Aldosterone in obesity

The New Challenge of Obesity - Obesity-Associated Nephropathy

In recent years, obesity has become one of the major diseases that affect human health and consume human health resources, especially when it causes comorbidities such as hypertension, diabetes, cardiovascular disease and kidney disease. Many studies have demonstrated that obesity is associated with the development of chronic kidney disease and can exacerbate the progression of end-stage renal disease. This review described the mechanisms associated with the development of obesity-associated nephropathy and the current relevant therapeutic modalities, with the aim of finding new therapeutic targets for obesity-associated nephropathy. The mechanisms of obesity-induced renal injury include, in addition to the traditional alterations in renal hemodynamics, the involvement of various mechanisms such as macrophage infiltration in adipose tissue, alterations in adipokines (leptin and adiponectin), and ectopic deposition of lipids. At present, there is no "point-to-point" treatment for obesity-induced kidney injury. The renin-angiotensin-aldosterone system (RAAS) inhibitors, sodium-dependent glucose transporter 2 (SGLT-2) inhibitors and bariatric surgery described in this review can reduce urinary protein to varying degrees and delay the progression of kidney disease. In addition, recent studies on the therapeutic effects of intestinal flora on obesity may reduce the incidence of obesity-related kidney disease from the perspective of primary prevention. Both of these interventions have their own advantages and disadvantages, so the continuous search for the mechanism of obesity-induced related kidney disease will be extremely helpful for the future treatment of obesity-related kidney disease.

Pathogenesis of Hypertension in Metabolic Syndrome: The Role of Fructose and Salt

Metabolic syndrome is manifested by visceral obesity, hypertension, glucose intolerance, hyperinsulinism, and dyslipidemia. According to the CDC, metabolic syndrome in the US has increased drastically since the 1960s leading to chronic diseases and rising healthcare costs. Hypertension is a key component of metabolic syndrome and is associated with an increase in morbidity and mortality due to stroke, cardiovascular ailments, and kidney disease. The pathogenesis of hypertension in metabolic syndrome, however, remains poorly understood. Metabolic syndrome results primarily from increased caloric intake and decreased physical activity. Epidemiologic studies show that an enhanced consumption of sugars, in the form of fructose and sucrose, correlates with the amplified prevalence of metabolic syndrome. Diets with a high fat content, in conjunction with elevated fructose and salt intake, accelerate the development of metabolic syndrome. This review article discusses the latest literature in the pathogenesis of hypertension in metabolic syndrome, with a specific emphasis on the role of fructose and its stimulatory effect on salt absorption in the small intestine and kidney tubules.

[Features of steroidogenesis in men with hypogonadism and type 2 diabetes]

BACKGROUND

BACKGROUND: Type 2 diabetes mellitus (DM2) in men is associated with a high incidence of hypogonadism. Testosterone is a steroid hormone and one of the final metabolites of steroidogenesis, which causes interest in assessing the content of key steroid hormones, their precursors and metabolites in hypogonadal and eugonadal men with T2DM.

AIMS

AIMS: Assessment of the features of steroidogenesis in men with hypogonadism in T2DM using tandem mass spectrometry.

MATERIALS AND METHODS

MATERIALS AND METHODS: A full-design, cross-sectional, screening, single-center, non-interventional study included men with T2DM, who were he was treated in Endocrinology Research Centre, Moscow. The study was conducted from October 2021 to January 2022. Medical history assessment, physical examination with determination of body mass index (BMI), measurement of key steroid hormones, their precursors and metabolites by isotope dilution liquid chromatography/tandem mass spectrometry, glycated hemoglobin (HbA1c) were performed. The groups were compared using the Mann-Whitney U-test for quantitative indicators and χ² with Yates’ correction for qualitative ones. Correlation analysis was performed by the Spearman correlation method. When determining the criterion of statistical significance, the Bonferroni correction was applied.

RESULTS

RESULTS: Patients with hypogonadism had statistically significantly more pronounced obesity compared with eugonadal men. In a comparative analysis of patients, depending on the presence of hypogonadism, there were statistically significantly lower levels of androgen precursors 17-hydroxypregnenolone and 17-hydroxyprogesterone in hypogonadal men. At the same time, a positive statistically significant correlation was found between total testosterone and 17-hydroxyprogesterone. In addition, 17-hydroxyprogesterone, although to a lesser extent, but positively correlated with other androgens - androstenedione (r=0,328; p<0,001) and dehydroepiandrosterone (r=0,183; p=0,004). >< 0,001) and dehydroepiandrosterone (r=0,183; p=0,004).

CONCLUSIONS

CONCLUSIONS: In this investigation the prevalence of male hypogonadism in type 2 diabetes, determined by high-precision tandem mass spectrometry, was 69,5%. There was no effect of the disease on the mineralocorticoid and glucocorticoid links of adrenal steroidogenesis. Hypogonadism was associated with decreased levels of a number of testosterone precursors. The most significant of them was 17-hydroxyprogesterone, which can be considered as a marker of testicular steroidogenesis.

Aldosterone-Regulated Sodium Transport and Blood Pressure

Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K⁺ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na⁺ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na⁺ reabsorption through ENaC.

Immunoinflammatory, Thrombohaemostatic, and Cardiovascular Mechanisms in COVID-19

The global coronavirus disease 2019 (COVID-19) pandemic has deranged the recent history of humankind, afflicting more than 27 million individuals to date. While the majority of COVID-19 patients recuperate, a considerable number of patients develop severe complications. Bilateral pneumonia constitutes the hallmark of severe COVID-19 disease but an involvement of other organ systems, namely the cardiovascular system, kidneys, liver, and central nervous system, occurs in at least half of the fatal COVID-19 cases. Besides respiratory failure requiring ventilation, patients with severe COVID-19 often display manifestations of systemic inflammation and thrombosis as well as diffuse microvascular injury observed postmortem. In this review, we survey the mechanisms that may explain how viral entry and activation of endothelial cells by severe acute respiratory syndrome coronavirus 2 can give rise to a series of events including systemic inflammation, thrombosis, and microvascular dysfunction. This pathophysiological scenario may be particularly harmful in patients with overt cardiovascular disease and may drive the fatal aspects of COVID-19. We further shed light on the role of the renin-angiotensin aldosterone system and its inhibitors in the context of COVID-19 and discuss the potential impact of antiviral and anti-inflammatory treatment options. Acknowledging the comorbidities and potential organ injuries throughout the course of severe COVID-19 is crucial in the clinical management of patients affecting treatment approaches and recovery rate.

Aldosterone as a mediator of severity in retinal vascular disease: Evidence and potential mechanisms

Diabetic retinopathy (DR) and retinal vein occlusion (RVO) are the two most common retinal vascular diseases and are major causes of vision loss and blindness worldwide. Recent and ongoing development of medical therapies including anti-vascular endothelial growth factor and corticosteroid drugs for treatment of these diseases have greatly improved the care of afflicted patients. However, severe manifestations of retinal vascular disease result in persistent macular edema, progressive retinal ischemia and incomplete visual recovery. Additionally, choroidal vascular diseases including neovascular age-related macular degeneration (NVAMD) and central serous chorioretinopathy (CSCR) cause vision loss for which current treatments are incompletely effective in some cases and highly burdensome in others. In recent years, aldosterone has gained attention as a contributor to the various deleterious effects of retinal and choroidal vascular diseases via a variety of mechanisms in several retinal cell types. The following is a review of the role of aldosterone in retinal and choroidal vascular diseases as well as our current understanding of the mechanisms by which aldosterone mediates these effects.

Genetics of primary macronodular adrenal hyperplasia

Recent advances in molecular genetics investigations of primary macronodular adrenal hyperplasia (PMAH) have been providing new insights for the research on this issue. The cAMP-dependent pathway is physiologically triggered by ACTH and its receptor, MC2-R, in adrenocortical cells. Different mechanisms of this cascade may be altered in some functioning adrenal cortical disorders. Activating somatic mutations of the GNAS gene (known as gsp oncogene) which encodes the stimulatory G protein alpha-subunit (Gsα) have been found in a small number of adrenocortical secreting adenomas and rarely in PMAH. Lately, ARMC5 was linked to the cyclic AMP signaling pathway, which could be implicated in all of mechanisms of cortisol-secreting by macronodules adrenal hyperplasia and the molecular defects in: G protein aberrant receptors; MC2R; GNAS; PRKAR1A; PDE11A; PDE8B. Around 50 % of patient's relatives with PMAH and 30 % of apparently sporadic hypercortisolism carried ARMC5 mutations. Therefore, PMAH is genetically determined more frequently than previously believed. This review summarizes the most important molecular mechanisms involved in PMAH.

Dietary sodium intake and its relationship to adiposity in young black and white adults: The African-PREDICT study

Obesity and salt intake are both established factors contributing to cardiovascular disease development. Recently, studies found a controversial positive relationship between dietary salt and obesity. Therefore, the authors investigated whether obesity-related measures are associated with 24-hour urinary sodium in a healthy biethnic population. The study included 761 adults (20-30 years) with complete 24-hour urinary sodium, anthropometry, and bioelectrical impedance measurements. In single regression analyses all obesity-related measures related positively with 24-hour urinary sodium (P ≤ .008). However, with multivariate adjustments for energy intake, accelerometery, age, sex, black and white ethnicity, and other covariates, only body surface area (BSA) remained independently associated with 24-hour urinary sodium (R2  = 0.72, β = .05, P = .039). To conclude, we found a consistent and robust positive relationship between BSA and estimated salt intake - but not with traditional obesity measures such as body mass index (BMI). Further studies are needed to investigate body surface area and potentially, skin area, in salt handling.

Mineralocorticoid receptor antagonism prevents obesity-induced cerebral artery remodeling and reduces white matter injury in rats

OBJECTIVE

Midlife obesity is a risk factor for dementia development. Obesity has also been linked to hyperaldosteronism, and this can be modeled in rats by high fat (HF) feeding from weaning. Aldosterone, or activation of the mineralocorticoid receptor (MR) causes cerebrovascular injury in lean hypertensive rats. We hypothesized that rats fed a HF diet would show inward middle cerebral artery (MCA) remodeling that could be prevented by MR antagonism. We further proposed that the cerebral artery remodeling would be associated with white mater injury.

METHODS

Three-week-old male Sprague-Dawley rats were fed a HF diet ± the MR antagonist canrenoic acid (Canr) for 17 weeks. Control rats received normal chow (control NC). MCA structure was assessed by pressure myography.

RESULTS

The MCAs from HF fed rats had smaller lumens and thicker walls when compared to arteries from control NC rats; Canr prevented the MCA remodeling associated with HF feeding. HF feeding increased the mRNA expression of markers of cell proliferation and vascular inflammation in cerebral arteries and Canr treatment prevented this. White mater injury was increased in the rats fed the HF diet and this was reduced by Canr treatment. The expression of doublecortin, a marker of new and immature neurons was reduced in HF fed rats, and MR antagonism normalized this.

CONCLUSIONS

These data suggest that HF feeding leads to MR dependent remodeling of the MCA and this is associated with markers of dementia development.

Obesity and the diagnostic accuracy for primary aldosteronism

The effects of body mass index on the diagnostic accuracy of primary aldosteronism (PA) are inconsistent and yet important considering the high prevalence and frequent co-occurrence of obesity and hypertension. The current study included 59 adult patients who underwent a stepwise evaluation for PA, using aldosterone to renin ratio for case detection and plasma aldosterone concentration after saline suppression test and/or 24-hour urinary aldosterone after oral sodium loading for case confirmation. Body mass index had a quadratic (U-shaped) correlation with plasma aldosterone concentration, plasma renin activity, aldosterone to renin ratio, and plasma aldosterone concentration after saline suppression test. Among patients with a body mass index ≥30 kg/m² , the aldosterone to renin ratio yielded lower case detection accuracy of PA. We conclude that obesity results in a nonlinear correlation with plasma aldosterone concentration, plasma renin activity, and aldosterone to renin ratio, which affects the accuracy of case detection for PA. Patients with a body mass index ≥30 kg/m² are less accurately identified as having PA when saline suppression and/or oral salt loading tests are used for case confirmation.

Obesity and hypertension

Obesity and in particular the excessive visceral fat distribution is accompanied by several alterations at hormonal, inflammatory and endothelial level. These alterations induce a stimulation of several other mechanisms that contribute to the hypertensive state and on the other side to increase the cardiovascular morbidity. In these chapter we will examine the main mechanisms of obesity and obesity-related hypertension and in particular the role of sympathetic nervous system, the alterations of the renal function and at the microvascular level. We will also depict the role of insulin resistance as factor stimulating and potentiating the other mechanisms. The second part will be focalized on the major target organ damage linked with obesity and obesity-related hypertension. We will finally describe the management and treatment of obesity and the antihypertensive drug therapies more effective in hypertensive obeses.

Very low-density lipoprotein (VLDL)-induced signals mediating aldosterone production

Aldosterone, secreted by the adrenal zona glomerulosa, enhances sodium retention, thus increasing blood volume and pressure. Excessive production of aldosterone results in high blood pressure and contributes to cardiovascular and renal disease, stroke and visual loss. Hypertension is also associated with obesity, which is correlated with other serious health risks as well. Although weight gain is associated with increased blood pressure, the mechanism by which excess fat deposits increase blood pressure remains unclear. Several studies have suggested that aldosterone levels are elevated with obesity and may represent a link between obesity and hypertension. In addition to hypertension, obese patients typically have dyslipidemia, including elevated serum levels of very low-density lipoprotein (VLDL). VLDL, which functions to transport triglycerides from the liver to peripheral tissues, has been demonstrated to stimulate aldosterone production. Recent studies suggest that the signaling pathways activated by VLDL are similar to those utilized by AngII. Thus, VLDL increases cytosolic calcium levels and stimulates phospholipase D (PLD) activity to result in the induction of steroidogenic acute regulatory (StAR) protein and aldosterone synthase (CYP11B2) expression. These effects seem to be mediated by the ability of VLDL to increase the phosphorylation (activation) of their regulatory transcription factors, such as the cAMP response element-binding (CREB) protein family of transcription factors. Thus, research into the pathways by which VLDL stimulates aldosterone production may identify novel targets for the development of therapies for the treatment of hypertension, particularly those associated with obesity, and other aldosterone-modulated pathologies.

Review: Renin-angiotensin-aldosterone system intervention in the cardiometabolic syndrome and cardio-renal protection

The metabolic syndrome, also known as the cardiometabolic syndrome (CMS), is a state of metabolic and vascular dysregulation that is associated with activation of the renin-angiotensin-aldosterone system (RAAS). Clinical components of the CMS include central or visceral obesity, hypertension (HTN), dyslipidemia, insulin resistance/hyperinsulinemia, and microalbuminuria that collectively convey increases in oxidative stress, inflammation, and subsequent endothelial dysfunction. The cardio-renal inflammation and oxidative stress enhanced in the CMS increases the risk for cardiovascular disease (CVD) and renal disease end-points such as stroke, congestive heart failure, and chronic kidney disease (CKD). The development of proteinuria is known to herald progressive kidney disease (e.g. CKD) and both are now well accepted as CVD risk factors. Evidence suggests a role for visceral obesity, insulin resistance/hyperinsulinemia, HTN, and other components of the CMS lead to an increased risk for proteinuria and progressive loss of renal function. Intervention with agents that block the RAAS (e.g. ACE inhibitors and Angiotensin type 1 receptor blockers) have been shown to reduce proteinuria, CKD progression, and CVD events. Herein, we will examine the relationship between RAAS intervention and reductions in CKD and CVD events.

Steroid biosynthesis in adipose tissue

Tissue-specific expression of steroidogenic enzymes allows the modulation of active steroid levels in a local manner. Thus, the measurement of local steroid concentrations, rather than the circulating levels, has been recognized as a more accurate indicator of the steroid action within a specific tissue. Adipose tissue, one of the largest endocrine tissues in the human body, has been established as an important site for steroid storage and metabolism. Locally produced steroids, through the enzymatic conversion from steroid precursors delivered to adipose tissue, have been proven to either functionally regulate adipose tissue metabolism, or quantitatively contribute to the whole body's steroid levels. Most recently, it has been suggested that adipose tissue may contain the steroidogenic machinery necessary for the initiation of steroid biosynthesis de novo from cholesterol. This review summarizes the evidence indicating the presence of the entire steroidogenic apparatus in adipose tissue and discusses the potential roles of local steroid products in modulating adipose tissue activity and other metabolic parameters.

Crosstalk between adipose tissue and blood vessels in cardiometabolic syndrome: implication of steroid hormone receptors (MR/GR)

Crosstalk between adipose tissue and blood vessels is vital to vascular homeostasis and is disturbed in cardiovascular and metabolic diseases such as hypertension, diabetes and obesity. Cardiometabolic syndrome (CMS) refers to the clustering of obesity-related metabolic disorders such as insulin resistance, glucose and lipid profile alterations, hypertension and cardiovascular diseases. Mechanisms underlying these associations remain unclear. Adipose tissue associated with the vasculature [known as perivascular adipose tissue (PVAT)] has been shown to produce myriads of adipose tissue-derived substances called adipokines, including hormones, cytokines and reactive oxygen species (ROS), which actively participate in the regulation of vascular function and local inflammation by endocrine and/or paracrine mechanisms. As a result, the signaling from PVAT to the vasculature is emerging as a potential therapeutic target for obesity and diabetes-related vascular dysfunction. Accumulating evidence supports a shift in our understanding of the crucial role of elevated plasma levels of aldosterone in obesity, promoting insulin resistance and hypertension. In obesity, aldosterone/mineralocorticoid receptor (MR) signaling induces an abnormal secretion of adipokines, ROS production and systemic inflammation, which in turn contribute to impaired insulin signaling, reduced endothelial-mediated vasorelaxation, and associated cardiovascular abnormalities. Thus, aldosterone excess exerts detrimental metabolic and vascular effects that participate to the development of the CMS and its associated cardiovascular abnormalities. In this review, we focus on the physiopathological roles of corticosteroid receptors in the interplay between PVAT and the vasculature, which underlies their potential as key regulators of vascular function.

Obesity and renovascular disease

Obesity remains a prominent public health concern. Obesity not only contributes greatly to cardiovascular events but has also been identified to initiate and affect the progression of preexisting chronic kidney disease. The prevalence of renal artery stenosis is growing world-wide, especially in the elderly population and in individuals with atherosclerotic risk factors such as obesity. Prolonged renovascular disease causes inflammation and microvascular remodeling within the post-stenotic kidney, which promote tissue scarring and may account for irreversible renal damage. Obesity has been shown to aggravate kidney damage via several pathways, including exacerbation of microvascular regression and renal cell injury mediated by adipocytes and insulin resistance, thereby worsening the structural and functional outcomes of the kidney in renovascular disease. Dietary modification and inhibition of the renin-angiotensin-aldosterone system have been shown to alleviate obesity-induced tissue injury and remodeling. Possibly, angiogenic factors may boost microvascular repair in the ischemic kidney in the obesity milieu. Novel therapeutic interventions targeting deleterious pathways that are activated by obesity and responsible for kidney damage need to be explored in future studies.

Primary Aldosteronism and ARMC5 Variants

CONTEXT

Primary aldosteronism is one of the leading causes of secondary hypertension, causing significant morbidity and mortality. A number of genetic defects have recently been identified in primary aldosteronism, whereas we identified mutations in ARMC5, a tumor-suppressor gene, in cortisol-producing primary macronodular adrenal hyperplasia.

OBJECTIVE

We investigated a cohort of 56 patients who were referred to the National Institutes of Health for evaluation of primary aldosteronism for ARMC5 defects.

METHODS

Patients underwent step-wise diagnosis, with measurement of serum aldosterone and plasma renin activity followed by imaging, saline suppression and/or oral salt loading tests, plus adrenal venous sampling. Cortisol secretion was also evaluated; unilateral or bilateral adrenalectomy was performed, if indicated. DNA, protein, and transfection studies in H295R cells were conducted by standard methods.

RESULTS

We identified 12 germline ARMC5 genetic alterations in 20 unrelated and two related individuals in our cohort (39.3%). ARMC5 sequence changes in 6 patients (10.7%) were predicted to be damaging by in silico analysis. All affected patients carrying a variant predicted to be damaging were African Americans (P = .0023).

CONCLUSIONS

Germline ARMC5 variants may be associated with primary aldosteronism. Additional cohorts of patients with primary aldosteronism and metabolic syndrome, particularly African Americans, should be screened for ARMC5 sequence variants because these may underlie part of the known increased predisposition of African Americans to low renin hypertension.

Obesity and insulin resistance in resistant hypertension: implications for the kidney

There is recognition that the obesity epidemic contributes substantially to the increasing incidence of CKD and resistant hypertension (HTN). The mechanisms by which obesity promotes resistance are an area of active interest and intense investigation. It is thought that increases in visceral adiposity lead to a proinflammatory, pro-oxidative milieu that promote resistance to the metabolic actions of insulin. This resistance to insulin at the level of skeletal muscle tissue impairs glucose disposal/utilization through actions on the endothelium that include vascular rarefaction, reductions in vascular relaxation, and vascular remodeling. Insulin resistance derived from increased adipose tissue and obesity has system-wide implications for other tissue beds such as the kidney that affects blood pressure regulation. The additional autocrine and paracrine activities of adipose tissue contribute to inappropriate activation of the renin-angiotensin-aldosterone system and the sympathetic nervous system that promote kidney microvascular remodeling, stiffness, and sodium (Na(+)) retention that in turn promote HTN and in the CKD patient, resistance. In this review, we will summarize the important mechanisms that link obesity to CKD as they relate to resistant HTN.

Modulation of glucose metabolism by the renin-angiotensin-aldosterone system

The renin-angiotensin-aldosterone system (RAAS) is an enzymatic cascade functioning in a paracrine and autocrine fashion. In animals and humans, RAAS intrinsic to tissues modulates food intake, metabolic rate, adiposity, insulin sensitivity, and insulin secretion. A large array of observations shows that dysregulation of RAAS in the metabolic syndrome favors type 2 diabetes. Remarkably, angiotensin-converting enzyme inhibitors, suppressing the synthesis of angiotensin II (ANG II), and angiotensin receptor blockers, targeting the ANG II type 1 receptor, prevent diabetes in patients with hypertensive or ischemic cardiopathy. These drugs interrupt the negative feedback loop of ANG II on the RAAS cascade, which results in increased production of angiotensins. In addition, they change the tissue expression of RAAS components. Therefore, the concept of a dual axis of RAAS regarding glucose homeostasis has emerged. The RAAS deleterious axis increases the production of inflammatory cytokines and raises oxidative stress, exacerbating the insulin resistance and decreasing insulin secretion. The beneficial axis promotes adipogenesis, blocks the production of inflammatory cytokines, and lowers oxidative stress, thereby improving insulin sensitivity and secretion. Currently, drugs targeting RAAS are not given for the purpose of preventing diabetes in humans. However, we anticipate that in the near future the discovery of novel means to modulate the RAAS beneficial axis will result in a decisive therapeutic breakthrough.

Aldosterone blockade in CKD: emphasis on pharmacology

Besides its epithelial effect on sodium retention and potassium excretion in the distal tubule, aldosterone promotes inflammation and fibrosis in the heart, kidneys, and blood vessels. As glomerular filtration rate falls, aldosterone is inappropriately elevated relative to extracellular fluid expansion. In addition, studies in CKD patients on angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and/or direct renin inhibitors have shown that aldosterone levels paradoxically rise in approximately 30% to 40% of patients on these renin-angiotensin system-blocking drugs. Hence, there is interest in using mineralocorticoid receptor blockers that directly target the inflammatory and fibrotic effects of aldosterone in CKD patients. This interest, however, is tempered by a number of unresolved issues, including the safety of using such drugs in advanced CKD and ESRD populations, and the potential for differences in drug efficacy according to race and ethnicity of patient populations. A better understanding of mineralocorticoid receptor blocker pharmacology should help inform future research directions and clinical practice decisions as to how best to use these agents in CKD.

Regulation of aldosterone synthesis and secretion

Aldosterone is a steroid hormone synthesized in and secreted from the outer layer of the adrenal cortex, the zona glomerulosa. Aldosterone is responsible for regulating sodium homeostasis, thereby helping to control blood volume and blood pressure. Insufficient aldosterone secretion can lead to hypotension and circulatory shock, particularly in infancy. On the other hand, excessive aldosterone levels, or those too high for sodium status, can cause hypertension and exacerbate the effects of high blood pressure on multiple organs, contributing to renal disease, stroke, visual loss, and congestive heart failure. Aldosterone is also thought to directly induce end-organ damage, including in the kidneys and heart. Because of the significance of aldosterone to the physiology and pathophysiology of the cardiovascular system, it is important to understand the regulation of its biosynthesis and secretion from the adrenal cortex. Herein, the mechanisms regulating aldosterone production in zona glomerulosa cells are discussed, with a particular emphasis on signaling pathways involved in the secretory response to the main controllers of aldosterone production, the renin-angiotensin II system, serum potassium levels and adrenocorticotrophic hormone. The signaling pathways involved include phospholipase C-mediated phosphoinositide hydrolysis, inositol 1,4,5-trisphosphate, cytosolic calcium levels, calcium influx pathways, calcium/calmodulin-dependent protein kinases, diacylglycerol, protein kinases C and D, 12-hydroxyeicostetraenoic acid, phospholipase D, mitogen-activated protein kinase pathways, tyrosine kinases, adenylate cyclase, and cAMP-dependent protein kinase. A complete understanding of the signaling events regulating aldosterone biosynthesis may allow the identification of novel targets for therapeutic interventions in hypertension, primary aldosteronism, congestive heart failure, renal disease, and other cardiovascular disorders.

The multifaceted mineralocorticoid receptor

The primary adrenal cortical steroid hormones, aldosterone, and the glucocorticoids cortisol and corticosterone, act through the structurally similar mineralocorticoid (MR) and glucocorticoid receptors (GRs). Aldosterone is crucial for fluid, electrolyte, and hemodynamic homeostasis and tissue repair; the significantly more abundant glucocorticoids are indispensable for energy homeostasis, appropriate responses to stress, and limiting inflammation. Steroid receptors initiate gene transcription for proteins that effect their actions as well as rapid non-genomic effects through classical cell signaling pathways. GR and MR are expressed in many tissues types, often in the same cells, where they interact at molecular and functional levels, at times in synergy, others in opposition. Thus the appropriate balance of MR and GR activation is crucial for homeostasis. MR has the same binding affinity for aldosterone, cortisol, and corticosterone. Glucocorticoids activate MR in most tissues at basal levels and GR at stress levels. Inactivation of cortisol and corticosterone by 11β-HSD2 allows aldosterone to activate MR within aldosterone target cells and limits activation of the GR. Under most conditions, 11β-HSD1 acts as a reductase and activates cortisol/corticosterone, amplifying circulating levels. 11β-HSD1 and MR antagonists mitigate inappropriate activation of MR under conditions of oxidative stress that contributes to the pathophysiology of the cardiometabolic syndrome; however, MR antagonists decrease normal MR/GR functional interactions, a particular concern for neurons mediating cognition, memory, and affect.

Role of aldosterone blockade in resistant hypertension

Apparent treatment-resistant hypertension (aTRH), defined as uncontrolled blood pressure using 3 or more antihypertensive medications or controlled using 4 or more antihypertensive medications, affects approximately 30% of uncontrolled and 12% of controlled blood pressure (BP) patients. aTRH is used when pseudoresistance cannot be excluded (eg, BP measurement artifacts, mainly office resistance, suboptimal adherence, suboptimal treatment regimens, and true TRH). True TRH comprises approximately 30% to 50% of TRH. Patients with TRH have a high prevalence of obesity, insulin resistance, sleep apnea, and volume expansion. Aldosterone, a mineralocorticoid, is an important contributor to TRH, with primary aldosteronism present in approximately 20% of patients. Spironolactone, a mineralocorticoid-receptor antagonist, as a fourth-line agent, decreases BP 20 to 25/10 to 12 mm Hg in TRH patients with and without primary aldosteronism. The BP response to spironolactone is roughly double that of other classes of antihypertensive medications in TRH. Although approximately 70% of patients with uncontrolled TRH have estimated glomerular filtration rate of 50 or greater and a serum potassium level of 4.5 or less, which are associated with a low risk for hyperkalemia, only a small percentage receive a mineralocorticoid-receptor antagonist. This review examines the clinical epidemiology and pharmacotherapy of controlled and uncontrolled hypertension with an emphasis on aTRH, the role of aldosterone in blood pressure regulation, and the potential benefits of mineralocorticoid-receptor antagonist in uncontrolled TRH.

Aldosterone blockade in chronic kidney disease

Although blockade of the renin-angiotensin-aldosterone system with angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers has become standard therapy for chronic kidney disease (CKD), renewed interest in the role of aldosterone in mediating the injuries and progressive insults of CKD has highlighted the potential role of treatments targeting the mineralocorticoid receptor (MR). Although salt restriction is an important component of mitigating the profibrotic effects of MR activation, a growing body of literature has shown that MR antagonists, spironolactone and eplerenone, can reduce proteinuria and blood pressure in patients at all stages of CKD. These agents carry a risk of hyperkalemia, but this risk likely can be predicted based on baseline renal function and mitigated using dietary modifications and adjustments of concomitant medications. Data on hard outcomes, such as progression to end-stage renal disease and overall mortality, still are lacking in patients with CKD.

Increased aldosterone: mechanism of hypertension in obesity

The prevalence of both obesity and hypertension are increasing worldwide. Hypertension is a common consequence of obesity. Increased central adiposity is associated with increased aldosterone levels and blood pressure in human beings. A number of small studies have shown an association between obesity-mediated hypertension and mechanisms directly linked to increased levels of aldosterone. These studies have shown a trend toward relatively greater blood pressure reduction using aldosterone-receptor blockers compared with other classes of antihypertensive agents. Other than treatment for weight loss, treatment of hypertension with specific antihypertensive medications that block or reduce aldosterone action are appropriate in obese patients. Further research is needed to understand the exact role of the adipocyte in obesity-mediated hypertension.

The heart in obesity-hypertension

There is growing recognition that obesity is reaching epidemic proportions throughout the world. In adults, obesity is associated with increased cardiovascular morbidity and mortality. A series of endocrine, metabolic and hemodynamic mechanisms have been responsible for the development of obesity-hypertension. These mechanisms include: a suppressed biologic activity and availability of natriuretic peptide, increased sympathetic adrenergic activity, release of angiotensin ll from adipocytes and activation of the renin-angiotensin-aldosterone system, leptin resistance, chronic hyperleptinemia and hyperinsulinemia. The systemic hemodynamic profile of obesity includes high intravascular volume, increased cardiac output and inappropriately normal peripheral resistance. The cardiovascular adaptations to these changes include changes in vascular responsiveness and concentric-eccentric left ventricular hypertrophy, and may be responsible for increased risk of congestive heart failure, arrhythmia and sudden death.

Adiposity has unique influence on the renin-aldosterone axis and blood pressure in black children

OBJECTIVE

To comparatively examine the effects of adiposity on the levels of plasma renin activity (PRA), plasma aldosterone concentration (PAC), and aldosterone-renin ratio (ARR) in young black and white children.

STUDY DESIGN

We prospectively assessed 248 black and 345 white children and adolescents. A novel analytical technique was used to assess the concurrent influences of age and body mass index (BMI) on PRA, PAC, and ARR. The estimated effects were depicted by colored contour plots.

RESULTS

In contrast to whites, blacks had lower PRA (2.76 vs 3.36 ng/mL/h; P < .001) and lower PAC (9.01 vs 14.59 ng/dL; P < .001). In blacks, BMI was negatively associated with PRA (P = .001), consistent with an association with a more expanded plasma volume; there was no association with PAC. In whites, BMI was positively associated with PAC (P = .005); we did not detect a BMI-PRA association. The effects of BMI on ARR were directionally similar in the two race groups but more pronounced in blacks. Mean systolic blood pressure was greater in blacks with lower PRA (P < .01), higher PAC (P = .015), and higher ARR (P = .49).

CONCLUSIONS

An increase in adiposity was associated with a suppressed PRA in blacks and an increase in PAC in whites. The unique relationship between adiposity and renin-aldosterone axis in blacks suggests the possible existence of a population-specific mechanism characterized by volume expansion, which could in turn enhance the influences of adiposity on blood pressure in black children and adolescents.

A critical review of the evidence supporting aldosterone in the etiology and its blockade in the treatment of obesity-associated hypertension

Obesity is epidemic and is associated with increased blood pressure, which often manifests as treatment-resistant hypertension. Mineralocorticoids have been hypothesized to have a pathogenic role in human obesity-associated hypertension. In this review, we critically appraise the existing data regarding aldosterone in the pathophysiology and treatment of obesity-associated hypertension. We begin by reviewing the mechanisms by which obesity may increase mineralocorticoid activity. We then discuss human studies of plasma and urine aldosterone in obesity and with weight loss. From these studies, we conclude that aldosterone is often, but not always, mildly increased in obesity. Further study is needed to define circumstances in which aldosterone is increased in obesity. We discuss clinical studies in which measures of body size or weight were evaluated as potential predictors of response to mineralocorticoid receptor antagonists. In addition, we review three randomized, controlled clinical trials that exemplify a rigorous approach to determining the role of mineralocorticoid activity in a human disease. We propose that a similar clinical trial is warranted in order to definitively clarify the role of inappropriate mineralocorticoid activity in the etiology of human obesity-associated hypertension. Finally, we conclude that additional research is needed into the possible role of non-aldosterone mineralocorticoids in human obesity-associated hypertension.

Expression and roles of steroidogenic acute regulatory (StAR) protein in 'non-classical', extra-adrenal and extra-gonadal cells and tissues

The activity of the steroidogenic acute regulatory (StAR) protein is indispensable and rate limiting for high output synthesis of steroid hormones in the adrenal cortex and the gonads, known as the 'classical' steroidogenic organs (StAR is not expressed in the human placenta). In addition, studies of recent years have shown that StAR is also expressed in many tissues that produce steroid hormones for local use, potentially conferring some functional advantage by acting via intracrine, autocrine or paracrine fashion. Others hypothesized that StAR might also function in non-steroidogenic roles in specific tissues. This review highlights the evidence for the presence of StAR in 17 extra-adrenal and extra-gonadal organs, cell types and malignancies. Provided is the physiological context and the rationale for searching for the presence of StAR in such cells. Since in many of the tissues the overall level of StAR is relatively low, we also reviewed the methods used for StAR detection. The gathered information suggests that a comprehensive understanding of StAR activity in 'non-classical' tissues will require the use of experimental approaches that are able to analyze StAR presence at single-cell resolution.

Endothelial mineralocorticoid receptor activation mediates endothelial dysfunction in diet-induced obesity

Aims

Aldosterone plays a crucial role in cardiovascular disease. ‘Systemic’ inhibition of its mineralocorticoid receptor (MR) decreases atherosclerosis by reducing inflammation and oxidative stress. Obesity, an important cardiovascular risk factor, is an inflammatory disease associated with increased plasma aldosterone levels. We have investigated the role of the ‘endothelial’ MR in obesity-induced endothelial dysfunction, the earliest stage in atherogenesis.

Methods and results

C57BL/6 mice were exposed to a normal chow diet (ND) or a high-fat diet (HFD) alone or in combination with the MR antagonist eplerenone (200 mg/kg/day) for 14 weeks. Diet-induced obesity impaired endothelium-dependent relaxation in response to acetylcholine, whereas eplerenone treatment of obese mice prevented this. Expression analyses in aortic endothelial cells isolated from these mice revealed that eplerenone attenuated expression of pro-oxidative NADPH oxidase (subunits p22phox, p40phox) and increased expression of antioxidative genes (glutathione peroxidase-1, superoxide dismutase-1 and -3) in obesity. Eplerenone did not affect obesity-induced upregulation of cyclooxygenase (COX)-1 or prostacyclin synthase. Endothelial-specific MR deletion prevented endothelial dysfunction in obese (exhibiting high ‘endogenous’ aldosterone) and in ‘exogenous’ aldosterone-infused lean mice. Pre-incubation of aortic rings from aldosterone-treated animals with the COX-inhibitor indomethacin restored endothelial function. Exogenous aldosterone administration induced endothelial expression of p22phox in the presence, but not in the absence of the endothelial MR.

Conclusion

Obesity-induced endothelial dysfunction depends on the ‘endothelial’ MR and is mediated by an imbalance of oxidative stress-modulating mechanisms. Therefore, MR antagonists may represent an attractive therapeutic strategy in the increasing population of obese patients to decrease vascular dysfunction and subsequent atherosclerotic complications.

Oxidative stress in the cardiorenal metabolic syndrome

Excess visceral adiposity contributes to inappropriate activation of the renin-angiotensin-aldosterone system despite a state of volume expansion and of salt retention that contributes to subclinical elevations of pro-oxidant mechanisms. These adverse effects are mediated by excess generation of reactive oxygen species (ROS) and diminished antioxidant defense mechanisms. Excess tissue (i.e., skeletal muscle, liver, heart) free oxygen radicals contribute to impairments in the insulin-dependent metabolic signaling pathways that regulate glucose utilization/disposal and systemic insulin sensitivity. The generation of ROS is required for normal cell signaling and physiological responses. It is a loss of redox homeostasis that results in a proinflammatory/profibrotic milieu that promotes impairments in insulin metabolic signaling, reduced endothelial-mediated vasorelaxation, and associated cardiovascular and renal structural and functional abnormalities. These maladaptive processes are increasingly recognized as important in the progression of hypertension in the cardiorenal metabolic phenotype. There is increasing evidence to support a critical role for Ang II signaling through the AT(1)R and aldosterone actions through the MR in conjunction with an altered redox-mediating impaired endothelial, cardiac and renal function in this metabolic phenotype. There are emerging clinical data that indicate that therapies that target the renin angiotensin-aldosterone system (RAAS) also attenuate oxidative stress, and improve endothelial, cardiac and renal functions, which collectively contribute to reductions in hypertension.

Obesity-related hypertension: epidemiology, pathophysiology, treatments, and the contribution of perivascular adipose tissue

The advent of the obesity epidemic has highlighted the need to re-assess more closely the pathophysiology of obesity-related hypertension with the aim of identifying new therapies. In this article, we review the role of the renin-angiotensin-aldosterone system, sympathetic nervous system, and inflammation in relation to the pathophysiology of this condition. We also discuss the potential role of the perivascular adipose tissue in the context of obesity-related hypertension.

Mineralocorticoid receptors in the pathophysiology of chronic kidney diseases and the metabolic syndrome

Recent studies indicate that aldosterone/mineralocorticoid receptor (MR) is a major contributor of chronic kidney disease (CKD) progression. Aldosterone/MR induces glomerular podocyte injury, causing the disruption of the glomerular filtration barrier and proteinuria. Conversely, MR antagonists substantially reduce proteinuria, which can be partly attributable to the protective effects on podocytes. Aldosterone excess, caused by adipocyte-derived aldosterone-releasing factors and other mechanisms, can be pathologically important in the renal complication of metabolic syndrome. A rat model of metabolic syndrome exhibits podocyte injury and proteinuria with serum aldosterone elevation, and the renal damage is prevented by MR blockade. Accumulating data also indicate that MR inhibition can confer renoprotection in a subgroup with low or normal aldosterone levels. We have recently identified the cross-talk between MR and small GTPase Rac1, providing one theoretical basis for the renoprotective effects of MR antagonists in non-high-aldosterone subjects. MR blockade can be a promising strategy for preventing CKD progression, and future clinical trials will conclusively determine the efficacy and tolerability of selective MR inhibition in CKD and metabolic syndrome.

Central regulation of blood pressure by the mineralocorticoid receptor

Addition of mineralocorticoid receptor (MR) antagonists to standard therapy for heart failure, kidney disease, metabolic syndrome, and diabetes is increasing steadily in response to clinical trials demonstrating clear benefits. In addition to blocking deleterious activity of MR within the heart, vessels and kidneys, MR antagonists target MR in hemodynamic regulatory centers in the brain, thereby decreasing excessive sympathetic nervous system drive, vasopressin release, abnormal baroreceptor function, and circulating and tissue pro-inflammatory cytokines. However, brain MR are also involved with cognition, memory, affect and functions yet to be determined. Understanding specific central mechanisms involved in blood pressure regulation by MR is necessary for the development of agents to target downstream events specific to central hemodynamic regulation, not only to avoid the hypokalemia caused by inhibition of renal tubular MR, but also to avoid untoward long term effects of inhibiting brain MR that are not involved in blood pressure control.

Adrenal cell aldosterone production is stimulated by very-low-density lipoprotein (VLDL)

Very low-density lipoproteins (VLDL) are a class of large lipoprotein synthesized in the liver. The key function of VLDL, in vivo, is to carry triglyceride from the liver to adipose tissue. As a steroidogenic organ, the adrenal gland mainly uses lipoproteins as sources of cholesterol. Although VLDL receptors have been detected in the human adrenal, the function of VLDL in the adrenal gland remains unknown. Herein, we used primary cultures of human and bovine adrenal cells and the adrenocortical cell line H295R as models to determine the effects of VLDL on adrenal steroidogenesis. Our studies revealed that VLDL significantly increased aldosterone synthesis in all of the models tested. This increase was largely due to VLDL's stimulation of the expression of steroidogenic acute regulatory (StAR) protein and aldosterone synthase (CYP11B2). VLDL increased CYP11B2 mRNA expression in a concentration-dependent manner. Effects of VLDL on CYP11B2 transcript levels were not additive with angiotensin II or potassium but were additive with the cAMP pathway agonists ACTH and forskolin. Nifedipine completely inhibited the effects of VLDL on CYP11B2 mRNA, suggesting that calcium is the main signal transduction pathway used by VLDL in adrenal cells. Indeed, VLDL increased cytosolic free calcium levels. An in vivo study conducted in sucrose-fed rats showed a positive correlation between elevated triglyceride (VLDL) levels in plasma and CYP11B2 expression in the adrenal. In conclusion, we have shown that VLDL can stimulate aldosterone synthesis in adrenocortical cells by increasing StAR and CYP11B2 expression, an event likely mediated by a calcium-initiated signaling cascade.

Serum aldosterone is associated with inflammation and aortic stiffness in normotensive overweight and obese young adults

Circulating aldosterone is increased in obesity and is associated with arterial stiffening in hypertensives and older adults. The aim of this article was to determine whether serum aldosterone is associated with pulse wave velocity (PWV), a measure of arterial stiffness, in normotensive overweight and obese adults aged 20-45 years (n = 344). Heart-femoral, femoral-ankle, and brachial-ankle PWV were measured. The sample was 77% female with mean body mass index 32.9 kg/m(2) (SD 3.9), median serum aldosterone 106.5 pg/mL (interquartile range 79.9, 155.5), and mean 24-hour urinary sodium excretion 185.9 mEq/day (SD 69.6). Higher serum aldosterone was not significantly correlated with any PWV measure in bivariate analysis. However, in multiple linear regression, adjusting for age, sex, race, height, heart rate, mean arterial pressure, and waist circumference, higher log aldosterone was associated with greater log heart-femoral PWV (β(se) = 0.042(0.021), P = .049). After adjusting for C-reactive protein, this association was no longer significant (β(se) = 0.035(0.021), P = .10). Circulating aldosterone may play an important role in vascular inflammation and aortic stiffening in normotensive overweight and obese adults.

Hypertension in obesity

Obesity and HTN are on the rise in the world. HTN seems to be the most common obesity-related health problem and visceral obesity seems to be the major culprit. Unfortunately, only 31% of hypertensives are treated to goal. This translates into an increased incidence of CVD and related morbidity and mortality. Several mechanisms have been postulated as the causes of obesity-related HTN. Activation of the RAAS, SNS, insulin resistance, leptin, adiponectin, dysfunctional fat, FFA, resistin, 11 Beta dehydrogenase, renal structural and hemodynamic changes, and OSA are some of the abnormalities in obesity-related HTN. Many of these factors are interrelated. Treatment of obesity should begin with weight loss via lifestyle modifications, medications, or bariatric surgery. According to the mechanisms of obesity-related HTN, it seems that drugs that blockade the RAAS and target the SNS should be ideal for treatment. There is not much evidence in the literature that one drug is better than another in controlling obesity-related HTN. There have only been a few studies specifically targeting the obese hypertensive patient, but recent trials that emphasize the importance of BP control have enrolled both overweight and obese subjects. Until we have further studies with more in-depth information about the mechanisms of obesity-related HTN and what the targeted treatment should be, the most important factor necessary to control the obesity-related HTN pandemic and its CVD and CKD consequences is to prevent and treat obesity and to treat HTN to goal.

Cardiac hypertrophy and fibrosis in the metabolic syndrome: a role for aldosterone and the mineralocorticoid receptor

Obesity and hypertension, major risk factors for the metabolic syndrome, render individuals susceptible to an increased risk of cardiovascular complications, such as adverse cardiac remodeling and heart failure. There has been much investigation into the role that an increase in the renin-angiotensin-aldosterone system (RAAS) plays in the pathogenesis of metabolic syndrome and in particular, how aldosterone mediates left ventricular hypertrophy and increased cardiac fibrosis via its interaction with the mineralocorticoid receptor (MR). Here, we review the pertinent findings that link obesity with elevated aldosterone and the development of cardiac hypertrophy and fibrosis associated with the metabolic syndrome. These studies illustrate a complex cross-talk between adipose tissue, the heart, and the adrenal cortex. Furthermore, we discuss findings from our laboratory that suggest that cardiac hypertrophy and fibrosis in the metabolic syndrome may involve cross-talk between aldosterone and adipokines (such as adiponectin).

Association of plasma aldosterone with the metabolic syndrome in two German populations

OBJECTIVE

The aim of this study was to analyze the potential association of the plasma aldosterone concentration (PAC) with the metabolic syndrome (MetS) and its components in two German population-based studies.

METHODS

We selected 2830 and 2901 participants (31-80 years) from the follow-ups of the Study of Health in Pomerania (SHIP)-1 and the Cooperative Health Research in the Region of Augsburg (KORA) F4 respectively. MetS was defined as the presence of at least three out of the following five criteria: waist circumference ≥94 cm (men (m)) and ≥80 cm (women (w)); high-density lipoprotein (HDL) cholesterol <1.0 mmol/l (m) and <1.3 mmol/l (w); blood pressure ≥130/85 mmHg or antihypertensive treatment; non-fasting glucose (SHIP-1) ≥8 mmol/l, fasting glucose (KORA F4) ≥5.55 mmol/l or antidiabetic treatment; non-fasting triglycerides (SHIP-1) ≥2.3 mmol/l, fasting triglycerides (KORA F4) ≥1.7 mmol/l, or lipid-lowering treatment. We calculated logistic regression models by comparing the highest study- and sex-specific PAC quintiles versus all lower quintiles.

RESULTS

MetS was common with 48.1% (m) and 34.8% (w) in SHIP-1 and 42.7% (m) and 27.5% (w) in KORA F4. Our logistic regression models revealed associations of PAC with MetS, elevated triglycerides, and decreased HDL cholesterol in SHIP-1 and KORA F4.

CONCLUSIONS

Our findings add to the increasing evidence supporting a relation between aldosterone and MetS and suggest that aldosterone may be involved in the pathophysiology of MetS and lipid metabolism disorders.

Obesity-related hypertension: epidemiology, pathophysiology, and clinical management

The prevalence of obesity, including childhood obesity, is increasing worldwide. Weight gain is associated with increases in arterial pressure, and it has been estimated that 60-70% of hypertension in adults is attributable to adiposity. Centrally located body fat, associated with insulin resistance and dyslipidemia, is a more potent determinant of blood pressure elevation than peripheral body fat. Obesity-related hypertension may be a distinct hypertensive phenotype with distinct genetic determinants. Mechanisms of obesity-related hypertension include insulin resistance, sodium retention, increased sympathetic nervous system activity, activation of renin-angiotensin-aldosterone, and altered vascular function. In overweight individuals, weight loss results in a reduction of blood pressure, however, this effect may be attenuated in the long term. An increasing number of community-based programs (including school programs and worksite programs) are being developed for the prevention and treatment of obesity. Assessment and treatment of the obese hypertensive patient should address overall cardiovascular disease (CVD) risk. There are no compelling clinical trial data to indicate that any one class of antihypertensive agents is superior to others, and in general the principles of pharmacotherapy for obese hypertensive patients are not different from nonobese patients. Future research directions might include: (i) development of effective, culturally sensitive strategies for the prevention and treatment of obesity; (ii) clinical trials to identify the most effective drug therapies for reducing CVD in obese, hypertensive patients; (iii) continued search for the genetic determinants of the obese, hypertensive phenotype.

Aldosterone: a forgotten mediator of the relationship between psychological stress and heart disease

Numerous studies support the notion that cumulative exposure to chronic stress is a risk factor for cardiovascular disease (CVD). Various stress-related hormones have been proposed as potential mediators of the relationship between psychological stress and CVD, including catecholamines and more indirectly, cortisol. Somewhat surprisingly, although aldosterone is also released in response to hypothalamic-pituitary-adrenal (HPA) axis activation, it has not been considered as relevant for this relationship. In the present review we will consider aldosterone as a potentially important mediator of the relationship between negative affective states and CVD. First, we will briefly review the known functions and roles of aldosterone, and then consider its actions in both the brain and the periphery. We will then review the available literature on the role of aldosterone in CVD, and also consider links between aldosterone and various forms of chronic psychological stress. Finally we will present an integrated model of how aldosterone may mediate effects of chronic stress on CVD, recommend new directions for research, and identify important methodological and design issues for this work.

Clinical effects of eplerenone, a selective aldosterone blocker, in Japanese patients with essential hypertension

Eplerenone, a selective aldosterone blocker, has become clinically available in Japan since 2007. It has been reported that eplerenone has a potential antihypertensive effect, with a profile slightly different from that of spironolactone, and has fewer adverse reactions, suggesting that it may become a first-line treatment for hypertension. However, clinical data on hypertensive patients in Japan are lacking for eplerenone. In this study, we explored the clinical efficacy of eplerenone when it is added to an angiotensin-converting enzyme (ACE) inhibitor or a long-acting calcium channel blocker (CCB) in 68 (31 males, 37 females) Japanese patients with essential hypertension. After adding 50 mg of eplerenone to their basal treatment, blood pressure was significantly reduced at 4 weeks, and further reduced after 24 weeks of eplerenone treatment. Urinary albumin excretion decreased significantly after 24 weeks. There were no significant differences in general biochemical test values or electrolytes, but fasting serum triglycerides were significantly decreased after eplerenone treatment. The serum potassium level showed no significant change during treatment. There were no significant correlations between plasma renin activity or plasma aldosterone concentration (PAC) before eplerenone treatment and blood pressure after eplerenone treatment, showing that the antihypertensive effect of eplerenone is not affected by the patient's renin profile or pretreatment PAC values. Eplerenone was also effective in hypertensive patients with metabolic syndrome. In conclusion, eplerenone, when coadministered with an ACE inhibitor or a long-acting CCB, caused an extremely beneficial antihypertensive effect in Japanese patients with essential hypertension, without few clinically important adverse events.