Aldosterone increases VEGF-A production in human neutrophils through PI3K, ERK1/2 and p38 pathways

Ex Vivo 13C-Metabolic Flux Analysis of Porcine Circulating Immune Cells Reveals Cell Type-Specific Metabolic Patterns and Sex Differences in the Pentose Phosphate Pathway

In general, females present with stronger immune responses than males, but scarce data are available on sex-specific differences in immunometabolism. In this study, we characterized porcine peripheral blood mononuclear cell (PBMC) and granulocyte energy metabolism using a Bayesian 13C-metabolic flux analysis, which allowed precise determination of the glycolytic, pentose phosphate pathway (PPP), and tricarboxylic acid cycle (TCA) fluxes, together with an assessment of the superoxide anion radical (O2•-) production and mitochondrial O2 consumption. A principal component analysis allowed for identifying the cell type-specific patterns of metabolic plasticity. PBMCs displayed higher TCA cycle activity, especially glutamine-derived aspartate biosynthesis, which was directly related to mitochondrial respiratory activity and inversely related to O2•- production. In contrast, the granulocytes mainly utilized glucose via glycolysis, which was coupled to oxidative PPP utilization and O2•- production rates. The granulocytes of the males had higher oxidative PPP fluxes compared to the females, while the PBMCs of the females displayed higher non-oxidative PPP fluxes compared to the males associated with the T helper cell (CD3+CD4+) subpopulation of PBMCs. The observed sex-specific differences were not directly attributable to sex steroid plasma levels, but we detected an inverse correlation between testosterone and aldosterone plasma levels and showed that aldosterone levels were related with non-oxidative PPP fluxes of both cell types.

Aldosterone Increases Vascular Permeability in Rat Skin

The aim of this study was to evaluate the effect of acute aldosterone (ALDO) administration on the vascular permeability of skin. ALDO was injected intradermally into rats, and vascular permeability was measured. Eplerenone (EPL), a selective mineralocorticoid receptor (MR) antagonist, was used. Skin biopsies were carried out for immunohistochemical (IHC) staining, and polymerase chain reactions were performed to analyze the expression of MR, 11β-hydroxysteroid dehydrogenase type 2, von Willebrand factor (vWF), vascular endothelial growth factor (VEGF), and zonula occludens 1. Our study showed the presence of MR in the rat skin vasculature for the first time. It was found that ALDO injection resulted in a more than 30% increase in vascular permeability and enhanced the endothelial exocytosis of vWF. The effect of ALDO diminished after EPL administration. An accumulation of vWF and a reduction in VEGF IHC staining were observed following chronic EPL administration. No effect of ALDO or EPL on the mRNA expression of the studied genes or skin structure was observed. The results suggest that ALDO increases vascular permeability in the skin via an MR-dependent mechanism. This effect of ALDO on skin microcirculation may have important therapeutic implications for diseases characterized by increased levels of ALDO and coexisting skin microangiopathy.

Vascular and hormonal interactions in the adrenal gland

Primary aldosteronism is the most common form of secondary arterial hypertension, due to excessive aldosterone production from the adrenal gland. Although somatic mutations have been identified in aldosterone producing adenoma, the exact mechanisms leading to increased cell proliferation and nodule formation remain to be established. One hypothesis is that changes in vascular supply to the adrenal cortex, due to phenomena of atherosclerosis or high blood pressure, may influence the morphology of the adrenal cortex, resulting in a compensatory growth and nodule formation in response to local hypoxia. In this review, we will summarize our knowledge on the mechanisms regulating adrenal cortex development and function, describe adrenal vascularization in normal and pathological conditions and address the mechanisms allowing the cross-talk between the hormonal and vascular components to allow the extreme tissue plasticity of the adrenal cortex in response to endogenous and exogenous stimuli. We will then address recent evidence suggesting a role for alterations in the vascular compartment that could eventually be involved in nodule formation and the development of primary aldosteronism.

Neutrophil gelatinase-associated lipocalin as an immunomodulator in endocrine hypertension

In recent studies, primary aldosteronism (PA) has been reported as the most common etiology for secondary hypertension of endocrine origin, accounting for approximately 10% of cases. In PA, excess aldosterone production can lead to deleterious effects at the cardiovascular (CV) and renal levels by activating mineralocorticoid receptors, which involves an increase in pro-inflammatory and pro-fibrotic mediators. Among these mediators, neutrophil gelatinase-associated lipocalin (NGAL), a secretion glycoprotein belonging to the lipocalin superfamily, has been closely linked to CV and renal damage in several pathological conditions. Because NGAL can be detected in biofluids such as plasma and urine, it has been proposed as a damage biomarker for target tissues and has also been studied for its role in hypertension and associated with PA. NGAL is produced by many different cell types, can be carried on extracellular vesicles, and is modulated by microRNAs, which would support its use as a biomarker for endocrine hypertension due to PA. Over the last decade, studies have shown that NGAL is necessary for the development of aldosterone-induced hypertension and that is associated with end-organ damage. In addition, it has been proposed that some mechanisms are dependent on the activation of immune cells, such as dendritic cells and macrophages, where the release of specific cytokines (i.e., interleukin [IL]-23) or chemokines (i.e., CCL-5) induced by aldosterone would depend on NGAL. Subsequently, this activates the T helper (Th) lymphocytes, such as Th₁₇ and Th₂, resulting in CV and renal fibrosis due to the high aldosterone levels. Although the immune system has been closely associated with essential hypertension, its participation in endocrine hypertension has not been fully elucidated. This review discusses the link between NGAL and endocrine hypertension, particularly in the context of PA, and their possible regulators and mechanisms, with a focus on its role as an immunomodulator.

Angiotensin-converting enzyme 2: a key enzyme in key organs

2020 marked the 20th anniversary of the discovery of the angiotensin-converting enzyme 2 (ACE2). This major event that changed the way we see the renin-angiotensin system today could have passed quietly. Instead, the discovery that ACE2 is a major player in the severe acute respiratory syndrome coronavirus 2 pandemic has blown up the literature regarding this enzyme. ACE2 connects the classical arm renin-angiotensin system, consisting mainly of angiotensin II peptide and its AT1 receptor, with a protective arm, consisting mainly of the angiotensin 1-7 peptide and its Mas receptor. In this brief article, we have reviewed the literature to describe how ACE2 is a key protective arm enzyme in the function of many organs, particularly in the context of brain and cardiovascular function, as well as in renal, pulmonary and digestive homeostasis. We also very briefly review and refer to recent literature to present an insight into the role of ACE2 in determining the course of coronavirus diseases 2019.

Mesenchymal stem cell-derived exosomes for gastrointestinal cancer

Gastrointestinal (GI) malignancies, a series of malignant conditions originating from the digestive system, include gastric cancer, hepatocellular carcinoma, pancreatic cancer, and colorectal cancer. GI cancers have been regarded as the leading cancer-related cause of death in recent years. Therefore, it is essential to develop effective treatment strategies for GI malignancies. Mesenchymal stem cells (MSCs), a type of distinct non-hematopoietic stem cells and an important component of the tumor microenvironment, play important roles in regulating GI cancer development and progression through multiple mechanisms, such as secreting cytokines and direct interactions. Currently, studies are focusing on the anti-cancer effect of MSCs on GI malignancies. However, the effects and functional mechanisms of MSC-derived exosomes on GI cancer are less studied. MSC-derived exosomes can regulate GI tumor growth, drug response, metastasis, and invasion through transplanting proteins and miRNA to tumor cells to activate the specific signal pathway. Besides, the MSC-derived exosomes are also seen as an important drug delivery system and have shown potential in anti-cancer treatment. This study aims to summarize the effect and biological functions of MSC-derived exosomes on the development of GI cancers and discuss their possible clinical applications for the treatment of GI malignancies.

Propranolol Participates in the Treatment of Infantile Hemangioma by Inhibiting HUVECs Proliferation, Migration, Invasion, and Tube Formation

OBJECTIVE

Infantile hemangiomas (IHs) are the most common benign tumors in infancy. The purpose of this study was to study the effects of propranolol on the function of human umbilical vein endothelial cells (HUVECs), in order to preliminarily elucidate the mechanism of propranolol in the treatment of IHs.

METHODS

HUVECs were treated with different concentrations of propranolol (30 μM, 60 μM, 90 μM, and 120 μM) with or without VEGF. Their proliferation, migration, invasion, adhesion, and tube formation ability were tested by using CCK-8, wound healing assay, transwell, cell adhesion assay, and tube formation assay. The expressions of HUVECs angiogenesis signaling molecules pERK/ERK, pAKT/AKT, p-mTOR/mTOR, and pFAK/FAK were detected by Western blot.

RESULTS

Compared with the control group, propranolol could significantly inhibit the proliferation, migration, invasion, adhesion, and tube formation of HUVECs. Further studies showed that it could not only inhibit the migration, invasion, and tube formation ability of HUVECs after VEGF induction but also inhibit the phosphorylated protein expressions of angiogenesis-related signaling molecules like AKT, mTOR, ERK, and FAK in HUVECs, with a concentration-dependent inhibitory effect.

CONCLUSION

Propranolol can inhibit the proliferation, migration, invasion, adhesion, and tube formation of hemangioma endothelial cells; block VEGF-mediated angiogenesis signaling pathway; suppress the expressions of downstream angiogenesis-related signaling molecules; and ultimately achieve the effect of treatment of IHs.

Is Spironolactone the Preferred Renin-Angiotensin-Aldosterone Inhibitor for Protection Against COVID-19?

ABSTRACT

The high mortality of specific groups from COVID-19 highlights the importance of host-viral interactions and the potential benefits from enhancing host defenses. SARS-CoV-2 requires angiotensin-converting enzyme (ACE) 2 as a receptor for cell entry and infection. Although both ACE inhibitors and spironolactone can upregulate tissue ACE2, there are important points of discrimination between these approaches. The virus requires proteolytic processing of its spike protein by transmembrane protease receptor serine type 2 (TMPRSS2) to enable binding to cellular ACE2. Because TMPRSS2 contains an androgen promoter, it may be downregulated by the antiandrogenic actions of spironolactone. Furin and plasmin also process the spike protein. They are inhibited by protease nexin 1 or serpin E2 (PN1) that is upregulated by angiotensin II but downregulated by aldosterone. Therefore, spironolactone should selectively downregulate furin and plasmin. Furin also promotes pulmonary edema, whereas plasmin promotes hemovascular dysfunction. Thus, a downregulation of furin and plasmin by PN1 could be a further benefit of MRAs beyond their well-established organ protection. We review the evidence that spironolactone may be the preferred RASSi to increase PN1 and decrease TMPRSS2, furin, and plasmin activities and thereby reduce viral cell binding, entry, infectivity, and bad outcomes. This hypothesis requires direct investigation.

Vasculometabolic and Inflammatory Effects of Aldosterone in Obesity

CONTEXT

Not all obese individuals develop cardiovascular disease (CVD). Hyperaldosteronism is suggested to cause inflammation and metabolic dysregulation, and might contribute to CVD development in obese individuals.

OBJECTIVE

We aimed to investigate the association of aldosterone concentrations with inflammation, metabolic disturbances, and atherosclerosis in overweight and obese individuals. Additionally, we measured renin concentrations to investigate whether the observed effects reflected general activation of the renin-angiotensin-aldosterone system (RAAS).

DESIGN

A cross-sectional cohort study (300-OB study) was conducted. Various inflammatory parameters, traits of the metabolic syndrome, lipidome and metabolome parameters, fat distribution, and carotid atherosclerosis were associated with plasma aldosterone and renin levels.

SETTING

The setting of this study was the Radboudumc (i.o. Radboudumc), the Netherlands.

PATIENTS

A total of 302 individuals with a body mass index greater than or equal to 27 kg/m2 participated.

MAIN OUTCOME MEASURES AND RESULTS

Aldosterone was associated with various markers of inflammation and metabolic dysregulation, which partly differed from the associations observed for renin. Although both were associated with inflammatory cell numbers, only renin was associated with classical markers of systemic inflammation. Both were associated with the metabolic syndrome and hepatic steatosis. Of the traits that constitute metabolic syndrome, aldosterone, but not renin, was associated with triglyceride concentrations. Accordingly, aldosterone was associated with large very low-density lipoprotein particles; metabolomics studies further associated aldosterone with urate concentrations and derivatives of the linoleic acid metabolism pathway. Neither aldosterone nor renin was associated with atherosclerotic plaque thickness.

CONCLUSIONS

Aldosterone is not an important driver of systemic inflammation in the obese, whereas aldosterone concentrations and metabolic dysregulation are strongly intertwined in these individuals. Although prospective studies are necessary to validate these results, the independent effects of aldosterone on carotid atherosclerosis appear modest.

Angiotensin-Converting Enzyme 2: SARS-CoV-2 Receptor and Regulator of the Renin-Angiotensin System: Celebrating the 20th Anniversary of the Discovery of ACE2

ACE2 (angiotensin-converting enzyme 2) has a multiplicity of physiological roles that revolve around its trivalent function: a negative regulator of the renin-angiotensin system, facilitator of amino acid transport, and the severe acute respiratory syndrome-coronavirus (SARS-CoV) and SARS-CoV-2 receptor. ACE2 is widely expressed, including, in the lungs, cardiovascular system, gut, kidneys, central nervous system, and adipose tissue. ACE2 has recently been identified as the SARS-CoV-2 receptor, the infective agent responsible for coronavirus disease 2019, providing a critical link between immunity, inflammation, ACE2, and cardiovascular disease. Although sharing a close evolutionary relationship with SARS-CoV, the receptor-binding domain of SARS-CoV-2 differs in several key amino acid residues, allowing for stronger binding affinity with the human ACE2 receptor, which may account for the greater pathogenicity of SARS-CoV-2. The loss of ACE2 function following binding by SARS-CoV-2 is driven by endocytosis and activation of proteolytic cleavage and processing. The ACE2 system is a critical protective pathway against heart failure with reduced and preserved ejection fraction including, myocardial infarction and hypertension, and against lung disease and diabetes mellitus. The control of gut dysbiosis and vascular permeability by ACE2 has emerged as an essential mechanism of pulmonary hypertension and diabetic cardiovascular complications. Recombinant ACE2, gene-delivery of Ace2, Ang 1-7 analogs, and Mas receptor agonists enhance ACE2 action and serve as potential therapies for disease conditions associated with an activated renin-angiotensin system. rhACE2 (recombinant human ACE2) has completed clinical trials and efficiently lowered or increased plasma angiotensin II and angiotensin 1-7 levels, respectively. Our review summarizes the progress over the past 20 years, highlighting the critical role of ACE2 as the novel SARS-CoV-2 receptor and as the negative regulator of the renin-angiotensin system, together with implications for the coronavirus disease 2019 pandemic and associated cardiovascular diseases.

Maternal protein restriction differentially alters the expression of AQP1, AQP9 and VEGFr-2 in the epididymis of rat offspring

Background: Maternal protein restriction causes sperm alterations in the offspring, most of which are associated with epididymal functions. Because fluid reabsorption/secretion dynamics in the epididymal environment play important roles in the process of sperm maturation and concentration, we investigated the effects of maternal protein restriction on the expression of aquaporins (AQP1 and AQP9), vascular endothelial growth factor (VEGFa), and its receptor VEGFr-2 in different stages of postnatal epididymal development. Methods: Pregnant rats were divided into groups that received normoprotein (17% protein) and low-protein diets (6% protein) during gestation and lactation. After weaning, male rats only received the standard diet and were euthanized at the predetermined ages of 21, 44 and 120 days. Results: Maternal protein restriction decreased AQP1 and AQP9 expression in the initial segment and caput epididymis compared to the increased expression of these proteins observed in the corpus and cauda at all ages. Although protein restriction reduced the microvasculature density (MVD) on postnatal day (PND) 21 and 44, the MVD was unaltered on PND 120. Conclusions: Maternal protein restriction changed the structure or function of the offspring’s epididymis, specifically by affecting fluid dynamics and vasculogenesis in important stages of epididymis development.

Evaluation of serum miR-191-5p, miR-24-3p, miR-128-3p, and miR-376c-3 in multiple sclerosis patients

BACKGROUND

Biomarkers that could be used in early diagnosis of multiple sclerosis (MS), segregation of disease subtypes, and discrimination of the aggressive disease course from the benign one are urgently needed.

OBJECTIVE

The aim of this study was to investigate the specificity of circulating microRNAs: miR-191-5p, miR-128-3p, miR-24-3p, and miR-376c-3p in MS and evaluate their association with disease activity and disability progression.

METHODS

The expressions of circulating miRNAs were studied in serum of 100 subjects (53 relapsing-remitting (RRMS), 20 primary progressive (PPMS), and 27 controls), using miScript serum miRNA RT-PCR assay techniques.

RESULTS

In comparison with controls, miR-191-5p and miR-24-3p were overexpressed in RRMS and PPMS, with no differences between the subtypes. miR-24-3p correlated positively with the disability progression index in the combined group of all patients with MS. miR-128-3p showed tendency toward the predominant expression in PPMS and correlated positively with the annual relapse rate in RRMS. miR-376c-3p expression levels did not differ between the groups, and no associations were found to clinical parameters.

CONCLUSION

This study highlighted the connection of circulating miRNAs to MS. miR-24-3p and miR-128-3p showed a tendency of association with disability accumulation and disease activity, respectively. Further studies should evaluate their suitability for clinical use.

NDV-D90 suppresses growth of gastric cancer and cancer-related vascularization

Recent reports suggest promises on using oncolytic Newcastle disease viruses (NDV) to treat different cancers, while the effects of a NDV-D90 strain on gastric cancer remain unknown. Here we showed that NDV-D90 induced gastric cancer cell apoptosis in a dose-dependent manner in 3 gastric cancer cell lines BGC-823, SGC-7901 and MKN-28. Pronounced reduction in cell invasion was detected in NDV-D90-treated BGC-823 and SGC-7901 cells, but not in MKN-28 cells. The increases in cell apoptosis and reduction in cell growth in NDV-D90-treated gastric cancer cells seemingly resulted from augmentation of p38 signaling and suppression of ERK1/2 and Akt signaling. In vivo, orthotopic injection of NDV-D90 impaired tumor growth and induced intratumoral necrosis. Tumor cells that had been pre-treated with NDV-D90 showed defect in development of implanted tumor. Moreover, NDV-D90 appeared to reduce gastric tumor vascularization, possibly through suppression of vascular endothelial growth factor A and Matrix Metallopeptidase 2. Together, our data suggest that NDV-D90 may have potential anti-cancer effects on gastric cancer.

Bone marrow-derived cells and their conditioned medium induce microvascular repair in uremic rats by stimulation of endogenous repair mechanisms

The reduced number of circulating stem/progenitor cells that is found in chronic kidney disease (CKD) patients may contribute to impaired angiogenic repair and decreased capillary density in the heart. Cell therapy with bone marrow-derived cells (BMDCs) has been shown to induce positive effects on the microvasculature and cardiac function, most likely due to secretion of growth factors and cytokines, all of which are present in the conditioned medium (CM); however, this is controversial. Here we showed that treatment with BMDC or CM restored vascular density and decreased the extent of fibrosis in a rat model of CKD, the 5/6 nephrectomy. Engraftment and differentiation of exogenous BMDCs could not be detected. Yet CM led to the mobilization and infiltration of endogenous circulating cells into the heart. Cell recruitment was facilitated by the local expression of pro-inflammatory factors such as the macrophage chemoattractant protein-1, interleukin-6, and endothelial adhesion molecules. Consistently, in vitro assays showed that CM increased endothelial adhesiveness to circulating cells by upregulating the expression of adhesion molecules, and stimulated angiogenesis/endothelial tube formation. Overall, our results suggest that both treatments exert vasculoprotective effects on the heart of uremic rats by stimulating endogenous repair mechanisms.

Natriuretic peptide receptor guanylyl cyclase-A pathway counteracts glomerular injury evoked by aldosterone through p38 mitogen-activated protein kinase inhibition

Guanylyl cyclase-A (GC-A) signaling, a natriuretic peptide receptor, exerts renoprotective effects by stimulating natriuresis and reducing blood pressure. Previously we demonstrated massive albuminuria with hypertension in uninephrectomized, aldosterone-infused, and high salt-fed (ALDO) systemic GC-A KO mice with enhanced phosphorylation of p38 mitogen-activated protein kinase (MAPK) in podocytes. In the present study, we examined the interaction between p38 MAPK and GC-A signaling. The administration of FR167653, p38 MAPK inhibitor, reduced systolic blood pressure (SBP), urinary albumin excretion, segmental sclerosis, podocyte injury, and apoptosis. To further investigate the local action of natriuretic peptide and p38 MAPK in podocytes, we generated podocyte-specific (pod) GC-A conditional KO (cKO) mice. ALDO pod GC-A cKO mice demonstrated increased urinary albumin excretion with marked mesangial expansion, podocyte injury and apoptosis, but without blood pressure elevation. FR167653 also suppressed urinary albumin excretion without reducing SBP. Finally, we revealed that atrial natriuretic peptide increased phosphorylation of MAPK phosphatase-1 (MKP-1) concomitant with inhibited phosphorylation of p38 MAPK in response to MAPK kinase 3 activation, thereby resulting in decreased mRNA expression of the apoptosis-related gene, Bax, and Bax/Bcl2 ratio in cultured podocytes. These results indicate that natriuretic peptide exerts a renoprotective effect via inhibiting phosphorylation of p38 MAPK in podocytes.

Mineralocorticoid regulation of cell function: the role of rapid signalling and gene transcription pathways

The mineralocorticoid receptor (MR) and mineralocorticoids regulate epithelial handling of electrolytes, and induces diverse effects on other tissues. Traditionally, the effects of MR were ascribed to ligand-receptor binding and activation of gene transcription. However, the MR also utilises a number of intracellular signalling cascades, often by transactivating unrelated receptors, to change cell function more rapidly. Although aldosterone is the physiological mineralocorticoid, it is not the sole ligand for MR. Tissue-selective and mineralocorticoid-specific effects are conferred through the enzyme 11β-hydroxysteroid dehydrogenase 2, cellular redox status and properties of the MR itself. Furthermore, not all aldosterone effects are mediated via MR, with implication of the involvement of other membrane-bound receptors such as GPER. This review will describe the ligands, receptors and intracellular mechanisms available for mineralocorticoid hormone and receptor signalling and illustrate their complex interactions in physiology and disease.

Role of the Renin-Angiotensin-Aldosterone System beyond Blood Pressure Regulation: Molecular and Cellular Mechanisms Involved in End-Organ Damage during Arterial Hypertension

Arterial hypertension is a common condition worldwide and an important predictor of several complicated diseases. Arterial hypertension can be triggered by many factors, including physiological, genetic, and lifestyle causes. Specifically, molecules of the renin-angiotensin-aldosterone system not only play important roles in the control of blood pressure, but they are also associated with the genesis of arterial hypertension, thus constituting a need for pharmacological interventions. Chronic high pressure generates mechanical damage along the vascular system, heart, and kidneys, which are the principal organs affected in this condition. In addition to mechanical stress, hypertension-induced oxidative stress, chronic inflammation, and the activation of reparative mechanisms lead to end-organ damage, mainly due to fibrosis. Clinical trials have demonstrated that renin-angiotensin-aldosterone system intervention in hypertensive patients lowers morbidity/mortality and inflammatory marker levels as compared to placebo patients, evidencing that this system controls more than blood pressure. This review emphasizes the detrimental effects that a renin-angiotensin-aldosterone system (RAAS) imbalance has on health considerations above and beyond high blood pressure, such as fibrotic end-organ damage.

Aldosterone up-regulates MMP-9 and MMP-9/NGAL expression in human neutrophils through p38, ERK1/2 and PI3K pathways

Aldosterone and mineralocorticoid receptors are important regulators of inflammation. During this process, chemokines and extracellular matrix degradation by matrix metalloproteases, such as MMP-9, help leukocytes reaching swiftly and infiltrating the injured tissue, two processes essential for tissue repair. Leukocytes, such as neutrophils, are a rich source of MMP-9 and possess mineralocorticoid receptors (MR). The aim of our study was to investigate whether aldosterone was able to regulate proMMP-9, active MMP-9 and MMP-9/NGAL production in human neutrophils. Here we show that aldosterone increased MMP-9 mRNA in a dose- and time-dependent manner. This hormone up-regulated also dose-dependently proMMP-9 and active MMP-9 protein release as well as the MMP-9/NGAL protein complex. PI3K, p38 and ERK1/2 inhibition diminished these aldosterone-induced neutrophil productions. Furthermore, spironolactone, a MR antagonist, counteracted aldosterone-induced increases of proMMP-9, active MMP-9 and MMP-9/NGAL complex. These findings indicate that aldosterone could participate in tissue repair by modulating neutrophil activity and favoring extracellular matrix degradation.

Non-genomic effects of spironolactone and eplerenone in cardiomyocytes of neonatal Wistar rats: do they evoke cardioprotective pathways?

Mineralocorticoid receptor (MR) antagonists of aldosterone (spironolactone and eplerenone) display beneficial effects in the treatment of cardiopathies; however, many of these responses are independent of this antagonism. The mechanisms of action of these drugs are not well known; few studies have comparatively evaluated whether eplerenone as well as spironolactone display cardioprotective effects independent of the blockade of aldosterone. To study these mechanisms, which lead to cardioprotective responses, and to evaluate comparatively their effects in vitro, we have evaluated the proliferative effect of spironolactone and eplerenone in primary culture of cardiomyocytes and fibroblasts of neonatal Wistar rats in the presence and absence of aldosterone. Spironolactone and eplerenone promoted proliferation of cardiomyocyte even in the absence of aldosterone, suggesting a signaling pathway independent of the antagonism over aldosterone. Spironolactone was able to reduce the proliferation of fibroblasts and to reverse the proliferation promoted by aldosterone, which was also displayed by eplerenone. To elucidate the biochemical pathways evoked by these drugs, we sought to analyze Ca(2+), cAMP, and cGMP, and the activity of PKC and ERK1/2. Spironolactone and eplerenone increased the levels of Ca(2+), cGMP and activity of ERK 1/2, and reversed the action of aldosterone on the activity of PKC and ERK1/2. Interestingly, only spironolactone increased the levels of cAMP. Our data support the fact that in addition to aldosterone, both spironolactone and eplerenone display rapid responses (non-genomic) such as an increase on cAMP, Ca(2+), and cGMP by spironolactone, and Ca(2+) and cGMP by eplerenone. We have observed a more consistent cardioprotection promoted by spironolactone; however, these effects have yet to be tested clinically. Therefore, our data show that these drugs do not only act as an antagonist of MR, but could lead to a new pharmacological classification of these drugs.

Roles of the circulating renin-angiotensin-aldosterone system in human pregnancy

This review describes the changes that occur in circulating renin-angiotensin-aldosterone system (RAAS) components in human pregnancy. These changes depend on endocrine secretions from the ovary and possibly the placenta and decidua. Not only do these hormonal secretions directly contribute to the increase in RAAS levels, they also cause physiological changes within the cardiovascular system and the kidney, which, in turn, induce reflex release of renal renin. High levels of ANG II play a critical role in maintaining circulating blood volume, blood pressure, and uteroplacental blood flow through interactions with the ANG II type I receptor and through increased production of downstream peptides acting on a changing ANG receptor phenotype. The increase in ANG II early in gestation is driven by estrogen-induced increments in angiotensinogen (AGT) levels, so there cannot be negative feedback leading to reduced ANG II production. AGT can exist in various forms in terms of redox state or complexed with other proteins as polymers; these affect the ability of renin to cleave ANG I from AGT. Thus, during pregnancy the rate of ANG I production varies not only because levels of renin change in response to homeostatic demand but also because AGT changes not only in concentration but in form. Activation of the circulating and intrarenal RAASs is essential for normal pregnancy outcome subserving the increased demand for salt and, hence, water during pregnancy. Thus, the complex integration of the secretions and actions of the circulating maternal renin-angiotensin system in pregnancy plays a key role in pregnancy outcome.

Aldosterone-induced osteopontin expression in vascular smooth muscle cells involves MR, ERK, and p38 MAPK

Osteopontin (OPN) is known to be one of the cytokines that is involved in the vascular inflammation caused by aldosterone (Ald). Previous reports have shown that Ald increases OPN expression, and the mechanisms for this remain to be clarified. In this study, we investigated how Ald increases OPN expression in the vascular smooth muscle cells (VSMCs) of rats. Ald increased OPN expression time dependently as well as dose dependently. This increase was diminished by spironolactone, a mineralocorticoid receptor (MR) antagonist. PD98059, an inhibitor of p42/44 MAPK pathway, and SB203580, an inhibitor of p38 MAPK pathway, suppressed Ald-induced OPN expression and secretion in VSMCs. VSMCs migration stimulated by aldosterone required OPN expression. In conclusion, these data suggest that Ald-induced OPN expression in VSMC is mediated by MR and signaling cascades involving ERK and p38 MAPK. These molecules may represent therapeutic targets for the prevention of pathological vascular remodeling.

Roles of aldosterone and oxytocin in abnormalities caused by sevoflurane anesthesia in neonatal rats

BACKGROUND

The authors sought to determine whether subjects with pathophysiological conditions that are characterized by increased concentrations of aldosterone have increased susceptibility to the side effects of neonatal anesthesia with sevoflurane.

METHODS

Postnatal day 4-20 (P4-P20) rats were exposed to sevoflurane, 6% and 2.1%, for 3 min and 60-360 min, respectively. Exogenous aldosterone was administered to imitate pathophysiological conditions with increased concentrations of aldosterone.

RESULTS

Six hours of anesthesia with sevoflurane on P4-P5 rats resulted in a more than 30-fold increase in serum concentrations of aldosterone (7.02 ± 1.61 ng/dl vs. 263.75 ± 22.31 ng/dl, mean ± SE, n = 5-6) and reduced prepulse inhibition of the acoustic startle response (F(2,37) = 5.66, P < 0.001). Administration of exogenous aldosterone during anesthesia with sevoflurane enhanced seizure-like electroencephalogram patterns in neonatal rats (48.25 ± 15.91 s vs. 222.00 ± 53.87 s, mean ± SE, n = 4) but did not affect electroencephalographic activity in older rats. Exogenous aldosterone increased activation of caspase-3 (F(3,28) = 11.02, P < 0.001) and disruption of prepulse inhibition of startle (F(3,46) = 6.36; P = 0.001) caused by sevoflurane. Intracerebral administration of oxytocin receptor agonists resulted in depressed seizure-like electroencephalogram patterns (F(2,17) = 6.37, P = 0.009), reduced activation of caspase-3 (t(11) = 2.83, P = 0.016), and disruption of prepulse inhibition of startle (t(7) = -2.9; P = 0.023) caused by sevoflurane.

CONCLUSIONS

These results suggest that adverse developmental effects of neonatal anesthesia with sevoflurane may involve both central and peripheral actions of the anesthetic. Subjects with increased concentrations of aldosterone may be more vulnerable, whereas intracerebral oxytocin receptor agonists may be neuroprotective.