Does androgen excess contribute to the cardiovascular risk profile in postmenopausal women with type 2 diabetes?

An ovary-intact postmenopausal HFpEF mouse model; menopause is more than just estrogen deficiency

The incidence of heart failure with preserved ejection fraction (HFpEF) in women significantly increases following menopause. This trend cannot solely be attributed to chronological aging, as evidenced by the more gradual increase in prevalence among men, suggesting that menopause is a provocative event for HFpEF. However, the underlying mechanisms remain elusive and challenging to investigate in human subjects; moreover, an attempt to create HFpEF in ovariectomized (OVX) mice was unsuccessful. In this study, we created an animal model that resembles HFpEF in women undergoing natural menopause. We used 4-vinylcyclohexene dioxide (VCD) to induce "ovary-intact" menopause, combined with the 2hit regimen (HFpEF inducing regimen) to model postmenopausal HFpEF. The female-VCD-2hit mice demonstrate diastolic dysfunction. At the left ventricle (LV) levels, the increased stiffness coefficient of end-diastolic pressure-volume relation (EDPVR), elevated LV end-diastolic pressure, and increased relaxation time constant indicate a heightened LV stiffness, delayed relaxation, and elevated LV filling pressure. At the cardiomyocyte level, the female-VCD-2hit mice exhibit increased cellular diastolic stiffness and delayed relaxation, suggesting that the observed LV dysfunction is derived from the cardiomyocytes. In addition, plasma N-terminal pro-β-type natriuretic peptide (NT-pro-BNP) levels were elevated, whereas Xbp1s transcript levels were reduced, further supporting the existence of HFpEF. Plasma-free testosterone was increased in VCD mice compared with premenopausal and OVX models. Further studies are required to determine whether the relative increase in testosterone is the factor driving HFpEF susceptibility in VCD mice. Ovary-intact postmenopausal status makes female mice vulnerable to HFpEF development. The VCD-2hit model develops a robust HFpEF-like phenotype and is suitable for studying female HFpEF.NEW & NOTEWORTHY Although ovariectomized mice were observed to be resistant to developing HFpEF, ovary-intact postmenopausal mice exhibited an HFpEF-like phenotype under metabolic stress conditions. The increased susceptibility of ovary-intact postmenopausal mice may be due to relative androgen excess conditions, as postmenopausal ovaries retain the ability to secrete androgens. Menopause should be viewed as the imbalance of estrogen and androgens rather than merely an estrogen deficiency, and the role of female androgens in postmenopausal HFpEF warrants further investigation.

The Role of Estrogens and Vitamin D in Cardiomyocyte Protection: A Female Perspective

Women experience a dramatical raise in cardiovascular events after menopause. The decline in estrogens is pointed to as the major responsible trigger for the increased risk of cardiovascular disease (CVD). Indeed, the menopausal transition associates with heart macro-remodeling, which results from a fine-tuned cell micro-remodeling. The remodeling of cardiomyocytes is a biomolecular response to several physiologic and pathologic stimuli, allowing healthy adaptation in normal conditions or maladaptation in an unfavorable environment, ending in organ architecture disarray. Estrogens largely impinge on cardiomyocyte remodeling, but they cannot fully explain the sex-dimorphism of CVD risk. Albeit cell remodeling and adaptation are under multifactorial regulation, vitamin D emerges to exert significant protective effects, controlling some intracellular paths, often shared with estrogen signaling. In post-menopause, the unfavorable association of hypoestrogenism-D hypovitaminosis may converge towards maladaptive remodeling and contribute to increased CVD risk. The aim of this review is to overview the role of estrogens and vitamin D in female cardiac health, speculating on their potential synergistic effect in cardiomyocyte remodeling, an issue that is not yet fully explored. Further learning the crosstalk between these two steroids in the biomolecular orchestration of cardiac cell fate during adaptation may help the translational approach to future cardioprotective strategies for women health.

Androgens, Bilateral Oophorectomy, and Cardiovascular Disease Mortality in Postmenopausal Women With and Without Diabetes: The Study of Osteoporotic Fractures

OBJECTIVE

Diabetes elevates cardiovascular disease (CVD) risk more markedly in women than in men. Because the high risk of CVD among women with type 2 diabetes (DM2) may be partly due to increased ovarian androgen production, we investigated whether a history of bilateral salpingo oophorectomy (BSO) is inversely associated with CVD mortality among women with DM2.

RESEARCH DESIGN AND METHODS

Data were obtained from 7,977 women (a random subset of 564 had measurements of sex-steroid hormones) enrolled in the Study of Osteoporotic Fractures (SOF), a community-based, multicenter study that monitored women aged ≥65 years for a mean of 15.1 years. Adjusted hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards regression.

RESULTS

The average age at baseline was 71.5 years, with 6.3% and 18% of participants reporting a history of diabetes or BSO, respectively. In the subset of the SOF cohort with sex-steroid hormone measurements, those with DM2 had 43.6% significantly higher levels of free testosterone that were partly explained by age and adiposity, whereas total and free testosterone levels were lower in women with BSO than in those with intact ovaries. CVD mortality was elevated in women with DM2 without BSO (HR 1.95, 95% CI 1.62-2.35) as well as in women with DM2 and BSO (HR 2.56, 95% CI 1.79-3.65; P = 0.190 for interaction). Overall, BSO was not associated with CVD mortality (HR 1.05, 95% CI 0.89-1.23).

CONCLUSIONS

The association of diabetes with CVD was not reduced by BSO, suggesting that ovarian hyperandrogenemia may not be a primary mechanism to explain the high risk for CVD among women with DM2.

Cardiovascular disease among women with and without diabetes mellitus and bilateral oophorectomy

AIMS

Women with type-2 diabetes (DM2) are at high risk of cardiovascular disease (CVD) which may be partly due to increased ovarian androgen production. Since the association of bilateral oophorectomy (BSO) with CVD remains controversial, we evaluated whether BSO is inversely associated with CVD among DM2.

METHODS

Data were obtained from a national sample of 9599 postmenopausal women. Adjusted estimates and 95% confidence intervals (CIs) were calculated using logistic and Cox regression.

RESULTS

At baseline 2426 women had type-2 diabetes, of whom 580 had BSO. DM2 had adverse CVD risk profiles compared to women without diabetes, as did women with BSO with or without diabetes compared to those with intact ovaries. In DM2, BSO was positively associated with prevalent CVD (odds ratio: 1.63, 95%CI: 1.16-2.30). However, the higher odds were limited to women who had BSO before age 45 years (OR: 2.11, CI: 1.45-3.08). During a mean follow-up of 12.7 years, BSO in DM2 was positively associated with CVD mortality (hazard ratio: 2.23, CI: 1.25-3.99). Among women with BSO, those with family members who had MI before age 50 had elevated odds of CVD (OR: 2.29, CI: 1.56-3.37) compared to those without such family history (OR: 0.90, CI: 0.67-1.20), Pinteraction=0.04.

CONCLUSIONS

The risk of CVD is increased not decreased with BSO in DM2. Further, we propose that the association of BSO and CVD in young women with diabetes may partly reflect genetic susceptibility to CVD rather than an effect of ovarian hormones.

MENSTRUAL AND REPRODUCTIVE FUNCTION IN WOMEN WITH TYPE 1 DIABETES

OBJECTIVE

Menstrual irregularities, reproductive abnormalities, and androgen excess are reported to be more prevalent in women with type 1 diabetes (T1D). The objective of this study was to investigate the prevalence of menstrual irregularities, reproductive abnormalities, and androgen excess among women with T1D and their age-matched controls.

METHODS

A survey requesting information regarding menstrual and reproductive histories was administered to all participants. Results were stratified according to age (18 to 40, 40 to 50, and >50 years).

RESULTS

There were no significant differences between women with and without diabetes in age at menarche, cycle length, or androgen excess in any group. Women who self-reported difficulty with glycemic control were more likely to report irregular menses than controls (P = .04). Among women who reported ever being pregnant, there were fewer pregnancies (P = .02) and live births (P = .002) in women with T1D. Women with T1D reported a lower frequency of oral contraceptive use (P = .003), despite being less likely to smoke (P = .016).

CONCLUSION

Menstrual and reproductive abnormalities were not observed more frequently in women with T1D in this study. Subtle but measurable differences in menstrual and reproductive function were confined to the subgroup of women who perceived poor control of their diabetes. Additional prospective studies of T1D and menstrual and reproductive function would be useful.

Blueberries improve glucose tolerance without altering body composition in obese postmenopausal mice

OBJECTIVE

Metabolic syndrome (MetS) risk increases significantly during menopause and remains elevated postmenopause. Several botanicals, including blueberries (BB), have been shown to delay MetS progression, but few studies have been conducted in postmenopausal animal models. Here, the effects of BB supplementation on obese postmenopausal mice using a chemically induced menopause model were examined.

METHODS

After induction of menopause, mice were fed a high-fat diet or the same diet supplemented with 4% BB powder for 12 weeks. Body weight and body composition were measured, and mice were subjected to glucose and insulin tolerance tests. Serum triglycerides and adiponectin were measured, and liver histology and hepatic gene expression were assessed.

RESULTS

Menopausal and BB-supplemented mice had significantly higher body weights and fat mass than control mice, while menopausal mice had impaired glucose tolerance and higher serum triglycerides when compared with control and BB-supplemented mice. Menopausal mice also had hepatic steatosis that was prevented by BB supplementation and correlated with expression of genes involved in hepatic fatty acid oxidation.

CONCLUSIONS

BB supplementation prevents the glucose intolerance and hepatic steatosis that occur in obese postmenopausal mice, and these effects are independent of body weight.

In vitro palmitate treatment of myotubes from postmenopausal women leads to ceramide accumulation, inflammation and affected insulin signaling

Menopause is associated with an increased incidence of insulin resistance and metabolic diseases. In a chronic palmitate treatment model, we investigated the role of skeletal muscle fatty acid exposure in relation to the metabolic deterioration observed with menopause. Human skeletal muscle satellite cells were isolated from premenopausal (n = 6) and postmenopausal (n = 5) women. In an in vitro model, the myotubes were treated with palmitate (300 µM) for one-, two- or three days during differentiation. Effects on lipid accumulation, inflammation and insulin signaling were studied. Palmitate treatment led to a 108% (CI 95%: 50%; 267%) increase in intramyocellular ceramide in the myotubes from the postmenopausal women (post-myotubes) compared with a 26% (CI 95%: -57%; 96%) increase in myotubes from the premenopausal women (pre-myotubes), (p<0.05). Furthermore, post-myotubes had a 22% (CI 95%: 4%; 34%) increase in pJNK (p = 0.04) and a 114% (CI 95%: 50%; 177%) increase in Hsp70 protein expression (p = 0.03) after three days of palmitate treatment, compared with pre-myotubes, in which no increase in either pJNK (-12% (CI 95: -26%; 2%)) or Hsp70 (7% (CI 95: -78%; 91%)) was detected. Furthermore, post-myotubes showed a blunted insulin stimulated phosphorylation of AS160 in response to chronic palmitate treatment compared with pre-myotubes (p = 0.02). The increased intramyocellular ceramide content in the post-myotubes was associated with a significantly higher mRNA expression of Serine Palmitoyltransferase1 (SPT1) after one day of palmitate treatment (p = 0.03) in post-myotubes compared with pre-myotubes. Our findings indicate that post-myotubes are more prone to develop lipid accumulation and defective insulin signaling following chronic saturated fatty acid exposure as compared to pre-myotubes.

Menopause is associated with decreased whole body fat oxidation during exercise

The purpose of this study was to examine if fat oxidation was affected by menopausal status and to investigate if this could be related to the oxidative capacity of skeletal muscle. Forty-one healthy women were enrolled in this cross-sectional study [premenopausal (n = 19), perimenopausal (n = 8), and postmenopausal (n = 14)]. Estimated insulin sensitivity was obtained from an oral glucose tolerance test. Body composition was measured by dual-energy X-ray absorptiometry and magnetic resonance imaging. Fat oxidation and energy expenditure were measured during an acute exercise bout of 45 min of ergometer biking at 50% of maximal oxygen consumption (Vo2 max). Muscle biopsies from the vastus lateralis of the quadriceps muscle were obtained before and immediately after the exercise bout. Postmenopausal women had 33% [confidence interval (CI) 95%: 12-55] lower whole body fat oxidation (P = 0.005) and 19% (CI 95%: 9-22) lower energy expenditure (P = 0.02) during exercise, as well as 4.28 kg lower lean body mass (LBM) than premenopausal women. Correction for LBM reduced differences in fat oxidation to 23% (P = 0.05), whereas differences in energy expenditure disappeared (P = 0.22). No differences between groups were found in mRNA [carnitine palmitoyltransferase I, β-hydroxyacyl-CoA dehydrogenase (β-HAD), peroxisome proliferator-activated receptor-α, citrate synthase (CS), pyruvate dehydrogenase kinase 4, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α)], protein [phosphorylated AMP-activated protein kinase (AMPK), vascular endothelial growth factor, pyruvate dehydrogenase-1Eα, cytochrome oxidase I], or enzyme activities (β-HAD, CS) in resting skeletal muscle, except for an increased protein level of cytochrome c in the post- and perimenopausal women relative to premenopausal women. Postmenopausal women demonstrated a trend to a blunted exercise-induced increase in phosphorylation of AMPK compared with premenopausal women (P = 0.06). We conclude that reduced whole body fat oxidation after menopause is associated with reduced LBM.

Gender-specific care of diabetes

Diabetic men have benefited in the last 30 years from a significant improvement in total and cardiovascular mortality, whereas diabetic women have had no improvement at all. Moreover, recent research focused on the role of sex hormones in glucose homeostasis, and might account for different pathophysiologic mechanisms in the development of diabetes-related complications. Thus, care of diabetic women is a challenge that requires particular attention. The available data regarding gender-specific care of diabetes mellitus are uneven, rich in some domains but very poor in others. The large prospective trials performed in the last 20 years have assumed that the natural history of diabetes mellitus in men and women, as well as the efficiency of glucose-lowering therapies and management of hyperglycemic-related complications, could be attributable without distinction to men and women. We propose in this paper to analyze the published medical literature according to the specific management of diabetes mellitus in women, and to try to distinguish some particular features. We found important distinctions between diabetic men and women regarding the patterns of abnormalities of glucose regulation, epidemiology, development of diabetes-related complications, ischemic heart disease, morbidity and mortality, impact of cardiovascular risk factors, development of the metabolic syndrome, depression and osteoporosis, as well as the impact of lifestyle modifications or primary and secondary preventions on cardiovascular risk factors, and finally medical therapeutics. Moreover, special considerations were given to some particular aspects of the medical life in diabetic women, such as the features of gestational diabetes mellitus and the management of pregnancy in pregestational diabetic women, use of contraception, hormone-replacement therapy and polycystic ovary syndrome.

Body adipose distribution among patients with type 2 diabetes mellitus

SUMMARY

Both diabetes mellitus (DM) and obesity are prevalent in adults. The relationship between DM and body adipose tissue (AT) distribution is complex and although it has been investigated extensively, the subject remains controversial. Although a causal association between DM and obesity and AT distribution cannot be established on the basis of existing data, it is possible to conclude from many studies that gene, serum sex steroids level, daily physical activity and food supply can be the risk of obesity and AT redistribution factor among type 2 DM patients (T2DM). Obesity and AT redistribution of T2DM patients can increase the risk of insulin resistant (IR), cardiovascular disease and many other disorders. Even though obesity and AT redistribution screening or prophylactic treatment in all patients with T2DM is not being recommended at present, such patient populations should be given general guidelines regarding exercise, food intake control, and even medicinal treatment. The extent of diagnostic and therapeutic interventions should be based on the individual's risk profile.:

Severity and outcome of acute stroke in women: relation to adrenal sex steroid levels

Adrenal sex steroids exert diverse metabolic and neurobiological actions. Their levels have been associated with cardiovascular disease, but data concerning cerebrovascular disease are lacking. The objective of our study was to investigate the role of adrenal sex steroids in a female population suffering an acute stroke. We addressed the question of whether their levels are associated with disease severity and prognosis. A 2-year cohort study was performed in 2 tertiary hospitals, where we prospectively studied 302 consecutive postmenopausal female patients hospitalized for an acute stroke. Neurological severity on admission was assessed by the National Institutes of Health Stroke Scale; and handicap 1 month after stroke, with the modified Rankin Scale. Δ4-androstenedione levels were positively and dehydroepiandrosterone sulfate was inversely associated with stroke severity (r = 0.142, P = .014 and r = -0.153, P = .008, respectively), and both parameters remained as significant determinants even after entering other confounders in the multivariate model (r = 0.118, P = .039 and r = -0.150, P = .011, respectively). Levels of Δ4-androstenedione were significantly associated with 1-month mortality in the multivariate analysis (odds ratio with 95% confidence intervals: 1.540 [1.107-2.138)], P = .010). Δ4-androstenedione and dehydroepiandrosterone sulfate levels were associated with poor outcome in the univariate analysis, that is, combined severe handicap (modified Rankin Scale ≥4) and death, 1 month poststroke, although this was not significant in the multivariate analysis. Adrenal sex steroids, and especially Δ4-androstenedione, are significantly associated with stroke severity on admission and short-term prognosis among female stroke subjects. Well-designed prospective studies will further clarify their role in cerebrovascular disease.

Influence of menopause on diabetes and diabetes risk

Many postmenopausal women live with diabetes mellitus; however, little information is available about how the changes that occur around the time of menopause might uniquely affect management of diabetes mellitus in this population. Although the weight gain that commonly occurs during the menopausal transition is largely attributable to aging rather than the transition itself, changes in body composition have been independently associated with menopausal status. These changes in body composition have, in turn, been associated with alterations in insulin sensitivity and glucose metabolism in postmenopausal women. Hormone therapy seems to have neutral or beneficial effects on the adverse changes in body composition associated with menopause. Whether menopausal status independently influences diabetes risk remains controversial. Nevertheless, consistent findings from large clinical trials suggest that postmenopausal hormone therapy decreases the risk of developing diabetes mellitus. Similarly, many studies suggest that postmenopausal hormone therapy has neutral or beneficial effects on glycemic control among women already diagnosed as having diabetes mellitus. Future studies are needed to elucidate the mechanisms that underlie these relationships and to determine how these observations should influence recommendations for the care of postmenopausal women with diabetes mellitus.

Loss of ovarian function in the VCD mouse-model of menopause leads to insulin resistance and a rapid progression into the metabolic syndrome

Factors comprising the metabolic syndrome occur with increased incidence in postmenopausal women. To investigate the effects of ovarian failure on the progression of the metabolic syndrome, female B(6)C(3)F(1) mice were treated with 4-vinylcyclohexene diepoxide (VCD) and fed a high-fat (HF) diet for 16 wk. VCD destroys preantral follicles, causing early ovarian failure and is a well-characterized model for the gradual onset of menopause. After 12 wk on a HF diet, VCD-treated mice had developed an impaired glucose tolerance, whereas cycling controls were unaffected [12 wk AUC HF mice 13,455 +/- 643 vs. HF/VCD 17,378 +/- 1140 mg/dl/min, P < 0.05]. After 16 wk on a HF diet, VCD-treated mice had significantly higher fasting insulin levels (HF 5.4 +/- 1.3 vs. HF/VCD 10.1 +/- 1.4 ng/ml, P < 0.05) and were significantly more insulin resistant (HOMA-IR) than cycling controls on a HF diet (HF 56.2 +/- 16.7 vs. HF/VCD 113.1 +/- 19.6 mg/dl x microU/ml, P < 0.05). All mice on a HF diet gained more weight than mice on a standard diet, and weight gain in HF/VCD mice was significantly increased compared with HF cycling controls. Interestingly, even without a HF diet, progression into VCD-induced menopause caused a significant increase in cholesterol and free fatty acids. Furthermore, in mice fed a standard diet (6% fat), insulin resistance developed 4 mo after VCD-induced ovarian failure. Insulin resistance following ovarian failure (menopause) was prevented by estrogen replacement. Studies here demonstrate that ovarian failure (menopause) accelerates progression into the metabolic syndrome and that estrogen replacement prevents the onset of insulin resistance in VCD-treated mice. Thus, the VCD model of menopause provides a physiologically relevant means of studying how sex hormones influence the progression of the metabolic syndrome.

Gender-specific care of diabetes mellitus: particular considerations in the management of diabetic women

In the past 30 years, the all-cause mortality and cardiovascular mortality rates for women with diabetes mellitus (DM), in contrast to men, have not declined. Furthermore, the difference between all-cause mortality rates in women with DM and those without DM has more than doubled. This urgently needs addressing. This review will analyse published medical literature relating to the specific management of DM in women and try to identify areas where gender affects care. We have identified specific gender differences in the pathophysiology of glucose homeostasis disorder, diabetes-related complications and any female gender-specific features of women with diabetes, such as contraception and the menopause. These gender-specific features of DM may offer a route to improved care for women and new therapeutic possibilities.

Effects of androgens on insulin action in women: is androgen excess a component of female metabolic syndrome?

Hyperinsulinemia as a consequence of insulin resistance causes hyperandrogenemia in women. The objective was to review evidence for the converse situation, i.e. whether androgens adversely influence insulin action. Androgen excess could potentially contribute to the pathogenesis of insulin resistance in women with polycystic ovary syndrome (PCOS), metabolic syndrome/type 2 diabetes, and in obese peripubertal girls. An Entrez-PubMed search was conducted to identify studies addressing the relationship of androgens with metabolic syndrome/type 2 diabetes in women. Studies reporting outcomes of androgen administration, interventions to reduce androgen effects in hyperandrogenemic women, and basic studies investigating androgen effects on insulin target tissues were reviewed. Multiple studies showed associations between serum testosterone and insulin resistance or metabolic syndrome/type 2 diabetes risk in women, but their cross-sectional nature did not allow conclusions about causality. Androgen administration to healthy women was associated with development of insulin resistance. Intervention studies in women with hyperandrogenism were limited by small subject numbers and use of indirect methods for assessing insulin sensitivity. However, in three of the seven studies using euglycemic hyperinsulinemic clamps, reduction of androgen levels or blockade of androgen action improved insulin sensitivity. Testosterone administration to female rats caused skeletal muscle insulin resistance. Testosterone induced insulin resistance in adipocytes of women in vitro. In conclusion, the metabolic consequences of androgen excess in women have been under-researched. Studies of long-term interventions that lower androgen levels or block androgen effects in young women with hyperandrogenism are needed to determine whether these might protect against metabolic syndrome/type 2 diabetes in later life.