Estradiol prevents fat accumulation and overcomes leptin resistance in female high-fat diet mice

Inactivation of a non-canonical gp130 signaling arm attenuates chronic systemic inflammation and multimorbidity induced by a high-fat diet

Interleukin-6 (IL-6) is a major pro-inflammatory cytokine for which the levels in plasma demonstrate a robust correlation with age and body mass index (BMI) as part of the senescence-associated secretory phenotype. IL-6 cytokines also play a crucial role in metabolic homeostasis and regenerative processes, primarily via the canonical STAT3 pathway. Thus, selective modulation of IL-6 signaling may offer a unique opportunity for therapeutic interventions. Recently, we discovered that a non-canonical signaling pathway downstream of tyrosine (Y) 814 within the intracellular domain of gp130, the IL-6 co-receptor, is responsible for the recruitment and activation of SRC family of kinases (SFK). Mice with constitutive genetic inactivation of gp130 Y814 (F814 mice) show accelerated resolution of inflammatory response and superior regenerative outcomes in skin wound healing and posttraumatic models of osteoarthritis. The current study was designed to explore if selective genetic or pharmacological inhibition of the non-canonical gp130-Y814/SFK signaling reduces systemic chronic inflammation and multimorbidity in a high-fat diet (HFD)-induced model of accelerated aging. F814 mice showed significantly reduced inflammatory response to HFD in adipose and liver tissue, with significantly reduced levels of systemic inflammation compared to wild type mice. F814 mice were also protected from HFD-induced bone loss and cartilage degeneration. Pharmacological inhibition of gp130-Y814/SFK in mice on HFD mirrored the effects observed in F814 mice on HFD; furthermore, this pharmacological treatment also demonstrated a marked increase in physical activity levels and protective effects against inflammation-associated suppression of neurogenesis in the brain tissue compared to the control group. These findings suggest that selective inhibition of SFK signaling downstream of gp130 receptor represents a promising strategy to alleviate systemic chronic inflammation. Increased degenerative changes and tissue senescence are inevitable in obese and aged organisms, but we demonstrated that the systemic response and inflammation-associated multi-morbidity can be therapeutically mitigated.

Maternal preconception stress produces sex-specific effects at the maternal:fetal interface to impact offspring development and phenotypic outcomes†

Entering pregnancy with a history of adversity, including adverse childhood experiences and racial discrimination stress, is a predictor of negative maternal and fetal health outcomes. Little is known about the biological mechanisms by which preconception adverse experiences are stored and impact future offspring health outcomes. In our maternal preconception stress (MPS) model, female mice underwent chronic stress from postnatal days 28-70 and were mated 2 weeks post-stress. Maternal preconception stress dams blunted the pregnancy-induced shift in the circulating extracellular vesicle proteome and reduced glucose tolerance at mid-gestation, suggesting a shift in pregnancy adaptation. To investigate MPS effects at the maternal:fetal interface, we probed the mid-gestation placental, uterine, and fetal brain tissue transcriptome. Male and female placentas differentially regulated expression of genes involved in growth and metabolic signaling in response to gestation in an MPS dam. We also report novel offspring sex- and MPS-specific responses in the uterine tissue apposing these placentas. In the fetal compartment, MPS female offspring reduced expression of neurodevelopmental genes. Using a ribosome-tagging transgenic approach we detected a dramatic increase in genes involved in chromatin regulation in a PVN-enriched neuronal population in females at PN21. While MPS had an additive effect on high-fat-diet (HFD)-induced weight gain in male offspring, both MPS and HFD were necessary to induce significant weight gain in female offspring. These data highlight the preconception period as a determinant of maternal health in pregnancy and provides novel insights into mechanisms by which maternal stress history impacts offspring developmental programming.

Pregnancy-associated Steroid Effects on Insulin Sensitivity, Adipogenesis, and Lipogenesis: Role of Wnt/β-Catenin Pathway

Context

The shift in maternal energy metabolism characteristic of pregnancy is thought to be driven by various hormonal changes, especially of ovarian and placental steroids. Imbalances in circulating estradiol (E2) and progesterone (P4) levels during this period are often associated with metabolic disturbances leading to the development of gestational diabetes mellitus (GDM). Since abnormalities in the Wnt pathway effector transcription factor 7-like 2 (TCF7L2) are commonly associated with the occurrence of GDM, we hypothesized that the canonical or β-catenin-dependent Wnt signaling pathway mediates the metabolic actions of E2 and P4.

Objective

Our study was aimed at elucidating the metabolic function of the steroids E2 and P4, and examining the role of the canonical Wnt signaling pathway in mediating the actions of these steroids.

Methods

The ovariectomized (OVX) rat was used as a model system to study the effect of known concentrations of exogenously administered E2 and P4. Niclosamide (Nic) was administered to block Wnt signaling. 3T3-L1 cells were used to analyze changes in differentiation in the presence of the steroids or niclosamide.

Results

In the present study, we observed that E2 enhanced insulin sensitivity and inhibited lipogenesis while P4 increased lipogenic gene expression-in 3T3-L1 adipocytes, and in adipose tissue and skeletal muscle of OVX rats when the dosage of E2 and P4 mimicked that of pregnancy. Both E2 and P4 were also found to upregulate Wnt signaling. Nic nhibited the steroid-mediated increase in Wnt signaling in adipocytes and OVX rats. The insulin-sensitizing and antilipogenic actions of E2 were found to be mediated by the canonical Wnt pathway, but the effects of P4 on lipogenesis appeared to be independent of it. Additionally, it was observed that inhibition of Wnt signaling by Nic hastened adipogenic differentiation, and the inhibitory effect of E2 on differentiation was prevented by Nic.

Conclusion

The findings presented in this study highlight the role of steroids and Wnt pathway in glucose and lipid metabolism and are relevant to understanding the pathophysiology of metabolic disorders arising from hormonal disturbances.

Butyrate mitigates metabolic dysfunctions via the ERα-AMPK pathway in muscle in OVX mice with diet-induced obesity

The higher prevalence of metabolic syndrome (MetS) in women after menopause is associated with a decrease in circulating 17β-oestradiol. To explore novel treatments for MetS in women with oestrogen deficiency, we studied the effect of exogenous butyrate on diet-induced obesity and metabolic dysfunctions using ovariectomized (OVX) mice as a menopause model. Oral administration of sodium butyrate (NaB) reduced the body fat content and blood lipids, increased whole-body energy expenditure, and improved insulin sensitivity. Additionally, NaB induced oestrogen receptor alpha (ERα) expression, activated the phosphorylation of AMPK and PGC1α, and improved mitochondrial aerobic respiration in cultured skeletal muscle cells. In conclusion, oral NaB improves metabolic parameters in OVX mice with diet-induced obesity. Oral supplementation with NaB might provide a novel therapeutic approach to treating MetS in women with menopause. Video Abstract.

Malic Enzyme 1 (ME1) Promotes Adiposity and Hepatic Steatosis and Induces Circulating Insulin and Leptin in Obese Female Mice

Malic Enzyme 1 (ME1) supports lipogenesis, cholesterol synthesis, and cellular redox potential by catalyzing the decarboxylation of L-malate to pyruvate, and the concomitant reduction of NADP to NADPH. We examined the contribution of ME1 to the development of obesity by provision of an obesogenic diet to C57BL/6 wild type (WT) and MOD-1 (lack ME1 protein) female mice. Adiposity, serum hormone levels, and adipose, mammary gland, liver, and small intestine gene expression patterns were compared between experimental groups after 10 weeks on a diet. Relative to WT female mice, MOD-1 female mice exhibited lower body weights and less adiposity; decreased concentrations of insulin, leptin, and estrogen; higher concentrations of adiponectin and progesterone; smaller-sized mammary gland adipocytes; and reduced hepatosteatosis. MOD-1 mice had diminished expression of Lep gene in abdominal fat; Lep, Pparg, Klf9, and Acaca genes in mammary glands; Pparg and Cdkn1a genes in liver; and Tlr9 and Ffar3 genes in the small intestine. By contrast, liver expression of Cdkn2a and Lepr genes was augmented in MOD-1, relative to WT mice. Results document an integrative role for ME1 in development of female obesity, suggest novel linkages with specific pathways/genes, and further support the therapeutic targeting of ME1 for obesity, diabetes, and fatty liver disease.

Potential therapeutic drug targets and pathways prediction for premature ovarian insufficiency -Based on network pharmacologic method

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of premature ovarian insufficiency (POI) is gradually increasing, the proportion is rising especially in female infertility patients. The risk of death of POI patients with cardiovascular disease also increases significantly. The cause of POI is complex and unclear, and clinical treatment is still in the exploratory stage, are two major constraints of treating POI. Traditional Chinese medicine (TCM) is widely used in the treatment of POI, and it is a good way to combine the development of modern new drugs with the help of TCM to predict the therapeutic targets.

AIM OF THE STUDY

In this study, four herbs commonly used in clinical treatment of POI, namely Radix Paeoniae, Polygonatum sibiricum, Rehmannia glutinosa and Eucommia ulmoides were selected to predict their mechanism in the treatment of POI, using network pharmacology methods. Then verify the predicted targets by animal test. Aim to find more effective POI potential core treatment targets and main pathways.

MATERIALS AND METHODS

We screened the active ingredients of drugs from the TCM System Pharmacology Analysis Platform (TCMSP), Performed target prediction of active ingredients from databases such as SwissTargetPrediction and compare and analyze the POI-related targets retrieved from them to obtain potential targets for drug treatment of POI. Used STRING database to construct a protein interaction network, Cytoscape 3.7.2 software to construct an active ingredient-target-pathway network, and DAVID database to conduct the Kyoto Encyclopedia of Genes and Genomes (KEGG) on the intersection targets and gene ontology (GO) enrichment analysis.

RESULTS

The result is: there were 25 key targets for the treatment of POI with Radix Paeoniae Alba, 31 for the treatment of POI by Eucommia ulmoides, 28 for the treatment of POI by Polygonatum sibiricum, and 8 key targets for the treatment of Rehmannia glutinosa. The intersection targets of four herbs were defined as the core targets, which are CYP19A1, EGF, ESR1, ESR2, MDM2, AR, PCYP17A1, PPARG. Four Chinese herbs treat POI mainly through HIF-1 signaling pathway, PI3K-Akt signaling pathway, FoxO signaling pathway, Estrogen signaling pathway etc. A mouse model of POI was constructed based on the results of network pharmacology to verify the predicted targets. The results showed that the protein expression of the core target changed, and the estrogen level was increased by reducing the expression of peroxisome proliferator-activated receptor gamma (PPARG).

CONCLUSIONS

This study predicts the mechanism of multiple herbs in the treatment of POI, screens out more potential therapeutic drug targets and main pathways of POI treatment and provides new ideas for the subsequent development of POI therapeutic drugs.

Improvement of Estrogen Deficiency Symptoms by the Intake of Long-Term Fermented Soybeans (Doenjang) Rich in Bacillus Species through Modulating Gut Microbiota in Estrogen-Deficient Rats

Traditionally made doenjang (TMD) produced by the long-term fermentation of soybeans with salt may improve symptoms of estrogen deficiency. We aimed to evaluate the effects of four TMD types, containing low and high amounts of Bacillus species and biogenic amines (HBHA, HBLA, LBHA, and LBLA), on energy, glucose, and lipid metabolism, by altering the gut microbiota in estrogen-deficient ovariectomized (OVX) rats. Their mechanisms were also examined. The OVX rats were divided into the control, cooked soybean (CSB), HBHA, LBHA, HBLA, and LBLA groups. Sham-operated rats were the normal control group. Serum 17β-estradiol concentrations were similar among all OVX groups. Tail skin temperatures, which are indicative of hot flashes, were higher in the control than the HBHA and HBLA groups and were similar to the normal control group. Weight gain and visceral fat mass were lower in the TMD and CSB intake groups but not as low as in the normal control group. Lean body mass showed a trend opposite to that of visceral fat in the respective groups. The hepatic triglyceride content decreased with the TMD intake compared to the control and CSB groups. mRNA expressions of the peroxisome proliferator-activated receptor-γ (PPAR-γ) and carnitine palmitoyltransferase-1 in the TMD and CSB groups were as high as in the normal control group, and the PPAR-γ mRNA expression was more elevated in the HBLA group than in the normal control group. The morphology of the intestines improved in the TMD groups compared to the control, and the HBHA and HBLA groups showed an enhanced improvement compared to the CSB group. The HBHA, HBLA, and LBHA groups increased the α-diversity of the cecal microbiota compared to the control. Akkermenia and Lactobacillus were higher in the HBLA and LBLA groups compared to the control. The expression of the estrogen, forkhead box proteins of the class-O subgroup, and insulin-signaling pathways were lower in the control group, and HBHA and HBLA prevented their decrement. In conclusion, long-term treatment with TMD containing high amounts of Bacillus potentially improves estrogen deficiency symptoms more than unfermented soybeans.

The effects of G protein-coupled receptor 30 (GPR30) on cardiac glucose metabolism in diabetic ovariectomized female rats

BACKGROUND

Diabetic cardiometabolic disorders are characterized by significant changes in cardiac metabolism and are increased in postmenopausal women, which emphasize the role of 17β-estradiol (E2). Despite this, there are few safe and effective pharmacological treatments for these disorders. The role of G protein-coupled estrogen receptor (GPR30), which mediates the non-genomic effects of E2, is mostly unexplored.

METHODS

In this study, we used ovariectomy (menopausal model) and type 2 diabetic (T2D) rats' models to evaluate the preclinical action of G-1 (GPR30 agonist) against cardiometabolic disorders. T2D was induced by a high-fat diet and a low dose of streptozotocin. G-1 was administrated for six weeks after the establishment of T2D.

RESULTS

We found that G-1 counteracts the effects of T2D and ovariectomy by increasing the body weight, reducing fasting blood sugar, heart weight, and heart weight to body weight ratio. Also, both ovariectomy and T2D led to decreases in the cardiac protein levels of hexokinase 2 (HK2) and GLUT4, while G-1-treated female rats reversed these changes and only increased HK2 protein level. In addition, T2D and ovariectomy increased glucose and glycogen content in the heart, but G-1 treatment significantly reduced them.

CONCLUSIONS

In conclusion, our work demonstrates that G-1 as a selective GPR30 agonist is a viable therapeutic approach against T2D and cardiometabolic diseases in multiple preclinical female models.

Potential mechanisms and modulators of food intake during pregnancy

Dietary choice during pregnancy is crucial not only for fetal development, but also for long-term health outcomes of both mother and child. During pregnancy, dramatic changes in endocrine, cognitive, and reward systems have been shown to take place. Interestingly, in different contexts, many of these mechanisms play a key role in guiding food intake. Here, we review how food intake may be impacted as a function of pregnancy-induced changes across species. We first summarize changes in endocrine and metabolic signaling in the course of pregnancy. Then, we show how these may be related to cognitive function and reward processing in humans. Finally, we link these to potential drivers of change in eating behavior throughout the course of pregnancy.

Associations of follicle-stimulating hormone and luteinizing hormone with metabolic syndrome during the menopausal transition from the National Health and Nutrition Examination Survey

BACKGROUND

The increased risk of metabolic syndrome (MetS) during the menopausal transition might partly attribute to the changes in follicle-stimulating hormone (FSH) and luteinizing hormone (LH). However, few studies were conducted to examine the associations of FSH and LH concentrations with MetS at the full range of reproductive aging, especially in the US population. The aim of this study is to examine the associations of FSH, LH, and LH/FSH ratio with the risk of MetS and severity score in the US women.

METHODS

Data were derived from the National Health and Nutrition Examination Survey. Women aged from 35 to 60 years were eligible. MetS was defined as having at least 3 of the following: a waist circumference ≥ 88 cm, a triglycerides level ≥ 150 mg/dL, a high density lipoprotein < 50 mg/dL, a systolic blood pressure ≥ 130 mm Hg or a diastolic blood pressure ≥ 85 mm Hg or taking hypertension medications, or a fasting plasma glucose level ≥100 mg/dL or taking diabetes medications. The MetS severity score was calculated according to race/ethnicity- specific equation.

RESULTS

There were 3,831 women included in this study. Increases in serum FSH and LH levels per 1 SD were separately linked to a 22.6% (OR: 0.774; 95% CI: 0.646, 0.929; and P= 0.006) and 18.5% (OR: 0.815; 95% CI: 0.690, 0.962; and P= 0.006) lower risk of MetS only in postmenopausal women. Meanwhile, increases in serum FSH and LH levels per 1SD were associated with a decrease of -0.157 (95% CI :-2.967, -2.034) and -0.078 (95% CI: -2.688, -1.806) MetS severity score in perimenopausal women and -0.195 (95% CI: -2.192, -1.023) and -0.098 (95% CI:-1.884, -0.733) in postmenopausal women. However, LH/FSH ratio had no connections with the risk of MetS and MetS severity score across the menopausal transition.

CONCLUSIONS

Elevated serum FSH and LH levels, but not LH/FSH ratio, were associated with a lower risk of MetS and MetS severity score, especially in postmenopausal women. Therefore, serum FSH and LH levels might be efficient predictors for screening and identifying women at risk of MetS across the menopausal transition.

Protective effects of calorie restriction and 17-β estradiol on cardiac hypertrophy in ovariectomized obese rats

Obesity and menopause lead to cardiovascular diseases. Calorie restriction (CR) can modulate estrogen deficiency and obesity-related cardiovascular diseases. The protective effects of CR and estradiol on cardiac hypertrophy in ovariectomized obese rats were explored in this study. The adult female Wistar rats were divided into sham and ovariectomized (OVX) groups that received a high-fat diet (60% HFD) or standard diet (SD) or 30% CR for 16 weeks, and then, 1mg/kg E2 (17-β estradiol) was injected intraperitoneally every 4 days for four weeks in OVX-rats. Hemodynamic parameters were evaluated before and after each diet. Heart tissues were collected for biochemical, histological, and molecular analysis. HFD consumption led to weight gain in sham and OVX rats. In contrast, CR and E2 led to body weight loss in these animals. Also, heart weight (HW), heart weight/body weight (HW/BW) ratio, and left ventricular weight (LVW) were enhanced in OVX rats that received SD and HFD. E2 reduced these indexes in both diet conditions but reduction effects of CR were seen only in HFD groups. HFD and SD feeding increased hemodynamic parameters, ANP (atrial natriuretic peptide) mRNA expression, and TGF-β1(transforming growth factor-beta 1) protein level in the OVX animals, while CR and E2 reduced these factors. Cardiomyocyte diameter and hydroxyproline content were increased in the OVX-HFD groups. Nevertheless, CR and E2 decreased these indicators. The results showed that CR and E2 treatment reduced obesity-induced-cardiac hypertrophy in ovariectomized groups (20% and 24% respectively). CR appears to have almost as reducing effects as estrogen therapy on cardiac hypertrophy. The findings suggest that CR can be considered a therapeutic candidate for postmenopausal cardiovascular disease.

RAGE displays sex-specific differences in obesity-induced adipose tissue insulin resistance

Background

The receptor for advanced glycation end products (RAGE) plays an important role in obesity-associated insulin sensitivity. We have also previously reported that RAGE deficiency improved insulin resistance in obesity-induced adipose tissue. The current study was aimed to elucidate the sex-specific mechanism of RAGE deficiency in adipose tissue metabolic regulation and systemic glucose homeostasis.

Methods

RAGE-deficient (RAGE^−/−) mice were fed a high-fat diet (HFD) and subjected to glucose and insulin tolerance tests. Subcutaneous adipose tissue (sAT) was collected, and macrophage polarization was assessed by quantitative real-time PCR. Immunoblotting was performed to evaluate the insulin signaling in adipose tissues.

Results

Under HFD feeding conditions, body weight and adipocyte size of female RAGE deficient (RAGE^−/−) were markedly lower than that of male mice. Female RAGE^−/− mice showed significantly improved glucose and insulin tolerance compared to male RAGE^−/− mice, accompanied with increased M2 macrophages polarization. Expressions of genes involved in anti-oxidant and browning were up-regulated in adipose tissues of female RAGE^−/− mice. Moreover, insulin-induced AKT phosphorylation was significantly elevated in adipose tissue in female RAGE^−/− mice compared to male RAGE^−/− mice.

Conclusions

Our findings suggest that RAGE-mediated adipose tissue insulin resistance is sex-specific, which is associated with different expression of genes involved in anti-oxidant and browning and insulin-induced AKT phosphorylation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00476-6.

Female RAGE^−/− mice showed significantly improved glucose and insulin tolerance compared to male RAGE^−/− mice.

Female RAGE deficiency promotes M2 macrophage polarization in adipose tissues.

Female RAGE deficiency prevents oxidative stress in adipose tissues.

Female RAGE deficiency protects insulin-AKT signaling in adipose tissues.

Alleviation of Metabolic Disturbance by Substituting Kanjang High in Bacillus for Salt through Modulation of Gut Microbiota in Estrogen-Deficient Rats

A high salt intake may exacerbate menopausal symptoms and substituting for different types of traditionally made kanjang (TMK; soy sauce) may prevent it. This study examined whether substituting salt with lyophilized TMK containing low and high Bacillus and biogenic amines in a high-fat diet might modulate the menopausal symptoms and the energy, glucose, and lipid metabolism in ovariectomized (OVX) rats. They were categorized into salt (Control), TMK with high Bacillus and low biogenic amines (HBLB), TMK with high Bacillus and high biogenic amines (HBHB), TMK with low Bacillus and low biogenic amines (LBLB), and TMK with low Bacillus and high biogenic amines (LBHB). Sham-operated rats consumed the same diet as the Control. HBLB, HBHB, and LBHB prevented increased tail skin temperature compared to the Control. HBHB and HBLB partially inhibited the increased weight gain and abdominal fat mass by reducing the food efficiency without changing the serum 17β-estradiol concentrations. Serum glucose and insulin concentrations and the insulin resistance index by the homeostatic model assessment for insulin resistance showed a positive association for weight gain. HBLB and HBHB decreased the serum malondialdehyde and tumor-necrosis factor-α levels. Hepatic triglyceride storage was lower in all TMK groups than in the Control, while hepatic glycogen accumulation was higher in the HBLB, HBHB, and LBHB groups than in the Control and LBLB groups. Accordingly, the mRNA expression of peroxisome proliferator-activated receptors-γ(PPAR-γ) was higher in the HBLB and HBHB groups compared to the Control, and that of fatty acid synthase was opposite to PPAR-γ expression. However, HBLB and HBHB improved dyslipidemia and insulin resistance compared to the Control, but their improvement did not reach that of the Normal-control. The acetic acid concentrations in the portal vein were lower in the LBLB than in the Control, while the butyric acid contents were higher in the LBHB and HBLB groups than in the Control. HBHB, HBLB, and LBHB elevated Akkermansia and Lactobacillus, and HBLB and LBLB increased Bacteroides and Ruminococcus compared to the Control. Polycyclic aromatic hydrocarbon degradation, bile acid synthesis, and unsaturated fatty acid biosynthesis were significantly higher in the HBLB group than in the Control group. In conclusion, substituting salts to TMK with a high Bacillus content regardless of the bioamine contents partially improved the menopausal symptoms and metabolic disturbance in estrogen-deficient animals.

The brain neuropeptides and STAT3 mediate the inhibitory effect of 17-β Estradiol on central leptin resistance in young but not aged female high-fat diet mice

Aging and menopause effect on body composition and energy balance. Estrogen (E2) plays an important role in body's metabolism. The aim of the present study was to determine changes in leptin function in young intact and ovariectomized (OVX) animals in comparison to the aged animals treated with E2. Young (Intact and OVX 4 months) and aged (19-21 months) female mice were fed High-fat diet (HFD) for 12 weeks and, then they were divided into eight groups including: Intact + OIL, Intact + E2, Intact + Pair body weight (PBW), OVX + OIL, OVX + E2, OVX + PBW, Aged + OIL, and Aged + E2. E2 was administered subcutaneously every four days for four weeks. Responsiveness to leptin was assessed by measuring energy balance components. Results showed that eating HFD increased weight and calorie consumption in young mice, and chronic treatment with E2 decreased both these variables in young animals. E2 only improved the sensitivity to leptin in young animals. Treatment with E2 resulted in increased α-MSH neuropeptide, reduced NPY and AgRP neuropeptides in the brain, and decreased serum leptin in the young animals. Also, treatment with E2 increased the expression of p-STAT3 molecular level in the hypothalamic arcuate nucleus (ARC) in the young animals. Our results indicated that response to E2 depended on age and E2 protects young HFD fed mice from obesity and improves leptin sensitivity.

Relationship Between Circulating Metabolic Hormones and Their Central Receptors During Ovariectomy-Induced Weight Gain in Rats

Although increasing research focuses on the phenomenon of body weight gain in women after menopause, the complexity of body weight regulation and the array of models used to investigate it has proven to be challenging. Here, we used ovariectomized (OVX) rats, which rapidly gain weight, to determine if receptors for ghrelin, insulin, or leptin in the dorsal vagal complex (DVC), arcuate nucleus (ARC), or paraventricular nucleus (PVN) change during post-ovariectomy weight gain. Female Sprague-Dawley rats with ad libitum access to standard laboratory chow were bilaterally OVX or sham OVX. Subgroups were weighed and then terminated on day 5, 33, or 54 post-operatively; blood and brains were collected. ELISA kits were used to measure receptors for ghrelin, insulin, and leptin in the DVC, ARC, and PVN, as well as plasma ghrelin, insulin, and leptin. As expected, body weight increased rapidly after ovariectomy. However, ghrelin receptors did not change in any of the areas for either group, nor did circulating ghrelin. Thus, the receptor:hormone ratio indicated comparable ghrelin signaling in these CNS areas for both groups. Insulin receptors in the DVC and PVN decreased in the OVX group over time, increased in the PVN of the Sham group, and were unchanged in the ARC. These changes were accompanied by elevated circulating insulin in the OVX group. Thus, the receptor:hormone ratio indicated reduced insulin signaling in the DVC and PVN of OVX rats. Leptin receptors were unchanged in the DVC and ARC, but increased over time in the PVN of the Sham group. These changes were accompanied by elevated circulating leptin in both groups that was more pronounced in the OVX group. Thus, the receptor:hormone ratio indicated reduced leptin signaling in the DVC and PVN of both groups, but only in the OVX group for the ARC. Together, these data suggest that weight gain that occurs after removal of ovarian hormones by ovariectomy is associated with selective changes in metabolic hormone signaling in the CNS. While these changes may reflect behavioral or physiological alterations, it remains to be determined whether they cause post-ovariectomy weight gain or result from it.

Menopause and development of Alzheimer's disease: Roles of neural glucose metabolism and Wnt signaling

Late onset Alzheimer´s disease (AD) is a neurodegenerative disease with gender differences in its onset and progression, being the prevalence predominant in women and at an earlier age than in men. The pathophysiology of the menopausal condition has been associated to this dementia, playing major roles regarding both endocrine and glucose metabolism changes, amongst other mechanisms. In the current review we address the role of estrogen deficiency in the processes involved in the development of AD, including amyloid precursor protein (APP) processing to form senile plaques, Tau phosphorylation forming neurofibrillary tangles, Wnt signaling and AD neuropathology, the role of glucose brain metabolism, Wnt signaling and glucose transport in the brain, and our research contribution to these topics.

Circulating oestradiol determines liver lipid deposition in rats fed standard diets partially unbalanced with higher lipid or protein proportions

The ingestion of excess lipids often produces the accumulation of liver fat. The modulation of diet energy partition affects this process and other metabolic responses, and oestrogens and androgens are implied in this process. Ten-week-old male and female rats were fed with either standard rat chow (SD), SD enriched with coconut oil (high-fat diet, HF), SD enriched with protein (high-protein diet, HP) or a ‘cafeteria’ diet (CAF) for 1 month. HF and CAF diets provided the same lipid-derived percentage of energy (40 %), HP diet protein energy derived was twice (40 %) that of the SD. Animals were killed under anaesthesia and samples of blood and liver were obtained. Hepatic lipid content showed sex-related differences: TAG accumulation tended to increase in HF and CAF fed males. Cholesterol content was higher only in the CAF males. Plasma oestradiol in HF and HP males was higher than in CAF. Circulating cholesterol was inversely correlated with plasma oestradiol. These changes agreed with the differences in the expression of some enzymes related to lipid and energy metabolism, such as fatty acid synthetase or phosphoglycolate phosphatase. Oestrogen protective effects extend to males with ‘normal’ diets, that is, not unbalanced by either lipid or protein, but this protection was not enough against the CAF diet. Oestradiol seems to actively modulate the liver core of 2C-3C partition of energy substrates, regulating cholesterol deposition and lactate production.

Estrogens and the regulation of glucose metabolism

The main estrogens: estradiol, estrone, and their acyl-esters have been studied essentially related to their classical estrogenic and pharmacologic functions. However, their main effect in the body is probably the sustained control of core energy metabolism. Estrogen nuclear and membrane receptors show an extraordinary flexibility in the modulation of metabolic responses, and largely explain gender and age differences in energy metabolism: part of these mechanisms is already sufficiently known to justify both. With regard to energy, the estrogen molecular species act essentially through four key functions: (1) Facilitation of insulin secretion and control of glucose availability; (2) Modulation of energy partition, favoring the use of lipid as the main energy substrate when more available than carbohydrates; (3) Functional protection through antioxidant mechanisms; and (4) Central effects (largely through neural modulation) on whole body energy management. Analyzing the different actions of estrone, estradiol and their acyl esters, a tentative classification based on structure/effects has been postulated. Either separately or as a group, estrogens provide a comprehensive explanation that not all their quite diverse actions are related solely to specific molecules. As a group, they constitute a powerful synergic action complex. In consequence, estrogens may be considered wardens of energy homeostasis.

Impact of Estrogen Withdrawal and Replacement in Female Mice along the Intestinal Tract. Comparison of E2 Replacement with the Effect of a Mixture of Low Dose Pollutants

Postmenopausal women represent a vulnerable population towards endocrine disruptors due to hormonal deficit. We previously demonstrated that chronic exposure of ovariectomized C57Bl6/J mice fed a high-fat, high-sucrose diet to a low-dose mixture of chemicals with one dioxin, one polychlorobiphenyl, one phthalate, and bisphenol A triggered metabolic alterations in the liver but the intestine was not explored. Yet, the gastrointestinal tract is the main route by which pollutants enter the body. In the present study, we investigated the metabolic consequences of ovarian withdrawal and E2 replacement on the various gut segments along with investigating the impact of the mixture of pollutants. We showed that genes encoding estrogen receptors (Esr1, Gper1 not Esr2), xenobiotic processing genes (e.g., Cyp3a11, Cyp2b10), and genes related to gut homeostasis in the jejunum (e.g., Cd36, Got2, Mmp7) and to bile acid biosynthesis in the gut (e.g., Fgf15, Slc10a2) and liver (e.g., Abcb11, Slc10a1) were under estrogen regulation. Exposure to pollutants mimicked some of the effects of E2 replacement, particularly in the ileum (e.g., Esr1, Nr1c1) suggesting that the mixture had estrogen-mimetic activities. The present findings have important implications for the understanding of estrogen-dependent metabolic alterations with regards to situations of loss of estrogens as observed after menopause.

Pulsed administration for physiological estrogen replacement in mice

Estrogens are important regulators of body physiology and have major effects on metabolism, bone, the immune- and central nervous systems. The specific mechanisms underlying the effects of estrogens on various cells, tissues and organs are unclear and mouse models constitute a powerful experimental tool to define the physiological and pathological properties of estrogens. Menopause can be mimicked in animal models by surgical removal of the ovaries and replacement therapy with 17β-estradiol in ovariectomized (OVX) mice is a common technique used to determine specific effects of the hormone. However, these studies are complicated by the non-monotonic dose-response of estradiol, when given as therapy. Increased knowledge of how to distribute estradiol in terms of solvent, dose, and administration frequency, is required in order to accurately mimic physiological conditions in studies where estradiol treatment is performed. In this study, mice were OVX and treated with physiological doses of 17β-estradiol-3-benzoate (E2) dissolved in miglyol or PBS. Subcutaneous injections were performed every 4 days to resemble the estrus cycle in mice. Results show that OVX induces an osteoporotic phenotype, fat accumulation and impairment of the locomotor ability, as expected. Pulsed administration of physiological doses of E2 dissolved in miglyol rescues the phenotypes induced by OVX. However, when E2 is dissolved in PBS the effects are less pronounced, possibly due to rapid wash out of the steroid.

Effects of Dietary Fatty Acid Composition on Lipid Metabolism and Body Fat Accumulation in Ovariectomized Rats

Background: Obesity is a state of excess energy storage resulting in body fat accumulation, and postmenopausal obesity is a rising issue. In this study using ovariectomized (OVX) rats, we mimicked low estrogen levels in a postmenopausal state in order to investigate the effects of different amounts and types of dietary fatty acids on body fat accumulation and body lipid metabolism. Methods: At 9 weeks of age, rats (n = 40) were given an ovariectomy, eight of which were sham-operated to serve as a control group (S). We then divided OVX rats into four different intervention groups: diet with 5% soybean oil (C), and diet with 5% (L), 15% (M), and 20% (H) (w/w) experimental oil, containing 60% monounsaturated fatty acids (MUFAs) and with a polyunsaturated/saturated fatty acid (P/S) ratio of 5. Results: After OVX, compared to the S group, the C group showed significantly higher body weight, and insulin and leptin levels. Compared to the C group, the H group had lower hepatic triglyceride level and FAS enzyme activity, and higher hepatic ACO and CPT-1 gene expressions and enzyme activities. Conclusions: An OVX leads to severe weight gain and lipid metabolism abnormalities, while according to previous studies, high fat diet may worsen the situation. However, during our experiment, we discovered that the experimental oil mixture with 60% MUFAs and P/S = 5 may ameliorate these imbalances.

Long-term oral administration of a novel estrogen receptor beta agonist enhances memory and alleviates drug-induced vasodilation in young ovariectomized mice

Development of estrogen therapies targeting the β (ERβ) but not α (ERα) estrogen receptor is critically needed for the treatment of negative menopausal symptoms, as ERα activation increases health risks like cancer. Here, we determined the effects of long-term oral treatment with EGX358, a novel highly selective ERβ agonist, on memory, vasodilation, and affect in young ovariectomized mice. Mice were orally gavaged daily for 9 weeks with vehicle, 17β-estradiol (E₂), the ERβ agonist diarylpropionitrile (DPN), or EGX358 at doses that enhance memory when delivered acutely. Tail skin temperature was recorded as a proxy for vasodilation following injection of vehicle or senktide, a tachykinin receptor 3 agonist used to model hot flashes. Anxiety-like behavior was assessed in the open field (OF) and elevated plus maze (EPM), and depression-like behavior was measured in the tail suspension (TST) and forced swim tests (FST). Finally, memory was assessed in object recognition (OR) and object placement (OP) tasks. E₂, DPN, and EGX358 reduced senktide-mediated increases in tail skin temperature compared to vehicle. All three treatments also enhanced memory in the OR and OP tasks, whereas vehicle did not. Although E₂ increased time spent in the center of the OF, no other treatment effects were observed in the OF, EPM, TST, or FST. These data suggest that long-term ERβ activation can reduce hot flash-like symptoms and enhance spatial and object recognition memories in ovariectomized mice. Thus, the highly selective ERβ agonist EGX358 may be a promising avenue for reducing menopause-related hot flashes and memory dysfunction.

Increased cholinergic activity under conditions of low estrogen leads to adverse cardiac remodeling

Cholinesterase inhibitors are used in postmenopausal women for the treatment of neurodegenerative diseases. Despite their widespread use in the clinical practice, little is known about the impact of augmented cholinergic signaling on cardiac function under reduced estrogen conditions. To address this gap, we subjected a genetically engineered murine model of systemic vesicular acetylcholine transporter overexpression (Chat-ChR2) to ovariectomy and evaluated cardiac parameters. Left-ventricular function was similar between Chat-ChR2 and wild-type (WT) mice. Following ovariectomy, WT mice showed signs of cardiac hypertrophy. Conversely, ovariectomized (OVX) Chat-ChR2 mice evolved to cardiac dilation and failure. Transcript levels for cardiac stress markers atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) were similarly upregulated in WT/OVX and Chat-ChR2/OVX mice. 17β-Estradiol (E2) treatment normalized cardiac parameters in Chat-ChR2/OVX to the Chat-ChR2/SHAM levels, providing a link between E2 status and the aggravated cardiac response in this model. To investigate the cellular basis underlying the cardiac alterations, ventricular myocytes were isolated and their cellular area and contractility were assessed. Myocytes from WT/OVX mice were wider than WT/SHAM, an indicative of concentric hypertrophy, but their fractional shortening was similar. Conversely, Chat-ChR2/OVX myocytes were elongated and presented contractile dysfunction. E2 treatment again prevented the structural and functional changes in Chat-ChR2/OVX myocytes. We conclude that hypercholinergic mice under reduced estrogen conditions do not develop concentric hypertrophy, a critical compensatory adaptation, evolving toward cardiac dilation and failure. This study emphasizes the importance of understanding the consequences of cholinesterase inhibition, used clinically to treat dementia, for cardiac function in postmenopausal women.

Multigenerational study of the obesogen effects of bisphenol S after a perinatal exposure in C57BL6/J mice fed a high fat diet

BACKGROUND

Bisphenol S is an endocrine disruptor exhibiting metabolic disturbances, especially following perinatal exposures. To date, no data are available on the obesogen effects of BPS in a mutligenerational issue.

OBJECTIVES

We investigated obesogen effects of BPS in a multigenerational study by focusing on body weight, adipose tissue and plasma parameters in male and female mice.

METHODS

Pregnant C57BL6/J mice were exposed to BPS (1.5 μg/kg bw/day ie a human equivalent dose of 0.12 μg/kg bw/day) by drinking water from gestational day 0 to post natal day 21. All offsprings were fed with a high fat diet during 15 weeks. Body weight was monitored weekly and fat mass was measured before euthanasia. At euthanasia, blood glucose, insuline, triglyceride, cholesterol and no esterified fatty acid plasma levels were determined and gene expressions in visceral adipose tissue were assessed. F1 males and females were mated to obtain the F2 generation. Likewise, the F2 mice were cross-bred to obtain F3. The same analyses were performed.

RESULTS

In F1 BPS induced an overweight in male mice associated to lipolysis gene expressions upregulation. In F1 females, dyslipidemia was observed. In F2, BPS exposure was associated to an increase in body weight, fat and VAT masses in males and females. Several plasma parameters were increased but with a sex related pattern (blood glucose, triglycerides and cholesterol in males and NEFA in females). We observed a down-regulation in mRNA expression of gene involved in lipogenesis and in lipolysis for females but only in the lipogenesis for males. In F3, a decrease in VAT mass and an upregulation of lipogenesis gene expression occurred only in females.

CONCLUSIONS

BPS perinatal exposure induced sex-dependent obesogen multigenerational effects, the F2 generation being the most impacted. Transgenerational disturbances persisted only in females.

Leptin administration during lactation leads to different nutritional, biometric, hemodynamic, and cardiac outcomes in prepubertal and adult female Wistar rats

Literature reports that insults, such as hormonal disturbances, during critical periods of development may modulate organism physiology and metabolism favoring cardiovascular diseases (CVDs) later in life. Studies show that leptin administration during lactation leads to cardiovascular dysfunction in young and adult male Wistar rats. However, there are sex differences regarding CVD. Thus, the present work aimed to investigate neonatal leptin administration's consequences on different outcomes in female rats at prepubertal and adult age. Newborn Wistar female rats were divided into two groups, Leptin and Control, receiving daily subcutaneous injections of this adipokine (8 μg/100 g) or saline for the first 10 of 21 d of lactation. Nutritional, biometric, hemodynamic, and echocardiographic parameters, as well as maximal effort ergometer performance, were determined at postnatal days (PND) 30 and 150. Leptin group presented lower food intake (p = 0.0003) and higher feed efficiency (p = 0.0058) between PND 21 and 30. Differences concerning echocardiographic parameters revealed higher left ventricle internal diameter (LVID) in systole (p = 0.0051), as well as lower left ventricle ejection fraction (LVEF) (p = 0.0111) and fractional shortening (FS) (p = 0.0405) for this group at PND 30. Older rats treated with leptin during lactation presented only higher LVID in systole (p = 0.0270). Systolic blood pressure and maximum effort ergometer test performance was similar between groups at both ages. These data suggest that nutritional, biometric, and cardiac outcomes due to neonatal leptin administration in female rats are age-dependent.

Treatment with a dual amylin and calcitonin receptor agonist improves metabolic health in an old, obese, and ovariectomized rat model

Objectives:

Menopause is often characterized by detrimental metabolic changes, such as obesity, insulin resistance, and impaired glucose tolerance, often requiring treatment. KeyBioscience Peptides (KBPs) are Dual Amylin and Calcitonin Receptor Agonists which have shown promising metabolic effects in rats. The objective of this study was to investigate the in vivo effect of KBP on the metabolic health in a model driven by unhealthy diet, age, and menopause.

Methods:

Female Sprague Dawley rats were fed a high-fat diet (HFD) for 3 months before the initiation of the study. At 6 months of age the rats were randomized into groups (n = 12) and subjected to ovariectomy surgery and treatment with KBP: (1) Lean-Sham, (2) HFD-Sham, (3) Lean-OVX, (4) HFD-OVX, (5) HFD-OVX-KBP (10 μg/kg/d), (6) HFD-OVX-KBP (20 μg/kg/d), (7) HFD-OVX-EE2 (30 μg/d 17a-ethynylestradiol). Body weight, food intake, oral glucose tolerance tests (OGTTs), subcutaneous fat, visceral fat, liver weight, and uterus weight were assessed during the 6-month study. Statistical analyses were conducted by one-way ANOVA with Tukey post-hoc test for multiple comparisons.

Results:

Combination of OVX and HFD led to significant induction of obesity (31% weight increase, P < 0.001) and insulin resistance (13% increase in tAUC_glucose during OGTT P < 0.01) compared with the relevant control groups (P < 0.05), and this could be completely rescued by EE2 therapy confirming the model system (P < 0.05).

Treatment of OVX-HFD rats with KBP for 26 weeks led to a significant reduction in body weight (13%, P < 0.001) in the high dose and 9% (P < 0.01) in the low dose, with corresponding improvements in fat depot sizes, all compared with HFD-OVX controls. As expected, food intake was suppressed, albeit mainly in the first 2 weeks of treatment, resulting in a reduction of overall caloric intake by 6.5% (P < 0.01) and 12.5% (P < 0.001) in the low and high doses respectively. Furthermore, treatment with KBP reduced the weight of visceral and subcutaneous fat tissues. Finally, KBP treatment significantly improved glucose tolerance, assessed using OGTTs at weeks 8, 16, and 24.

Conclusions:

The data presented here clearly indicate a positive and sustained effect of KBP treatment on body weight loss, fat depot size, and improved glucose tolerance, illustrating the potential of KBPs as treatments for metabolic complications of overweight and menopause.

Estrogen and gut satiety hormones in vagus-hindbrain axis

Estrogens modulate different physiological functions, including reproduction, inflammation, bone formation, energy expenditure, and food intake. In this review, we highlight the effect of estrogens on food intake regulation and the latest literature on intracellular estrogen signaling. In addition, gut satiety hormones, such as cholecystokinin, glucagon-like peptide 1 and leptin are essential to regulate ingestive behaviors in the postprandial period. These peripheral signals are sensed by vagal afferent terminals in the gut wall and transmitted to the hindbrain axis. Here we 1. review the role of the vagus-hindbrain axis in response to gut satiety signals and 2. consider the potential synergistic effects of estrogens on gut satiety signals at the level of vagal afferent neurons and nuclei located in the hindbrain. Understanding the action of estrogens in gut-brain axis provides a potential strategy to develop estrogen-based therapies for metabolic diseases and emphasizes the importance of sex difference in the treatment of obesity.

Effects of prenatal bisphenol A exposure on the hepatic transcriptome and proteome in rat offspring

Developmental exposure to bisphenol A (BPA) is associated with liver dysfunction and diseases in adulthood. The aims of this study were to assess the effects of prenatal BPA exposure on the hepatic transcriptome and proteome in female and male offspring and to understand adverse outcome pathways (AOPs) to observed phenotypic effects. Pregnant Wistar rats were exposed to 50 or 5000 μg BPA/kg bw/day, or 17β-estradiol (E2, 50 μg/kg bw/day) from embryonic day 3 to 18. The liver transcriptome and proteome profiles were analyzed in the newborn (postnatal day 1; PND1) and weaning (PND21) rat offspring. Based on the differentially expressed genes/proteins derived from transcriptome and proteome profiles, we performed pathway, transcription factor, and disease enrichment analyses. A principal component analysis of transcriptome data demonstrated that prenatal BPA exposure caused masculinization of the hepatic transcriptome in females. Both of transcriptomic and proteomic data showed that prenatal BPA exposure led to the disruption of cell cycle, lipid homeostasis, and hormone balance in offspring. Most of the effects at the transcript level were extended from newborn to weaning in males, but were moderated until weaning in females. The alterations at the transcript and protein levels were accordant with the observation of increases in body weight and anogenital distance and changes in hepatosomatic index in the offspring. Collectively, we constructed AOPs with evidence of sex- and age-specific actions of prenatal BPA exposure in the offspring.

Aging Reduces Estradiol Protection Against Neural but Not Metabolic Effects of Obesity in Female 3xTg-AD Mice

Vulnerability to Alzheimer's disease (AD) is increased by several risk factors, including midlife obesity, female sex, and the depletion of estrogens in women as a consequence of menopause. Conversely, estrogen-based hormone therapies have been linked with protection from age-related increases in adiposity and dementia risk, although treatment efficacy appears to be affected by the age of initiation. Potential interactions between obesity, AD, aging, and estrogen treatment are likely to have significant impact on optimizing the use of hormone therapies in postmenopausal women. In the current study, we compared how treatment with the primary estrogen, 17β-estradiol (E2), affects levels of AD-like neuropathology, behavioral impairment, and other neural and systemic effects of preexisting diet-induced obesity in female 3xTg-AD mice. Importantly, experiments were conducted at chronological ages associated with both the early and late stages of reproductive senescence. We observed that E2 treatment was generally associated with significantly improved metabolic outcomes, including reductions in body weight, adiposity, and leptin, across both age groups. Conversely, neural benefits of E2 in obese mice, including decreased β-amyloid burden, improved behavioral performance, and reduced microglial activation, were observed only in the early aging group. These results are consistent with the perspective that neural benefits of estrogen-based therapies require initiation of treatment during early rather than later phases of reproductive aging. Further, the discordance between E2 protection against systemic versus neural effects of obesity across age groups suggests that pathways other than general metabolic function, perhaps including reduced microglial activation, contribute to the mechanism(s) of the observed E2 actions. These findings reinforce the potential systemic and neural benefits of estrogen therapies against obesity, while also highlighting the critical role of aging as a mediator of estrogens' protective actions.

Sex differences in response to short-term high fat diet in mice

BACKGROUND

Consumption of high-fat diet (HF) leads to hyperphagia and increased body weight in male rodents. Female rodents are relatively resistant to hyperphagia and weight gain in response to HF, in part via effects of estrogen that suppresses food intake and increases energy expenditure. However, sex differences in energy expenditure and activity levels with HF challenge have not been systemically described. We hypothesized that, in response to short-term HF feeding, female mice will have a higher energy expenditure and be more resistant to HF-induced hyperphagia than male mice.

METHODS

Six-week-old male and female C57BL/6 J mice were fed either low fat (LF, 10% fat) or moderate HF (45% fat) for 5 weeks, and energy expenditure, activity and meal pattern measured using comprehensive laboratory animal monitoring system (CLAMS).

RESULTS

After 5 weeks, HF-fed male mice had a significant increase in body weight and fat mass, compared with LF-fed male mice. HF-fed female had a significant increase in body weight compared with LF-fed female mice, but there was no significant difference in fat mass. HF-fed male mice had lower energy expenditure compared to HF-fed female mice, likely due in part to reduced physical activity in the light phase. HF-fed male mice also had increased energy intake in the dark phase compared to LF-fed male mice and a reduced response to exogenous cholecystokinin-induced inhibition of food intake. In contrast, there was no difference in energy intake between LF-fed and HF-fed female mice.

CONCLUSIONS

The data show that female mice are generally protected from short-term HF-induced alterations in energy balance, possibly by maintaining higher energy expenditure and an absence of hyperphagia. However, HF-feeding in male mice induced weight and fat mass gain and hyperphagia. These findings suggest that there is a sex difference in the response to short-term HF-feeding in terms of both energy expenditure and control of food intake.

Sexual differentiation of brain and other tissues: Five questions for the next 50 years

This paper is part of the celebration of the 50th anniversary of founding of the journal Hormones and Behavior, the official journal of the Society for Behavioral Neuroendocrinology. All sex differences in phenotypic development stem from the sexual imbalance in X and Y chromosomes, which are the only known differences in XX and XY zygotes. The sex chromosome genes act within cells to cause differences in phenotypes of XX and XY cells throughout the body. In the gonad, they determine the type of gonad, leading to differences in secretion of testicular vs. ovarian hormones, which cause further sex differences in tissue function. These current ideas of sexual differentiation are briefly contrasted with a hormones-only view of sexual differentiation of the last century. The multiple, independent action of diverse sex-biasing agents means that sex-biased factors can be synergistic, increasing sex differences, or compensatory, making the two sexes more equal. Several animal models have been fruitful in demonstrating sex chromosome effects, and interactions with gonadal hormones. MRI studies of human brains demonstrate variation in brain structure associated with both differences in gonadal hormones, and in the number of X and Y chromosomes. Five unanswered questions are posed as a challenge to future investigators to improve understanding of sexual differentiation throughout the body.

Obesity: sex and sympathetics

Obesity increases sympathetic nerve activity (SNA) in men, but not women. Here, we review current evidence suggesting that sexually dimorphic sympathoexcitatory responses to leptin and insulin may contribute. More specifically, while insulin increases SNA similarly in lean males and females, this response is markedly amplified in obese males, but is abolished in obese females. In lean female rats, leptin increases a subset of sympathetic nerves only during the high estrogen proestrus reproductive phase; thus, in obese females, because reproductive cycling can become impaired, the sporadic nature of leptin-induced sympathoexcitaton could minimize its action, despite elevated leptin levels. In contrast, in males, obesity preserves or enhances the central sympathoexcitatory response to leptin, and current evidence favors leptin’s contribution to the well-established increases in SNA induced by obesity in men. Leptin and insulin increase SNA via receptor binding in the hypothalamic arcuate nucleus and a neuropathway that includes arcuate neuropeptide Y (NPY) and proopiomelanocortin (POMC) projections to the paraventricular nucleus. These metabolic hormones normally suppress sympathoinhibitory NPY neurons and activate sympathoexcitatory POMC neurons. However, obesity appears to alter the ongoing activity and responsiveness of arcuate NPY and POMC neurons in a sexually dimorphic way, such that SNA increases in males but not females. We propose hypotheses to explain these sex differences and suggest areas of future research.

Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines

Aging causes changes in body composition and energy balance. Estrogen plays an important role in body's metabolism. The aim of this study was to determine whether estrogen has beneficial effects on leptin responsiveness in aged mice. Young 4 months and aged 19-21 female mice fed High Fat Diet (HFD) or Standard Diet (SD) for 12 weeks and following received estrogen for 4 weeks. Responsiveness to leptin was compared by measuring energy balance parameters. Results showed that HFD caused weight gain compared to SD in young, but had no effect on aged animals. Estrogen reduced body weight, energy intake and visceral fat in young, while none of these parameters was affected in aged animals. Although there was leptin sensitivity in aged compared to ovariectomized animals, estrogen only improved the sensitivity of young to leptin. Estrogen prevented increase in TNF-α and a decrease in IL-10 in HFD young and aged animals. Response to estrogen depended on age, and estrogen increased leptin sensitivity only in young animals. Determining the exact mechanism of this action is suggested in future studies.

Follicle-Stimulating Hormone Positively Associates with Metabolic Factors in Perimenopausal Women

OBJECTIVE

Menopause is associated with the increased risk of metabolic syndrome (MetS) and cardiovascular (CV) disease. Most studies have focused the postmenopausal women and the relationships among estrogen, androgen, and Mets risk. The main aim of the study was to investigate the Mets risk in perimenopausal women and whether the variation of FSH is associated with metabolic factors.

METHODS

A single-center cross-sectional retrospective analysis including 154 premenopausal women and 124 perimenopausal women was performed.

RESULTS

The prevalence of Mets in the perimenopausal group was much higher than the premenopausal group (49.19% vs. 35.71%, p = 0.023). The prevalence of central obesity and NAFLD also increased in the perimenopausal group than in the premenopausal group. We grouped the population by FSH tertiles; compared with women in the lowest tertile, women in the highest tertile had higher age, WC, serum TC, LDL-C, AST, ALT, and creatine levels. The prevalence of hypertriglyceridemia, raised BP and Mets also increased in the highest tertile group. Further, we subdivided the perimenopausal women according to FSH tertiles. Compared with perimenopausal women in the lowest tertile, the prevalence of raised BP significantly increased in the highest tertile.

CONCLUSIONS

The risk of Mets increased in perimenopausal females than in premenopausal women. And a higher FSH level was associated with higher WC, TG, BPs, and the risk of Mets in perimenopausal women. Elevated FSH level appears to be a risk factor of MetS biomarkers in perimenopausal women.

The capacity for oestrogen to influence obesity through brown adipose tissue thermogenesis in animal models: A systematic review and meta-analysis

Pharmacological interventions to aid weight loss have historically targeted either appetite suppression or increased metabolic rate. Brown adipose tissue (BAT) possesses the capacity to expend energy in a futile cycle, thus increasing basal metabolic rate. In animal models, oestrogen has been implicated in the regulation of body weight, and it is hypothesized that oestrogen is acting by modulating BAT metabolism. A systematic search was performed, to identify research articles implementing in vivo oestrogen-related interventions and reporting outcome measures that provide direct or indirect measures of BAT metabolism. Meta-analyses were conducted where sufficient data were available. The final library of 67 articles were predominantly in rodent models and provided mostly indirect measures of BAT metabolism. Results of this review found that oestrogen's effects on body weight, in rats and possibly mice, are likely facilitated by both metabolic and appetitive mechanisms but are largely only found in ovariectomized models. There is a need for further studies to clarify the potential effects of oestrogen on BAT metabolism in gonad-intact and castrated male animal models.

The developmental Wnt signaling pathway effector β-catenin/TCF mediates hepatic functions of the sex hormone estradiol in regulating lipid metabolism

The bipartite transcription factor β-catenin (β-cat)/T cell factor (TCF), formed by free β-cat and a given TCF family member, serves as the effector of the developmental Wnt signaling cascade. β-cat/TCFs also serve as effectors of certain peptide hormones or growth factors during adulthood. We reported that liver-specific expression of dominant-negative Transcription factor 7 like 2 (TCF7L2DN) led to impaired glucose disposal. Here we show that, in this LTCFDN transgenic mouse model, serum and hepatic lipid contents were elevated in male but not in female mice. In hepatocytes, TCF7L2DN adenovirus infection led to stimulated expression of genes that encode lipogenic transcription factors and lipogenic enzymes, while estradiol (E2) treatment attenuated the stimulation, associated with Wnt-target gene activation. Mechanistically, this E2-mediated activation can be attributed to elevated β-cat Ser675 phosphorylation and TCF expression. In wild-type female mice, ovariectomy (OVX) plus high-fat diet (HFD) challenge impaired glucose disposal and insulin tolerance, associated with increased hepatic lipogenic transcription factor sterol regulatory element-binding protein 1-c (SREBP-1c) expression. In wild-type mice with OVX, E2 reconstitution attenuated HFD-induced metabolic defects. Some of the attenuation effects, including insulin intolerance, elevated liver-weight gain, and hepatic SREBP-1c expression, were not affected by E2 reconstitution in HFD-fed LTCFDN mice with OVX. Finally, the effects of E2 in hepatocytes on β-cat/TCF activation can be attenuated by the G-protein-coupled estrogen receptor (GPER) antagonist G15. Our study thus expanded the scope of functions of the Wnt pathway effector β-cat/TCF, as it can also mediate hepatic functions of E2 during adulthood. This study also enriches our mechanistic understanding of gender differences in the risk and pathophysiology of metabolic diseases.

Pancreastatin inhibitor, PSTi8 ameliorates metabolic health by modulating AKT/GSK-3β and PKCλ/ζ/SREBP1c pathways in high fat diet induced insulin resistance in peri-/post-menopausal rats

Increase in the prevalence of insulin resistance (IR) in peri-/post-menopause women is mainly due to hormone deficiency and lifestyle. PSTi8 (PEGKGEQEHSQQKEEEEEMAV-amide) is a pancreastatin inhibitor peptide which showed potent antidiabetic activity in genetic and lifestyle induced type 2 diabetic mice. In the present work, we have investigated the antidiabetic activity of PSTi8 in rat models of peri-/post-menopausal IR. 4-vinylcyclohexenediepoxide treated and ovariectomized rats were fed with high fat diet for 12 weeks to develop the peri-/post-menopausal IR. PSTi8 peptide was administered after the development of peri-/post-menopausal IR rats. PSTi8 (1 mg/kg, i.p) improved the glucose homeostasis which is characterized by elevated glycogenesis, enhanced glycolysis and reduced gluconeogenesis. PSTi8 suppressed palmitate- and PST- induced IR in HepG2 cells. PSTi8 treatment enhanced energy expenditure in peri-/post-menopausal IR rats. PSTi8 treatment increased insulin sensitivity in peri-/post-menopausal IR rats, may be mediated by modulating IRS1-2-phosphatidylinositol-3-kinase-AKT-GSK3β and IRS1-2-phosphatidylinositol-3-kinase-PKCλ/ζ-SREBP1c signaling pathways in the liver. PSTi8 can act as a potential therapeutic peptide for the treatment of peri-/post-menopausal IR.

Moderate intake of aspartame and sucralose with meals, but not fructose, does not exacerbate energy and glucose metabolism in estrogen-deficient rats

Both nutritive and non-nutritive sweeteners may influence energy and glucose metabolism differently. The hypothesis that sucrose, fructose, aspartame, and sucralose intake differently modulate energy and glucose metabolism was tested in an estrogen-deficient animal model. At 30 min after giving aspartame and sucralose (10 mg/kg body weight), an oral glucose tolerance test (OGTT) was conducted with glucose, sucrose, and fructose in ovariectomized (OVX) rats. After OGTT, they were continuously fed high fat diets including either 10% corn starch (Control), 10% sucrose (Sucrose), 10% fructose (Fructose), 0.05% aspartame + 9.95% starch (Aspartame) or 0.05% sucralose + 9.95% starch (Sucralose) for 8 week. During 30 min after acute administration of aspartame and sucralose, serum glucose concentrations increased despite slightly increased serum insulin levels before glucose infusion. However, glucose tolerance was not significantly different among the groups. In chronic study, serum glucose concentrations were lowest and insulin highest at the overnight-fasted state in Aspartame and Sucralose. Postprandial serum glucagon-like peptide-1 (GLP-1) and insulin levels were higher in Aspartame and Sucralose than Control. Hepatic insulin signaling (pAkt → pGSK-3β) and phosphoenolpyruvate carboxykinase (PEPCK) expression were lower in Sucralose and Aspartame than the Fructose. Serum acetate levels produced by gut microbiota were higher were lower in the fructose group than Aspartame and Sucralose groups. In conclusion, aspartame and sucralose with a meal might be preferable sweeteners to fructose and sucrose in estrogen deficient rats, and possibly post-menopausal women; however, this needs to be confirmed in human studies.

Encapsulated Mulberry Fruit Extract Alleviates Changes in an Animal Model of Menopause with Metabolic Syndrome

Currently, the therapeutic strategy against metabolic syndrome and its complications is required due to the increasing prevalence and its impact. Due to the benefits of both mulberry fruit extract and encapsulation technology, we hypothesized that encapsulated mulberry fruit extract (MME) could improve metabolic parameters and its complication risk in postmenopausal metabolic syndrome. To test this hypothesis, female Wistar rats were induced experimental menopause with metabolic syndrome by bilateral ovariectomy (OVX) and high-carbohydrate high-fat (HCHF) diet. Then, they were orally given MME at doses of 10, 50, and 250 mg/kg BW for 8 weeks and the parameters, such as percentage of body weight gain, total cholesterol, triglycerides, HDL-C, LDL-C, atherogenic index, fasting blood glucose, plasma glucose area under the curve, serum angiotensin-converting enzyme (ACE), oxidative stress status, histology, and protein expression of PPAR-γ, TNF-α, and NF-κB in adipose tissues were determined. MME improved body weight gain, adiposity index, glucose intolerance, lipid profiles, atherogenic index, ACE, oxidative stress status, and protein expression of TNF-α and NF-κB. Moreover, MME attenuated adipocyte hypertrophy and enhanced PPAR-γ expression. Taken altogether, MME decreased metabolic syndrome and its complication via the increased PPAR-γ expression. Therefore, MME is the potential candidate for improving metabolic syndrome and its related complications. However, further research in clinical trial is still necessary.

Influence of Estradiol Status on Physical Activity in Premenopausal Women

PURPOSE

This study aimed to determine the effects of 5 months of ovarian hormone suppression in premenopausal women on objectively measured physical activity (PA).

METHODS

Participants (age, 35 ± 8 yr; body mass index, 27 ± 6 kg·m) received monthly intramuscular injections of gonadotropin-releasing hormone agonist (GnRHAG) therapy, which suppresses pituitary gonadotropins and results in suppression of ovarian sex hormones. Women were randomized to receive concurrent transdermal E2 (GnRHAG + E2; n = 30) or placebo (GnRHAG + PL, n = 31). PA was assessed for 1 wk before and during each month of the 5-month intervention using a hip-worn accelerometer (Actical, Mini Mitter Co., Inc., Bend, OR). Estimates of time spent in sedentary, light, and moderate-to-vigorous PA (MVPA) were derived using a previously published equation. Subsets of participants in each group were also randomized to a supervised progressive resistance exercise training program.

RESULTS

Total MVPA tended toward being higher (P = 0.08) in the GnRHAG + E2 group at month 4. There were no significant effects of intervention or time in sedentary or light PA. In the subset of women who did not participate in structured exercise training for which Actical data were obtained (n = 16 in each group), total MVPA was higher at month 4 (P = 0.01).

CONCLUSIONS

PA levels seem to be maintained at a higher level in women undergoing pharmacological suppression of ovarian function with E2 add-back when compared with women treated with placebo. These data provide proof-of-concept data that E2 contributes to the regulation of PA in humans. However, given the exploratory nature of this study, future confirmatory investigations will be necessary.

History of Estrogen: Its Purification, Structure, Synthesis, Biologic Actions, and Clinical Implications

This mini-review summarizes key points from the Clark Sawin Memorial Lecture on the History of Estrogen delivered at Endo 2018 and focuses on the rationales and motivation leading to various discoveries and their clinical applications. During the classical period of antiquity, incisive clinical observations uncovered important findings; however, extensive anatomical dissections to solidify proof were generally lacking. Initiation of the experimental approach followed later, influenced by Claude Bernard's treatise "An Introduction to the Study of Experimental Medicine." With this approach, investigators began to explore the function of the ovaries and their "internal secretions" and, after intensive investigations for several years, purified various estrogens. Clinical therapies for hot flashes, osteoporosis, and dysmenorrhea were quickly developed and, later, methods of hormonal contraception. Sophisticated biochemical methods revealed the mechanisms of estrogen synthesis through the enzyme aromatase and, after discovery of the estrogen receptors, their specific biologic actions. Molecular techniques facilitated understanding of the specific transcriptional and translational events requiring estrogen. This body of knowledge led to methods to prevent and treat hormone-dependent neoplasms as well as a variety of other estrogen-related conditions. More recently, the role of estrogen in men was uncovered by prismatic examples of estrogen deficiency in male patients and by knockout of the estrogen receptor and aromatase in animals. As studies became more extensive, the effects of estrogen on nearly every organ were described. We conclude that the history of estrogen illustrates the role of intellectual reasoning, motivation, and serendipity in advancing knowledge about this important sex steroid.

WITHDRAWN: Sex differences in glucocorticoids-induced anabolic effects on energy balance

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error.