Timing of Estradiol Treatment After Menopause May Determine Benefit or Harm to Insulin Action

Timing Matters: Effects of Early and Late Estrogen Replacement Therapy on Glucose Metabolism and Vascular Reactivity in Ovariectomized Aged Wistar Rats

Cardiovascular disease incidence increases after menopause due to the loss of estrogen cardioprotective effects. However, there are conflicting data regarding the timing of estrogen therapy (ERT) and its effect on vascular dysfunction associated with impaired glucose metabolism. The aim of this work was to evaluate the effect of early and late ERT on blood glucose/insulin balance and vascular reactivity in aged ovariectomized Wistar rats. Eighteen-month-old female Wistar rats were randomized as follows: (1) sham, (2) 10-week postovariectomy (10 w), (3) 10 w postovariectomy+early estradiol therapy (10 w-early E2), (4) 20-week postovariectomy (20 w), and (5) 20-week postovariectomy+late estradiol therapy (20 w-late E2). Early E2 was administered 3 days after ovariectomy and late therapy after 10 weeks, in both groups. 17β-Estradiol (E2) was administered daily for 10 weeks (5 μg/kg/day). Concentration-response curves to angiotensin II, KCl, and acetylcholine (ACh) were performed. Heart rate (HR), diastolic and systolic blood pressure (DBP and SBP), glucose, insulin, HOMA-IR, and nitric oxide (NO) levels were determined. Higher glucose levels were found in all groups compared to the sham group, except the 20 w-late E2 group. Insulin was increased in all ovariectomized groups compared to sham. The HOMA-IR index showed insulin resistance in all ovariectomized groups, except for the 10 w-early E2 group. The 10 w-early E2 group increased NO levels vs. the 10 w group. After 10 w postovariectomy, the vascular response to KCl and Ach increases, despite early E2 administration. Early and late E2 treatment decreased vascular reactivity to Ang II. At 20-week postovariectomy, DBP increased, even with E2 administration, while SBP and HR remained unchanged. The effects of E2 therapy on blood glucose/insulin balance and vascular reactivity depend on the timing of therapy. Early ERT may provide some protective effects on insulin resistance and vascular function, whereas late ERT may not have the same benefits.

Hormones and Aging: An Endocrine Society Scientific Statement

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

Sex Hormones and Diabetes in 45- to 74-year-old Men and Postmenopausal Women: The Hispanic Community Health Study

Previous studies demonstrated associations of endogenous sex hormones with diabetes. Less is known about their dynamic relationship with diabetes progression through different stages of the disease, independence of associations, and role of the hypothalamic-pituitary gonadal axis. The purpose of this analysis was to examine relationships of endogenous sex hormones with incident diabetes, prediabetes, and diabetes traits in 693 postmenopausal women and 1015 men aged 45 to 74 years without diabetes at baseline participating in the Hispanic Community Health Study/Study of Latinos and followed for 6 years. Baseline hormones included estradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH), sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), and, in men, testosterone and bioavailable testosterone. Associations were analyzed using multivariable Poisson and linear regressions. In men, testosterone was inversely associated with conversion from prediabetes to diabetes (incidence rate ratio [IRR] for 1 SD increase in testosterone: 0.821; 95% CI, 0.676, 0.997; P = 0.046), but not conversion from normoglycemia to prediabetes. Estradiol was positively associated with increase in fasting insulin and homeostatic model assessment of insulin resistance. In women, SHBG was inversely associated with change in glycosylated hemoglobin, postload glucose, and conversion from prediabetes to diabetes (IRR = 0.62; 95% CI, 0.44, 0.86, P = 0.005) but not from normoglycemia to prediabetes. Relationships with other hormones varied across glycemic measures. Stronger associations of testosterone and SHBG with transition from prediabetes to diabetes than from normoglycemic to prediabetes suggest they are operative at later stages of diabetes development. Biologic pathways by which sex hormones affect glucose homeostasis await future studies.

Estrogens in Adipose Tissue Physiology and Obesity-Related Dysfunction

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

Treating menopause - MHT and beyond

Every woman who lives past midlife will experience menopause, which, by definition, is complete cessation of ovarian function. This process might occur spontaneously (natural menopause) or be iatrogenic (secondary menopause), and can be further classified as 'early' if it occurs before the age of 45 years and 'premature' if it occurs before the age of 40 years. Globally, the mean age of natural menopause is 48.8 years, with remarkably little geographic variation. A woman's age at menopause influences health outcomes in later life. Early menopause is associated with a reduced risk of breast cancer, but increased risks of premature osteoporosis, cardiovascular disease and premature death. The cardinal symptoms of menopause, and adverse health sequelae, are due to loss of ovarian oestrogen production. Consequently, menopausal hormone therapy (MHT) that includes oestrogen or an oestrogenic compound ameliorates menopausal symptoms, while preventing menopause-associated bone loss and cardiometabolic changes. Importantly, comprehensive care of postmenopausal women involves lifestyle optimization (attention to nutrition and physical activity, reducing alcohol consumption and not smoking) and treating other established chronic disease risk factors. This Review offers a commentary specifically on the contemporary use of MHT and novel pharmaceutical alternatives to manage menopausal symptoms.

Reproductive Life Span and Severe Hypoglycemia Risk in Postmenopausal Women with Type 2 Diabetes Mellitus

BACKGROUND

Estrogen promotes glucose homeostasis, enhances insulin sensitivity, and maintains counterregulatory responses in recurrent hypoglycemia in women of reproductive age. Postmenopausal women with type 2 diabetes mellitus (T2DM) might be more vulnerable to severe hypoglycemia (SH) events. However, the relationship between reproductive factors and SH occurrence in T2DM remains unelucidated.

METHODS

This study included data on 181,263 women with postmenopausal T2DM who participated in a national health screening program from January 1 to December 31, 2009, obtained using the Korean National Health Insurance System database. Outcome data were obtained until December 31, 2018. Associations between reproductive factors and SH incidence were assessed using Cox proportional hazards models.

RESULTS

During the mean follow-up of 7.9 years, 11,279 (6.22%) postmenopausal women with T2DM experienced SH episodes. A longer reproductive life span (RLS) (≥40 years) was associated with a lower SH risk compared to a shorter RLS (<30 years) (adjusted hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.69 to 0.80; P for trend <0.001) after multivariable adjustment. SH risk decreased with every 5-year increment of RLS (with <30 years as a reference [adjusted HR, 0.91; 95% CI, 0.86 to 0.95; P=0.0001 for 30-34 years], [adjusted HR, 0.80; 95% CI, 0.76 to 0.84; P<0.001 for 35-39 years], [adjusted HR, 0.74; 95% CI, 0.68 to 0.81; P<0.001 for ≥40 years]). The use of hormone replacement therapy (HRT) was associated with a lower SH risk than HRT nonuse.

CONCLUSION

Extended exposure to endogenous ovarian hormone during lifetime may decrease the number of SH events in women with T2DM after menopause.

Management of menopause: a view towards prevention

Women spend approximately one-third of their lives with menopause, which occurs around 50 years of age. It is now appreciated that several important metabolic and cardiovascular disease risks emerge during the menopausal transition. Many important conditions occur 10-15 years after menopause, including weight gain and obesity, metabolic syndrome, diabetes, osteoporosis, arthritis, cardiovascular disease, dementia, and cancer; therefore, the occurrence of menopause heralds an important opportunity to institute preventative strategies. These strategies will lead to improved quality of life and decreased mortality. Various strategies are presented for treating symptoms of menopause and diseases that are asymptomatic. Among several strategies is the use of hormone therapy, which has efficacy for symptoms and osteoporosis, and can improve metabolic and cardiovascular health. When instituted early, which is key, in younger postmenopausal women (under 60 years) oestrogen has been found to consistently decrease mortality with a favourable risk-benefit profile in low-risk women. Prospective data show that long-term therapy might not be required for this benefit.

Role of Estrogen and Its Receptors in Adipose Tissue Glucose Metabolism in Pre- and Postmenopausal Women

CONTEXT

Reduced estrogen levels in postmenopausal women predispose them to metabolic side effects, including insulin resistance and type 2 diabetes; however, the cellular mechanisms are not well understood.

OBJECTIVE

This work aimed to study the expression of estrogen receptors in adipose tissue from pre- and postmenopausal women and the effects of estradiol (E2) on glucose uptake of adipocytes.

METHODS

Subcutaneous (SAT) and visceral adipose tissue (VAT) obtained from pre- and postmenopausal women (19-51 and 46-75 years old, respectively) were used to measure gene expression of ESR1 and ESR2. SAT tissue was incubated with E2, and glucose uptake and estrogen receptor levels were measured. Polymorphisms in ESR1 and ESR2 were addressed in public databases to identify single nucleotide polymorphisms associated with metabolic traits.

RESULTS

ESR2 expression was lower in pre- vs postmenopausal women, corresponding to lower ESR1:ESR2 gene expression ratio in postmenopausal women. In premenopausal women, the expression of ESR1 was higher in VAT than in SAT. In both pre- and postmenopausal women, ESR2 expression was lower in VAT than in SAT. In late, but not pre- or early postmenopausal women, E2 reduced glucose uptake and GLUT4 protein and increased expression of ESR2. ESR1 polymorphisms were associated with weight, body fat distribution, and total cholesterol, and ESR2 polymorphisms were associated with total cholesterol and triglyceride levels and with body fat percentage.

CONCLUSION

E2 inhibits glucose utilization in human adipocytes in late postmenopausal women. Changes in glucose utilization over time since menopause may be explained by a lower ESR1:ESR2 ratio. This can have clinical implications on the timing of estrogen treatment in postmenopausal women.

Menopausal Hormone Replacement Therapy and Reduction of All-Cause Mortality and Cardiovascular Disease: It Is About Time and Timing

ABSTRACT

The totality of evidence indicates menopausal hormone replacement therapy (HRT) effects are determined by timing of initiation according to age and/or time since menopause, underlying health of target tissue, and duration of therapy. Initiated in women at younger than 60 years and/or at or near menopause, HRT significantly reduces all-cause mortality and cardiovascular disease (CVD), whereas other primary CVD prevention therapies such as lipid-lowering fail to do so. The magnitude and type of HRT-associated risks, including breast cancer, stroke, and venous thromboembolism, are rare (<10 events/10,000 women), not unique to HRT, and comparable with other medications. Hormone replacement therapy is a sex-specific and time-dependent primary CVD prevention therapy that concomitantly reduces all-cause mortality, as well as other aging-related diseases with an excellent risk profile. Keeping in mind that prevention strategies must be personalized, health care providers and patients can use cumulated HRT data in making clinical decisions concerning chronic disease prevention including CVD and mortality reduction.

Interactions between estradiol, diabetes, and brain aging and the risk for cognitive impairment

The Women's Health Initiative Memory Study reported that older women using conjugated equine estrogens hormone therapy (HT) with or without medroxyprogesterone acetate were at increased risk for probable dementia and smaller brain volumes. These adverse effects were greatest among women who had type 2 diabetes mellitus (T2DM) at baseline or who developed the disease during follow-up. This review summarizes existing literature from randomized trials, observational studies, and preclinical studies to provide a fundamental understanding of the effects of the interaction between T2DM and HT on cognitive and metabolic health changes in brain aging.

Association between Coronary Artery Spasm and the risk of incident Diabetes: A Nationwide population-based Cohort Study

Background: Non-diabetic coronary artery spasm (CAS) without obstructive coronary artery disease increases insulin resistance. We investigated the risk of incident type 2 diabetes (diabetes) associated with CAS. Methods: Patient records were retrospectively collected from the Taiwan National Health Insurance Research Database during the period 2000-2012. The matched cohorts consisted of 12,413 patients with CAS and 94,721 patients in the control group. Results: During the entire follow-up, the incidence of newly-diagnosed diabetes was 22.2 events per 1000 person-years in the CAS group and 13.9 events per 1000 person-years in the control group. The increased risk of CAS-related incident diabetes was observed regardless of sex and length of follow-up. The median time to incident diabetes was 2.9 and 3.5 years in the CAS and the control group (P <0.001), respectively, regardless of sex. Although age did not affect the risk of CAS-related incident diabetes, the risk was less apparent in the subgroups of male, dyslipidemia, chronic obstructive pulmonary disease, stroke, gout and medicated hypertension. However, CAS patients aged <50 years compared with patients ≥50 years had a greater risk of incident diabetes in females but not in males. Older CAS patients developed diabetes in a shorter length of time than younger patients. Conclusion: CAS is a risk factor for incident diabetes regardless of sex. However, females aged <50 years have a more apparent risk for CAS-related diabetes than old females, which is not observed in males. The median time of 2.9 years to incident diabetes warrants close follow-up.

Ketogenic diet as a potential intervention for lipedema

Lipedema (LI) is a common yet misdiagnosed condition, often misconstrued with obesity. LI affects women almost exclusively, and its painful and life-changing symptoms have long been thought to be resistant to the lifestyle interventions such as diet and exercise. In this paper, we discuss possible mechanisms by which patients adopting a ketogenic diet (KD) can alleviate many of the unwanted clinical features of LI. This paper is also an effort to provide evidence for the hypothesis of the potency of this dietary intervention for addressing the symptoms of LI. Specifically, we examine the scientific evidence of effectiveness of adopting a KD by patients to alleviate clinical features associated with LI, including excessive and disproportionate lower body adipose tissue (AT) deposition, pain, and reduction in quality of life (QoL). We also explore several clinical features of LI currently under debate, including the potential existence and nature of edema, metabolic and hormonal dysfunction, inflammation, and fibrosis. The effectiveness of a KD on addressing clinical features of LI has been demonstrated in human studies, and shows promise as an intervention for LI. We hope this paper leads to an improved understanding of optimal nutritional management for patients with LI and stimulates future research in this area of study.

Sex Differences in Adipose Tissue Function

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

Influence of Menopausal Hormone Therapy on Body Composition and Metabolic Parameters

The loss of estrogen with menopause is associated with an increase in central fat. The objective of this study was to evaluate the effects of menopause hormone therapy (HT) on body composition and metabolic parameters in postmenopausal women. A prospective study was conducted among postmenopausal women from the Climacteric clinic, Universidade Federal de São Paulo. Thirty-two participants, median age 51 years, were included. Sixteen women were eligible to receive a low-dose continuous combined HT, containing 1 mg of E2 plus 0.125 mg of trimegestone for 6 months. The other 16 women remained in the control group. In the HT group, significant decreases from baseline were evident for the total cholesterol (TC) (p < 0.05) and LDL levels (p < 0.05). The HDL significantly decreased (p < 0.05). However, the TC/HDL ratio also decreased (p = 0.05). The parameters of body composition, after 6 months of HT, were maintained. In the control group, body mass index levels increased from baseline, however, with nonstatistically significant differences (p = 0.06). Analyzing the body composition showed a significant increase in the trunk body fat (p = 0.04), trunk region fat (p = 0.04), and total region fat (p = 0.03) after 6 months. In conclusion, the present study provides evidence that HT can stunt the increase in total body fat and prevent the shift from a more central fat distribution observed in early postmenopausal period.

Acute estradiol treatment reduces skeletal muscle protein breakdown markers in early- but not late-postmenopausal women

OBJECTIVES

Menopause and decline in estradiol (E₂) may contribute to sarcopenia (i.e., age-related decline in muscle mass and strength) in women. E₂ may directly impact skeletal muscle protein breakdown via estrogen receptor (ER) signaling, primarily ERα. It is not yet known whether: 1) E₂ regulates pathways of skeletal muscle protein breakdown; 2) E₂-mediated changes in protein breakdown markers are associated with ERα activation and insulin sensitivity; and 3) the effects of E₂ on protein breakdown markers differ by increasing time since menopause.

STUDY DESIGN

We studied 27 women who were ≤6 years past menopause (early postmenopausal, EPM; n = 13) or ≥10 years past menopause (late postmenopausal, LPM; n = 14). Fasted skeletal muscle samples were collected following 1 week of transdermal E₂ or placebo treatment in a randomized cross-over design.

MAIN OUTCOME MEASURES

We analyzed for cytosolic protein content of the: 1) structural proteins myosin heavy chain (MHC) and tropomyosin; and 2) protein regulatory markers: protein kinase B (Akt), muscle-specific ring finger protein1 (MuRF1), atrogin1, and forkhead box O3 (FOXO3) using Western blot.

RESULTS

In response to acute E₂, FOXO3 activation (dephosphorylation) and MuRF1 protein expression decreased in EPM but increased in LPM women (p < 0.05). ERα activation was not associated with these protein breakdown markers, but FOXO3 activation tended to be inversely correlated (r = -0.318, p = 0.065) to insulin sensitivity.

CONCLUSIONS

These preliminary studies suggest the effects of E₂ on skeletal muscle protein breakdown markers were dependent on time since menopause, which is consistent with our previous study on insulin sensitivity.

Peptide Conjugates with Small Molecules Designed to Enhance Efficacy and Safety

Peptides constitute molecular diversity with unique molecular mechanisms of action that are proven indispensable in the management of many human diseases, but of only a mere fraction relative to more traditional small molecule-based medicines. The integration of these two therapeutic modalities offers the potential to enhance and broaden pharmacology while minimizing dose-dependent toxicology. This review summarizes numerous advances in drug design, synthesis and development that provide direction for next-generation research endeavors in this field. Medicinal studies in this area have largely focused upon the application of peptides to selectively enhance small molecule cytotoxicity to more effectively treat multiple oncologic diseases. To a lesser and steadily emerging extent peptides are being therapeutically employed to complement and diversify the pharmacology of small molecule drugs in diseases other than just cancer. No matter the disease, the purpose of the molecular integration remains constant and it is to achieve superior therapeutic outcomes with diminished adverse effects. We review linker technology and conjugation chemistries that have enabled integrated and targeted pharmacology with controlled release. Finally, we offer our perspective on opportunities and obstacles in the field.

NAMS 3rd Utian Translational Science Symposium, October 2016, Orlando, Florida A conversation about hormone therapy: is there an appropriate dose, route, and duration of use?

The North American Menopause Society (NAMS) held the 3rd Utian Translational Symposium on October 4, 2016, in Orlando, Florida, to answer questions about the benefits and risks of hormone therapy (HT) for postmenopausal women. This report is a record of the proceedings of that symposium.The maxim about HT for the past 15 years since the publication of the initial results of the Women's Health Initiative (WHI) has been to prescribe the "lowest dose for the shortest period of time." With new clinical trials, observational data, and further analysis of the WHI and the cumulative 13 years' follow-up, it was time to hold a conversation about the state of the evidence and recommendations for HT dose, route, and duration of use.The symposium brought together experts in the field of HT to speak on these topics, organized by session, after which working groups gathered to synthesize the presentations into areas of what still needs to be known and how to proceed with areas of needed research. After the presentations, there was consensus that postmenopausal women aged younger than 60 years or within 10 years of menopause onset without contraindications and who desire to take HT for relief of vasomotor symptoms or prevention of bone loss if at elevated risk can safely do so.The working groups raised the possibility that the use of "Big Data" (pharmacy and cancer databases) would allow answers that cannot be found in clinical trials. This could lead to more appropriate FDA labeling and patient package inserts reflecting the true risks associated with various types and formulations of HT, with differences among estrogen alone, estrogen with a progestogen, and estrogen plus a selective estrogen-receptor modulator for the younger women most likely to initiate these therapies for symptom relief. Differences were found for potential risk among estrogen alone, estrogen with synthetic progestins contrasted to progesterone, lower doses, nonoral doses, and low-dose vaginal estrogen.With all of the available routes and dosages, including vaginal estrogen alone for genitourinary symptoms, there are many options when considering the most appropriate type, dose, formulation, route of administration, and duration of use, taking into account the age of the woman at initiation of HT and the time from menopause.

G-Protein-Coupled Estrogen Receptor (GPER) and Sex-Specific Metabolic Homeostasis

Obesity and metabolic syndrome display disparate prevalence and regulation between males and females. Human, as well as rodent, females with regular menstrual/estrous cycles exhibit protection from weight gain and associated chronic diseases. These beneficial effects are predominantly attributed to the female hormone estrogen, specifically 17β-estradiol (E2). E2 exerts its actions via multiple receptors, nuclear and extranuclear estrogen receptor (ER) α and ERβ, and the G-protein-coupled estrogen receptor (GPER, previously termed GPR30). The roles of GPER in metabolic homeostasis are beginning to emerge but are complex and remain unclear. The discovery of GPER-selective pharmacological agents (agonists and antagonists) and the availability of GPER knockout mice have significantly enhanced our understanding of the functions of GPER in normal physiology and disease. GPER action manifests pleiotropic effects in metabolically active tissues such as the pancreas, adipose, liver, and skeletal muscle. Cellular and animal studies have established that GPER is involved in the regulation of body weight, feeding behavior, inflammation, as well as glucose and lipid homeostasis. GPER deficiency leads to increased adiposity, insulin resistance, and metabolic dysfunction in mice. In contrast, pharmacologic stimulation of GPER in vivo limits weight gain and improves metabolic output, revealing a promising novel therapeutic potential for the treatment of obesity and diabetes.

Increased body fat mass explains the positive association between circulating estradiol and insulin resistance in postmenopausal women

The relationship between circulating estrogen levels and cardiometabolic risk factors such as insulin resistance is unclear in postmenopausal women. High estradiol (E₂) levels have been reported to predict increased risk of type 2 diabetes in this population. We aimed to examine associations among estrogen levels, adiposity measurements, and cardiometabolic risk variables including insulin resistance in postmenopausal women. One hundred-one healthy participants (mean ± SD: age 57 ± 4 yr, BMI 27.9 ± 4.8 kg/m²) were included in the analysis. Fifteen plasma steroids or metabolites were measured by liquid chromatography-tandem mass spectrometry. Insulin sensitivity was assessed with a hyperinsulinemic-euglycemic clamp. Body composition and fat distribution were determined with hydrostatic weighing and computed tomography, respectively. Blood lipids and circulating cytokines were also measured. Circulating E₂ was positively correlated with all adiposity indexes ( r = 0.62 to 0.42, P < 0.0001) except waist-to-hip ratio. E₂ was positively correlated with VLDL-cholesterol, plasma-, VLDL-, and HDL-triglyceride levels ( r = 0.31 to 0.24, P < 0.02) as well as with hs-CRP and IL-6 ( r = 0.52 and 0.29, P < 0.005) and negatively with HDL-cholesterol, adiponectin, and insulin sensitivity ( r = -0.36 to -0.20, P < 0.02). With adjustments for percent body fat, correlations between E₂ and metabolic risk variables were no longer significant. Similar results were observed for circulating estrone (E₁) and estrone-sulfate (E₁-S) levels. In conclusion, circulating estrogen concentrations are proportional to adipose mass in postmenopausal women, although they remain in the low range. Insulin resistance as well as altered blood lipids and cytokines are observed when circulating estrogen levels are high within that range, but these differences are explained by concomitant variation in total adiposity.

Time since menopause and skeletal muscle estrogen receptors, PGC-1α, and AMPK

Objective:

Short-term administration of estradiol (E₂) improves insulin-stimulated glucose disposal rate in early postmenopausal (EPM) women compared with a reduction in late postmenopausal (LPM) women. The underlying mechanisms by which E₂ action on glucose disposal rate reversed from beneficial early to harmful late in menopause is unknown, but might include adverse changes in estrogen receptors (ERs) or other biomarkers of cellular energy metabolism with age or duration of estrogen deficiency.

Methods:

We retrospectively analyzed skeletal muscle samples from 27 postmenopausal women who were 6 years or less past menopause (EPM; n = 13) or at least 10 years past menopause (LPM; n = 14). Fasted skeletal muscle (vastus lateralis) samples were collected after 1 week administration of transdermal E₂ or placebo, in random cross-over design.

Results:

Compared with EPM, LPM had reduced skeletal muscle ERα and ERβ nuclear protein. Short-term E₂ treatment did not change nuclear ERα or ERβ, but decreased cytosolic ERα, so the proportion of ERα in the nucleus compared with the cytosol tended to increase. There was a group-by-treatment interaction (P < 0.05) for nuclear proliferator-activated receptor γ co-activator 1-α and phosphorylated adenosine monophosphate-activated protein kinase, such that E₂ increased these proteins in EPM, but decreased these proteins in LPM.

Conclusions:

These preliminary studies of skeletal muscle from early and late postmenopausal women treated with E₂ suggest there may be declines in skeletal muscle ER and changes in the E₂-mediated regulation of cellular energy homeostasis with increasing time since menopause.

Dehydroepiandrosterone supplementation is not beneficial in the late postmenopausal period in diet-induced obese rats

AIMS

Dehydroepiandrosterone (DHEA) is an adrenal steroid hormone that is a precursor of sexual hormones. It is reduced during aging and is strongly associated with insulin resistance and obesity. There is evidence for beneficial effects of this steroid, in both human and animal models, during perimenopause. However, the impact of DHEA treatment during late postmenopause on glucose metabolism is not clearly documented. We tested the hypothesis that DHEA supplementation could improve insulin sensitivity in an ovariectomized obese rat model (OVX) that was fed a high-fat diet for 11 weeks.

MAIN METHODS

Female Wistar rats at 8 weeks of age were OVX or SHAM-operated. Eight weeks after the surgery, the animals were randomly treated with vehicle or DHEA for 3 weeks. Food intake, metabolic parameters and insulin sensitivity were evaluated.

KEY FINDINGS

Following the ovariectomy, increased body weight gain, adiposity index, and feeding efficiency were observed, despite there being no change in food and energy intake. The OVX rats also displayed glucose intolerance, insulin resistance, decreased insulin-induced IRS1/2 tyrosine phosphorylation in the skeletal muscle, and reduced serum VLDL-c and TAG levels. OVX rats treated with 10 mg/kg DHEA (OVX + DHEA) exhibited estradiol (E₂) serum levels similar to SHAM animals, with no change in uterus mass. DHEA treatment also resulted in an increase in energy intake.

SIGNIFICANCE

Despite the positive effects of DHEA supplementation observed in menopausal women and ovariectomized rats, a potential negative effect on glucose metabolism and insulin action in the late postmenopausal condition in diet-induced obese OVX rats are reported.

A theory of eu-estrogenemia: a unifying concept

OBJECTIVE

The aim of the study was to propose a unifying theory for the role of estrogen in postmenopausal women through examples in basic science, randomized controlled trials, observational studies, and clinical practice.

METHODS

Review and evaluation of the literature relating to estrogen.

DISCUSSION

The role of hormone therapy and ubiquitous estrogen receptors after reproductive senescence gains insight from basic science models. Observational studies and individualized patient care in clinical practice may show outcomes that are not reproduced in randomized clinical trials. The understanding gained from the timing hypothesis for atherosclerosis, the critical window theory in neurosciences, randomized controlled trials, and numerous genomic and nongenomic actions of estrogen discovered in basic science provides new explanations to clinical challenges that practitioners face. Consequences of a hypo-estrogenemic duration in women's lives are poorly understood. The Study of Women Across the Nation suggests its magnitude is greater than was previously acknowledged. We propose that the healthy user bias was the result of surgical treatment (hysterectomy with oophorectomy) for many gynecological maladies followed by pharmacological and physiological doses of estrogen to optimize patient quality of life. The past decade of research has begun to demonstrate the role of estrogen in homeostasis.

CONCLUSIONS

The theory of eu-estrogenemia provides a robust framework to unify the timing hypothesis, critical window theory, randomized controlled trials, the basic science of estrogen receptors, and clinical observations of patients over the past five decades.

Sex and gender differences in therapy of type 2 diabetes

Clinical guidelines for the management of type 2 diabetes recommend individual therapy considering age, duration of disease, presence of complication and risk of hypoglycaemia. However, at present, the patient's sex has no impact on clinical decisions. Yet, there is mounting data pointing at biological and psychosocial differences between men and women with great impact on progression of disease and complications. Moreover, choices and preferences of therapeutic strategies as well as adherence to lifestyle and pharmacological interventions differ in both sexes. In addition, drug therapy may have sex-specific side effects. Therefore, there is need of more research on biological differences and of evidence-based individualised targeted sex-sensitive therapeutic concepts. Clinical guidelines must consider relevant sex-differences. Development and implementation of sex-specific programs may help to improve adherence to therapy and to reduce progression of disease and development of complications. A more gender-sensitive clinical approach may improve quality of life and increase health and life expectancy in men and women with type 2 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.

Estradiol-mediated improvements in adipose tissue insulin sensitivity are related to the balance of adipose tissue estrogen receptor α and β in postmenopausal women

We recently demonstrated that short-term estradiol (E₂) treatment improved insulin-mediated suppression of lipolysis in postmenopausal women, but to a greater extent in those who were late compared to early postmenopausal. In this follow-up study we tested whether subcutaneous adipose tissue (SAT) expression of estrogen receptors (ER) α and β differs between early and late postmenopausal women. We further tested whether the balance of ERα to ERβ in SAT determined the effect of E₂ on SAT insulin sensitivity. The present study included 35 women who were ≤6 years past menopause (EPM; n = 16) or ≥10 years past menopause (LPM; n = 19). Fasted SAT samples were taken following 1-week transdermal E₂ treatment or placebo (PL) in a random cross-over design. Samples were analyzed for nuclear/cytosolic protein content and mRNA expression using Western blot and qPCR, respectively. While ESR1 increased slightly (~1.4-fold) following E₂ treatment in both groups, ERα and ERβ protein expression did not differ between groups at baseline or in response to E₂. However, the balance of ERα/ERβ protein in the SAT nuclear fraction increased 10% in EPM compared to a 25% decrease in LPM women (group x treatment interaction, p<0.05). A greater proportion of ERα/ERβ protein in the nuclear fraction of SAT at baseline (placebo day) was associated with greater reduction in SAT insulin resistance (i.e., better suppression of lipolysis, EC₅₀) in response to E₂ (r = -0.431, p<0.05). In conclusion, there do not appear to be differences in the proportion of adipose tissue ERα/ERβ protein in late, compared to early, postmenopausal women. However, the balance of ERα/ERβ may be important for E₂-mediated improvement in adipose tissue insulin sensitivity.

Trial Registration: Clinical Trials#:NCT01605071

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.

Hormone-replacement therapy: current thinking

For several decades, the role of hormone-replacement therapy (HRT) has been debated. Early observational data on HRT showed many benefits, including a reduction in coronary heart disease (CHD) and mortality. More recently, randomized trials, including the Women's Health Initiative (WHI), studying mostly women many years after the the onset of menopause, showed no such benefit and, indeed, an increased risk of CHD and breast cancer, which led to an abrupt decrease in the use of HRT. Subsequent reanalyzes of data from the WHI with age stratification, newer randomized and observational data and several meta-analyses now consistently show reductions in CHD and mortality when HRT is initiated soon after menopause. HRT also significantly decreases the incidence of various symptoms of menopause and the risk of osteoporotic fractures, and improves quality of life. In younger healthy women (aged 50-60 years), the risk-benefit balance is positive for using HRT, with risks considered rare. As no validated primary prevention strategies are available for younger women (<60 years of age), other than lifestyle management, some consideration might be given to HRT as a prevention strategy as treatment can reduce CHD and all-cause mortality. Although HRT should be primarily oestrogen-based, no particular HRT regimen can be advocated.

The role of sex steroids in white adipose tissue adipocyte function

With the increasing knowledge that gender influences normal physiology, much biomedical research has begun to focus on the differential effects of sex on tissue function. Sexual dimorphism in mammals is due to the combined effects of both genetic and hormonal factors. Hormonal factors are mutable particularly in females in whom the estrous cycle dominates the hormonal milieu. Given the severity of the obesity epidemic and the fact that there are differences in the obesity rates in men and women, the role of sex in white adipose tissue function is being recognized as increasingly important. Although sex differences in white adipose tissue distribution are well established, the mechanisms affecting differential function of adipocytes within white adipose tissue in males and females remain largely understudied and poorly understood. One of the largest differences in the endocrine environment in males and females is the concentration of circulating androgens and estrogens. This review examines the effects of androgens and estrogens on lipolysis/lipogenesis, adipocyte differentiation, insulin sensitivity and adipokine production in adipocytes from white adipose tissue with a specific emphasis on the sexual dimorphism of adipocyte function in white adipose tissue during both health and disease.

Menopause, hormone therapy and diabetes

Over the past three decades, the prevalence of diabetes has increased four-fold. Coupled with the global obesity epidemic and aging of the world's population, a perfect metabolic storm is brewing. The influence of menopause and exogenous estrogen and progestogens must be included in this equation. In this review, criteria for diagnosing diabetes and recommendations for screening are described. The reported effects of menopause on diabetes risk in healthy women are reviewed as well as the relationship between established diabetes and the timing of menopause. The effects of menopausal hormone therapies (MHT) on glucose control in women with diabetes and the effect of MHT on diabetes risk in menopausal women without diabetes are described. Evidence-based strategies to prevent diabetes in midlife women are highlighted. The augmenting effect of diabetes on chronic health concerns of aging women, such as cardiovascular disease, osteoporosis, and cancer, along with current recommendations for screening and prevention are presented. Given the current demographics of today's world, the content of this review may apply to as many as one-third of the average practitioner's postmenopausal patient population.

Middle-Aged Diabetic Females and Males Present Distinct Susceptibility to Alzheimer Disease-like Pathology

Type 2 diabetes (T2D) is a highly concerning public health problem of the twenty-first century. Currently, it is estimated that T2D affects 422 million people worldwide with a rapidly increasing prevalence. During the past two decades, T2D has been widely shown to have a major impact in the brain. This, together with the cognitive decline and increased risk for dementia upon T2D, may arise from the complex interaction between normal brain aging and central insulin signaling dysfunction. Among the several features shared between T2D and some neurodegenerative disorders (e.g., Alzheimer disease (AD)), the impairment of insulin signaling may be a key link. However, these may also involve changes in sex hormones' function and metabolism, ultimately contributing to the different susceptibilities between females and males to some pathologies. For example, female sex has been pointed as a risk factor for AD, particularly after menopause. However, less is known on the underlying molecular mechanisms or even if these changes start during middle-age (perimenopause). From the above, we hypothesized that sex differentially affects hormone-mediated intracellular signaling pathways in T2D brain, ultimately modulating the risk for neurodegenerative conditions. We aimed to evaluate sex-associated alterations in estrogen/insulin-like growth factor-1 (IGF-1)/insulin-related signaling, oxidative stress markers, and AD-like hallmarks in middle-aged control and T2D rat brain cortices. We used brain cortices homogenates obtained from middle-aged (8-month-old) control Wistar and non-obese, spontaneously T2D Goto-Kakizaki (GK) male and female rats. Peripheral characterization of the animal models was done by standard biochemical analyses of blood, plasma, or serum. Steroid sex hormones, oxidative stress markers, and AD-like hallmarks were given by specific ELISA kits and colorimetric techniques, whereas the levels of intracellular signaling proteins were determined by Western blotting. Albeit the high levels of plasma estradiol and progesterone observed in middle-aged control females suggested that they were still under their reproductive phase, some gonadal dysfunction might be already occurring in T2D ones, hence, anticipating their menopause. Moreover, the higher blood and lower brain cholesterol levels in female rats suggested that its dysfunctional uptake into the brain cortex may also hamper peripheral estrogen uptake and/or its local brain steroidogenic metabolism. Despite the massive drop in IGF-1 levels in females' brains, particularly upon T2D, they might have developed some compensatory mechanisms towards the maintenance of estrogen, IGF-1, and insulin receptors function and of the subsequent Akt- and ERK1/2-mediated signaling. These may ultimately delay the deleterious AD-like brain changes (including oxidative damage to lipids and DNA, amyloidogenic processing of amyloid precursor protein and increased tau protein phosphorylation) associated with T2D and/or age (reproductive senescence) in female rats. By demonstrating that differential sex steroid hormone profiles/action may play a pivotal role in brain over T2D progression, the present study reinforces the need to establish sex-specific preventive and/or therapeutic approaches and an appropriate time window for the efficient treatment against T2D and AD.

Body fat distribution, menopausal hormone therapy and incident type 2 diabetes in postmenopausal women of the MESA study

OBJECTIVES

We investigated the association between menopausal hormone therapy (MHT) and incident type 2 diabetes in postmenopausal women, and explored the potential modifying role of body fat distribution on this association.

METHODS

We included 2210 postmenopausal women without prevalent diabetes at recruitment (2000-2002) from the Multiethnic Study of Atherosclerosis. Cox proportional hazards models were used to examine associations of MHT and MHT types with incident diabetes, testing for variation according to body fat distribution.

RESULTS

Over a median follow-up of 11.1 years, there were 226 incident cases of diabetes. There were no significant interactions with central or generalized body fatness. In fully adjusted models, current and past MHT use was associated with a greater risk of incident diabetes [HR: 1.66 (1.18-2.35) and 1.60 (1.11-2.30) respectively]. Estrogen only (ET) and combined progestin and estrogen (PET) formulations were similarly associated with a greater risk of incident diabetes [HR: 1.52 (1.03-2.24) and 1.77 (1.15-2.72) respectively].

CONCLUSIONS

In our observational study of middle-aged and older, non-diabetic postmenopausal women, a current or past use of MHT was independently associated with a greater risk of incident diabetes. ET and PET are associated with similar risks of incident diabetes in postmenopausal women. The association of MHT use with incident diabetes is the same irrespective of body mass index (BMI) or waist circumference.

Sex and Gender Differences in Risk, Pathophysiology and Complications of Type 2 Diabetes Mellitus

The steep rise of type 2 diabetes mellitus (T2DM) and associated complications go along with mounting evidence of clinically important sex and gender differences. T2DM is more frequently diagnosed at lower age and body mass index in men; however, the most prominent risk factor, which is obesity, is more common in women. Generally, large sex-ratio differences across countries are observed. Diversities in biology, culture, lifestyle, environment, and socioeconomic status impact differences between males and females in predisposition, development, and clinical presentation. Genetic effects and epigenetic mechanisms, nutritional factors and sedentary lifestyle affect risk and complications differently in both sexes. Furthermore, sex hormones have a great impact on energy metabolism, body composition, vascular function, and inflammatory responses. Thus, endocrine imbalances relate to unfavorable cardiometabolic traits, observable in women with androgen excess or men with hypogonadism. Both biological and psychosocial factors are responsible for sex and gender differences in diabetes risk and outcome. Overall, psychosocial stress appears to have greater impact on women rather than on men. In addition, women have greater increases of cardiovascular risk, myocardial infarction, and stroke mortality than men, compared with nondiabetic subjects. However, when dialysis therapy is initiated, mortality is comparable in both males and females. Diabetes appears to attenuate the protective effect of the female sex in the development of cardiac diseases and nephropathy. Endocrine and behavioral factors are involved in gender inequalities and affect the outcome. More research regarding sex-dimorphic pathophysiological mechanisms of T2DM and its complications could contribute to more personalized diabetes care in the future and would thus promote more awareness in terms of sex- and gender-specific risk factors.

Diabetes and Menopause

During menopause, women's body composition, sex hormone profile, and metabolic profile may change dramatically. In this review, we summarize studies examining whether the menopausal transition and physiologic factors characterizing the transition are associated with increased risk of diabetes. We review the evidence for estrogen therapy and diabetes risk and studies examining the relationship between diabetes and menarche, which represents an extension of the reproductive life span at the opposite end of the age spectrum. Although studied less extensively, the presence of type 1 or type 2 diabetes may increase the risk of ovarian failure, and we review this literature. In conclusion, we note that the evidence linking menopausal sex hormone changes with increased diabetes risk is weak, although rapid changes as observed with oophorectomy may increase risk. Further studies should investigate the contradictory effects of estrogen therapy upon hepatic and glucose metabolism in mid-life women.