The long-term impact of 2-3 years of hormone replacement therapy on cardiovascular mortality and atherosclerosis in healthy women

Understanding the Role of Sex Hormones in Cardiovascular Kidney Metabolic Syndrome: Toward Personalized Therapeutic Approaches

Cardiovascular kidney metabolic (CKM) syndrome represents a complex interplay of cardiovascular disease (CVD), chronic kidney disease (CKD), and metabolic comorbidities, posing a significant public health challenge. Gender exerts a critical influence on CKM syndrome, affecting the disease severity and onset through intricate interactions involving sex hormones and key physiological pathways such as the renin-angiotensin system, oxidative stress, inflammation, vascular disease and insulin resistance. It is widely known that beyond the contribution of traditional risk factors, men and women exhibit significant differences in CKM syndrome and its components, with distinct patterns observed in premenopausal women and postmenopausal women compared to men. Despite women generally experiencing a lower incidence of CVD, their outcomes following cardiovascular events are often worse compared to men. The disparities also extend to the treatment approaches for kidney failure, with a higher prevalence of dialysis among men despite women exhibiting higher rates of CKD. The impact of endogenous sex hormones, the correlations between CKM and its components, as well as the long-term effects of treatment modalities using sex hormones, including hormone replacement therapies and gender-affirming therapies, have drawn attention to this topic. Current research on CKM syndrome is hindered by the scarcity of large-scale studies and insufficient integration of gender-specific considerations into treatment strategies. The underlying mechanisms driving the gender disparities in the pathogenesis of CKM syndrome, including the roles of estrogen, progesterone and testosterone derivatives, remain poorly understood, thus limiting their application in personalized therapeutic interventions. This review synthesizes existing knowledge to clarify the intricate relationship between sex hormones, gender disparities, and the progression of CVD within CKM syndrome. By addressing these knowledge gaps, this study aims to guide future research efforts and promote tailored approaches for effectively managing CKD syndrome.

Cardiometabolic health, menopausal estrogen therapy and the brain: How effects of estrogens diverge in healthy and unhealthy preclinical models of aging

Research in preclinical models indicates that estrogens are neuroprotective and positively impact cognitive aging. However, clinical data are equivocal as to the benefits of menopausal estrogen therapy to the brain and cognition. Pre-existing cardiometabolic disease may modulate mechanisms by which estrogens act, potentially reducing or reversing protections they provide against cognitive decline. In the current review we propose mechanisms by which cardiometabolic disease may alter estrogen effects, including both alterations in actions directly on brain memory systems and actions on cardiometabolic systems, which in turn impact brain memory systems. Consideration of mechanisms by which estrogen administration can exert differential effects dependent upon health phenotype is consistent with the move towards precision or personalized medicine, which aims to determine which treatment interventions will work for which individuals. Understanding effects of estrogens in both healthy and unhealthy models of aging is critical to optimizing the translational link between preclinical and clinical research.

Identification of Circulating Diagnostic Biomarkers for Coronary Microvascular Disease in Postmenopausal Women Using Machine-Learning Techniques

Coronary microvascular disease (CMD) is a common form of heart disease in postmenopausal women. It is not due to plaque formation but dysfunction of microvessels that feed the heart muscle. The majority of the patients do not receive a proper diagnosis, are discharged prematurely and must go back to the hospital with persistent symptoms. Because of the lack of diagnostic biomarkers, in the current study, we focused on identifying novel circulating biomarkers of CMV (cytomegalovirus) that could potentially be used for developing a diagnostic test. We hypothesized that plasma metabolite composition is different for postmenopausal women with no heart disease, CAD (coronary artery disease), or CMD. A total of 70 postmenopausal women, 26 healthy individuals, 23 individuals with CMD and 21 individuals with CAD were recruited. Their full health screening and tests were completed. Basic cardiac examination, including detailed clinical history, additional disease and prescribed drugs, were noted. Electrocardiograph, transthoracic echocardiography and laboratory analysis were also obtained. Additionally, we performed full metabolite profiling of plasma samples from these individuals using gas chromatography-mass spectrometry (GC–MS) analysis, identified and classified circulating biomarkers using machine learning approaches. Stearic acid and ornithine levels were significantly higher in postmenopausal women with CMD. In contrast, valine levels were higher for women with CAD. Our research identified potential circulating plasma biomarkers of this debilitating heart disease in postmenopausal women, which will have a clinical impact on diagnostic test design in the future.

The impact of menopausal hormone therapy on overall mortality - a comprehensive review

Menopausal hormone therapy (MHT) is indicated for menopausal symptom relief. However, MHT has also been shown to be beneficial for prevention of long-term estrogen deficiency sequelae including mortality. Based on a comprehensive literature review on MHT and mortality, the authors' recommendations are as follows: in postmenopausal women, MHT appears to confer a (significant) reduction in overall mortality; the benefit especially applies to women who initiate long-term MHT early after menopause; in women with prevalent cardiovascular risk factors (except for diabetes mellitus, where results are mixed), the benefit of MHT on overall mortality is even more pronounced; and, however, study results are difficult to compare due to heterogeneous study designs.

Meat intake and incidence of cardiovascular disease in Japanese patients with type 2 diabetes: analysis of the Japan Diabetes Complications Study (JDCS)

PURPOSE

Excessive meat intake has been researched as a major cause of cardiovascular disease (CVD) among healthy adults, but data on this topic in Asian patients with diabetes are sparse. The quantity and variety of available meats vary widely between Asian and Western countries. As part of a nationwide cohort study we investigated the relationship between meat intake and incidence of CVD in Japanese patients with type 2 diabetes aged 40-70 years with HbA1c ≥ 6.5%.

METHODS

Analyzed were 1353 responders to a baseline dietary survey assessed by the Food Frequency Questionnaire based on food groups. Primary outcome was the 8-year risk of a CVD event, including coronary heart disease (CHD) and stroke. Cox regression analyses estimated hazard ratios (HRs) for dietary intake adjusted for age, gender, body mass index, HbA1c, smoking, energy intake, and other confounders.

RESULTS

Mean meat intake in quartiles ranged from 9.9 to 97.7 g/day. After adjusting for confounders, HRs of CHD in the 2nd, 3rd, and 4th quartiles for meat intake compared with the 1st quartile were 2.84 (95% confidence interval 1.29-6.24, p = 0.01), 3.02 (1.36-6.70, p < 0.01), and 2.99 (1.35-6.65, p = 0.01), respectively. In two groups according to meat intake, patients consuming ≥ 20 g/day of meat had a 2.94-fold higher risk of CHD than those consuming < 20 g/day (p < 0.01). There was no significant association of stroke with meat intake.

CONCLUSIONS

An elevated incidence of CHD in Japanese patients with type 2 diabetes was associated with high meat intake.

Progesterone amplifies oxidative stress signal and promotes NO production via H2O2 in mouse kidney arterial endothelial cells

The role of progesterone on the cardiovascular system is controversial. Our present research is to specify the effect of progesterone on arterial endothelial cells in response to oxidative stress. Our result showed that H2O2 (150 μM and 300 μM) induced cellular antioxidant response. Glutathione (GSH) production and the activity of Glutathione peroxidase (GPx) were increased in H2O2-treated group. The expression of glutamate cysteine ligase catalytic subunit (GCLC) and modifier subunit (GCLM) was induced in response to H2O2. However, progesterone absolutely abolished the antioxidant response through increasing ROS level, inhibiting the activity of Glutathione peroxidase (GPx), decreasing GSH level and reducing expression of GClC and GCLM. In our study, H2O2 induced nitrogen monoxide (NO) production and endothelial nitric oxide synthase (eNOS) expression, and progesterone promoted H2O2-induced NO production. Progesterone increased H2O2-induced expression of hypoxia inducible factor-α (HIFα) which in turn regulated eNOS expression and NO synthesis. Further study demonstrated that progesterone increased H2O2 concentration of culture medium which may contribute to NO synthesis. Exogenous GSH decreased the content of H2O2 of culture medium pretreated by progesterone combined with H2O2 or progesterone alone. GSH also inhibited expression of HIFα and eNOS, and abolished NO synthesis. Collectively, our study demonstrated for the first time that progesterone inhibited cellular antioxidant effect and increased oxidative stress, promoted NO production of arterial endothelial cells, which may be due to the increasing H2O2 concentration and amplified oxidative stress signal.

Long-term consequences of estrogens administered in midlife on female cognitive aging

This article is part of a Special Issue "Estradiol and cognition". Many of the biochemical, structural, and functional changes that occur as the female brain ages are influenced by changes in levels of estrogens. Administration of estrogens begun during a critical window near menopause is hypothesized to prevent or delay age-associated cognitive decline. However, due to potential health risks women often limit use of estrogen therapy to a few years to treat menopausal symptoms. The long-term consequences for the brain of short-term use of estrogens are unknown. Interestingly, there are preliminary data to suggest that short-term use of estrogens during the menopausal transition may afford long-term cognitive benefits to women as they age. Thus, there is the intriguing possibility that short-term estrogen therapy may provide lasting benefits to the brain and cognition. The focus of the current review is an examination of the long-term impact for cognition of midlife use of estrogens. We review data from our lab and others indicating that the ability of midlife estrogens to impact estrogen receptors in the hippocampus may contribute to its ability to exert lasting impacts on cognition in aging females.

Anti-osteoporotic drugs and vascular calcification: the bidirectional calcium traffic

During the last years, numerous epidemiological studies have demonstrated a direct relationship between vascular calcification and low bone mineral density. This observation is in line with experimental data demonstrating the osteogenic characteristics of calcified arteries. Various common risk factors have been suggested to link vascular calcification and bone loss, including aging, estrogen deficiency, vitamin D and K deficiency, diabetes mellitus, renal failure, smoking, chronic inflammation and oxidative stress. Although the underlying pathogenetic mechanisms are not yet clear, current research is focusing on anti-osteoporotic agents that could potentially affect the deposition of calcium in the arterial wall and thus provide an additional therapeutic strategy in elderly osteoporotic women prone to calcific cardiovascular disease.

Ovariectomy reinstates the infarct size-limiting effect of postconditioning in female rabbits

Gender seems to interfere with the cardioprotective effect of ischemic preconditioning (PreC) and postconditioning (PostC); PreC-conferred protection is weaker or lost in female animals after ovariectomy (Ov), while the role of PostC is still in dispute. We sought to investigate the effect of PostC in female rabbits, its interaction with Ov, and the potential implicated intracellular pathways. Intact or Ov adult female rabbits (n = 46) were subjected to 30 min ischemia and reperfusion with PostC (PostC or OvPostC), which consisted of six cycles of 30-s ischemia/30-s reperfusion at the end of ischemia, or without PostC (Fem or OvFem). Infarct size (I) and area at risk (R) were determined by TTC staining and fluorescent particles, respectively, after 3-h reperfusion in 30 out of 46 animals. Plasma levels of estradiol and nitrite/nitrate (NO x ) were evaluated. ERKs, p38-MAPK, and Akt assessment was performed in excised hearts 1-min after starting the final reperfusion period in the remaining 16 animals. Infarct size was significantly reduced only in OvPostC group (I/R ratio, 25.3 ± 2.7, vs 48.1 ± 2.0, 43.6 ± 4.2 and 55.1 ± 5.6 % in Fem, OvFem, and PostC groups, p < 0.05). In ovariectomized rabbits, plasma estradiol and NO x levels were lower than in the normal ones. Akt phosphorylation in ischemic regions was significantly higher in OvPostC group, whereas ERK1/2 and p38-MAPK activation was observed in all ovariectomized animals irrespective of PostC. PostC is not effective in female rabbits, but the protection is reinstated after Ov potentially via the RISK pathway.

Vascular effects of estrogenic menopausal hormone therapy

Cardiovascular disease (CVD) is more common in men and postmenopausal women (Post-MW) than premenopausal women (Pre-MW). Despite recent advances in preventive measures, the incidence of CVD in women has shown a rise that matched the increase in the Post-MW population. The increased incidence of CVD in Post-MW has been related to the decline in estrogen levels, and hence suggested vascular benefits of endogenous estrogen. Experimental studies have identified estrogen receptor ERα, ERβ and a novel estrogen binding membrane protein GPR30 (GPER) in blood vessels of humans and experimental animals. The interaction of estrogen with vascular ERs mediates both genomic and non-genomic effects. Estrogen promotes endothelium-dependent relaxation by increasing nitric oxide, prostacyclin, and hyperpolarizing factor. Estrogen also inhibits the mechanisms of vascular smooth muscle (VSM) contraction including [Ca2+]i, protein kinase C and Rho-kinase. Additional effects of estrogen on the vascular cytoskeleton, extracellular matrix, lipid profile and the vascular inflammatory response have been reported. In addition to the experimental evidence in animal models and vascular cells, initial observational studies in women using menopausal hormonal therapy (MHT) have suggested that estrogen may protect against CVD. However, randomized clinical trials (RCTs) such as the Heart and Estrogen/ progestin Replacement Study (HERS) and the Women's Health Initiative (WHI), which examined the effects of conjugated equine estrogens (CEE) in older women with established CVD (HERS) or without overt CVD (WHI), failed to demonstrate protective vascular effects of estrogen treatment. Despite the initial set-back from the results of MHT RCTs, growing evidence now supports the 'timing hypothesis', which suggests that MHT could increase the risk of CVD if started late after menopause, but may produce beneficial cardiovascular effects in younger women during the perimenopausal period. The choice of an appropriate MHT dose, route of administration, and estrogen/progestin combination could maximize the vascular benefits of MHT and minimize other adverse effects, especially if given within a reasonably short time after menopause to women that seek MHT for the relief of menopausal symptoms.

Primary Prevention of Cardiovascular Disease with HRT

Prevention of cardiovascular disease has increasingly important health implications as our population ages. Menopause is associated with the development of cardiovascular risk factors and there are many plausible biological mechanisms through which estrogen may confer cardiovascular protection. Despite a wealth of observational data to support the use of estrogen, large randomized controlled trials failed to demonstrate a benefit. It is now becoming clearer that the beneficial cardiovascular effects of estrogen are greatest in younger women and those closest to menopause. This has led to the development of the timing hypothesis. Use of age-appropriate estrogen doses is crucial to maximize cardiovascular benefits while minimizing risk of adverse effects such as venous thromboembolism and stroke.

Nicotine and vascular endothelial dysfunction in female ovariectomized rats: role of estrogen replacement therapy

OBJECTIVES

The protective effects of estrogen replacement therapy (ERT) against oxidative injury and endothelial dysfunction in the aortic tissues induced with nicotine in ovariectomized (OVX) rats were investigated.

METHODS

Female rats were divided into a sham-operated group (n = 8) and four groups in which OVX rats received either vehicle (0.1 ml sesame oil, i.m., n = 8), or nicotine (0.1 mg/kg, s.c., n = 8), or estradiol benzoate (0.1 mg/kg, i.m., n = 8), or both nicotine and estradiol benzoate (n = 8) starting at week 5 after the surgery and continuing for the following 6 weeks.

KEY FINDINGS

ERT was effective in preventing the rise in plasma lipid profile, atherogenic index and the level of induced endothelin-1 (ET-1) in nicotine-treated OVX rats. It also reduced aortic malondialdehyde, hydroxyproline levels, calcium content and caspase-3 expression induced in nicotine-treated OVX rats. ERT increased serum estradiol, high-density lipoprotein cholesterol and nitric oxide levels in nicotine-treated OVX rats. Furthermore, ERT was effective in restoring reduced glutathione and cyclic guanosine monophosphate contents and endothelial nitric oxide synthase expression in aortic tissues of nicotine-treated OVX rats.

CONCLUSIONS

Short-term ERT could be a promising therapeutic strategy to minimize nicotine-induced oxidative stress and vascular endothelial dysfunction in menopausal women subjected to environmental smoke.

Estrogen, hormonal replacement therapy and cardiovascular disease

PURPOSE OF REVIEW

Premenopausal women have a lower risk and incidence of hypertension and cardiovascular disease (CVD) compared to age-matched men and this sex advantage for women gradually disappears after menopause, suggesting that sexual hormones play a cardioprotective role in women. However, randomized prospective primary or secondary prevention trials failed to confirm that hormone replacement therapy (HRT) affords cardioprotection. This review highlights the factors that may contribute to this divergent outcome and could reveal why young or premenopausal women are protected from CVD and yet postmenopausal women do not benefit from HRT.

RECENT FINDINGS

In addition to the two classical estrogen receptors, ERα and ERβ, a third, G-protein-coupled estrogen receptor GPR30, has been identified. New intracellular signaling pathways and actions for the cardiovascular protective properties of estrogen have been proposed. In addition, recent Women's Health Initiative (WHI) studies restricted to younger postmenopausal women showed that initiation of HRT closer to menopause reduced the risk of CVD. Moreover, dosage, duration, the type of estrogen and route of administration all merit consideration when determining the outcome of HRT.

SUMMARY

HRT has become one of the most controversial topics related to women's health. Future studies are necessary if we are to understand the divergent published findings regarding HRT and develop new therapeutic strategies to improve the quality of life for women.

Endothelial biology in the post-menopausal obese woman

Women generally have a reduced risk of cardiovascular disease (CVD). However, this protection of gender diminishes rapidly after menopause and with advancing age, particularly in obese women. Alterations in vascular function are thought to a key early step in the development of atherosclerosis. In this review, we will describe the features of endothelial dysfunction in the post-menopausal obese female and discuss the interplay of aging, estrogen withdrawal, and obesity. The objectives include (1) a review of endothelial biology and endothelial dysfunction, and (2) a discussion how the endothelial function is altered in the context of aging, hormonal changes and insulin resistance. The clinical consequences of endothelial dysfunction and CVD will also be reviewed.

Coronary Calcification and Hormones

The pathogenesis of coronary artery calcification and its role in atherogenesis has not been completely understood but is a new focus of interest in experimental and clinical research. Various bioactive substances, including hormones, have been implicated in the process of arterial calcification. This review considers the relationship between coronary artery calcification and hormones. These hormones may become therapeutic targets for the prevention of arterial calcification.

The effects of hormone replacement therapy on myocardial performance in early postmenopausal women

OBJECTIVES

The results of the studies in which the effect of hormone replacement therapy (HRT) on cardiac function have been evaluated are rather disputable. In these studies, cardiac function was evaluated with conventional echocardiographic methods. This study was planned in order to investigate the effects of HRT on myocardial velocities and myocardial performance index (MPI) in healthy early postmenopausal women.

METHOD

In a prospective, controlled study, 60 healthy postmenopausal women were assigned to two groups (32 in the HRT group and 28 in the control group). After conventional echocardiographic parameters were measured, tissue Doppler echocardiography recordings were obtained from the mitral and tricuspid annulus. Systolic myocardial velocity (Sm), early and late diastolic myocardial velocities (Em and Am) and time intervals were measured and MPI was calculated. Then the symptom-limited exercise stress test using the Bruce protocol was performed. After 3 and 6 months of HRT (oral 0.625 mg conjugated estrogen + 2.5 mg medroxyprogesterone acetate/day), the same examinations were repeated. The effects of HRT on myocardial velocities, MPI and exercise time were evaluated at the 3rd and 6th months.

RESULTS

The parameters of the control group remained statistically unchanged during the study. HRT did not have any effect on segmental and mean left ventricular (LV) Sm or right ventricular (RV) Sm. However, LV Em/Am and RV Em/Am ratios significantly increased at the 6th month of HRT, and LV and RV MPI values were observed to decrease significantly as compared to basal values. Additionally, a significant increase was observed in exercise duration and metabolic equivalent values after 3 months of HRT, and this increase continued at the 6th month as well. The favorable changes in all parameters in the HRT group were significantly different from those of the control group.

CONCLUSION

Data obtained in this study suggest that HRT is not only effective for treating menopausal complaints but also increases cardiovascular performance by improving especially diastolic functions in early postmenopausal women.

Transient estradiol exposure during middle age in ovariectomized rats exerts lasting effects on cognitive function and the hippocampus

We determined whether transient exposure to estradiol during middle age in ovariectomized rats would exert lasting effects on cognition and the brain beyond the period of exposure. Two experiments were conducted. Rats 10-11 months of age were ovariectomized and received vehicle control treatment throughout the experiment, continuous estradiol treatment throughout the experiment, or 40 d of transient exposure to estradiol that ended 3 d before behavioral training. In the first experiment, rats were trained on a radial-maze working memory task and killed 2 months after the termination of transient exposure to estradiol. The hippocampus was immunostained for choline acetyltransferase and estrogen receptors alpha (ER alpha) and beta (ER beta) by Western blotting. In a second experiment to determine the durability of treatment effects, rats were behaviorally tested every other month until brains were collected for Western blotting 8 months after the termination of transient exposure to estradiol. Maze testing included delay trials and scopolamine trials, in which dose-effect curves for the muscarinic receptor antagonist were determined. Transient exposure to estradiol enhanced working memory and attenuated amnestic effects of scopolamine as effectively as continuous estradiol exposure. Enhancements persisted for up to 7 months. Transient exposure to estradiol increased hippocampal levels of ER alpha and choline acetyltransferase 2 months and ER alpha 8 months after termination of the exposure. Neither estradiol treatment altered estrogen receptor beta levels. Results demonstrate that short-term treatment with estradiol during middle age enhances working memory well beyond the duration of treatment and suggest ER alpha as a potential mechanism for this effect.

Androgen receptor-dependent transactivation of growth arrest-specific gene 6 mediates inhibitory effects of testosterone on vascular calcification

Recent epidemiological studies have found that androgen deficiency is associated with a higher incidence of cardiovascular disease in men. However, little is known about the mechanism underlying the cardioprotective effects of androgens. Here we show the inhibitory effects of testosterone on vascular calcification and a critical role of androgen receptor (AR)-dependent transactivation of growth arrest-specific gene 6 (Gas6), a key regulator of inorganic phosphate (P(i))-induced calcification of vascular smooth muscle cells (VSMC). Testosterone and nonaromatizable androgen dihydrotestosterone inhibited P(i)-induced calcification of human aortic VSMC in a concentration-dependent manner. Androgen inhibited P(i)-induced VSMC apoptosis, an essential process for VSMC calcification. The effects on VSMC calcification were mediated by restoration of P(i)-induced down-regulation of Gas6 expression and a subsequent reduction of Akt phosphorylation. These effects of androgen were blocked by an AR antagonist, flutamide, but not by an estrogen receptor antagonist, ICI 182,780. We then explored the mechanistic role of the AR in Gas6 expression and found an abundant expression of AR predominantly in the nucleus of VSMC and two consensus ARE sequences in the Gas6 promoter region. Dihydrotestosterone stimulated Gas6 promoter activity, and this effect was abrogated by flutamide and by AR siRNA. Site-specific mutation revealed that the proximal ARE was essential for androgen-dependent transactivation of Gas6. Furthermore, chromatin immunoprecipitation assays demonstrated ligand-dependent binding of the AR to the proximal ARE of Gas6. These results indicate that AR signaling directly regulates Gas6 transcription, which leads to inhibition of vascular calcification, and provides a mechanistic insight into the cardioprotective action of androgens.

Long-Term Prevention with Hormone-Replacement Therapy after the Menopause: Which Women should be Targeted?

For decades, hormone-replacement therapy (HRT) was considered safe and was the first choice in prevention of postmenopausal osteoporosis induced by estrogen deficiency. Numerous experimental and epidemiological studies further supported a protective effect of exogenous female sex hormones on atherogenesis and coronary heart disease (CHD) in women after the menopause. However, the fact that these promising results were not translated into lower incidences of CHD events in hormone-treated women compared with placebo in subsequent, large, randomized studies of healthy subjects as well as women with known CHD raised a very intense debate concerning the safety of HRT in terms of cardiovascular risk. A critical mass of data points toward a protective influence of HRT on cardiovascular disease end points in early postmenopausal women, but increased harm in elderly women, especially those with abdominal adiposity or metabolic syndrome. Once the quasi-hysterical reaction to the largest of the randomized studies (the Women's Health Initiative) has abated, a future strategy should be to concentrate on identifying those relatively few individuals who are not suitable for HRT, as HRT still remains the most thoroughly investigated pharmacological prevention strategy of osteoporosis.

Androgen-induced progression of arterial calcification in apolipoprotein E-null mice is uncoupled from plaque growth and lipid levels

Arterial calcification has prognostic significance for cardiovascular outcomes, but its pathogenesis remains unclear. Calcification increases with age, but its prevalence in men suggests hormonal influence. In this study we analyzed the effect of exogenous androgens on calcification of advanced atherosclerotic lesions in the arterial tree of gonadally intact 34-wk-old male and female apolipoprotein E-null mice. Testosterone (T) increased calcification 3- to 4-fold (P < 0.05) in lesions of the innominate artery and aortic sinus. A nonaromatizable androgen, dihydrotestosterone, also increased lesion calcification in the innominate artery (2.4-fold, P < 0.05) but not the aortic sinus. The androgen-induced effects were independent of sex and occurred despite corresponding reductions in plaque area, the latter correlating inversely with increased serum high-density lipoprotein cholesterol levels. Androgen-induced calcification in the innominate artery was observed with up-regulation of local androgen receptor (AR) expression in response to T and dihydrotestosterone for both males and females but neither androgen influenced innominate artery estrogen receptor (ER)-alpha or -beta expression in either sex. Conversely, T-induced calcification in the aortic sinus was associated with down-regulation of ERalpha but not ERbeta expression in both sexes, whereas androgen-induced AR expression was increased in female but decreased in male mice. This study demonstrates for the first time that calcification of advanced atherosclerotic lesions is an androgen-sensitive process and postulates potential roles for both AR- and ER-mediated pathways in androgen-induced vascular calcification. We demonstrate a novel direct link between vascular calcification and the major male hormone, T, uncoupled from conventional relationships with plaque growth and lipid levels.

Oral bioavailability and bone-sparing effects of estetrol in an osteoporosis model

OBJECTIVES

To measure the oral bioavailability of estetrol (E(4)) in rats relative to its subcutaneous administration and to test the bone-sparing effect of oral E(4) compared to that of ethinylestradiol (EE).

METHODS

In the bioavailability study, E(4) was administered as a single dose of 0.05, 0.5 or 5.0 mg/kg orally or subcutaneously to female rats. Plasma was analyzed using an LC-MS/MS method. The bone study was conducted in 3-month-old female rats assigned to the following seven treatment groups of ten animals each: no treatment; sham-operated + vehicle; bilaterally ovariectomized (OVX) + vehicle; OVX + E(4) 0.1, 0.5, or 2.5 mg/kg/day and OVX + EE 0.1 mg/kg/day. Once-daily treatment by oral gavage was given for 4 weeks and the following measurements were performed: serum osteocalcin, bone mineral density, bone mineral content and bone mineral area of lumbar vertebrae L3-L6, peripheral quantitative computed tomography of the left tibiae and the biomechanical properties of the distal femora.

RESULTS

Oral bioavailability of E(4), relative to that of subcutaneous dosing, was 70% and above at the 0.05 and 0.5 mg/kg doses based on the AUC(0-t last). Subcutaneous dosing provided significantly higher E(4) levels at the 1-h time point only, and was comparable to oral dosing after 0.5, 2, 4 and 8 h. In the bone study, E(4) dose-dependently and significantly (1) inhibited the OVX-related increase in osteocalcin levels, (2) increased bone mineral density and content, and (3) increased bone strength, all attenuated by ovariectomy. In this rat model, the relative potency of the highest dose of E(4) (2.5 mg/kg/day) was comparable to the EE dose, used as positive control.

CONCLUSIONS

Estetrol exhibits high oral bioavailability in the rat, a species considered relevant for pharmacological studies that are predictive for effects on human bone. Oral administration of E(4) conveys dose-dependent bone-sparing effects of high-quality bone in estrogen-depleted OVX rats. Based on its bone-sparing effects, its oral bioavailability and its preclinical safety and efficacy profile, E(4) may be superior to other estrogens and is a potential drug for the prevention of osteoporosis in postmenopausal women.

The medical management of menopause: to treat or not to treat?

The evidence concerning the effects of hormone therapy (HT) has been greatly expanded by the publication of very large randomized controlled trials. A consequence has been concern among women about the risks of HT such that the number of menopausal women using HT for relief of menopausal symptoms has declined. It is now appropriate to look at the best evidence available and to consider current policies. Women in the early postmenopausal phase, generally younger than 60 years of age, who are troubled by menopausal symptoms should be reassured that, for their circumstances, medical management of menopause in the form of HT is appropriate. If they go on to use HT for several years, it is possible that they will experience skeletal and coronary health benefits, but the evidence for such benefits is a matter of ongoing debate.

Rationale for low-dose systemic hormone replacement therapy and review of estradiol 0.5 mg/NETA 0.1 mg

The menopausal transition is associated with several symptoms, for which both non-pharmacological and pharmacological measures are available to provide relief. However, present knowledge indicates that the former is not highly effective, and that the latter, in terms of systemic oestrogen and progestogen-based hormone replacement therapy (HRT), although being effective (e.g. on vasomotor symptoms, bleeding control, bone mineral density, vaginal atrophy and quality of life), can be associated with some caveats. Amongst these are an increased risk for coronary heart disease, breast cancer, venous thromboembolism and stroke. In recent years, literature has indicated a dose dependency for HRT on some of the caveats, hence authorities (Food and Drug Administration, and the European Medicines Agency) and menopause societies (International Menopause Society and North American Menopause Society) now recommend that women deemed in need of HRT should receive the lowest possible dose without compromising the effect of symptom relief. Estradiol 0.5 mg/norethisterone acetate (NETA) 0.1 mg, despite being a lower dose than conventional hormones, is a compound, among a few other low-dose options, that can be used in such therapy. As a first-line oral option, it has demonstrated its effectiveness (which seems comparable to other compounds), with high tolerability and, apparently, no safety concerns, in a 6-month study. Further long-term clinical trials and observational studies are mandatory in order to capture any potential harm as well as to elucidate this compound's full potential. Following a thorough literature search using PubMed and MEDLINE from the earliest publication dates through to January 2008, including results from various types of clinical trials and statements on HRT, we review the rationale for these recommendations. We also review the effects and safety of a novel 'ultra-low-dose' oral continuous combined HRT tablet, estradiol 0.5 mg/NETA 0.1 mg.

Dose-dependent cardiac effect of oestrogen replacement in mice post-myocardial infarction

Hormonal replacement therapy (HRT) has recently been shown to increase the risk of cardiovascular events in women. However, it is not clear whether the adverse effect of HRT is related to dosage and/or the presence of progestin. Using a mouse model of myocardial infarction (MI), we studied the dose-effect of oestrogen replacement on mortality and cardiac remodelling and dysfunction post-MI in the absence of progestin. Six-week-old females were subjected to ovariectomy (OVX). A pellet containing a low, moderate or high dose of 17beta-oestradiol (E(2); 0.42, 4.2 or 18.8 microg day(-1)) or placebo was implanted subcutaneously on the day of OVX. Myocardial infarction was induced 8 weeks later, and cardiac morphology and function were evaluated 8 weeks after MI. We found that E(2) at moderate and high doses adversely affected mortality. A low dose of E(2) that restored plasma oestrogen close to physiological levels had no significant effect on mortality but tended to improve cardiac function and remodelling, associated with reduced fibrosis and increased capillary density. At the moderate dose, E(2) exacerbated cardiac fibrosis, hypertrophy, dysfunction and dilatation, associated with liver and kidney enlargement and ascites. Protein kinase C and extracellular signal-regulated kinase were increased by MI but were not affected by E(2). In summary, E(2) at a low dose tended to be cardioprotective. At increased doses that raised plasma oestrogen far beyond the physiological level, E(2) was detrimental to the heart. Our data suggest that dosage should be an important consideration when studying the effect of oestrogen replacement on the heart.

Advances in hormone replacement therapy: weight benefits of drospirenone, a 17alpha-spirolactone-derived progestogen

Hormone replacement therapy (HRT) remains the most effective treatment for menopausal symptom relief, and may provide cardiovascular benefits in younger women initiating treatment soon after menopause. However, large surveys indicate that many symptomatic women refuse or discontinue HRT prematurely owing to fear of weight gain. A continuous combined HRT containing 17beta-estradiol (E(2)) 1 mg plus drospirenone (DRSP) 2 mg is effective in relieving menopausal symptoms and preventing postmenopausal osteoporosis. DRSP is a unique synthetic progestogen with a pharmacological profile similar to that of natural progesterone, including antialdosterone activity, a property not exhibited by other synthetic progestogens. DRSP can therefore reduce estrogen-related sodium and water retention in postmenopausal women receiving HRT via the renin-angiotensin-aldosterone system, which regulates sodium and water balance. This may translate into weight benefits. Pooled data from two placebo-controlled clinical trials (n = 333) indicated statistically significant weight loss of -1.5 kg at 6 and 12 months in postmenopausal women receiving E(2)/DRSP vs. placebo (p < 0.001). In a third randomized controlled trial (n = 1147), women receiving E(2)/DRSP maintained or lost weight, whereas weight increases were observed in women receiving E(2) monotherapy (p < 0.0125). E(2)/DRSP could help maintain or even slightly decrease body weight during treatment, potentially improving HRT acceptance and compliance.

Novel perspectives for progesterone in hormone replacement therapy, with special reference to the nervous system

The utility and safety of postmenopausal hormone replacement therapy has recently been put into question by large clinical trials. Their outcome has been extensively commented upon, but discussions have mainly been limited to the effects of estrogens. In fact, progestagens are generally only considered with respect to their usefulness in preventing estrogen stimulation of uterine hyperplasia and malignancy. In addition, various risks have been attributed to progestagens and their omission from hormone replacement therapy has been considered, but this may underestimate their potential benefits and therapeutic promises. A major reason for the controversial reputation of progestagens is that they are generally considered as a single class. Moreover, the term progesterone is often used as a generic one for the different types of both natural and synthetic progestagens. This is not appropriate because natural progesterone has properties very distinct from the synthetic progestins. Within the nervous system, the neuroprotective and promyelinating effects of progesterone are promising, not only for preventing but also for reversing age-dependent changes and dysfunctions. There is indeed strong evidence that the aging nervous system remains at least to some extent sensitive to these beneficial effects of progesterone. The actions of progesterone in peripheral target tissues including breast, blood vessels, and bones are less well understood, but there is evidence for the beneficial effects of progesterone. The variety of signaling mechanisms of progesterone offers exciting possibilities for the development of more selective, efficient, and safe progestagens. The recognition that progesterone is synthesized by neurons and glial cells requires a reevaluation of hormonal aging.

HRT and the primary prevention of cardiovascular disease

Observational studies have consistently shown a benefit of hormone replacement therapy (HRT) on coronary heart disease (CHD), but some randomised studies have not shown any significant effect. Thus questions still remains as to whether HRT is beneficial for CHD, and in whom this benefit might be achieved. The biological effects of oestrogen on the cardiovascular system have been extensively studied, and beneficial effects on metabolic CHD risk factors, as well as on arterial function and on surrogate clinical markers of CHD, have been demonstrated. Thus it seems implausible that HRT should not benefit CHD in postmenopausal women. Most randomised trials using clinical outcomes have studied just one dose of one HRT regimen, a dose inappropriately high with the average starting age of the participants being in their mid-60s. The observational population studies largely comprise women starting on HRT at appropriate dose around the age of menopause, i.e. early 50s. In fact, it was the older women in the randomised trials that failed to show benefit, whereas there was a trend to benefit in the younger ones for whom the starting dose of HRT was appropriate. Furthermore, a pilot study of lower dose HRT in older women did not show any cardiovascular harm. Inappropriately high doses of oestrogen could cause cardiovascular harm due to transient disturbances in thrombogenesis and vascular remodelling. Whilst the greatest CHD benefit may be seen by starting HRT in the early postmenopause, this does not exclude benefit in older women given appropriate low dose therapy.

Development of low-dose reproductive hormone therapies in China

A historical account is presented of the development of sex hormone treatment from its beginning at the Peking Union Medical College to its present-day generalization throughout China. The general theme of this work has been to test low-dose hormone regimens. Notable successes include low-dose oral contraception and menopausal hormone treatment. In support of the latter, we present a new clinical study of the effects of low-dose, intermittent, patient-metered hormone replacement therapy (HRT), which shows decreased menopausal symptoms, maintenance of bone health and height, and improved cardiovascular status compared with untreated controls. Cardiovascular testing, included carotid artery ultrasound scanning and computed tomographic coronary angiography, supports a cardioprotective effect of long-term (up to 31 years) low-dose HRT that is begun during the menopausal transition. These results highlight the urgent need for larger, prospective trials of long-term low-dose HRT started during the perimenopausal period.