to premenopausal women, ESR1 and the ratio of ESR1 to ESR2 were lower (p≤0.05) in postmenopausal abdominal and femoral SAT. ESR1 and ESR1:ESR2 were inversely associated with age in abdominal SAT (r=-0.380 and r=-0.463, respectively; p<0.05) and femoral SAT (r=-0.353 and r=-0.472, respectively; p<0.05). ESR2 was not related to age or menopause. The inverse association between ESR1 and age persisted after adjusting for trunk fat mass, estradiol, or leptin.

CONCLUSION

Among healthy pre- and postmenopausal women, increased age was associated with a decreased balance of ERα to ERβ in abdominal and femoral subcutaneous adipose tissue.

Sex Hormones and Cardiometabolic Health: Role of Estrogen and Estrogen Receptors

With increased life expectancy, women will spend over three decades of life postmenopause. The menopausal transition increases susceptibility to metabolic diseases such as obesity, diabetes, cardiovascular disease, and cancer. Thus, it is more important than ever to develop effective hormonal treatment strategies to protect aging women. Understanding the role of estrogens, and their biological actions mediated by estrogen receptors (ERs), in the regulation of cardiometabolic health is of paramount importance to discover novel targeted therapeutics. In this brief review, we provide a detailed overview of the literature, from basic science findings to human clinical trial evidence, supporting a protective role of estrogens and their receptors, specifically ERα, in maintenance of cardiometabolic health. In so doing, we provide a concise mechanistic discussion of some of the major tissue-specific roles of estrogens signaling through ERα. Taken together, evidence suggests that targeted, perhaps receptor-specific, hormonal therapies can and should be used to optimize the health of women as they transition through menopause, while reducing the undesired complications that have limited the efficacy and use of traditional hormone replacement interventions.

Melanocortin 4 receptor is not required for estrogenic regulations on energy homeostasis and reproduction

BACKGROUND

Brain estrogen receptor-α (ERα) is essential for estrogenic regulation of energy homeostasis and reproduction. We previously showed that ERα expressed by pro-opiomelanocortin (POMC) neurons mediates estrogen's effects on food intake, body weight, negative regulation of hypothalamic-pituitary-gonadal axis (HPG axis) and fertility.

RESULTS AND CONCLUSIONS

We report here that global deletion of a key downstream receptor for POMC peptide, the melanocortin 4 receptor (MC4R), did not affect normal negative feedback regulation of estrogen on the HPG axis, estrous cyclicity and female fertility. Furthermore, loss of the MC4R did not influence estrogenic regulation on food intake and body weight. These results indicate that the MC4R is not required for estrogen's effects on metabolic and reproductive functions.

Serotonin transporter deficiency drives estrogen-dependent obesity and glucose intolerance

Depression and use of antidepressant medications are both associated with increased risk of obesity, potentially attributed to a reduced serotonin transporter (SERT) function. However, how SERT deficiency promotes obesity is unknown. Here, we demonstrated that SERT^−/− mice display abnormal fat accumulation in both white and brown adipose tissues, glucose intolerance and insulin resistance while exhibiting suppressed aromatase (Cyp19a1) expression and reduced circulating 17β-estradiol levels. 17β-estradiol replacement in SERT^−/− mice reversed the obesity and glucose intolerance, supporting a role for estrogen in SERT deficiency-associated obesity and glucose intolerance. Treatment of wild type mice with paroxetine, a chemical inhibitor of SERT, also resulted in Cyp19a1 suppression, decreased circulating 17β-estradiol levels, abnormal fat accumulation, and glucose intolerance. Such effects were not observed in paroxetine-treated SERT^−/− mice. Conversely, pregnant SERT^−/− mice displayed normalized estrogen levels, markedly reduced fat accumulation, and improved glucose tolerance, which can be eliminated by an antagonist of estrogen receptor α (ERα). Together, these findings support that estrogen suppression is involved in SERT deficiency-induced obesity and glucose intolerance, and suggest approaches to restore 17β-estradiol levels as a novel treatment option for SERT deficiency associated obesity and metabolic abnormalities.

Sequential Exposure to Obesogenic Factors in Females Rats: From Physiological Changes to Lipid Metabolism in Liver and Mesenteric Adipose Tissue

During their lifetime, females are subjected to different nutritional and hormonal factors that could increase the risk of obesity and associated comorbidities. From early postnatal periods until the postmenopausal phase, exposure to over nutrition, high-energy diet and oestrogen deficiency, are considered as significant obesity risk factors in women. In this study, we assessed how key transitional life events and exposure to different nutrition influence energy homeostasis in a rat model. Specifically, we assessed the sequential exposure to postnatal over nutrition, high-fat diet (HFD) after weaning, followed later by ovariectomy (OVX; as a model of menopause). Each obesity risk factor increased significantly body weight (BW) and adiposity, with additive effects after sequential exposure. Increased energy intake in both HFD and/or OVX groups, and decreased locomotor activity and energy expenditure after OVX can explain these metabolic changes. Our study also documents decreased lipogenic pathway in mesenteric adipose tissue after HFD and/or OVX, independent of previous postnatal programming, yet only HFD evoked this effect in liver. In addition, we report an increase in the expression of the hepatic PEPCK depending on previous metabolic status. Overall, our results identify the impact of different risk factors, which will help in understanding the development of obesity in females.

The effect of selective estrogen receptor modulators on type 2 diabetes onset in women: Basic and clinical insights

Selective estrogen receptor modulators (SERMs) are a class of compounds that interact with estrogen receptors (ERs) and exert agonist or antagonist effects on ERs in a tissue-specific manner. Tamoxifen, a first generation SERM, is used for treatment of ER positive breast cancer. Raloxifene, a second generation SERM, was used to prevent postmenopausal osteoporosis. The third-generation SERM bazedoxifene (BZA) effectively prevents osteoporosis while preventing estrogenic stimulation of breast and uterus. Notably, BZA combined with conjugated estrogens (CE) is a new menopausal treatment. The menopausal state predisposes to metabolic syndrome and type 2 diabetes, and therefore the effects of SERMs on metabolic homeostasis are gaining attention. Here, we summarize knowledge of SERMs' impacts on metabolic, homeostasis, obesity and diabetes in rodent models and postmenopausal women.

Modulation of SHBG binding to testosterone and estradiol by sex and morbid obesity

OBJECTIVE

Sex hormone-binding globulin (SHBG) binds and transports testosterone and estradiol in plasma. The possibility that SHBG is a mixture of transporting proteins has been postulated. We analyzed in parallel the effects of obesity status on the levels and binding capacity of circulating SHBG and their relationship with testosterone and estradiol.

DESIGN

Anthropometric measures and plasma were obtained from apparently healthy young (i.e. 35 ± 7 years) premenopausal women (n = 32) and men (n = 30), with normal weight and obesity (BMI >30 kg/m²).

METHODS

SHBG protein (Western blot), as well as the plasma levels of testosterone, estradiol, cortisol and insulin (ELISA) were measured. Specific binding of estradiol and testosterone to plasma SHBG was analyzed using tritium-labeled hormones.

RESULTS

Significant differences in SHBG were observed within the obesity status and gender, with discordant patterns of change in testosterone and estradiol. In men, testosterone occupied most of the binding sites. Estrogen binding was much lower in all subjects. Lower SHBG of morbidly obese (BMI >40 kg/m²) subjects affected testosterone but not estradiol. The ratio of binding sites to SHBG protein levels was constant for testosterone, but not for estradiol. The influence of gender was maximal in morbid obesity, with men showing the highest binding/SHBG ratios.

CONCLUSIONS

The results reported here are compatible with SHBG being a mixture of at least two functionally different hormone-binding globulins, being affected by obesity and gender and showing different structure, affinities for testosterone and estradiol and also different immunoreactivity.

Estradiol effects on hypothalamic AMPK and BAT thermogenesis: A gateway for obesity treatment?

In addition to their prominent roles in the control of reproduction, estrogens are important modulators of energy balance, as evident in conditions of deficiency of estrogens, which are characterized by increased feeding and decreased energy expenditure, leading to obesity. AMP-activated protein kinase (AMPK) is a ubiquitous cellular energy gauge that is activated under conditions of low energy, increasing energy production and reducing energy wasting. Centrally, the AMPK pathway is a canonical route regulating energy homeostasis, by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. As a result of those actions, hypothalamic AMPK modulates feeding, as well as brown adipose tissue (BAT) thermogenesis and browning of white adipose tissue (WAT). Here, we will review the central actions of estrogens on energy balance, with particular focus on hypothalamic AMPK. The relevance of this interaction is noteworthy, because some agents with known actions on metabolic homeostasis, such as nicotine, metformin, liraglutide, olanzapine and also natural molecules, such as resveratrol and flavonoids, exert their actions by modulating AMPK. This evidence highlights the possibility that hypothalamic AMPK might be a potential target for the treatment of obesity.

The Glycolytic Enzyme PFKFB3 Is Involved in Estrogen-Mediated Angiogenesis via GPER1

The endogenous estrogen 17β-estradiol (E2) is a key factor in promoting endothelial healing and angiogenesis. Recently, proangiogenic signals including vascular endothelial growth factor and others have been shown to converge in endothelial cell metabolism. Because inhibition of the glycolytic enzyme activator phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) reduces pathologic angiogenesis and estrogen receptor (ER) signaling stimulates glucose uptake and glycolysis by inducing PFKFB3 in breast cancer, we hypothesized that E2 triggers angiogenesis in endothelial cells via rapid ER signaling that requires PFKFB3 as a downstream effector. We report that treatment with the selective G protein-coupled estrogen receptor (GPER1) agonist G-1 (10^-10 to 10^-7 M) mimicked the chemotactic and proangiogenic effect of E2 as measured in a number of short-term angiogenesis assays in human umbilical vein endothelial cells (HUVECs); in addition, E2 treatment upregulated PFKFB3 expression in a time- and concentration-dependent manner. Such an effect peaked at 3 hours and was also induced by G-1 and abolished by pretreatment with the GPER1 antagonist G-15 or GPER1 siRNA, consistent with engagement of membrane ER. Experiments with the PFKFB3 inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one showed that PFKFB3 activity was required for estrogen-mediated HUVEC migration via GPER1. In conclusion, E2-induced angiogenesis was mediated at least in part by the membrane GPER1 and required upregulation of the glycolytic activator PFKFB3 in HUVECs. These findings unravel a previously unrecognized mechanism of estrogen-dependent endocrine-metabolic crosstalk in HUVECs and may have implications in angiogenesis occurring in ischemic or hypoxic tissues.

Aromatase: Contributions to Physiology and Disease in Women and Men

Aromatase (estrogen synthetase; EC 1.14.14.1) catalyzes the demethylation of androgens' carbon 19, producing phenolic 18-carbon estrogens. Aromatase is most widely known for its roles in reproduction and reproductive system diseases, and as a target for inhibitor therapy in estrogen-sensitive diseases including cancer, endometriosis, and leiomyoma (141, 143). However, all tissues contain estrogen receptor-expressing cells, the majority of genes have a complete or partial estrogen response element that regulates their expression (61), and there are plentiful nonreceptor effects of estrogens (79); therefore, the effect of aromatase through the provision of estrogen is almost universal in terms of health and disease. This review will provide a brief but comprehensive overview of the enzyme, its role in steroidogenesis, the problems that arise with its functional mutations and mishaps, the roles in human physiology of aromatase and its product estrogens, its current clinical roles, and the effects of aromatase inhibitors. While much of the story is that of the consequences of the formation of its product estrogens, we also will address alternative enzymatic roles of aromatase as a demethylase or nonenzymatic actions of this versatile molecule. Although this short review is meant to be thorough, it is by no means exhaustive; rather, it is meant to reflect the cutting-edge, exciting properties and possibilities of this ancient enzyme and its products.

Sex-specific, reciprocal regulation of ERα and miR-22 controls muscle lipid metabolism in male mice

Control of energy homeostasis and metabolism is achieved by integrating numerous pathways, and miRNAs are involved in this process by regulating expression of multiple target genes. However, relatively little is known about the posttranscriptional processing of miRNAs and a potential role for the precursors they derive from. Here, we demonstrate that mature miRNA-22 is more abundant in muscle from male mice relative to females and that this enables sex-specific regulation of muscular lipid metabolism and body weight by repressing estrogen receptor alpha (ERα) expression. We found that the ERα adjusts its own activity by preventing processing of miR-22 via direct binding to a conserved ERα-binding element within the primary miR-22 precursor. Mutation of the ERα binding site within the pri-miR-22 in vivo eliminates sex-specific differences in miR-22 expression. We reason that the resulting tissue selective negative feedback regulation is essential to establish sex-specific differences in muscle metabolism and body weight development.

A Life without Hunger: The Ups (and Downs) to Modulating Melanocortin-3 Receptor Signaling

Melanocortin neurons conserve body mass in hyper- or hypo-caloric conditions by conveying signals from nutrient sensors into areas of the brain governing appetite and metabolism. In mice, melanocortin-3 receptor (MC3R) deletion alters nutrient partitioning independently of hyperphagia, promoting accumulation of fat over muscle mass. Enhanced rhythms in insulin and insulin-responsive metabolic genes during hypocaloric feeding suggest partial insulin resistance and enhanced lipogenesis. However, exactly where and how MC3Rs affect metabolic control to alter nutrient partitioning is not known. The behavioral phenotypes exhibited by MC3R-deficient mice suggest a contextual role in appetite control. The impact of MC3R-deficiency on feeding behavior when food is freely available is minor. However, homeostatic responses to hypocaloric conditioning involving increased expression of appetite-stimulating (orexigenic) neuropeptides, binge-feeding, food anticipatory activity (FAA), entrainment to nutrient availability and enhanced feeding-related motivational responses are compromised with MC3R-deficiency. Rescuing Mc3r transcription in hypothalamic and limbic neurons improves appetitive responses during hypocaloric conditioning while having minor effects on nutrient partitioning, suggesting orexigenic functions. Rescuing hypothalamic MC3Rs also restores responses of fasting-responsive hypothalamic orexigenic neurons in hypocaloric conditions, suggesting actions that sensitize fasting-responsive neurons to signals from nutrient sensors. MC3R signaling in ventromedial hypothalamic SF1(+ve) neurons improves metabolic control, but does not restore appetitive responses or nutrient partitioning. In summary, desensitization of fasting-responsive orexigenic neurons may underlie attenuated appetitive responses of MC3R-deficient mice in hypocaloric situations. Further studies are needed to identify the specific location(s) of MC3Rs controlling appetitive responses and partitioning of nutrients between fat and lean tissues.

Sex differences in obesity: X chromosome dosage as a risk factor for increased food intake, adiposity and co-morbidities

Obesity is a world-wide problem, and a risk factor for cardiovascular disease, diabetes, cancer and other diseases. It is well established that sex differences influence fat storage. Males and females exhibit differences in anatomical fat distribution, utilization of fat stores, levels of adipose tissue-derived hormones, and obesity co-morbidities. The basis for these sex differences may be parsed into the effects of male vs. female gonadal hormones and the effects of XX vs. XY chromosome complement. Studies employing mouse models that allow the distinction of gonadal from chromosomal effects have revealed that X chromosome dosage influences food intake, which in turn affects adiposity and the occurrence of adverse metabolic conditions such as hyperinsulinemia, hyperlipidemia, and fatty liver. The identification of X chromosome dosage as a player in the behavior and physiology related to obesity suggests novel molecular mechanisms that may underlie sex differences in obesity and metabolism.

Metabolism disrupting chemicals and metabolic disorders

The recent epidemics of metabolic diseases, obesity, type 2 diabetes(T2D), liver lipid disorders and metabolic syndrome have largely been attributed to genetic background and changes in diet, exercise and aging. However, there is now considerable evidence that other environmental factors may contribute to the rapid increase in the incidence of these metabolic diseases. This review will examine changes to the incidence of obesity, T2D and non-alcoholic fatty liver disease (NAFLD), the contribution of genetics to these disorders and describe the role of the endocrine system in these metabolic disorders. It will then specifically focus on the role of endocrine disrupting chemicals (EDCs) in the etiology of obesity, T2D and NAFLD while finally integrating the information on EDCs on multiple metabolic disorders that could lead to metabolic syndrome. We will specifically examine evidence linking EDC exposures during critical periods of development with metabolic diseases that manifest later in life and across generations.

The Risk of Being Obese According to Short Sleep Duration Is Modulated after Menopause in Korean Women

We previously reported that women with short sleep duration consumed more dietary carbohydrate and showed an increased risk for obesity compared to those who slept adequately, but not for men. Using a cross-sectional study of 17,841 Korean women, we investigated the influence of sleep duration on obesity-related variables and consumption of dietary carbohydrate-rich foods in relation to menopausal status. Premenopausal women with short sleep duration had significantly greater body weight (p = 0.007), body mass index (p = 0.003), systolic and diastolic blood pressures (p = 0.028 and p = 0.024, respectively), prevalence of obesity (p < 0.016), and consumption of more carbohydrate-rich foods such as staple foods (p = 0.026) and simple sugar-rich foods (p = 0.044) than those with adequate sleep duration after adjustment for covariates. Premenopausal women with short sleep duration were more obese by 1.171 times compared to subjects adequate sleep duration (95% confidence interval = 1.030–1.330). However, obesity-related variables, dietary consumption, and odds of being obese did not differ according to sleep duration for postmenopausal women. The findings suggest that the increased risk for obesity and consumption of dietary carbohydrate-rich foods with short sleep duration appeared to disappear after menopause in Korean women.

Sex differences in microglial CX3CR1 signalling determine obesity susceptibility in mice

Female mice are less susceptible to the negative metabolic consequences of high-fat diet feeding than male mice, for reasons that are incompletely understood. Here we identify sex-specific differences in hypothalamic microglial activation via the CX3CL1-CX3CR1 pathway that mediate the resistance of female mice to diet-induced obesity. Female mice fed a high-fat diet maintain CX3CL1-CX3CR1 levels while male mice show reductions in both ligand and receptor expression. Female Cx3cr1 knockout mice develop 'male-like' hypothalamic microglial accumulation and activation, accompanied by a marked increase in their susceptibility to diet-induced obesity. Conversely, increasing brain CX3CL1 levels in male mice through central pharmacological administration or virally mediated hypothalamic overexpression converts them to a 'female-like' metabolic phenotype with reduced microglial activation and body-weight gain. These data implicate sex differences in microglial activation in the modulation of energy homeostasis and identify CX3CR1 signalling as a potential therapeutic target for the treatment of obesity.

Sex-gender-related therapeutic approaches for cardiovascular complications associated with diabetes

Diabetes is a chronic disease associated with micro- and macrovascular complications and is a well-established risk factor for cardiovascular disease. Cardiovascular complications associated with diabetes are among the most important causes of death in diabetic patients. Interestingly, several sex-gender differences have been reported to significantly impact in the pathophysiology of diabetes. In particular, sex-gender differences have been reported to affect diabetes epidemiology, risk factors, as well as cardiovascular complications associated with diabetes. This suggests that different therapeutic approaches are needed for managing diabetes-associated cardiovascular complications in men and women. In this review, we will discuss about the sex-gender differences that are known to impact on diabetes, mainly focusing on the cardiovascular complications associated with the disease. We will then discuss the therapeutic approaches for managing diabetes-associated cardiovascular complications and how differences in sex-gender can influence the existing therapeutic approaches.

Tributyltin exposure at noncytotoxic doses dysregulates pancreatic β-cell function in vitro and in vivo

Tributyltin (TBT) is an endocrine disruptor. TBT can be found in food and in human tissues and blood. Several animal studies revealed that organotins induced diabetes with decreased insulin secretion. The detailed effect and mechanism of TBT on pancreatic β-cell function still remain unclear. We investigated the effect and mechanism of TBT exposure at noncytotoxic doses relevant to human exposure on β-cell function in vitro and in vivo. The β-cell-derived RIN-m5F cells and pancreatic islets from mouse and human were treated with TBT (0.05-0.2 μM) for 0.5-4 h. Adult male mice were orally exposed to TBT (25 μg/kg/day) with or without antioxidant N-acetylcysteine (NAC) for 1-3 weeks. Assays for insulin secretion and glucose metabolism were carried out. Unlike previous studies, TBT at noncytotoxic concentrations significantly increased glucose-stimulated insulin secretion and intracellular Ca²⁺ ([Ca²⁺]_i) in β-cells. The reactive oxygen species (ROS) production and phosphorylation of protein kinase C (PKC-pan) and extracellular signal-regulated kinase (ERK)1/2 were also increased. These TBT-triggered effects could be reversed by antiestrogen ICI182780 and inhibitors of ROS, [Ca²⁺]_i, and PKC, but not ERK. Similarly, islets treated with TBT significantly increased glucose-stimulated insulin secretion, which could be reversed by ICI182780, NAC, and PKC inhibitor. Mice exposed to TBT for 3 weeks significantly increased blood glucose and plasma insulin and induced glucose intolerance and insulin resistance, which could be reversed by NAC. These findings suggest that low/noncytotoxic doses of TBT induce insulin dysregulation and disturb glucose homeostasis, which may be mediated through the estrogen receptor-regulated and/or oxidative stress-related signaling pathways.