Hormone Replacement Therapy and Cardiovascular Disease

Dihydrotanshinone I targets ESR1 to induce DNA double-strand breaks and proliferation inhibition in hepatocellular carcinoma

BACKGROUND

Due to its high incidence and elevated mortality, hepatocellular carcinoma (HCC) has emerged as a formidable global healthcare challenge. The intricate interplay between gender-specific disparities in both incidence and clinical outcomes has prompted a progressive recognition of the substantial influence exerted by estrogen and its corresponding receptors (ERs) upon HCC pathogenesis. Estrogen replacement therapy (ERT) emerged for the treatment of HCC by administering exogenous estrogen. However, the powerful side effects of estrogen, including the promotion of breast cancer and infertility, hinder the further application of ERT. Identifying effective therapeutic targets for estrogen and screening bioactive ingredients without E2-like side effects is of great significance for optimizing HCC ERT.

METHODS

In this study, we employed an integrative approach, harnessing data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, clinical paraffin sections, adenoviral constructs as well as in vivo studies, to unveil the association between estrogen, estrogen receptor α (ESR1) and HCC. Leveraging methodologies encompassing molecular dynamics simulation and cellular thermal shift assay (CETSA) were used to confirm whether ESR1 is a molecular target of DHT. Multiple in vitro and in vivo experiments were used to identify whether i) ESR1 is a crucial gene that promotes DNA double-strand breaks (DSBs) and proliferation inhibition in HCC, ii) Dihydrotanshinone I (DHT), a quinonoid monomeric constituent derived from Salvia miltiorrhiza (Dan shen) exerts anti-HCC effects by regulating ESR1 and subsequent DSBs, iii) DHT has the potential to replace E2.

RESULTS

DHT could target ESR1 and upregulate its expression in a concentration-dependent manner. This, in turn, leads to the downregulation of breast cancer type 1 susceptibility protein (BRCA1), a pivotal protein involved in the homologous recombination repair (HRR) process. The consequence of this downregulation is manifested through the induction of DSBs in HCC, subsequently precipitating a cascade of downstream events, including apoptosis and cell cycle arrest. Of particular significance is the comparative assessment of DHT and isodose estradiol treatments, which underscores DHT's excellent HCC-suppressive efficacy without concomitant perturbation of endogenous sex hormone homeostasis.

CONCLUSION

Our findings not only confirm ESR1 as a therapeutic target in HCC management but also underscores DHT's role in upregulating ESR1 expression, thereby impeding the proliferation and invasive tendencies of HCC. In addition, we preliminarily identified DHT has the potential to emerge as an agent in optimizing HCC ERT through the substitution of E2.

Cardioprotective O-GlcNAc signaling is elevated in murine female hearts via enhanced O-GlcNAc transferase activity

The post-translational modification of intracellular proteins by O-linked β-GlcNAc (O-GlcNAc) has emerged as a critical regulator of cardiac function. Enhanced O-GlcNAcylation activates cytoprotective pathways in cardiac models of ischemia-reperfusion (I/R) injury; however, the mechanisms underpinning O-GlcNAc cycling in response to I/R injury have not been comprehensively assessed. The cycling of O-GlcNAc is regulated by the collective efforts of two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which catalyze the addition and hydrolysis of O-GlcNAc, respectively. It has previously been shown that baseline heart physiology and pathophysiology are impacted by sex. Here, we hypothesized that sex differences in molecular signaling may target protein O-GlcNAcylation both basally and in ischemic hearts. To address this question, we subjected male and female WT murine hearts to ex vivo ischemia or I/R injury. We assessed hearts for protein O-GlcNAcylation, abundance of OGT, OGA, and glutamine:fructose-6-phosphate aminotransferase (GFAT2), activity of OGT and OGA, and UDP-GlcNAc levels. Our data demonstrate elevated O-GlcNAcylation in female hearts both basally and during ischemia. We show that OGT activity was enhanced in female hearts in all treatments, suggesting a mechanism for these observations. Furthermore, we found that ischemia led to reduced O-GlcNAcylation and OGT-specific activity. Our findings provide a foundation for understanding molecular mechanisms that regulate O-GlcNAcylation in the heart and highlight the importance of sex as a significant factor when assessing key regulatory events that control O-GlcNAc cycling. These data suggest the intriguing possibility that elevated O-GlcNAcylation in females contributes to reduced ischemic susceptibility.

Hyaluronic Acid Conjugated with 17β-Estradiol Effectively Alleviates Estropause-Induced Cognitive Deficits in Rats

Women are at a higher risk of cognitive impairments and Alzheimer's disease (AD), particularly after the menopause, when the estrous cycle becomes irregular and diminishes. Numerous studies have shown that estrogen deficiency, especially estradiol (E2) deficiency, plays a key role in this phenomenon. Recently, a novel polymeric drug, hyaluronic acid-17β-estradiol conjugate (HA-E2), has been introduced for the delivery of E2 to brain tissues. Studies have indicated that HA-E2 crosses the blood-brain barrier (BBB) and facilitates a prolonged E2 release profile while lowering the risk of estrogen-supplement-related side effects. In this study, we used ovariohysterectomy (OHE) rats, a postmenopausal cognitive deficit model, to explore the effect of a 2-week HA-E2 treatment (210 ng/kg body weight, twice a week) on the cholinergic septo-hippocampal innervation system, synaptic transmission in hippocampal pyramidal neurons and cognitive improvements. Our study revealed an 11% rise in choline acetyltransferase (ChAT) expression in both the medial septal nucleus (MS nucleus) and the hippocampus, along with a 14-18% increase in dendritic spine density in hippocampal pyramidal neurons, following HA-E2 treatment in OHE rats. These enhancements prompted the recovery of cognitive functions such as spatial learning and memory. These findings suggest that HA-E2 may prevent and improve estrogen-deficiency-induced cognitive impairment and AD.

Gender-based research underscores sex differences in biological processes, clinical disorders and pharmacological interventions

Earlier research has presumed that the male and female biology is similar in most organs except the reproductive system, leading to major misconceptions in research interpretations and clinical implications, with serious disorders being overlooked or misdiagnosed. Careful research has now identified sex differences in the cardiovascular, renal, endocrine, gastrointestinal, immune, nervous, and musculoskeletal systems. Also, several cardiovascular, immunological, and neurological disorders have shown differences in prevalence and severity between males and females. Genetic variations in the sex chromosomes have been implicated in several disorders at young age and before puberty. The levels of the gonadal hormones estrogen, progesterone and testosterone and their receptors play a role in the sex differences between adult males and premenopausal women. Hormonal deficiencies and cell senescence have been implicated in differences between postmenopausal and premenopausal women. Specifically, cardiovascular disorders are more common in adult men vs premenopausal women, but the trend is reversed with age with the incidence being greater in postmenopausal women than age-matched men. Gender-specific disorders in females such as polycystic ovary syndrome, hypertension-in-pregnancy and gestational diabetes have attained further research recognition. Other gender-related research areas include menopausal hormone therapy, the "Estrogen Paradox" in pulmonary arterial hypertension being more predominant but less severe in young females, and how testosterone may cause deleterious effects in the kidney while having vasodilator effects in the coronary circulation. This has prompted the National Institutes of Health (NIH) initiative to consider sex as a biological variable in research. The NIH and other funding agencies have provided resources to establish state-of-the-art centers for women health and sex differences in biology and disease in several academic institutions. Scientific societies and journals have taken similar steps to organize specialized conferences and publish special issues on gender-based research. These combined efforts should promote research to enhance our understanding of the sex differences in biological systems beyond just the reproductive system, and provide better guidance and pharmacological tools for the management of various clinical disorders in a gender-specific manner.

Familial Hypertrophic Cardiomyopathy: Diagnosis and Management

Hypertrophic cardiomyopathy (HCM) is widely recognized as one of the most common inheritable cardiac disorders. Since its initial description over 60 years ago, advances in multimodality imaging and translational genetics have revolutionized our understanding of the disorder. The diagnosis and management of patients with HCM are optimized with a multidisciplinary approach. This, along with increased safety and efficacy of medical, percutaneous, and surgical therapies for HCM, has afforded more personalized care and improved outcomes for this patient population. In this review, we will discuss our modern understanding of the molecular pathophysiology that underlies HCM. We will describe the range of clinical presentations and discuss the role of genetic testing in diagnosis. Finally, we will summarize management strategies for the hemodynamic subtypes of HCM with specific emphasis on the rationale and evidence for the use of implantable cardioverter defibrillators, septal reduction therapy, and cardiac myosin inhibitors.

GPR30 Alleviates Pressure Overload-Induced Myocardial Hypertrophy in Ovariectomized Mice by Regulating Autophagy

The incidence of heart failure mainly resulting from cardiac hypertrophy and fibrosis increases sharply in post-menopausal women compared with men at the same age, which indicates a cardioprotective role of estrogen. Previous studies in our group have shown that the novel estrogen receptor G Protein Coupled Receptor 30 (GPR30) could attenuate myocardial fibrosis caused by ischemic heart disease. However, the role of GPR30 in myocardial hypertrophy in ovariectomized mice has not been investigated yet. In this study, female mice with bilateral ovariectomy or sham surgery underwent transverse aortic constriction (TAC) surgery. After 8 weeks, mice in the OVX + TAC group exhibited more severe myocardial hypertrophy and fibrosis than mice in the TAC group. G1, the specific agonist of GPR30, could attenuate myocardial hypertrophy and fibrosis of mice in the OVX + TAC group. Furthermore, the expression of LC3II was significantly higher in the OVX + TAC group than in the OVX + TAC + G1 group, which indicates that autophagy might play an important role in this process. An in vitro study showed that G1 alleviated AngiotensionII (AngII)-induced hypertrophy and reduced the autophagy level of H9c2 cells, as revealed by LC3II expression and tandem mRFP-GFP-LC3 fluorescence analysis. Additionally, Western blot results showed that the AKT/mTOR pathway was inhibited in the AngII group, whereas it was restored in the AngII + G1 group. To further verify the mechanism, PI3K inhibitor LY294002 or autophagy activator rapamycin was added in the AngII + G1 group, and the antihypertrophy effect of G1 on H9c2 cells was blocked by LY294002 or rapamycin. In summary, our results demonstrate that G1 can attenuate cardiac hypertrophy and fibrosis and improve the cardiac function of mice in the OVX + TAC group through AKT/mTOR mediated inhibition of autophagy. Thus, this study demonstrates a potential option for the drug treatment of pressure overload-induced cardiac hypertrophy in postmenopausal women.

Does the concept of "ultra-processed foods" help inform dietary guidelines, beyond conventional classification systems? NO

The Nova classification of ultra-processed foods (UPFs) rests on poorly defined food processes and the presence of food additives from a chemically heterogeneous group, easily leading to misclassification. UPFs are claimed to promote overconsumption of energy and obesity due to high palatability, but little evidence supports effects beyond those that can be accounted for by nutrient composition, energy density, and food matrices. Observational studies link dietary intake of UPFs with obesity, but none have demonstrated independent associations after controlling for likely confounders. A highly cited randomized controlled feeding study that compared a UPF diet with an unprocessed diet showed a rapidly weaning effect on energy intake that can be entirely explained by more conventional and quantifiable dietary factors, including energy density, intrinsic fiber, glycemic load, and added sugar. Clearly, many aspects of food processing can affect health outcomes, but conflating them into the notion of ultra-processing is unnecessary, because the main determinants of chronic disease risk are already captured by existing nutrient profiling systems. In conclusion, the Nova classification adds little to existing nutrient profiling systems; characterizes several healthy, nutrient-dense foods as unhealthy; and is counterproductive to solve the major global food production challenges.

Premature and early menopause among US women with or at risk for HIV

OBJECTIVE

Little is known about the prevalence and treatment of premature and early menopause among people with HIV. We described premature and early menopause and subsequent hormonal treatment in a longitudinal cohort of women living with or at risk for HIV in the US.

METHODS

Data from the Women's Interagency HIV Study between 2008 and 2020 were analyzed to describe premature and early menopause among cohort participants under the age of 51.

RESULTS

Of 3,059 eligible women during the study period, 1% (n = 35) underwent premature menopause before age 41, 3% (n = 101) underwent menopause between ages 41 and 46, and 21% (n = 442) underwent menopause between ages 46 and 50, inclusive. Of participants who experienced menopause before age 41, between age 41 and 45, and between ages 46 and 50, 51%, 24%, and 7% (respectively) received either menopausal hormone therapy or hormonal contraception.

CONCLUSION

These findings suggest that disparities in receipt of recommended hormone therapy for premature and early menopause may contribute, in part, to evident health disparities, such as cardiovascular disease, osteoporosis, and overall mortality. They also suggest a substantial need for education among people experiencing early menopause and their providers, with the goal of improving access to hormone therapy based on guidelines to address health disparities and minimize future health consequences.

Chronic mercury exposure induces oxidative stress in female rats by endothelial nitric oxide synthase uncoupling and cyclooxygenase-2 activation, without affecting oestrogen receptor function

Mercury has been shown to be a significant health risk factor and is positively associated with cardiovascular diseases. Evidence reveals that men are more likely to develop cardiovascular diseases than women during reproductive age. However, the effects of mercury in females remain poorly investigated, despite the finding that female hormones demonstrate a cardioprotective role. In the present study, we evaluated whether chronic mercury chloride exposure could alter blood pressure and vascular function of the female rat aorta. Ten-week-old female Wistar rats were divided into two groups: control (vehicle) and mercury treated (first dose of 4.6 μg/kg, subsequent daily doses of 0.07 μg/kg), im. Mercury treatment did not modify systolic blood pressure (SBP) but increased vascular reactivity due to the reduction of nitric oxide bioavailability associated with the increase in reactive oxygen species from endothelial nitric oxide synthase (eNOS) uncoupling. Furthermore, increased participation of the cyclooxygenase-2 pathway occurred through an imbalance in thromboxane 2 and prostacyclin 2. However, the oestrogen signalling pathway was not altered in either group. These results demonstrated that chronic exposure to mercury in females induced endothelial dysfunction and, consequently, increased aortic vascular reactivity, causing vascular damage to the female rat aorta and representing a risk of cardiovascular diseases.

Effects of Estrogen on Cardiac mRNA and LncRNA Expression Profiles in Hypertensive Mice

Estrogen is a vascular protection factor and plays a protective role in the pathogenesis of gender differences in cardiovascular diseases. This study was to address the possible mechanisms that may explain the relationship between estradiol configuration-17β-estradiol (E2) and ventricular remodeling. Here, we show that a total of 1499 LncRNAs and 680 mRNAs significantly differently expressed were identified. This result indicates that estradiol has a global role in regulating heart gene expression profiles in female mice. Go and Pathway functional cluster analysis showed that the antagonism of E2 on cardiac remodeling and AngII-induced pathological changes in female mice may be related to physiological processes such as circadian rhythm disorder and ion channel dysfunction. Graphical Abstract.

Hypertension in Women Across the Lifespan

PURPOSE OF REVIEW

We will highlight the biological processes across a women's lifespan from young adulthood through menopause and beyond that impact blood pressure and summarize women's representation in hypertension clinical trials.

RECENT FINDINGS

Throughout their lifetime, women potentially undergo several unique sex-specific changes that may impact their risk of developing hypertension. Blood pressure diagnostic criteria for pregnant women remains 140/90 mmHg and has not been updated for concordance with the 2017 ACC/AHA guideline due to a lack of data. Although on a population level, women develop hypertension at later ages than men, new data shows women's BP starts to increase as early as the third decade. Understanding how age and sex both contribute to hypertension in elderly women is crucial to identify optimal blood pressure and treatment targets. Effective screening, monitoring, and treatment of hypertension throughout a women's lifespan are necessary to reduce CVD risk. We highlight several gaps in the literature pertaining to understanding sex-specific hypertension mechanisms.

The effects of estrogen and hormone replacement therapy on cardiovascular systems

Postmenopausal women have an increased risk of cardiovascular disease, which is believed to correlate with lower estrogen level. There are conflicting data regarding hormone replacement therapy (HRT) based on the timing of this therapy. After large randomized trials showed no cardiovascular benefit of hormone replacement, estrogen replacement therapy was dramatically reduced even though starting hormone replacement in early postmenopausal period had shown significant benefit. There are hardly any reviews discussing in detail the effect of HRT on cardiovascular system while briefly discussing other effects of this therapy in postmenopausal women. The novelty of this review is the comprehensive discussion of this effect that can help researchers and clinicians to design future research or trials. In this manuscript, the effect of HRT on cardiovascular system in clinical trials and basic science will be reported and potentially erroneous conclusions drawn by various studies will be discussed. Furthermore, various noncardiovascular effect of HRT will be analyzed.

The imbalance in the aortic ceramide/sphingosine-1-phosphate rheostat in ovariectomized rats and the preventive effect of estrogen

Background

The prevalence of hypertension in young women is lower than that in age-matched men while the prevalence of hypertension in women is significantly increased after the age of 50 (menopause) and is greater than that in men. It is already known that sphingosine-1-phosphate (S1P) and ceramide regulate vascular tone with opposing effects. This study aimed to explore the effects of ovariectomy and estrogen supplementation on the ceramide/S1P rheostat of the aorta in rats, and to explore a potential mechanism for perimenopausal hypertension and a brand-new target for menopausal hormone therapy to protect vessels.

Methods

In total, 30 female adult SD rats were randomly divided into three groups: The sham operation group (SHAM), ovariectomy group (OVX) and ovariectomy plus estrogen group (OVX + E). After 4 weeks of treatment, the blood pressure (BP) of the rats was monitored by a noninvasive system; the sphingolipid content (e.g., ceramide and S1P) was detected by liquid chromatography-mass spectrometry (LC-MS); the expression of the key enzymes involved in ceramide anabolism and catabolism was measured by real-time fluorescence quantitative polymerase chain reaction (qPCR); and the expression of key enzymes and proteins in the sphingosine kinase 1/2 (SphK1/2)-S1P-S1P receptor 1/2/3 (S1P1/2/3) signaling pathway was detected by qPCR and western blotting.

Results

In the OVX group compared with the SHAM group, the systolic BP (SBP), diastolic BP (DBP) and pulse pressure (PP) increased significantly, especially the SBP and PP (P < 0.001). For aortic ceramide metabolism, the mRNA level of key enzymes involved in anabolism and catabolism decreased in parallel 2–3 times, while the contents of total ceramide and certain long-chain subtypes increased significantly (P < 0.05). As for the S1P signaling pathway, SphK1/2, the key enzymes involved in S1P synthesis, decreased significantly, and the content of S1P decreased accordingly (P < 0.01). The S1P receptors showed various trends: S1P1 was significantly down-regulated, S1P2 was significantly up-regulated, and S1P3 showed no significant difference. No significant difference existed between the SHAM and OVX + E groups for most of the above parameters (P > 0.05).

Conclusions

Ovariectomy resulted in the imbalance of the aortic ceramide/S1P rheostat in rats, which may be a potential mechanism underlying the increase in SBP and PP among perimenopausal women. Besides, the ceramide/S1P rheostat may be a novel mechanism by which estrogen protects vessels.

Unconventional Estrogen Signaling in Health and Disease

Estrogen is a key hormone involved in the development and homeostasis of several tissue types in both males and females. By binding estrogen receptors, estrogen regulates essential functions of gene expression, metabolism, cell growth, and proliferation by acting through cytoplasmic signaling pathways or activating transcription in the nucleus. However, disruption or dysregulation of estrogen activity has been shown to play a key role in the pathogenesis and progression of many diseases. This review will expatiate on some of the unconventional roles of estrogen in homeostasis and disease.

Resistin Mediates Sex-Dependent Effects of Perivascular Adipose Tissue on Vascular Function in the Shrsp

Premenopausal women are relatively protected from developing hypertension compared to men. Perivascular adipose tissue (PVAT) has been shown to mediate vasoactive effects; however, a sex-dependent difference in PVAT function in the setting of hypertension has not yet been explored. We investigated the effect of PVAT on resistance vessel biology in male and female 16 week old stroke prone spontaneously hypertensive rats (SHRSP). This preclinical model of hypertension exhibits a sex-dependent difference in the development of hypertension similar to humans. Wire myography was used to assess vascular function in third-order mesenteric arteries. K_ATP channel-mediated vasorelaxation by cromakalim was significantly impaired in vessels from SHRSP males + PVAT relative to females (maximum relaxation: male + PVAT 46.9 ± 3.9% vs. female + PVAT 97.3 ± 2.7%). A cross-over study assessing the function of male PVAT on female vessels confirmed the reduced vasorelaxation response to cromakalim associated with male PVAT (maximum relaxation: female + PVAT_female90.6 ± 1.4% vs. female + PVAT_male65.8 ± 3.5%). In order to explore the sex-dependent differences in PVAT at a molecular level, an adipokine array and subsequent western blot validation identified resistin expression to be increased approximately 2-fold in PVAT from male SHRSP vessels. Further wire myography experiments showed that pre-incubation with resistin (40 ng/ml) significantly impaired the ability of female + PVAT vessels to relax in response to cromakalim (maximum relaxation: female + PVAT 97.3 ± 0.9% vs. female + PVAT + resistin_[40ng/ml]36.8 ± 2.3%). These findings indicate a novel role for resistin in mediating sex-dependent vascular function in hypertension through a K_ATP channel-mediated mechanism.

Equilin displays similar endothelium-independent vasodilator potential to 17β-estradiol regardless of lower potential to inhibit calcium entry

Conjugated equine estrogens (CEE) have been widely used by women who seek to relieve symptoms of menopause. Despite evidence describing protective effects against risk factors for cardiovascular diseases by naturally occurring estrogens, little is known about the vascular effects of equilin, one of the main components of CEE and not physiologically present in women. In this regard, the present study aims to compare the vascular effects of equilin in an experimental model of hypertension with those induced by 17β-estradiol. Resistance mesenteric arteries from female spontaneously hypertensive rats (SHR) were used for recording isometric tension in a small vessel myograph. As effectively as 17β-estradiol, equilin evoked a concentration-dependent relaxation in mesenteric arteries from female SHRs contracted with KCl, U46619, PDBu or ET-1. Equilin-induced vasodilation does not involve classical estrogen receptor activation, since the estrogen receptor antagonist (ICI 182,780) failed to inhibit relaxation in U46619-precontracted mesenteric arteries. Vasorelaxation was not affected by either endothelium removal or by inhibiting the release or action of endothelium-derived factors. Incubation with L-NAME (NOS inhibitor), ODQ (guanylyl cyclase inhibitor) or KT5823 (inhibitor of protein kinase G) did not affect equilin-induced relaxation. Similarly, indomethacin (COX inhibitor) or blockage of potassium channels with tetraethylammonium, glibenclamide, 4-aminopyridine, or ouabain did not affect equilin-induced relaxation. Inhibitors of adenylyl cyclase SQ22536 or protein kinase A (KT5720) also had no effects on equilin-induced relaxation. While 17β-estradiol inhibited calcium (Ca²⁺) -induced contractions in high-K⁺ depolarization medium in a concentration-dependent manner, equilin induced a slight rightward-shift in the contractile responses to Ca²⁺. Comparable pattern of responses were observed in the concentration-response curves to (S)-(-)-Bay K 8644, a L-type Ca²⁺ channel activator. Equilin was unable to block the transitory contraction produced by caffeine-induced Ca²⁺ release from intracellular stores. In conclusion, equilin blocks L-type Ca²⁺ channels less effectively than 17β-estradiol. Despite its lower effectiveness, equilin equally relaxes resistance mesenteric arteries by blocking Ca²⁺ entry on smooth muscle.

Concurrent use of Chinese herbal medicine among hormone users and its association with ischemic stroke risk: A population-based study

ETHNOPHARMACOLOGICAL RELEVANCE

Previous studies had indicated that hormone therapy (HT) may increase the risk of ischemic stroke (IS) in menopausal women. However, little is known about the benefits and risks of use of Chinese herbal medicine (CHM) in conditions related to hormone use. The aim of this study is to explore the risk of IS in menopausal women treated with HT and CHM.

MATERIALS AND METHODS

A total of 32,441 menopausal women without surgical menopause aged 40-65 years were selected from 2003 to 2010 using the 2-million random samples of the National Health Insurance Research Database in Taiwan. According to the medication usage of HT and CHM, we divided the current and recent users into two groups: an HT use-only group (n = 4989) and an HT/CHM group (n = 9265). Propensity-score matching samples (4079 pairs) were further created to deal with confounding by indication. The adjusted hazard ratios (HR) of IS were estimated by the robust Cox proportional hazards model.

RESULTS

The incidence rate of IS in the HT/CHM group was significantly lower than in the HT group (4.5 vs. 12.8 per 1000 person-year, p < 0.001). Multivariate analysis results indicated that additional CHM use had a lower risk of IS compared to the HT group (HR = 0.3; 95% confidence interval [CI], 0.21-0.43). Further subgroup analyses and sensitivity analyses had similar findings.

CONCLUSION

We found that combined use of HT and CHM was associated with a lower risk of IS. Further study is needed to examine possible mechanism underlying this association.

E2/ER β inhibit ISO-induced cardiac cellular hypertrophy by suppressing Ca2+-calcineurin signaling

Cardiovascular incidences are markedly higher in men than in pre-menstrual women. However, this advantage in women declines with aging and therefore can be correlated with the sex hormone 17β-Estradiol (E2) which is reported to protect heart cells by acting though estrogen receptors (ERs). In this study we have determined the effect of E2/ERβ against ISO induced cellular hypertrophy in H9c2 cardiomyoblast cells. The results confirm that ISO induced cardiac-hypertrophy by elevating the levels of hypertrophy associated proteins, ANP and BNP and further by upregulating p-CaMKII, calcineurin, p-GATA4 and NFATc3 which was correlated with a significant enlargement of the H9c2 cardiomyoblast. However, overexpression of ERβ and/or administration of E2 inhibited ISO-induced hypertrophy in H9c2 cells. In addition, E2/ERβ also inhibited ISO-induced NFATc3 translocation, and reduced the protein level of downstream marker, BNP. Furthermore, by testing with the calcineurin inhibitor (CsA), it was confirmed that calcineurin acted as a key mediator for the anti-hypertrophic effect of E2/ERβ. In cells treated with calcium blocker (BATPA), the inhibitory effect of E2/ERβ on ISO-induced Ca²⁺ influx and hypertrophic effects were totally blocked suggesting that E2/ERβ inhibited calcineurin activity to activate I-1 protein and suppress PP1, then induce PLB protein phosphorylation and activation, resulting in Ca²⁺ reuptake into sarcoplasmic reticulum through SR Ca²⁺ cycling modification. In conclusion, E2/ERβ suppresses the Ca²⁺ influx and calcineurin activity induced by ISO to enhance the PLB protein activity and SR Ca²⁺ cycling.

High salt intake does not aggravate glucose dysregulation and dyslipidemia induced by estrogen-progestin oral contraceptive

BACKGROUND

Estrogen-progestogen combined oral contraceptive (OC) use has been associated with increased cardiometabolic risk factors, including glucose dysregulation, dyslipidemia, hypertension, and pro-inflammatory state. However, the effect of a high-salt diet on these risk factors during OC use is not yet investigated. We therefore hypothesized that a high-salt diet would increase cardiometabolic risk factors in female rats treated with a combination of OC steroids, levonorgestrel (L) and ethinylestradiol (EE), and that elevated plasma levels of pro-inflammatory markers are associated with the cardiometabolic effects.

METHODS

Female Wistar rats were given (p.o.) vehicle, high-dose (1.0μg EE plus 5.0μgL) or low-dose (0.1μg EE plus 0.5μgL) OC with or without a high-salt diet (8%) daily for 8 weeks. Insulin resistance (IR) was estimated using the homeostatic model of assessment (HOMA).

RESULTS

Results showed that OC treatment or high salt diet led to significant increases in insulin resistance, plasma insulin, total cholesterol (TC), triglyceride (TG), TC/HDL-cholesterol, uric acid levels, and decreased glucose tolerance. OC treatment but not a high-salt diet resulted in increased plasma C-reactive protein and TG/HDL-cholesterol. However, a high-salt diet did not aggravate the effects of OC treatment.

CONCLUSION

The results from the present study indicate that glucose dysfunction and dyslipidemia induced by OC use, but not those induced by increased dietary salt are associated with elevated plasma C-reactive protein. Besides, increased dietary salt does not worsen abnormal cardiometabolic impact of OC use.

Anthocyanin Attenuates Doxorubicin-Induced Cardiomyotoxicity via Estrogen Receptor-α/β and Stabilizes HSF1 to Inhibit the IGF-IIR Apoptotic Pathway

Doxorubicin (Dox) is extensively used for chemotherapy in different types of cancer, but its use is limited to because of its cardiotoxicity. Our previous studies found that doxorubicin-induced insulin-like growth factor II receptor (IGF-IIR) accumulation causes cardiomyocytes apoptosis via down-regulation of HSF1 pathway. In these studies, we demonstrated a new mechanism through which anthocyanin protects cardiomyoblast cells against doxorubicin-induced injury. We found that anthocyanin decreased IGF-IIR expression via estrogen receptors and stabilized heat shock factor 1 (HSF1) to inhibit caspase 3 activation and apoptosis of cardiomyocytes. Therefore, the phytoestrogen from plants has been considered as another potential treatment for heart failure. It has been reported that the natural compound anthocyanin (ACN) has the ability to reduce the risk of cardiovascular disease (CVD). Here, we demonstrated that anthocyanin acts as a cardioprotective drug against doxorubicin-induced heart failure by attenuating cardiac apoptosis via estrogen receptors to stabilize HSF1 expression and down-regulated IGF-IIR-induced cardiomyocyte apoptosis.

Adaptive increases in expression and vasodilator activity of estrogen receptor subtypes in a blood vessel-specific pattern during pregnancy

Normal pregnancy is associated with adaptive hemodynamic, hormonal, and vascular changes, and estrogen (E2) may promote vasodilation during pregnancy; however, the specific E2 receptor (ER) subtype, post-ER signaling mechanism, and vascular bed involved are unclear. We tested whether pregnancy-associated vascular adaptations involve changes in the expression/distribution/activity of distinct ER subtypes in a blood vessel-specific manner. Blood pressure (BP) and plasma E2 were measured in virgin and pregnant (day 19) rats, and the thoracic aorta, carotid artery, mesenteric artery, and renal artery were isolated for measurements of ERα, ERβ, and G protein-coupled receptor 30 [G protein-coupled ER (GPER)] expression and tissue distribution in parallel with relaxation responses to E2 (all ERs) and the specific ER agonist 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)-tris-phenol (PPT; ERα), diarylpropionitrile (DPN; ERβ), and G1 (GPER). BP was slightly lower and plasma E2 was higher in pregnant versus virgin rats. Western blots revealed increased ERα and ERβ in the aorta and mesenteric artery and GPER in the aorta of pregnant versus virgin rats. Immunohistochemistry revealed that the increases in ERs were mainly in the intima and media. In phenylephrine-precontracted vessels, E2 and PPT caused relaxation that was greater in the aorta and mesenteric artery but similar in the carotid and renal artery of pregnant versus virgin rats. DPN- and G1-induced relaxation was greater in the mesenteric and renal artery than in the aorta and carotid artery, and aortic relaxation to G1 was greater in pregnant versus virgin rats. The nitric oxide synthase inhibitor N(ω)-nitro-l-arginine methyl ester with or without the cyclooxygenase inhibitor indomethacin with or without the EDHF blocker tetraethylammonium or endothelium removal reduced E2, PPT, and G1-induced relaxation in the aorta of pregnant rats, suggesting an endothelium-dependent mechanism, but did not affect E2-, PPT-, DPN-, or G1-induced relaxation in other vessels, suggesting endothelium-independent mechanisms. E2, PPT, DPN, and G1 caused relaxation of Ca(2+) entry-dependent KCl contraction, and the effect of PPT was greater in the mesenteric artery of pregnant versus virgin rats. Thus, during pregnancy, an increase in ERα expression in endothelial and vascular smooth muscle layers of the aorta and mesenteric artery is associated with increased ERα-mediated relaxation via endothelium-derived vasodilators and inhibition of Ca(2+) entry into vascular smooth muscle, supporting a role of aortic and mesenteric arterial ERα in pregnancy-associated vasodilation. GPER may contribute to aortic relaxation while enhanced ERβ expression could mediate other genomic vascular effects during pregnancy.

Circulating and adipose tissue matrix metalloproteinases in cardiometabolic risk environments: pathophysiological aspects

Matrix metalloproteinases (MMPs) play an important role during physiological tissue remodeling in embryonic development and angiogenesis, as well as in pathophysiological conditions such as obesity and development and vulnerability of atherosclerotic plaque. Moreover, MMP circulating levels have emerged as potential biomarkers of cardiovascular disease. MMP expression and activity are regulated by different factors such as insulin resistance and obesity. Expanded fat tissue has been demonstrated to be an active organ, where MMPs also exert a role in adipogenesis, angiogenesis, and proliferation of extracellular matrix (ECM). However, the lack of association between adipose tissue and plasma levels of some MMPs, specifically MMP-2 and MMP-9, suggests that this tissue is not a major contributor to circulating gelatinases. MMPs are also co-expressed or co-repressed in response to inflammatory adipocytokines, like adiponectin and leptin. Adiponectin may also play a protective role in plaque rupture through selectively increasing the tissue inhibitor of metalloproteinase (TIMP) expression. Leptin induces the expression of MMP-2 activators as well as the expression of MMP-2, MMP-9, and TIMP-1 in different human cells. Furthermore, sex hormones also participate in MMP regulation. In postmenopausal women, hormone replacement therapy produces an increase in MMP activity, leading to a breakdown in ECM homeostasis and accelerated progression of vascular pathologies. Besides, in men, an inverse relationship between testosterone levels and MMP-2 activity has been described. It is still necessary to go forward in the study of MMPs in different metabolic situations to corroborate their role as vulnerable plaque biomarkers.

Estrogen receptor subtypes mediate distinct microvascular dilation and reduction in [Ca2+]I in mesenteric microvessels of female rat

Estrogen interacts with estrogen receptors (ERs) to induce vasodilation, but the ER subtype and post-ER relaxation pathways are unclear. We tested if ER subtypes mediate distinct vasodilator and intracellular free Ca(2+) concentration ([Ca(2+)]i) responses via specific relaxation pathways in the endothelium and vascular smooth muscle (VSM). Pressurized mesenteric microvessels from female Sprague-Dawley rats were loaded with fura-2, and the changes in diameter and [Ca(2+)]i in response to 17β-estradiol (E2) (all ERs), PPT (4,4',4''-[4-propyl-(1H)-pyrazole-1,3,5-triyl]-tris-phenol) (ERα), diarylpropionitrile (DPN) (ERβ), and G1 [(±)-1-[(3aR*,4S*,9bS*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro:3H-cyclopenta(c)quinolin-8-yl]-ethanon] (GPR30) were measured. In microvessels preconstricted with phenylephrine, ER agonists caused relaxation and decrease in [Ca(2+)]i that were with E2 = PPT > DPN > G1, suggesting that E2-induced vasodilation involves ERα > ERβ > GPR30. Acetylcholine caused vasodilation and decreased [Ca(2+)]i, which were abolished by endothelium removal or treatment with the nitric oxide synthase blocker Nω-nitro-l-arginine methyl ester (L-NAME) and the K(+) channel blockers tetraethylammonium (nonspecific) or apamin (small conductance Ca(2+)-activated K(+) channel) plus TRAM-34 (1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole) (intermediate conductance Ca(2+)-activated K(+) channel), suggesting endothelium-derived hyperpolarizing factor-dependent activation of KCa channels. E2-, PPT-, DPN-, and G1-induced vasodilation and decreased [Ca(2+)]i were not blocked by L-NAME, TEA, apamin plus TRAM-34, iberiotoxin (large conductance Ca(2+)- and voltage-activated K(+) channel), 4-aminopyridine (voltage-dependent K(+) channel), glibenclamide (ATP-sensitive K(+) channel), or endothelium removal, suggesting an endothelium- and K(+) channel-independent mechanism. In endothelium-denuded vessels preconstricted with phenylephrine, high KCl, or the Ca(2+) channel activator Bay K 8644 (1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid methyl ester), ER agonist-induced relaxation and decreased [Ca(2+)]i were with E2 = PPT > DPN > G1 and not inhibited by the guanylate cyclase inhibitor ODQ [1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one], and showed a similar relationship between decreased [Ca(2+)]i and vasorelaxation, supporting direct effects on Ca(2+) entry in VSM. Immunohistochemistry revealed ERα, ERβ, and GPR30 mainly in the vessel media and VSM. Thus, in mesenteric microvessels, ER subtypes mediate distinct vasodilation and decreased [Ca(2+)]i (ERα > ERβ > GPR30) through endothelium- and K(+) channel-independent inhibition of Ca(2+) entry mechanisms of VSM contraction.

Regulation of endothelial nitric oxide synthase and high-density lipoprotein quality by estradiol in cardiovascular pathology

Estrogens have been recognized, in the last 3 decades, as important hormones in direct and indirect modulation of vascular health. In addition to their direct benefit on cardiovascular health, the presence of esterified estrogen in the lipid core of high-density lipoprotein (HDL) particles indirectly contributes to atheroprotection by significantly improving HDL quality and functionality. Estrogens modulate their physiological activity via genomic and nongenomic mechanisms. Genomic mechanisms are thought to be mediated directly by interaction of the hormone receptor complex with the hormone response elements that regulate gene expression. Nongenomic mechanisms are thought to occur via interaction of the estrogen with membrane-bound receptors, which rapidly activate intracellular signaling without binding of the hormone receptor complex to its hormone response elements. Estradiol in particular mediates early and late endothelial nitric oxide synthase (eNOS) activation via interaction with estrogen receptors through both nongenomic and genomic mechanisms. In the vascular system, the primary endogenous source of nitric oxide (NO) generation is eNOS. Nitric oxide primarily influences blood vessel relaxation, the heart rate, and myocyte contractility. The abnormalities in expression and/or functions of eNOS lead to the development of cardiovascular diseases, both in animals and in humans. Although considerable research efforts have been dedicated to understanding the mechanisms of action of estradiol in regulating cardiac eNOS, more research is needed to fully understand the details of such mechanisms. This review focuses on recent findings from animal and human studies on the regulation of eNOS and HDL quality by estradiol in cardiovascular pathology.

Sex hormone replacement therapy and modulation of vascular function in cardiovascular disease

Epidemiological and experimental studies suggest vascular protective effects of estrogen. Cardiovascular disease (CVD) is less common in premenopausal women than in men and postmenopausal women. Cytosolic/nuclear estrogen receptors (ERs) have been shown to mediate genomic effects that stimulate endothelial cell growth but inhibit vascular smooth muscle proliferation. However, the Heart and Estrogen/Progestin Replacement Study (HERS), HERS-II and Women's Health Initiative clinical trials demonstrated that hormone replacement therapy (HRT) may not provide vascular benefits in postmenopausal women and may instead trigger adverse cardiovascular events. HRT may not provide vascular benefits because of the type of hormone used. Oral estrogens are biologically transformed by first-pass metabolism in the liver. By contrast, transdermal preparations avoid first pass metabolism. Also, natural estrogens and phytoestrogens may provide alternatives to synthetic estrogens. Furthermore, specific ER modulators could minimize the adverse effects of HRT, including breast cancer. HRT failure in CVD could also be related to changes in vascular ERs. Genetic polymorphism and postmenopausal decrease in vascular ERs or the downstream signaling mechanisms may reduce the effects of HRT. HRT in the late postmenopausal period may not be as effective as during menopausal transition. Additionally, while HRT may aggravate pre-existing CVD, it may thwart its development if used in a timely fashion. Lastly, the vascular effects of progesterone and testosterone, as well as modulators of their receptors, may modify the effects of estrogen and thereby provide alternative HRT strategies. Thus, the beneficial effects of HRT in postmenopausal CVD can be enhanced by customizing the HRT type, dose, route of administration and timing depending on the subject's age and cardiovascular condition.

Subtype-specific estrogen receptor-mediated vasodilator activity in the cephalic, thoracic, and abdominal vasculature of female rat

Estrogen receptors (ERs) mediate genomic and nongenomic vasodilator effects, but estrogen therapy may not provide systemic vascular protection. To test whether this is because of regional differences in ER distribution or vasodilator activity, cephalic (carotid artery), thoracic (thoracic aorta and pulmonary artery), and abdominal arteries (abdominal aorta, mesenteric artery, and renal artery) from female Sprague-Dawley rats were prepared to measure contraction to phenylephrine and relaxation to acetylcholine (ACh) and the ER activators 17β-estradiol (E2) (all ERs), 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)-tris-phenol (PPT) (ERα), diarylpropionitrile (DPN) (ERβ), and (±)-1-[(3aR*,4S*,9bS*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone (G1) (GPR30). Phenylephrine caused contraction that was enhanced in endothelium-denuded aorta, supporting endothelial release of vasodilators. In cephalic and thoracic arteries, ACh relaxation was abolished by the nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME), suggesting a role of NO. In mesenteric vessels, ACh-induced relaxation was partly inhibited by the L-NAME + cyclooxygenase inhibitor indomethacin and blocked by the K+ channel blocker tetraethylammonium, suggesting a hyperpolarization pathway. E2 and PPT caused similar relaxation in all vessels. DPN and G1 caused smaller relaxation that was more prominent in abdominal vessels. Reverse transcription-polymerase chain reaction revealed variable ERα messenger RNA expression and increased ERβ in carotid artery and GPR30 in abdominal arteries. Western blots revealed greater amounts of ERα, ERβ, and GPR30 in abdominal arteries. In thoracic aorta, E2-, PPT-, and DPN-induced relaxation was blocked by L-NAME and was associated with increased nitrite/nitrate production, suggesting a role of NO. In abdominal vessels, E2-, PPT-, DPN-, and G1-induced relaxation persisted in L-NAME + indomethacin + tetraethylammonium-treated or endothelium-denuded arteries, suggesting direct effect on vascular smooth muscle. E2, PPT, DPN, and G1 caused greater relaxation of KCl-induced contraction in abdominal vessels, suggesting inhibitory effects on Ca2+ entry. Thus, E2 and ERα stimulation produces similar relaxation of the cephalic, thoracic, and abdominal arteries. In the cephalic and thoracic arteries, particularly the thoracic aorta, E2-induced and ERα- and ERβ-mediated vasodilation involves NO production. ERβ- and GPR30-mediated relaxation is greater in the abdominal arteries and seems to involve hyperpolarization and inhibition of vascular smooth muscle Ca2+ entry. Specific ER agonists could produce vasodilation in specific vascular beds without affecting other vessels in the systemic circulation.

Estrogen, vascular estrogen receptor and hormone therapy in postmenopausal vascular disease

Cardiovascular disease (CVD) is less common in premenopausal women than men of the same age or postmenopausal women, suggesting vascular benefits of estrogen. Estrogen activates estrogen receptors ERα, ERβ and GPR30 in endothelium and vascular smooth muscle (VSM), which trigger downstream signaling pathways and lead to genomic and non-genomic vascular effects such as vasodilation, decreased VSM contraction and growth and reduced vascular remodeling. However, randomized clinical trials (RCTs), such as the Women's Health Initiative (WHI) and Heart and Estrogen/progestin Replacement Study (HERS), have shown little vascular benefits and even adverse events with menopausal hormone therapy (MHT), likely due to factors related to the MHT used, ER profile, and RCT design. Some MHT forms, dose, combinations or route of administration may have inadequate vascular effects. Age-related changes in ER amount, distribution, integrity and post-ER signaling could alter the vascular response to MHT. The subject's age, preexisting CVD, and hormone environment could also reduce the effects of MHT. Further evaluation of natural and synthetic estrogens, phytoestrogens, and selective estrogen-receptor modulators (SERMs), and the design of appropriate MHT combinations, dose, route and 'timing' could improve the effectiveness of conventional MHT and provide alternative therapies in the peri-menopausal period. Targeting ER using specific ER agonists, localized MHT delivery, and activation of specific post-ER signaling pathways could counter age-related changes in ER. Examination of the hormone environment and conditions associated with hormone imbalance such as polycystic ovary syndrome may reveal the causes of abnormal hormone-receptor interactions. Consideration of these factors in new RCTs such as the Kronos Early Estrogen Prevention Study (KEEPS) could enhance the vascular benefits of estrogen in postmenopausal CVD.

Protective actions of progesterone in the cardiovascular system: potential role of membrane progesterone receptors (mPRs) in mediating rapid effects

The protective functions of progesterone in the cardiovascular system have received little attention even though evidence has accumulated that progesterone lowers blood pressure, inhibits coronary hyperactivity and has powerful vasodilatory and natriuretic effects. One possible reason why potential beneficial actions of progesterone on cardiovascular functions have not been extensively studied is that divergent effects to those of progesterone have been observed in many clinical trials with synthetic progestins such as medroxyprogesterone acetate which are associated with increased risk of coronary disease. Evidence that progesterone exerts protective effects on cardiovascular functions is briefly reviewed. The finding that progesterone administration decreases blood vessel vasoconstriction in several animal models within a few minutes suggests that rapid, nongenomic progesterone mechanisms are of physiological importance in regulating vascular tone. Rapid activation of second messenger pathways by progesterone has been observed in vascular endothelial and smooth muscle cells, resulting in alterations in endothelial nitric oxide synthase (eNOS) activity and calcium influx, respectively. Both nuclear progesterone receptors (PRs) and novel membrane progesterone receptors (mPRs) are candidates for the intermediaries in these rapid, cell-surface initiated progesterone actions in endothelial and smooth muscle vascular cells. PRs have been detected in both cell types. New data are presented showing mPRα, mPRβ and mPRγ are also present in human endothelial and smooth muscle vascular cells. Preliminary evidence suggests mPRs mediate rapid progestin signaling in these endothelial cells, resulting in down-regulation of cAMP production and increased nitric oxide synthesis. The role of mPRs in progesterone regulation of cardiovascular functions warrants further investigation.

Sexual dimorphism in rodent models of hypertension and atherosclerosis

Approximately one third of all deaths are attributed to cardiovascular disease (CVD), making it the biggest killer worldwide. Despite a number of therapeutic options available, the burden of CVD morbidity continues to grow indicating the need for continued research to address this unmet need. In this respect, investigation of the mechanisms underlying the protection that premenopausal females enjoy from cardiovascular-related disease and mortality is of interest. In this review, we discuss the essential role that rodent animal models play in enabling this field of research. In particular, we focus our discussion on models of hypertension and atherosclerosis.

Vascular effects of phytoestrogens and alternative menopausal hormone therapy in cardiovascular disease

Phytoestrogens are estrogenic compounds of plant origin classified into different groups including isoflavones, lignans, coumestans and stilbenes. Isoflavones such as genistein and daidzein are the most studied and most potent phytoestrogens, and are found mainly in soy based foods. The effects of phytoestrogens are partly mediated via estrogen receptors (ERs): ERα, ERβ and possibly GPER. The interaction of phytoestrogens with ERs is thought to induce both genomic and non-genomic effects in many tissues including the vasculature. Some phytoestrogens such as genistein have additional non-ER-mediated effects involving signaling pathways such as tyrosine kinase. Experimental studies have shown beneficial effects of phytoestrogens on endothelial cells, vascular smooth muscle, and extracellular matrix. Phytoestrogens may also affect other pathophysiologic vascular processes such as lipid profile, angiogenesis, inflammation, tissue damage by reactive oxygen species, and these effects could delay the progression of atherosclerosis. As recent clinical trials showed no vascular benefits or even increased risk of cardiovascular disease (CVD) and CV events with conventional menopausal hormone therapy (MHT), phytoestrogens are being considered as alternatives to pharmacologic MHT. Epidemiological studies in the Far East population suggest that dietary intake of phytoestrogens may contribute to the decreased incidence of postmenopausal CVD and thromboembolic events. Also, the WHO-CARDIAC study supported that consumption of high soybean diet is associated with lower mortalities from coronary artery disease. However, as with estrogen, there has been some discrepancy between the experimental studies demonstrating the vascular benefits of phytoestrogens and the data from clinical trials. This is likely because the phytoestrogens clinical trials have been limited in many aspects including the number of participants enrolled, the clinical end points investigated, and the lack of long-term follow-up. Further investigation of the cellular mechanisms underlying the vascular effects of phytoestrogens and careful evaluation of the epidemiological evidence and clinical trials of their potential vascular benefits would put forward the use of phytoestrogens as an alternative MHT for the relief of menopausal symptoms and amelioration of postmenopausal CVD.

Hypertension in postmenopausal women: pathophysiology and treatment

Hypertension is the most common chronic disease in industrialized countries and represents the most common major cardiovascular risk factor after the fifth decade of life in both men and women. The prevalence of hypertension is lower in premenopausal women than men, whereas in postmenopausal women it is higher than in men. Mechanisms responsible for the increase in blood pressure are complex and multifactorial, including loss of estrogen, oxidative stress, endothelial dysfunction, modification in renin-angiotensin system spillover and sympathetic activation. In addition, postmenopausal hypertension can be considered an isolated disease, more typical of elderly women, or part of the metabolic syndrome, which is indeed more common in early postmenopausal women. In particular, metabolic syndrome may be considered a potentially unfavourable prognostic factor in hypertensive postmenopausal women, because it seems to worsen the severity of hypertension and reduce the capacity to respond to specific treatments. This article summarizes the different causes of postmenopausal hypertension and the specific treatment recommended by guidelines for this condition.

Experimental benefits of sex hormones on vascular function and the outcome of hormone therapy in cardiovascular disease

Cardiovascular disease (CVD) is more common in men and postmenopausal women than premenopausal women, suggesting vascular benefits of female sex hormones. Experimental data have shown beneficial vascular effects of estrogen including stimulation of endothelium-dependent nitric oxide, prostacyclin and hyperpolarizing factor-mediated vascular relaxation. However, the experimental evidence did not translate into vascular benefits of hormone replacement therapy (HRT) in postmenopausal women, and HERS, HERS-II and WHI clinical trials demonstrated adverse cardiovascular events with HRT. The lack of vascular benefits of HRT could be related to the hormone used, the vascular estrogen receptor (ER), and the subject’s age and preexisting cardiovascular condition. Natural and phytoestrogens in small doses may be more beneficial than synthetic estrogen. Specific estrogen receptor modulators (SERMs) could maximize the vascular benefits, with little side effects on breast cancer. Transdermal estrogens avoid the first-pass liver metabolism associated with the oral route. Postmenopausal decrease and genetic polymorphism in vascular ER and post-receptor signaling mechanisms could also modify the effects of HRT. Variants of cytosolic/nuclear ER mediate transcriptional genomic effects that stimulate endothelial cell growth, but inhibit vascular smooth muscle (VSM) proliferation. Also, plasma membrane ERs trigger not only non-genomic stimulation of endothelium-dependent vascular relaxation, but also inhibition of [Ca²⁺]i, protein kinase C and Rho kinase-dependent VSM contraction. HRT could also be more effective in the perimenopausal period than in older postmenopausal women, and may prevent the development, while worsening preexisting CVD. Lastly, progesterone may modify the vascular effects of estrogen, and modulators of estrogen/testosterone ratio could provide alternative HRT combinations. Thus, the type, dose, route of administration and the timing/duration of HRT should be customized depending on the subject’s age and preexisting cardiovascular condition, and thereby make it possible to translate the beneficial vascular effects of sex hormones to the outcome of HRT in postmenopausal CVD.

Impact of sex hormone metabolism on the vascular effects of menopausal hormone therapy in cardiovascular disease

Epidemiological studies have shown that cardiovascular disease (CVD) is less common in pre-menopausal women (Pre-MW) compared to men of the same age or post-menopausal women (Post-MW), suggesting cardiovascular benefits of estrogen. Estrogen receptors (ERs) have been identified in the vasculature, and experimental studies have demonstrated vasodilator effects of estrogen/ER on the endothelium, vascular smooth muscle (VSM) and extracellular matrix. Several natural and synthetic estrogenic preparations have been developed for relief of menopausal vasomotor symptoms. However, whether menopausal hormone therapy (MHT) is beneficial in postmenopausal CVD remains controversial. Despite reports of vascular benefits of MHT from observational and experimental studies, randomized clinical trials (RCTs), such as the Heart and Estrogen/progestin Replacement Study (HERS) and the Women's Health Initiative (WHI), have suggested that, contrary to expectations, MHT may increase the risk of CVD. These discrepancies could be due to agerelated changes in sex hormone synthesis and metabolism, which would influence the effective dose of MHT and the sex hormone environment in Post-MW. Age-related changes in the vascular ER subtype, structure, expression, distribution, and post-ER signaling pathways in the endothelium and VSM, along with factors related to the design of RCTs, preexisting CVD condition, and structural changes in the blood vessels architecture have also been suggested as possible causes of MHT failure in CVD. Careful examination of these factors should help in identifying the causes of the changes in the vascular effects of estrogen with age. The sex hormone metabolic pathways, the active versus inactive estrogen metabolites, and their effects on vascular function, the mitochondria, the inflammatory process and angiogenesis should be further examined. Also, the genomic and non-genomic effects of estrogenic compounds should be viewed as integrated rather than discrete responses. The complex interactions between these factors highlight the importance of careful design of MHT RCTs, and the need of a more customized approach for each individual patient in order to enhance the vascular benefits of MHT in postmenopausal CVD.

Suppression of endothelial P-selectin expression contributes to reduced cell trafficking in females: an effect independent of NO and prostacyclin

OBJECTIVE

Sex hormones underlie the lower incidence of cardiovascular disease in premenopausal women. Vascular inflammation is involved in the pathogenesis of several cardiovascular diseases and it has been reported that sex hormones modulate inflammatory responses but mechanisms responsible for these effects are not yet fully established. Herein, we assessed whether sex differences in leukocyte recruitment might exist and investigated the underlying mechanisms involved in this response.

METHODS AND RESULTS

Treatment with interleukin-1β (IL-1β) or tumor necrosis factor-α caused leukocyte rolling, adhesion, and emigration in mesenteric postcapillary venules in vivo that was substantially reduced in female mice compared with male mice; this difference was abolished by ovariectomy and partially restored by estrogen replacement. Deletion of endothelial nitric oxide (NO) synthase or cyclooxygenase-1 alone or in combination did not alter the leukocyte recruitment in IL-1β-treated females but significantly enhanced this response in male mice. Treatment of murine pulmonary endothelial cells with IL-1β increased expression of P-selectin in male but not female cells.

CONCLUSIONS

We have demonstrated a profound estrogen-dependent and NO and prostacyclin-independent suppression of leukocyte recruitment in females.

Gender-specific reduction in contraction is associated with increased estrogen receptor expression in single vascular smooth muscle cells of female rat

Gender differences in the incidence of cardiovascular disease have been related to plasma estrogen levels; however, the role of vascular estrogen receptor (ER) subtypes in these sex differences is less clear. We tested whether the gender differences in vascular smooth muscle (VSM) function reflect differential expression/activity of ERalpha, ERbeta and the newly-identified GPR30. Single aortic VSM cells (VSMCs) were freshly isolated from male and female Sprague-Dawley rats, and their contraction to phenylephrine (PHE, 10(-5) M), AngII (10(-7) M) and membrane-depolarization by KCl (51 mM) was measured in the absence or presence of 10(-6) M 17beta-estradiol (E2, stimulant of most ERs), PPT (ERalpha agonist), DPN (ERbeta agonist), and ICI 182,780 (an ERalpha/ERbeta antagonist with GPR30 agonistic properties). The cells were fixed and fluorescently labeled with ERalpha, ERbeta or GPR30 antibody, and the subcellular distribution of ERs was examined using digital imaging microscopy. The mRNA expression and protein amount of aortic ER subtypes was examined using RT-PCR and Western blots. PHE, AngII, and KCl caused less contraction in VSMCs of females than males. Pretreatment of VSMCs with E2 reduced PHE-, AngII- and KCl-induced contraction in both males and females. PPT caused similar inhibition of PHE-, AngII- and KCl-induced contraction as E2, suggesting a role of ERalpha. DPN mainly inhibited PHE and KCl contraction, suggesting an interaction between ERbeta and Ca(2+) channels. ICI 182,780 did not reduce aortic VSMC contraction, suggesting little role for GPR30. RT-PCR and Western blots revealed greater expression of ERalpha and ERbeta in VSMCs of females than males, but similar amounts of GPR30. The total immunofluorescence signal for ERalpha and ERbeta was greater in VSMCs of females than males, and was largely localized in the nucleus. GPR30 fluorescence was similar in VSMCs of males and females, and was mainly in the cytosol. In PPT treated cells, nuclear ERalpha signal was enhanced. DPN did not affect the distribution of ERbeta, and ICI 182,780 did not significantly increase GPR30 in the cell surface. Thus, ER subtypes demonstrate similar responsiveness to specific agonists in VSMCs of male and female rats. The reduced contraction in VSMCs of females could be due to gender-related increase in the expression of ERalpha and ERbeta.

Research into Specific Modulators of Vascular Sex Hormone Receptors in the Management of Postmenopausal Cardiovascular Disease

Cardiovascular disease (CVD) is more common in men and postmenopausal women than premenopausal women, suggesting vascular benefits of female sex hormones. Studies on the vasculature have identified estrogen receptors ERα, ERβ and a novel estrogen binding membrane protein GPR30, that mediate genomic and/or non-genomic effects. Estrogen promotes endothelium-dependent relaxation by inducing the production/activity of nitric oxide, prostacyclin, and hyperpolarizing factor, and inhibits the mechanisms of vascular smooth muscle contraction including [Ca(2+)](i), protein kinase C, Rho kinase and mitogen-activated protein kinase. Additional effects of estrogen on the cytoskeleton, matrix metalloproteinases and inflammatory factors contribute to vascular remodeling. However, the experimental evidence did not translate into vascular benefits of menopausal hormone therapy (MHT), and the HERS, HERS-II and WHI clinical trials demonstrated adverse cardiovascular events. The discrepancy has been partly related to delayed MHT and potential changes in the vascular ER amount, integrity, affinity, and downstream signaling pathways due to the subjects' age and preexisting CVD. The adverse vascular effects of MHT also highlighted the need of specific modulators of vascular sex hormone receptors. The effectiveness of MHT can be improved by delineating the differences in phramcokinetics and pharmacodynamics of natural, synthetic, and conjugated equine estrogens. Estriol, "hormone bioidenticals" and phytoestrogens are potential estradiol substitutes. The benefits of low dose MHT, and transdermal or vaginal estrogens over oral preparations are being evaluated. Specific ER modulators (SERMs) and ER agonists are being developed to maximize the effects on vascular ERs. Also, the effects of estrogen are being examined in the context of the whole body hormonal environment and the levels of progesterone and androgens. Thus, the experimental vascular benefits of estrogen can be translated to the outcome of MHT in postmenopausal CVD, as more specific modulators of sex hormone receptors become available and are used at the right dose, route of administration and timing, depending on the subject's age and preexisting cardiovascular condition.

Sex differences in blood pressure response to antihypertensive therapy in Chinese patients with hypertension

BACKGROUND

Sex-specific responses to antihypertensive drugs are not very well understood.

OBJECTIVE

To investigate sex-related differences in blood pressure response to antihypertensive drugs in a community-based prospective clinical trial.

METHODS

We recruited 3535 untreated hypertensive patients (2326 women), aged 40-75 years, from 7 rural communities in China. Subjects were randomized to 1 of 4 drug groups: atenolol, hydrochlorothiazide (HCTZ), captopril, or sustained-released nifedipine; duration of the study was 8 weeks. Mean blood pressure reduction, blood pressure control rates, and frequency of adverse events were compared between men and women.

RESULTS

Women had a better response to HCTZ in relation to diastolic blood pressure (1.8 mm Hg lower) than did men (p < 0.05) and were 57% more likely to reach the control goal of diastolic blood pressure than were men (p < 0.05). In the atenolol group, mean systolic blood pressure decreased 3.9 mm Hg more in women than in men (p < 0.05), and women were 65% more likely to reach the control goal of systolic blood pressure and 57% more likely to reach the control goal of diastolic blood pressure than were men (p < 0.05). Significant sex-related differences were also found in drug-related adverse events in the nifedipine group (15.8% in women vs 9.8% in men; p = 0.017) and in the captopril group (14.3% in women vs 8.4% in men; p = 0.005), but no differences were seen with HCTZ or atenolol.

CONCLUSIONS

Women have better blood pressure responses to HCTZ and atenolol and experience more adverse effects with sustained-release nifedipine and captopril than do men, indicating that sex should be taken into account when selecting antihypertensive drugs.

2-Methoxyestradiol reduces monocyte adhesion to aortic endothelial cells in ovariectomized rats

2-Methoxyestradiol (2-ME) is an endogenous metabolite of estradiol with no affinity for estrogen receptors. It inhibits cell proliferation, thus is a potentially useful drug to block the progression of atherosclerosis. As a first step to examining the anti-atherosclerotic effects of 2-ME, we investigated monocyte adhesion to aortic endothelial cells, which is considered a prerequisite to atherosclerosis in vivo. Eight-week-old Sprague-Dawley rats were ovariectomized then treated by slow-release pellets with placebo, 17-beta-estradiol (5 microg/day), low-dose 2-ME (10 microg/day), or high-dose 2-ME (100 microg/day). After 6 weeks, en face analysis showed an increased number of monocytes adhering to endothelial cells of the thoracic aorta in ovariectomized rats compared with sham-operated controls. This increase was predominantly inhibited by treatment with 17beta-estradiol, and low-dose or high-dose 2-ME. The observed effects were unrelated to changes in serum lipids, blood glucose, or blood pressure. Our data suggested that 2-ME mediates the anti-atherosclerotic actions of estradiol at least in part by preventing monocyte adhesion to the aortic endothelium.

The endogenous estradiol metabolite 2-methoxyestradiol reduces atherosclerotic lesion formation in female apolipoprotein E-deficient mice

Estradiol, the major endogenous estrogen, reduces experimental atherosclerosis and metabolizes to 2-methoxyestradiol in vascular cells. Currently undergoing evaluation in clinical cancer trials, 2-methoxyestradiol potently inhibits cell proliferation independently of the classical estrogen receptors. This study examined whether 2-methoxyestradiol affects atherosclerosis development in female mice. Apolipoprotein E-deficient mice, a well-established mouse model of atherosclerosis, were ovariectomized and treated through slow-release pellets with placebo, 17beta-estradiol (6 microg/d), or 2-methoxyestradiol [6.66 microg/d (low-dose) or 66.6 microg/d (high-dose)]. After 90 d, body weight gain decreased and uterine weight increased in the high-dose but not low-dose 2-methoxyestradiol group. En face analysis showed that the fractional area of the aorta covered by atherosclerotic lesions decreased in the high-dose 2-methoxyestradiol (52%) but not in the low-dose 2-methoxyestradiol group. Total serum cholesterol levels decreased in the high- and low-dose 2-methoxyestradiol groups (19%, P < 0.05 and 21%, P = 0.062, respectively). Estradiol treatment reduced the fractional atherosclerotic lesion area (85%) and decreased cholesterol levels (42%). In conclusion, our study shows for the first time that 2-methoxyestradiol reduces atherosclerotic lesion formation in vivo. The antiatherogenic activity of an estradiol metabolite lacking estrogen receptor activating capacity may argue that trials on cardiovascular effects of hormone replacement therapy should use estradiol rather than other estrogens. Future research should define the role of 2-methoxyestradiol as a mediator of the antiatherosclerotic actions of estradiol. Furthermore, evaluation of the effects of 2-methoxyestradiol on cardiovascular disease endpoints in ongoing clinical trials is of great interest.

Sex hormones, vascular function and the outcome of hormone replacement therapy in cardiovascular disease

Cardiovascular disease is more common in men and post-menopausal women than premenopausal women, suggesting that female sex hormones have vascular benefits. Cytosolic/nuclear estrogen and progesterone receptors mediate genomic transcriptional effects that stimulate endothelial cell growth and inhibit smooth muscle proliferation. Sex hormone receptors on the plasma membrane trigger nongenomic stimulation of endothelium-dependent nitric oxide–cyclic (c)GMP, prostacyclin–cAMP and hyperpolarizing vascular relaxation pathways, as well as inhibition of [Ca2+]i, protein kinase C and Rho-kinase-dependent mechanisms of smooth muscle contraction. Despite the vasodilator effects of sex hormones, the Heart and Estrogen/progestin Replacement Study (HERS), HERS-II and Women’s Health Initiative clinical trials have shown minimal benefits of hormone replacement therapy (HRT) in post-menopausal cardiovascular disease. The prospect of HRT relies on further mechanistic analysis of the vascular effects of natural sex hormones and phytoestrogens, and the identification of specific estrogen receptor modulators. Androgens have vascular effects, and modulators of the estrogen/testosterone ratio could provide better HRT combinations. The timing/duration and the type, dose and route of administration of HRT should be customized according to the subject’s age and pre-existing cardiovascular condition, thereby enhancing the outcome of HRT in cardiovascular disease.

Mechanics of Fresh, Refrigerated, and Frozen Arterial Tissue

Arterial grafts and experimental soft tissues are commonly preserved using refrigeration and freezing. The present study was designed to investigate effects of common storage protocols on arterial mechanics. Porcine aortas were axially distracted to failure implementing fresh, refrigerated, and frozen storage conditions. Fresh tissues were tested within 24 h of sacrifice; refrigerated tissues were stored at +4 degrees C for 24 or 48 h prior to testing, and frozen tissues were stored at -20 or -80 degrees C for 3 months prior to testing. Blunt arterial injury experimentally occurred in distraction with intimal subfailure before ultimate failure in 82% of specimens. Subfailure stress decreased in refrigerated (0.59 +/- 0.19 MPa) compared to fresh (0.83 +/- 0.39 MPa) and frozen (0.99 +/- 0.41 MPa) specimens. Ultimate stress was also significantly decreased in refrigerated (0.83 +/- 0.19 MPa) compared to fresh (1.15 +/- 0.39 MPa) and frozen (1.32 +/- 0.31 MPa) specimens. Subfailure and ultimate strain were not significantly dependent upon storage technique. Young's modulus significantly decreased in refrigerated (1.89 +/- 0.63 MPa) compared to fresh (2.98 +/- 1.45 MPa) and frozen (3.49 +/- 1.32 MPa) specimens. Physiological, subfailure, and ultimate failure mechanics between fresh and frozen specimens were not significantly different. Clinically relevant intimal failures can be reproduced and injury mechanics determined while adhering to experimental protocols of freezing specimens before testing. However, short-term tissue refrigeration may affect mechanics.

Estradiol increases proteinuria and angiotensin II type 1 receptor in kidneys of rats receiving L-NAME and angiotensin II

Prospective, placebo-controlled clinical trials suggest that estrogen may have adverse effects on the vascular system in women. The goal of this study was to determine if 17beta-estradiol (E2) would have adverse effects on the renovasculature in a rat model of renal injury characterized by low nitric oxide (NO) and high angiotensin II (AngII). We studied female Wistar rats that were sham-operated (sham), ovariectomized (OVX), or ovariectomized and replaced with E2 (OVX/E2). All rats were maintained on a high salt diet and renovascular injury was caused by treating rats with an inhibitor of NO synthase, N(omega)-nitro-L-arginine-methyl-ester (L-NAME), for 14 days, plus AngII on days 11 through 14. L-NAME/AngII treatment, as compared to placebo, caused proteinuria, glomerular injury, and fibrinoid necrosis of renal arterioles in sham-operated rats. Ovariectomy reduced L-NAME/AngII-induced renal damage, whereas E2 treatment increased L-NAME/AngII-induced damage in OVX rats. In rats treated with L-NAME/AngII, levels of AngII type 1 receptor (AT(1)R) protein were higher in the renal cortex of sham and OVX/E2 rats than in OVX rats. AT(1)R protein correlated with renal injury. E2 treatment also increased expression of AT(1)R mRNA. Thus, under conditions of low NO and high AngII, E2 exacerbated renal injury. E2-mediated increases in renal cortical AT(1)R expression may represent a novel mechanism for the adverse renovascular effects of estrogen.

Surgical Menopause Increases Salt Sensitivity of Blood Pressure

Salt sensitivity of blood pressure is associated with an elevated risk of developing hypertension (HTN) and is an independent risk factor for cardiovascular disease. The prevalence of HTN increases after menopause. The aim of this study was to investigate prospectively whether the loss of ovarian hormones increases the occurrence of salt sensitivity among healthy premenopausal women. We enrolled 40 normotensive, nondiabetic women (age 47.2+/-3.5), undergoing hysterectomy-oophorectomy for nonneoplastic processes and not on hormone replacement, to determine the effect of changes in sodium intake on blood pressure the day before and subsequently 4 months after surgical menopause. Salt loading was achieved using a 2-L normal saline infusion and salt depletion produced by 40 mg of intravenous furosemide. A decrease >10 mm Hg in systolic blood pressure between salt loading and salt depletion was used to define salt sensitivity. Before and after menopause, salt-sensitive women exhibited higher waist/hip and waist/thigh ratios (P<0.01). Although all of the women remained normotensive, the prevalence of salt sensitivity was significantly higher after surgical menopause (21 women; 52.5%) than before (9 women; 22.5%; P=0.01), because 12 (38.7%) salt-resistant women developed salt sensitivity after menopause. In summary, we demonstrated that the prevalence of salt sensitivity doubled as early as 4 months after surgical menopause, without an associated increase in blood pressure. Epidemiological studies indicate that development of HTN may not occur until 5 to 10 years after menopause. The loss of ovarian hormones may unmask a population of women prone to salt sensitivity who, with aging, would be at higher risk for the subsequent development of HTN and cardiovascular disease.