SEX HORMONES AND THE CARDIOVASCULAR SYSTEM: EFFECTS ON ARTERIAL FUNCTION IN WOMEN

Estrogenic Action in Stress-Induced Neuroendocrine Regulation of Energy Homeostasis

Estrogens are among important contributing factors to many sex differences in neuroendocrine regulation of energy homeostasis induced by stress. Research in this field is warranted since chronic stress-related psychiatric and metabolic disturbances continue to be top health concerns, and sex differences are witnessed in these aspects. For example, chronic stress disrupts energy homeostasis, leading to negative consequences in the regulation of emotion and metabolism. Females are known to be more vulnerable to the psychological consequences of stress, such as depression and anxiety, whereas males are more vulnerable to the metabolic consequences of stress. Sex differences that exist in the susceptibility to various stress-induced disorders have led researchers to hypothesize that gonadal hormones are regulatory factors that should be considered in stress studies. Further, estrogens are heavily recognized for their protective effects on metabolic dysregulation, such as anti-obesogenic and glucose-sensing effects. Perturbations to energy homeostasis using laboratory rodents, such as physiological stress or over-/under- feeding dietary regimen prevalent in today’s society, offer hints to the underlying mechanisms of estrogenic actions. Metabolic effects of estrogens primarily work through estrogen receptor α (ERα), which is differentially expressed between the sexes in hypothalamic nuclei regulating energy metabolism and in extrahypothalamic limbic regions that are not typically associated with energy homeostasis. In this review, we discuss estrogenic actions implicated in stress-induced sex-distinct metabolic disorders.

Vascular Aging in Rodent Models: Contrasting Mechanisms Driving the Female and Male Vascular Senescence

Increasing scientific interest has been directed to sex as a biological and decisive factor on several diseases. Several different mechanisms orchestrate vascular function, as well as vascular dysfunction in cardiovascular and metabolic diseases in males and females. Certain vascular sex differences are present throughout life, while others are more evident before the menopause, suggesting two important and correlated drivers: genetic and hormonal factors. With the increasing life expectancy and aging population, studies on aging-related diseases and aging-related physiological changes have steeply grown and, with them, the use of aging animal models. Mouse and rat models of aging, the most studied laboratory animals in aging research, exhibit sex differences in many systems and physiological functions, as well as sex differences in the aging process and aging-associated cardiovascular changes. In the present review, we introduce the most common aging and senescence-accelerated animal models and emphasize that sex is a biological variable that should be considered in aging studies. Sex differences in the cardiovascular system, with a focus on sex differences in aging-associated vascular alterations (endothelial dysfunction, remodeling and oxidative and inflammatory processes) in these animal models are reviewed and discussed.

Neonatal glucocorticoid overexposure alters cardiovascular function in young adult horses in a sex-linked manner

Prenatal glucocorticoid overexposure has been shown to programme adult cardiovascular function in a range of species, but much less is known about the long-term effects of neonatal glucocorticoid overexposure. In horses, prenatal maturation of the hypothalamus-pituitary-adrenal axis and the normal prepartum surge in fetal cortisol occur late in gestation compared to other precocious species. Cortisol levels continue to rise in the hours after birth of full-term foals and increase further in the subsequent days in premature, dysmature and maladapted foals. Thus, this study examined the adult cardiovascular consequences of neonatal cortisol overexposure induced by adrenocorticotropic hormone administration to full-term male and female pony foals. After catheterisation at 2-3 years of age, basal arterial blood pressures (BP) and heart rate were measured together with the responses to phenylephrine (PE) and sodium nitroprusside (SNP). These data were used to assess cardiac baroreflex sensitivity. Neonatal cortisol overexposure reduced both the pressor and bradycardic responses to PE in the young adult males, but not females. It also enhanced the initial hypotensive response to SNP, slowed recovery of BP after infusion and reduced the gain of the cardiac baroreflex in the females, but not males. Basal diastolic pressure and cardiac baroreflex sensitivity also differed with sex, irrespective of neonatal treatment. The results show that there is a window of susceptibility for glucocorticoid programming during the immediate neonatal period that alters cardiovascular function in young adult horses in a sex-linked manner.

Genistein as Potential Therapeutic Candidate for Menopausal Symptoms and Other Related Diseases

Plant-derived compounds have recently attracted greater interest in the field of new therapeutic agent development. These compounds have been widely screened for their pharmacological effects. Polyphenols, such as soy-derived isoflavones, also called phytoestrogens, have been extensively studied due to their ability to inhibit carcinogenesis. These compounds are chemically similar to 17β-estradiol, and mimic the binding of estrogens to its receptors, exerting estrogenic effects in target organs. Genistein is an isoflavone derived from soy-rich products and accounts for about 60% of total isoflavones found in soybeans. Genistein has been reported to exhibit several biological effects, such as anti-tumor activity (inhibition of cell proliferation, regulation of the cell cycle, induction of apoptosis), improvement of glucose metabolism, impairment of angiogenesis in both hormone-related and hormone-unrelated cancer cells, reduction of peri-menopausal and postmenopausal hot flashes, and modulation of antioxidant effects. Additionally, epidemiological and clinical studies have reported health benefits of genistein in many chronic diseases, such as cardiovascular disease, diabetes, and osteoporosis, and aid in the amelioration of typical menopausal symptoms, such as anxiety and depression. Although the biological effects are promising, certain limitations, such as low bioavailability, biological estrogenic activity, and effects on target organs, have limited the clinical applications of genistein to some extent. Moreover, studies report that modification of its molecular structure may eliminate the biological estrogenic activity and its effects on target organs. In this review, we summarize the potential benefits of genistein on menopause symptoms and menopause-related diseases like cardiovascular, osteoporosis, obesity, diabetes, anxiety, depression, and breast cancer.

A Review of the Actions of Endogenous and Exogenous Vasoactive Substances during the Estrous Cycle and Pregnancy in Rats

Vascular endothelium plays a key role in regulating cardiovascular homeostasis by controlling the vascular tone. Variations in sex hormones during the reproductive cycle of females affect the homeostasis of the cardiovascular system. Also, the evidence shows that estrogens show a cardioprotective effect. On this basis, this study describes some vascular responses induced by vasoactive substances during the estrous cycle in rats. We obtained the information available on this topic from the online databases that included scientific articles published in the Web of Science, PubMed, and Scielo. Many investigations have evaluated the vasoactive response of substances such as acetylcholine and norepinephrine during the estrous cycle. In this review, we specifically described the vascular response to vasoactive substances in rats during the estrous cycle, pregnancy, and in ovariectomized rats. In addition, we discussed the existence of different signaling pathways that modulate vascular function. The knowledge of these effects is relevant for the optimization and development of new treatments for some vascular pathologies.

Effects of Estrogens on Central Nervous System Neurotransmission: Implications for Sex Differences in Mental Disorders

Nearly one of every five US individuals aged 12 years old or older lives with certain types of mental disorders. Men are more likely to use various types of substances, while women tend to be more susceptible to mood disorders, addiction, and eating disorders, all of which are risks associated with suicidal attempts. Fundamental sex differences exist in multiple aspects of the functions and activities of neurotransmitter-mediated neural circuits in the central nervous system (CNS). Dysregulation of these neural circuits leads to various types of mental disorders. The potential mechanisms of sex differences in the CNS neural circuitry regulating mood, reward, and motivation are only beginning to be understood, although they have been largely attributed to the effects of sex hormones on CNS neurotransmission pathways. Understanding this topic is important for developing prevention and treatment of mental disorders that should be tailored differently for men and women. Studies using animal models have provided important insights into pathogenesis, mechanisms, and new therapeutic approaches of human diseases, but some concerns remain to be addressed. The purpose of this chapter is to integrate human and animal studies involving the effects of the sex hormones, estrogens, on CNS neurotransmission, reward processing, and associated mental disorders. We provide an overview of existing evidence for the physiological, behavioral, cellular, and molecular actions of estrogens in the context of controlling neurotransmission in the CNS circuits regulating mood, reward, and motivation and discuss related pathology that leads to mental disorders.

Oestrogen upregulates the expression levels and functional activities of duodenal mucosal CFTR and SLC26A6

NEW FINDINGS

What is the central question of this study? Duodenal ulcer is a common disease. A sex-based difference in the incidence of duodenal ulcer has long been observed clinically, but the cause is unclear. What is the main finding and its importance? Duodenal mucosal bicarbonate secretion is the most important protective factor in duodenal mucosa against acid-induced damage. The cystic fibrosis transmembrane conductance regulator (CFTR) and the solute-linked carrier 26 gene family A6 (SLC26A6) are two key bicarbonate transport proteins that mediate duodenal mucosal bicarbonate secretion. We demonstrate that endogenous oestrogen upregulates the expression levels and functional activities of duodenal mucosal CFTR and SLC26A6, which contributes to the sex difference in the prevalence of duodenal ulcer. The incidence of duodenal ulcer is markedly lower in women than men, but the cause of the sex difference is not clear. The cystic fibrosis transmembrane conductance regulator (CFTR) and the solute-linked carrier 26 gene family A6 (SLC26A6) are two key bicarbonate transport proteins that mediate duodenal mucosal bicarbonate secretion, which is an important protective factor against acid-induced duodenal injury. The aim of this study was to investigate the effect of oestrogen on the expressions and functional activities of CFTR and SLC26A6 in duodenal mucosa. We found that the expression levels of duodenal CFTR and SLC26A6 were markedly higher in young (20- to 30-year-old) women than in young men and old (60- to 70-year-old) women and men. The expression levels of CFTR and SLC26A6 in young women were markedly higher in preovulatory phases than in premenstrual phases, which was consistent with the changes of serum estradiol concentrations. Further results showed that duodenal CFTR and SLC26A6 expression levels in female mice were markedly decreased after ovariectomy, and supplementation with estradiol reversed the changes in CFTR and SLC26A6. 17β-Estradiol increased CFTR and SLC26A6 expression levels of human duodenocytes in experiments in vitro. Functional experiments showed that basal and forskolin- and prostaglandin E₂ -stimulated duodenal bicarbonate secretion in ovariectomized mice was markedly decreased and, likewise, supplementation with 17β-estradiol reversed the changes. In conclusion, endogenous oestrogen upregulates the expressions and functional activities of CFTR and SLC26A6 in duodenal mucosa, which could contribute to protection of the duodenum and explain the sex difference in the prevalence of duodenal ulcer.

Shiftwork and decline in endothelial function among police officers

BACKGROUND

Our objective was to assess the influence of shiftwork on change in endothelial function.

METHODS

This longitudinal study was conducted in 188 police officers (78.2% men). Shiftwork status (day, afternoon, night) was assessed objectively using daily Buffalo, NY payroll work history records. Brachial artery flow-mediated dilation (FMD) was assessed using ultrasound. Mean change in FMD% between 2004-2009 and 2010-2015 was compared across shiftwork using analysis of variance/covariance.

RESULTS

Overall, mean FMD% decreased from 5.74 ± 2.83 to 3.88 ± 2.11 over an average of 7 years among all officers; P < 0.0001. Effect modification by gender was significant. Among men (but not women), those who worked day shifts had a smaller mean (±SE) decrease in FMD% (-0.89 ± 0.35) compared with those who worked the afternoon (-2.69 ± 0.39; P = 0.001) or night shifts (-2.31 ± 0.45; P = 0.020) after risk factor adjustment.

CONCLUSIONS

Larger declines in endothelial function were observed among men who worked afternoon or night shifts. Further investigation is warranted. Am. J. Ind. Med. 59:1001-1008, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Estrogen deficiency heterogeneously affects tissue specific stem cells in mice

Postmenopausal disorders are frequently observed in various organs, but their relationship with estrogen deficiency and mechanisms remain unclear. As tissue-specific stem cells have been found to express estrogen receptors, we examined the hypothesis that estrogen deficiency impairs stem cells, which consequently contributes to postmenopausal disorders. Six-week-old C57BL/6 female mice were ovariectomized, following which they received 17β-estradiol replacement or vehicle (control). Sham-operated mice were used as healthy controls. All mice were killed for evaluation 2 months after treatments. Compared with the healthy control, ovariectomy significantly decreased uterine weight, which was partially recovered by 17β-estradiol replacement. Ovariectomy significantly increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, but impaired their capacity to grow mixed cell-type colonies in vitro. Estrogen replacement further increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, without significantly affecting colony growth in vitro. The number of CD105-positive mesenchymal stem cells in bone marrow also significantly decreased after ovariectomy, but completely recovered following estrogen replacement. Otherwise, neither ovariectomy nor estrogen replacement changed the number of Pax7-positive satellite cells, which are a skeletal muscle-type stem cell. Estrogen deficiency heterogeneously affected tissue-specific stem cells, suggesting a likely and direct relationship with postmenopausal disorders.

Estrogen increases the severity of anaphylaxis in female mice through enhanced endothelial nitric oxide synthase expression and nitric oxide production

BACKGROUND

Clinical observations suggest that anaphylaxis is more common in adult women compared with adult men, although the mechanistic basis for this sex bias is not well understood.

OBJECTIVES

We sought to document sex-dependent differences in a mouse model of anaphylaxis and explore the role of female sex hormones and the mechanisms responsible.

METHODS

Passive systemic anaphylaxis was induced in female and male mice by using histamine, as well as IgE or IgG receptor aggregation. Anaphylaxis was assessed by monitoring body temperature, release of mast cell mediators and/or hematocrit, and lung weight as a measure of vascular permeability. A combination of ovariectomy, estrogen receptor antagonism, and estrogen administration techniques were used to establish estrogen involvement.

RESULTS

Anaphylactic responses were more pronounced in female than male mice. The enhanced severity of anaphylaxis in female mice was eliminated after pretreatment with an estrogen receptor antagonist or ovariectomy but restored after administration of estradiol in ovariectomized mice, demonstrating that the sex-specific differences are due to the female steroid estradiol. Estrogen did not affect mast cell responsiveness or anaphylaxis onset. Instead, it increased tissue expression of endothelial nitric oxide synthase (eNOS). Blockage of NOS activity with the inhibitor L-NG-nitroarginine methyl ester or genetic eNOS deficiency abolished the sex-related differences.

CONCLUSION

Our study defines a contribution of estrogen through its regulation of eNOS expression and nitric oxide production to vascular hyperpermeability and intensified anaphylactic responses in female mice, providing additional mechanistic insights into risk factors and possible implications for clinical management in the further exploration of human anaphylaxis.

Ovariectomy increases the participation of hyperpolarizing mechanisms in the relaxation of rat aorta

This study examines the downstream NO release pathway and the contribution of different vasodilator mediators in the acetylcholine-induced response in rat aorta 5-months after the loss of ovarian function. Aortic segments from ovariectomized and control female Sprague-Dawley rats were used to measure: the levels of superoxide anion, the superoxide dismutases (SODs) activity, the cGMP formation, the cGMP-dependent protein kinase (PKG) activity and the involvement of NO, cGMP, hydrogen peroxide and hyperpolarizing mechanisms in the ACh-induced relaxation. The results showed that ovariectomy did not alter ACh-induced relaxation; incubation with L-NAME, a NO synthase inhibitor, decreased the ACh-induced response to a lesser extent in aorta from ovariectomized than from control rats, while ODQ, a guanylate cyclase inhibitor, decreased that response to a similar extent; the blockade of hyperpolarizing mechanisms, by precontracting arteries with KCl, decreased the ACh-induced response to a greater extent in aortas from ovariectomized than those from control rats; catalase, that decomposes hydrogen peroxide, decreased the ACh-induced response only in aorta from ovariectomized rats. In addition, ovariectomy increased superoxide anion levels and SODs activity, decreased cGMP formation and increased PKG activity. Despite the increased superoxide anion and decreased cGMP in aorta from ovariectomized rats, ACh-induced relaxation is maintained by the existence of hyperpolarizing mechanisms in which hydrogen peroxide participates. The greater contribution of hydrogen peroxide in ACh-induced relaxation is due to increased SOD activity, in an attempt to compensate for increased superoxide anion formation. Increased PKG activity could represent a redundant mechanism to ensure vasodilator function in the aorta of ovariectomized rats.

Menopausal hot flushes do not associate with changes in heart rate variability in controlled testing: a randomized trial on hormone therapy

OBJECTIVE

To compare in controlled cardiovascular autonomic function tests the effects of hormone therapy (HT) on heart rate variability (HRV) responses in postmenopausal women with and without pretreatment hot flushes.

DESIGN

A randomized placebo-controlled trial.

SETTING

Finland, Helsinki University Central Hospital.

POPULATION

A total of 150 recently postmenopausal and healthy women with prospectively evaluated hot flushes.

METHODS

Women (72 with and 78 without hot flushes) were randomized to receive estradiol alone or in combination with medroxyprogesterone acetate or placebo for 6 months. Time and frequency domain measures of HRV were assessed at baseline and after HT with short-term recordings during paced quiet and deep breathing and with active orthostatic tests, both under carefully controlled laboratory conditions to avoid confounding factors present in long-term ambulatory HRV measurements.

MAIN OUTCOME MEASURES

Responses of time and frequency domain measures of HRV to HT.

RESULTS

At baseline HRV was similar in women with and without hot flushes. Pretreatment hot flushes did not associate with changes in time domain parameters of HRV during controlled quiet or deep breathing or active orthostatic tests after different types of HT. However, HT reduced HRV in very low frequency power in women with pretreatment hot flushes (from 371 ± 40 to 258 ± 28 ms(2) , p = 0.018). HT did not have an effect on other frequency domain measures during quiet breathing or active orthostatic tests.

CONCLUSIONS

Hormone therapy did not significantly modify the HRV responses in women with or without hot flushes under controlled short-term measurements of the cardiovascular autonomic nervous system.

G protein-coupled estrogen receptor in energy homeostasis and obesity pathogenesis

Obesity and its related metabolic diseases have reached a pandemic level worldwide. There are sex differences in the prevalence of obesity and its related metabolic diseases, with men being more vulnerable than women; however, the prevalence of these disorders increases dramatically in women after menopause, suggesting that sex steroid hormone estrogens play key protective roles against development of obesity and metabolic diseases. Estrogens are important regulators of several aspects of metabolism, including body weight and body fat, caloric intake and energy expenditure, and glucose and lipid metabolism in both males and females. Estrogens act in complex ways on their nuclear estrogen receptors (ERs) ERα and ERβ and transmembrane ERs such as G protein-coupled estrogen receptor. Genetic tools, such as different lines of knockout mouse models, and pharmacological agents, such as selective agonists and antagonists, are available to study function and signaling mechanisms of ERs. We provide an overview of the evidence for the physiological and cellular actions of ERs in estrogen-dependent processes in the context of energy homeostasis and body fat regulation and discuss its pathology that leads to obesity and related metabolic states.

The menopausal transition does not appear to accelerate age-related increases in arterial stiffness

OBJECTIVE

Arterial stiffness is an independent marker of cardiovascular risk that increases with age, hypertension, diabetes and hyperlipidemia, both for men and women (although more pronounced in women). This study was designed to establish whether menopause augments the age-dependent change.

METHODS

The study evaluated pulse wave analysis and pulse wave velocity using applanation tonometry in 468 women (aged 40-80 years) sampled from the general population. In multiple linear regression models, age was the predominant correlate of increasing aortic augmentation pressure (p < 0.0001), augmentation index (p < 0.0001), augmentation index adjusted to a heart rate of 75 beats/min (p < 0.0001) and carotid-femoral pulse wave velocity (p < 0.0001).

RESULTS

Analysis of covariance showed no significant difference in adjusted mean of augmentation pressure, augmentation index or pulse wave velocity between menopause groups (pre-, peri-, postmenopause). Adjusted means of augmentation pressure and pulse wave velocity were comparable between women on hormone therapy (n = 130) and non-users (n = 338).

CONCLUSIONS

The results of the present study challenge the assertion by some researchers that menopause accelerates age-dependent changes in arterial stiffness.

Vascular disease in diabetic women: Why do they miss the female protection?

Gender plays a pivotal role in the onset as well as in the progression of the cardiovascular disease with a higher morbidity and mortality being detected in men with respect to women. Type 2 Diabetes Mellitus (T2DM) may reduce gender-related differences in the prevalence of cardiovascular disease by fading the vascular protective effects afforded by estrogen in females. This article will discuss the role of sex and sex hormones on the incidence and mechanisms involved in vascular dysfunction associated to T2DM, which might explain why women with T2DM lack the vascular protection.

Estrogen potentiates prostaglandin E₂-stimulated duodenal mucosal HCO₃⁻ secretion in mice

The cause of lower prevalence of duodenal ulcer in young women compared with men is largely unknown. We recently found that sex difference in duodenal mucosal HCO₃⁻ secretion existed in humans and mice, but the mechanisms are not clear. Prostaglandin E₂ (PGE₂) is an important endogenous mediator that plays an important role in the regulation of duodenal HCO₃⁻ secretion. Therefore, in the present study, we investigated the effect of estrogen on PGE₂-stimulated duodenal HCO₃⁻ secretion and the underlying mechanisms. The results showed that 17β-estradiol at the physiological concentration (1 nM) had no significant effects on duodenal mucosal HCO₃⁻ secretion or short-circuit current (I(sc)) in mice. However, the pretreatment of 17β-estradiol (1 nM) markedly potentiated PGE₂-stimulated duodenal HCO₃⁻ secretion and I(sc) (P < 0.01 and P < 0.05). Global estrogen receptor (ER) antagonist ICI-182,780 and ERα-specific antagonist MPP, but not the ERβ-specific antagonist PHTPP, abolished estrogen-potentiated PGE₂-stimulated duodenal HCO₃⁻ secretion and I(sc). 17β-Estradiol and PGE₂ additively increased phosphatidylinositol 3-kinase (PI3K) activity and Akt phosphorylation. Wortmannin, a specific PI3K inhibitor, inhibited estrogen-potentiated PGE₂-stimulated duodenal HCO₃⁻ secretion and I(sc). In conclusion, estrogen at the physiological concentration potentiates PGE₂-stimulated duodenal mucosal HCO₃⁻ secretion through the activation of ERα and the PI3K-dependent mechanism, which may contribute to the sex difference in duodenal mucosal HCO₃⁻ secretion and the lower prevalence of duodenal ulcer in young women.

Vasomotor hot flashes and heart rate variability: a placebo-controlled trial of postmenopausal hormone therapy

OBJECTIVE

The aim of the study was to compare the responses of heart rate variability (HRV) with hormone therapy in recently postmenopausal women with and without vasomotor hot flashes.

METHODS

Seventy-two women with and 78 women without hot flashes were randomized to receive transdermal estradiol gel (1 g/day), oral estradiol alone (2 mg/day), oral estradiol combined with medroxyprogesterone acetate (MPA; 5 mg/day), or placebo for 6 months. Time- and frequency-domain measures of HRV were assessed using 24-hour electrocardiographic recordings at baseline and after hormone therapy.

RESULTS

At baseline, the cardiac variables were similar in women with and without hot flashes. In women with hot flashes, the mean 24-hour heart rate and nighttime heart rate showed a tendency toward reduction in estradiol-only users compared with those taking placebo and those taking estradiol combined with MPA. In women with hot flashes, oral estradiol versus transdermal estradiol reduced nighttime HRV in the time domain (triangular index, -27 ± 36 vs +8 ± 36, P = 0.042). In women without hot flashes, the use of oral estradiol with MPA reduced time-domain HRV (SD of all normal-to-normal intervals; -11 ± 13 ms, P = 0.048, and square root of the mean of the sum of the squares of differences between adjacent normal-to-normal intervals; -6 ± 8 ms, P = 0.036). The women with hot flashes had more supraventricular ectopic beats when using oral estradiol with MPA than when using oral estradiol only (71 ± 128 vs 12 ± 11, P = 0.018).

CONCLUSIONS

Oral estrogen, especially when combined with MPA, may have adverse effects on HRV in women with and without hot flashes, whereas transdermal estradiol showed no such effects. Furthermore, women with hot flashes receiving oral estrogen combined with MPA are possibly more prone to cardiac arrhythmias than are women using estrogen only.

CCN5/WISP-2: A micromanager of breast cancer progression

The gain of plasticity by a subset of cancer cells is a unique but common sequence of cancer progression from epithelial phenotype to mesenchymal phenotype (EMT) that is followed by migration, invasion and metastasis to a distant organ, and drug resistance. Despite multiple studies, it is still unclear how cancer cells regulate plasticity. Recent studies from our laboratory and others' proposed that CCN5/WISP-2, which is found intracellularly (in the nucleus and cytoplasm) and extracellularly, plays a negative regulator of plasticity. It prevents the EMT process in breast cancer cells as well as pancreatic cancer cells. Multiple genetic insults, including the gain of p53 mutations that accumulate over the time, may perturb CCN5 expression in non-invasive breast cancer cells, which ultimately helps cells to gain invasive phenotypes. Moreover, emerging evidence indicates that several oncogenic lesions such as miR-10b upregulation and activation of TGF-β-signaling can accumulate during CCN5 crisis in breast cancer cells. Collectively, these studies indicate that loss of CCN5 activity may promote breast cancer progression; application of CCN5 protein may represent a novel therapeutic intervention in breast cancer and possibly pancreatic cancer.

Sex differences in vascular compliance in normal-weight but not obese boys and girls: the effect of body composition

Objectives. To determine the effect of sex and obesity on vascular function in children and explore potential mechanisms that account for differences in vascular function. Methods. Participants were 61 (30 boys) normal-weight (BMI 25-75% ile for age and sex) and 62 (30 boys) obese (BMI ≥ 95% ile) children of ages 8-18 years. Measurements of large and small artery elastic index (LAEI and SAEI, resp.) and reactive hyperemia index (RHI) were obtained at rest, along with anthropometric and biochemical information. Results. In normal-weight children, LAEI was 16% higher in males than females (P = 0.04) with a similar trend for SAEI (13% higher in males, P = 0.067). In obese children, no sex-related differences in vascular measures were observed. In multivariable models, sex differences in arterial compliance were explained by higher lean mass in normal-weight boys. Fat mass predicted LAEI and SAEI in both normal-weight and obese females, but fat mass predicted arterial compliance in boys when fat mass exceeded 24 kg (37% of the sample). Conclusions. Normal-weight males have higher arterial compliance than normal-weight females due to increased lean mass, but sex-related differences were not observed among obese children due to a lack of sex-related differences in lean or fat mass.

Membrane-initiated signaling of estrogen related to neuroprotection. "Social networks" are required

Numerous studies indicate that estrogens are crucial in normal brain functioning and preservation against different injuries. At the neuronal membrane, estrogens, binding to estrogen receptors (ERs) or other surface targets, exert rapid actions involving a plethora of signaling pathways that may converge in neuronal survival. Emerging work reveals that at least part of these actions may require the compartmentalization of ERs in signaling platforms, composed of macromolecular signaling proteins and particular lipid composition integrated in lipid rafts. These particular microstructures may provide the optimal microenvironment to trigger multiple ER interactions that may be crucial for neuroprotection against different brain impairments, such as Alzheimer's disease (AD). In this order of ideas, recent evidence has demonstrated that a membrane ER (mER) physically interacts with a voltage-dependent anion channel (VDAC) in lipid rafts from septal, hippocampal and cortical neurons, and these interactions may have important consequences in the alternative mechanisms developed by estrogens to achieve neuroprotection against amyloid beta (Aβ)-induced toxicity. This review includes a survey of some of the rapid mechanisms developed by estrogen to prevent neuronal death, and the ER interactions that are involved in the structural maintenance and signal transduction mechanisms important for neuronal survival against AD neuro-pathology. A special emphasis is put on the biological relevance of neuronal membrane VDAC in Aβ-related neurotoxicity, and the potential modulation of this channel as a part of a signaling complex with mER, which may be modified in AD brains.

Menopausal hot flushes and vascular health

Hot flushes are complained of by approximately 75% of all postmenopausal women, and hormone therapy (HT) is the most effective way to alleviate them. Hot flushes are characterized by altered vascular function and sympathetic nervous system activity. Hot flushes occurred more often in women attending large, non-randomized observational studies (e.g. Nurses' Health Study), where HT use protected against cardiovascular disease (CVD). However, they were absent (or mild) in randomized HT trials where HT use was accompanied with an elevated risk for CVD. Hot flushes, if a factor for cardiovascular health, could partly explain the conflict between observational and randomized trials. Several cross-sectional studies imply that hot flushes are detrimental to the cardiovascular system. However, the data are not uniform, and hot flushes were recalled retrospectively or during HT use. In our prospective study hot flushes were accompanied with a vasodilatory effect during endothelial testing, and this was related to the severity of hot flushes. Night-time hot flushes were followed with transient rises in ambulatory blood pressure (BP). However, no effect of hot flushes on diurnal BP was detected. The use of estradiol showed no harmful effects on endothelial function in women with hot flushes, but in non-flushing women oral, but not transdermal, estradiol led to vasoconstrictive changes. Estradiol complemented with medroxyprogesterone acetate eliminated the vasoconstrictive effect of sole oral estradiol. Thus, both oral and transdermal estradiol are applicable in flushing women, whereas a transdermal route should be favored in non-flushing women if used e.g. for bone protection.

Reproductive history in women with abdominal aortic aneurysms

BACKGROUND

The prevalence of abdominal aortic aneurysms (AAAs) differs considerably between the sexes, illustrated by the male/female ratio 4-6:1. Women are also reported to have a higher risk of rupture, and a poorer outcome compared with men. The primary aim of this study was to investigate if women with AAA have a different reproductive history compared with other women. The secondary aim was to study if women with a larger AAA differ in their reproductive history from women with a smaller AAA.

METHOD

This case-control study was performed in October 2009 and included 140 consecutively monitored women with AAA and 140 with peripheral arterial disease (PAD) at the Department of Vascular Surgery at Karolinska University Hospital, Stockholm. AAA was defined as AAA diameter >3 cm, and women with AAA were subdivided into groups with AAA diameter ≥5 cm and diameter <5 cm. A validated questionnaire was used to obtain information about participants' reproductive history and general health. The response rate was 70% (n = 196).

RESULTS

Women with AAA were smokers to a greater extent than women with PAD (previous, 52% vs 46%; current, 46% vs 34%, P = .001). Diabetes mellitus was more prevalent in women with PAD (28%) than in women with AAA (15%, P = .034). Angina pectoris occurred more often in women with AAA (26%) than in women with PAD (11%, P = .026). No significant difference was found between PAD and AAA women regarding statin use, treatment for hypertension, prior myocardial infarction, and body mass index (BMI). The 54 women with AAA ≥5 cm and the 44 women with AAA <5 cm were similar in age (76 vs 76 years, P = .908) and BMI (25.7 vs 24.0 kg/m(2), P = .66). No difference was noted in the occurrence of other risk factors between women with AAA ≥5 cm and women with AAA <5 cm. Mean age at menopause was lower in women with AAA ≥5 cm than in women with AAA <5 cm and in women with PAD (47.7 vs 49.9 vs 49.7 years, P = .011). Apart from menopausal age, the groups had a similar reproductive history, including hormone replacement therapy, parity, use of contraceptives, prior gynecological surgery, and breast cancer.

CONCLUSION

These findings suggest that women with larger AAA reach menopausal age earlier, and this could influence an earlier onset of aneurysmatic disease or an increase in aneurysm growth. The true role of endogenous estrogen in aneurysm development and expansion is yet to be investigated.

The development and the use of experimental animal models to study the underlying mechanisms of CA formation

Cerebral aneurysms (CAs) have a high prevalence and can cause a lethal subarachnoid hemorrhage. Currently, CAs can only be treated with invasive surgical procedures. To unravel the underlying mechanisms of CA formation and to develop new therapeutic drugs for CAs, animal models of CA have been established, modified, and analyzed. Experimental findings from these models have clarified some of the potential mechanisms of CA formation, especially the relationship between hemodynamic stress and chronic inflammation. Increased hemodynamic stress acting at the site of bifurcation of cerebral arteries triggers an inflammatory response mediated by various proinflammatory molecules in arterial walls, inducing pathological changes in the models similar to those observed in the walls of human CAs. Findings from animal studies have provided new insights into CA formation and may contribute to the development of new therapeutic drugs for CAs.

Efficacy of genistein aglycone on some cardiovascular risk factors and homocysteine levels: A follow-up study

BACKGROUND AND AIM

Recent evidence suggests that genistein aglycone may act beneficially on surrogate cardiovascular risk markers in postmenopausal women. We assessed the effects of genistein aglycone on some cardiovascular risk factors and homocysteine levels after 3-years of continued therapy in a cohort of osteopenic, postmenopausal women.

METHODS AND RESULTS

The parent study was a randomized, double-blind, placebo-controlled trial involving 389 postmenopausal women with low bone mass for 24 months. Subsequently, a subcohort (138 patients) continued therapy for an additional year. Participants received 54mg of genistein aglycone (n=71) or placebo (n=67), daily. Both arms received calcium and vitamin D(3) in therapeutic doses. Moreover, 4 weeks before randomization procedures and during our follow-up study, all patients received dietary instructions in an isocaloric fat-restricted diet. Blood lipid profiles, fasting glucose and insulin, insulin resistance (HOMA-IR), fibrinogen, osteoprotegerin (OPG) and homocysteine at baseline and after 24 and 36 months of treatment were measured. Compared to placebo, genistein significantly decreased fasting glucose and insulin, HOMA-IR, fibrinogen and homocysteine after 24 and 36 months of treatment. By contrast, isoflavone administration did not affect high-density lipoprotein cholesterol and triglycerides though serum OPG was higher in the genistein recipients. There were no differences in adverse events or discomfort between groups. Results on routine biochemical, liver function, and hematologic testing did not change over time in placebo or genistein group.

CONCLUSIONS

After 3-years of treatment, genistein aglycone plus calcium, vitamin D(3) and a healthy diet showed positive effects on some cardiovascular risk factors and homocysteine levels in a cohort of postmenopausal women with low bone mass.

Effect of hot flushes on vascular function: a randomized controlled trial

OBJECTIVE

To compare the vascular responses to hormone therapy in women with and without hot flushes.

METHODS

We randomly assigned 143 healthy, recently postmenopausal women (mean age 52.4+/-0.2 years, time since menopause 19.5+/-0.9 months) with intolerable hot flushes (more than seven moderate/severe episodes per day) or tolerable hot flushes (fewer than three mild episodes per day) to receive 1 mg of transdermal estradiol gel, oral estradiol (2 mg) with and without daily medroxyprogesterone acetate, or placebo for 6 months. Vascular function was assessed by pulse-wave analysis and endothelial function testing with nitroglycerin and salbutamol challenges.

RESULTS

Hot flushes did not affect the changes in arterial or aortic stiffness or endothelial function in response to various forms of hormone therapy. However, in women with tolerable hot flushes, oral estradiol caused a decrease of 13.2% (P=.028) in the time to the first systolic peak (dependent on the rapid phase of ventricular ejection) after nitroglycerin. In addition, the time to the reflected wave (dependent on pulse-wave velocity) after nitroglycerin was decreased by 8.4% (P=.018). These effects were not seen in women with intolerable hot flushes or with the other treatment regimens.

CONCLUSION

Women without troublesome hot flushes are susceptible to unfavorable vascular effects after oral estrogen treatment, resulting in less compliant vasculature.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00668603.

LEVEL OF EVIDENCE

I.

Ovariectomy increases the formation of prostanoids and modulates their role in acetylcholine-induced relaxation and nitric oxide release in the rat aorta

AIMS

This study examines the effect of ovarian function on thromboxane A(2) (TXA(2)), prostaglandin (PG) I(2), PGF(2alpha), and PGE(2) release as well as the role of these substances in nitric oxide (NO) release and acetylcholine (ACh)-mediated relaxation.

METHODS AND RESULTS

Aortic segments from ovariectomized and control female Sprague-Dawley rats were used. Cyclooxygenase (COX-1 and COX-2) expression was studied. ACh-induced relaxation was analysed in the absence and presence of the COX-2 inhibitor NS-398, the TXA(2) synthesis inhibitor furegrelate, the PGI(2) synthesis inhibitor tranylcypromine (TCP), or the thromboxane-prostanoid receptor antagonist SQ-29548. TXA(2), PGI(2), PGF(2alpha), and PGE(2) release was measured, and the vasomotor effect of exogenous TXA(2), PGI(2,) PGF(2alpha), and PGE(2) was assessed. Basal and ACh-induced NO release in the absence and presence of NS-398, furegrelate, TCP, or TCP plus furegrelate was studied. Ovariectomy did not alter or increased COX-1 or COX-2 expression, respectively. NS-398 decreased, and furegrelate did not change, the ACh-induced relaxation in arteries from both groups. SQ29,548 decreased the ACh-induced relaxation only in aortas from ovariectomized rats. TCP decreased the ACh-induced relaxation in both groups, and furegrelate or SQ29,548 totally restored that response only in aortas from control rats. Ovariectomy increased the ACh-induced TXA(2), PGI(2), and PGE(2) release and the contractile responses induced by exogenous TXA(2), PGF(2alpha), or PGE(2), while it decreased the PGI(2)-induced vasodilator response. In aortas from control rats, NS-398 did not alter the ACh-induced NO release, and furegrelate, TCP, or TCP plus furegrelate increased that release. In arteries from ovariectomized rats, NS-398, furegrelate, TCP, or TCP plus furegrelate decreased the ACh-induced NO release.

CONCLUSION

Despite the prevalence of vasoconstrictor prostanoids derived from COX-2 in aortas from ovariectomized rats, the ACh-induced relaxation is maintained, probably as consequence of the positive regulation that prostanoids exert on eNOS activity.

Membrane estrogen receptor-alpha-mediated nongenomic actions of phytoestrogens in GH3/B6/F10 pituitary tumor cells

Background

Estradiol (E₂) mediates various intracellular signaling cascades from the plasma membrane via several estrogen receptors (ERs). The pituitary is an estrogen-responsive tissue, and we have previously reported that E₂ can activate mitogen-activated protein kinases (MAPKs) such as ERK1/2 and JNK1/2/3 in the membrane ERα (mERα)-enriched GH₃/B₆/F₁₀ rat pituitary tumor cell line. Phytoestrogens are compounds found in plants and foods such as soybeans, alfalfa sprouts, and red grapes. They are structurally similar to E₂ and share a similar mechanism of action through their binding to ERs. Phytoestrogens bind to nuclear ERs with a much lower affinity and therefore are less potent in mediating genomic responses. However, little is known about their ability to act via mERs to mediate nongenomic effects.

Methods

To investigate the activation of different nongenomic pathways, and determine the involvement of mERα, we measured prolactin (PRL) release by radio-immunoassay, MAPK activations (ERK1/2 and JNK1/2/3) via a quantitative plate immunoassay, and intracellular [Ca²⁺] by Fura-2 fluorescence imaging in cells treated with E₂ or four different phytoestrogens (coumestrol, daidzein, genistein, and trans-resveratrol).

Results

Coumesterol and daidzein increased PRL release similar to E₂ in GH₃/B₆/F₁₀ cells, while genistein and trans-resveratrol had no effect. All of these compounds except genistein activated ERK1/2 signaling at 1–10 picomolar concentrations; JNK 1/2/3 was activated by all compounds at a 100 nanomolar concentration. All compounds also caused rapid Ca²⁺ uptake, though in unique dose-dependent Ca²⁺ response patterns for several aspects of this response. A subclone of GH₃ cells expressing low levels of mERα (GH₃/B₆/D₉) did not respond to any phytoestrogen treatments for any of these responses, suggesting that these nongenomic effects were mediated via mERα.

Conclusion

Phytoestrogens were much more potent in mediating these nongenomic responses (activation of MAPKs, PRL release, and increased intracellular [Ca²⁺]) via mERα than was previously reported for genomic responses. The unique non-monotonic dose responses and variant signaling patterns caused by E₂ and all tested phytoestrogens suggest that complex and multiple signaling pathways or binding partners could be involved. By activating these different nongenomic signaling pathways, phytoestrogens could have significant physiological consequences for pituitary cell functions.

Differential response of peripheral arterial compliance-related indices to a vasoconstrictive stimulus

Peripheral arterial elastic properties are greatly affected by cardiovascular as well as other pathologies, and their assessment can provide useful diagnostic indicators. The photoplethysmographic technique can provide finger blood volume and pressure waveforms non-invasively, which can then be processed statically or beat-to-beat to characterize parameters of the vessel wall mechanics. We employ an occlusion-deflation protocol in 48 healthy volunteers to study peripheral artery compliance-related indices over positive and negative transmural pressure values as well as under the influence of a valid vasoconstrictor (cigarette smoking). We calculate beat-to-beat indices (compliance index CI, distensibility index DI, three viscoelastic model parameters (compliance C, viscosity R and inertia L), pressure-volume loop areas A and damping factor DF as well as symmetrical (C(max)) and asymmetrical (C(A)(max)) static compliance estimates, and their distributions over transmural pressure. All distributions are bell-shaped and centred on negative transmural pressure values. Distribution heights were significantly lower in the smoking group (w.r.t. the non-smoking group) for C, CI, DI and significantly higher in R and DF. The estimated volume signal time lag was also significantly lower in the smoking group. Left and right distribution widths were significantly different in all parameters/groups but DI (both groups), C(A)(max), A (smoking group) and L (non-smoking group), and positions of maxima/minima were significantly altered in C(A)(max), R and DF. C, DF and CI are seen to be most sensitive under this protocol, while C(max) and C(A)(max) are seen to be insensitive. These quantities provide complementary, time- and transmural pressure-dependent information about arterial wall mechanics, and the choice of index should depend on the physiological conditions at hand as well as relevant time resolution and transmural pressure range.

Sex steroids and vascular responses in hypertension and aging

BACKGROUND

Sex hormones play a significant role in human physiology. Estrogen may have protective effects in the cardiovascular system, as evidenced by the decreased incidence of cardiovascular disease (CVD) in premenopausal compared with postmenopausal women.

OBJECTIVE

This review highlights the acute and long-term effects of sex hormones on the vascular endothelium and vascular smooth muscle (VSM) in adults. Changes in the sex hormone mix, their receptors, and their effects on vascular function in hypertension and aging are also discussed.

METHODS

Literature collected from the National Centers for Biotechnology Information as identified by a PubMed database search, as well as our experimental work, was used to highlight current knowledge regarding vascular responses to sex hormones in hypertension and in aging.

RESULTS

Experiments in adult female animals have shown that estrogen induces endothelium-dependent vascular relaxation via the nitric oxide (NO), prostacyclin, and hyperpolarization pathways. Also, surface membrane estrogen receptors (ERs) decrease intracellular free Ca2+ concentration and perhaps protein kinase C-dependent VSM contraction. However, clinical trials such as the Heart and Estrogen/progestin Replacement Study (HERS), HERS-II, and the Women's Health Initiative did not support the experimental findings and demonstrated adverse cardiovascular events of hormone therapy (HT) in aging women. The lack of vascular benefits of HT may be related to the hormone used, the ER, or the patient's cardiovascular condition or age. Experiments on vascular strips from aging (16-month-old) female spontaneously hypertensive rats have shown reduced ER-mediated NO production from endothelial cells and decreased inhibitory effects of estrogen on Ca2+ entry mechanisms of VSM contraction. The age-related decrease in ER-mediated vascular relaxation may explain the decreased effectiveness of HT on CVD in aging women.

CONCLUSIONS

New HT strategies should further examine the benefits of natural estrogens and phytoestrogens. Transdermal estrogen may be more effective than the oral form, and specific ER modulators may maximize the vascular benefits and reduce the risk of invasive breast cancer. Variants of vascular ERs should be screened for genetic polymorphisms and postmenopausal decrease in the amount of downstream signaling mechanisms. HT may be more effective during the menopausal transition than in late menopause. Progesterone, testosterone, or their specific modulators may be combined with estrogen to provide alternative HT strategies. Thus, HT type, dose, route of administration, and timing should be customized, depending on the patient's cardiovascular condition and age, thereby enhancing the vascular benefits of HT in aging women.

Vocal nodules and edema may be due to vibration-induced rises in capillary pressure

HYPOTHESIS

Vocal fold vibration may physically raise intravascular pressure to levels high enough to damage capillaries and result in leakage of erythrocytes. This type of injury is commonly seen in benign vocal fold lesions and is not well explained.

STUDY DESIGN

Theoretical, retrospective.

METHODS

The relationship of intravascular pressure to vibration frequency and amplitude is derived and confirmed with a physical blood vessel model, then applied to published human measurements to estimate human intravascular pressures.

RESULTS

Vocal fold intravascular pressure is predicted to have a quadratic dependence on both frequency and amplitude. During speaking, the pressure may rise to over 20 cmH2O, and may reach levels far higher for screaming and singing. Such pressure magnitudes are known to trigger inflammatory cascades and can lead to fluid leakage. They also have the potential for pharmacologic control with beta-agonists.

CONCLUSIONS

Intravascular pressure likely rises significantly during vocal fold vibration and may lead to the type of injury seen in benign vocal fold lesions. The results support voice therapy aimed at reducing vibratory amplitude. More vibratory amplitude measurements need to be performed in a wider range of subjects before the full range of human vocal fold vascular pressures can be estimated.