Are there effects of renin-angiotensin system antagonists beyond blood pressure control?

Vascular remodelling in cardiovascular diseases: hypertension, oxidation, and inflammation

Optimal vascular structure and function are essential for maintaining the physiological functions of the cardiovascular system. Vascular remodelling involves changes in vessel structure, including its size, shape, cellular and molecular composition. These changes result from multiple risk factors and may be compensatory adaptations to sustain blood vessel function. They occur in diverse cardiovascular pathologies, from hypertension to heart failure and atherosclerosis. Dynamic changes in the endothelium, fibroblasts, smooth muscle cells, pericytes or other vascular wall cells underlie remodelling. In addition, immune cells, including macrophages and lymphocytes, may infiltrate vessels and initiate inflammatory signalling. They contribute to a dynamic interplay between cell proliferation, apoptosis, migration, inflammation, and extracellular matrix reorganisation, all critical mechanisms of vascular remodelling. Molecular pathways underlying these processes include growth factors (e.g., vascular endothelial growth factor and platelet-derived growth factor), inflammatory cytokines (e.g., interleukin-1β and tumour necrosis factor-α), reactive oxygen species, and signalling pathways, such as Rho/ROCK, MAPK, and TGF-β/Smad, related to nitric oxide and superoxide biology. MicroRNAs and long noncoding RNAs are crucial epigenetic regulators of gene expression in vascular remodelling. We evaluate these pathways for potential therapeutic targeting from a clinical translational perspective. In summary, vascular remodelling, a coordinated modification of vascular structure and function, is crucial in cardiovascular disease pathology.

The angiotensin II receptors type 1 and 2 modulate astrocytes and their crosstalk with microglia and neurons in an in vitro model of ischemic stroke

BACKGROUND

Astrocytes are the most abundant cell type of the central nervous system and are fundamentally involved in homeostasis, neuroprotection, and synaptic plasticity. This regulatory function of astrocytes on their neighboring cells in the healthy brain is subject of current research. In the ischemic brain we assume disease specific differences in astrocytic acting. The renin-angiotensin-aldosterone system regulates arterial blood pressure through endothelial cells and perivascular musculature. Moreover, astrocytes express angiotensin II type 1 and 2 receptors. However, their role in astrocytic function has not yet been fully elucidated. We hypothesized that the angiotensin II receptors impact astrocyte function as revealed in an in vitro system mimicking cerebral ischemia. Astrocytes derived from neonatal wistar rats were exposed to telmisartan (angiotensin II type 1 receptor-blocker) or PD123319 (angiotensin II type 2 receptor-blocker) under normal conditions (control) or deprivation from oxygen and glucose. Conditioned medium (CM) of astrocytes was harvested to elucidate astrocyte-mediated indirect effects on microglia and cortical neurons.

RESULT

The blockade of angiotensin II type 1 receptor by telmisartan increased the survival of astrocytes during ischemic conditions in vitro without affecting their proliferation rate or disturbing their expression of S100A10, a marker of activation. The inhibition of the angiotensin II type 2 receptor pathway by PD123319 resulted in both increased expression of S100A10 and proliferation rate. The CM of telmisartan-treated astrocytes reduced the expression of pro-inflammatory mediators with simultaneous increase of anti-inflammatory markers in microglia. Increased neuronal activity was observed after treatment of neurons with CM of telmisartan- as well as PD123319-stimulated astrocytes.

CONCLUSION

Data show that angiotensin II receptors have functional relevance for astrocytes that differs in healthy and ischemic conditions and effects surrounding microglia and neuronal activity via secretory signals. Above that, this work emphasizes the strong interference of the different cells in the CNS and that targeting astrocytes might serve as a therapeutic strategy to influence the acting of glia-neuronal network in de- and regenerative context.

Fibulin-1 promotes intimal hyperplasia after venous stent implantation through ACE mediated angiotensin II signaling

Objective

Stent intimal hyperplasia leads to in stent restenosis and thrombosis. This study determined whether Fibulin-1 activity in smooth muscle cells (SMCs) contributes to stent restenosis or thrombosis.

Methods

Stent implantation was conducted in a pig model. Target vessel samples were stained and analyzed by protein mass spectrometry. Cell experiments and Fibulin-1 SMC specific knockout mice (Fbln1SMKO) were used to investigate the mechanism of Fibulin-1 induced SMC proliferation and thrombosis.

Results

SMC proliferation and phenotypic transition are the main pathological changes of intimal hyperplasia in venous stents. Protein mass spectrometry analysis revealed a total of 67 upregulated proteins and 39 downregulated proteins in intimal hyperplasia after stent implantation compared with normal iliac vein tissues. Among them, Fibulin-1 ranked among the top proteins altered. Fibulin-1 overexpressing human SMCs (Fibulin-1-hSMCs) showed increased migration and phenotypic switching from contractile to secretory type and Fibulin-1 inhibition decreased the activity of SMCs. Mechanistically, Fibulin-1-hSMCs displayed increased levels of angiotensin converting enzyme (ACE) expression and angiotensin II signaling. Inhibition of ACE or angiotensin II signaling alleviated the migration of Fibulin-1-hSMCs. Using Fibulin-1 SMC specific knockout mice (Fbln1SMKO) and venous thrombosis model, we demonstrated that Fibulin-1 deletion attenuated intimal SMCs proliferation and thrombosis. Further, Fibulin-1 concentration was high in iliac vein compression syndrome (IVCS) patients treated with stent and was an independent predictor of venous insufficiency.

Conclusions

Fibulin-1 promotes SMC proliferation partially through ACE secretion and angiotensin II signaling after stent implantation. Fibulin-1 plays a role in venous insufficiency syndrome, implicating the protein in the detection and treatment of IVCS.

Polypill-based strategy vs. usual care for secondary prevention of cardiovascular disease: a meta-analysis of randomized controlled trials

AIMS

We aimed to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the impact of a polypill-based strategy (PBS) on therapeutic adherence and cardiovascular outcomes compared with usual care for secondary prevention of cardiovascular diseases (CVDs).

METHODS AND RESULTS

We systematically searched PubMed, Cochrane, and Scopus databases from inception to January 2023, including RCTs comparing PBS with usual care in patients with prior CVD. We assessed efficacy outcomes of therapeutic adherence, systolic blood pressure (SBP), and LDL-cholesterol (LDL-C) and safety outcomes of all-cause and cardiovascular mortality. Statistical analysis was performed with Review Manager 5.4.1 and R Version 4.2.1. A total of 8 RCTs with a population of 6541 individuals were included, of whom 3318 (50.7%) were treated with the PBS. Follow-up ranged from 6 to 60 months. The polypill-based strategy was associated with a significantly increased therapeutic adherence [risk ratio (RR) 1.22; 95% confidence interval (CI) 1.10-1.34; P < 0.001]. Cardiovascular mortality (RR 0.61; 95% CI 0.44-0.85; P = 0.004), SBP [mean difference (MD) -1.47 mmHg; 95% CI -2.86 to -0.09; P = 0.04], and LDL-C (MD -3.83 mg/dL; 95% CI -6.99 to -0.67; P = 0.02) were significantly lower in the PBS group. The incidence of all-cause mortality was similar between groups (RR 0.83; 95% CI 0.54-1.29; P = 0.41).

CONCLUSION

In patients with pre-existing CVD, a PBS is associated with lower cardiovascular mortality and improved therapeutic adherence, along with a modest decrease in SBP and LDL-C compared with usual care. Thus, a PBS may be considered a preferred option for this patient population.

Disease modification achievement in patients with lupus nephritis in a real-life setting: mission impossible?

OBJECTIVE

A preliminary definition of disease modification (DM) in lupus nephritis (LN) was recently developed focusing on long-term remission and damage prevention, with minimal treatment-associated toxicity. We aimed to further specify aspects of DM criteria in LN, assess DM achievement in a real-world setting and examine potential DM predictors and long-term outcomes.

METHODS

We collected clinical/laboratory and histological inception cohort data from biopsy-proven LN patients (82% females) with ≥72 months follow-up at two joint academic centres. Specific criteria for 24-hour proteinuria, estimated glomerular filtration rate (eGFR), renal flares and glucocorticoids dose were set at three time frames (months 0-12, 13-60 and 72) to assess DM. In the first model, DM was achieved if patients fulfilled all four criteria at all three time frames (achievers). In the second model, the continued glucocorticoids reduction criterion was excluded. Logistic regression analyses were performed. Possible different trends in DM achievement between past and recent decades were also investigated.

RESULTS

DM was achieved by 60% of patients, increased to 70% when glucocorticoids excluded from DM criteria. 24-hour proteinuria at 9 months predicted DM achievement (OR 0.72, 95% CI 0.53 to 0.97, p=0.03), but none of baseline characteristics. Among patients with >72 month follow-up, non-achievers had worse renal outcomes (flares, >30% proteinuria increase, eGFR decline) than achievers at the end of follow-up (median 138 months). Patients diagnosed between 1992 and 2005 were found to have significantly lower percentages of DM achievement and met less often the glucocorticoids dose reduction criterion in all three time frames, compared with those diagnosed between 2006 and 2016 (p=0.006 and p<0.01, respectively).

CONCLUSIONS

DM was achieved by only 60% of LN patients in a real-life setting, partly due to lack of glucocorticoids dose target attainment, while DM failure was associated with worse long-term renal outcomes. This may imply limitations in the effectiveness or implementation of current LN treatments, supporting the need for novel therapeutic strategies.

New pharmacological agents and novel cardiovascular pharmacotherapy strategies in 2022

Cardiovascular diseases (CVD) remain the leading cause of death worldwide and pharmacotherapy of most of them is suboptimal. Thus, there is a clear unmet clinical need to develop new pharmacological strategies with greater efficacy and better safety profiles. In this review, we summarize the most relevant advances in cardiovascular pharmacology in 2022 including the approval of first-in-class drugs that open new avenues for the treatment of obstructive hypertrophic cardiomyopathy (mavacamten), type 2 diabetes mellitus (tirzepatide), and heart failure (HF) independent of left ventricular ejection fraction (sodium-glucose cotransporter 2 inhibitors). We also dealt with fixed dose combination therapies repurposing different formulations of "old" drugs with well-known efficacy and safety for the treatment of patients with acute decompensated HF (acetazolamide plus loop diuretics), atherosclerotic cardiovascular disease (moderate-dose statin plus ezetimibe), Marfan syndrome (angiotensin receptor blockers plus β-blockers), and secondary cardiovascular prevention (i.e. low-dose aspirin, ramipril and atorvastatin), thereby filling existing gaps in knowledge, and opening new avenues for the treatment of CVD. Clinical trials confirming the role of dapagliflozin in patients with HF and mildly reduced or preserved ejection fraction, long-term evolocumab to reduce the risk of cardiovascular events, vitamin K antagonists for stroke prevention in patients with rheumatic heart disease-associated atrial fibrillation, antibiotic prophylaxis in patients at high risk for infective endocarditis before invasive dental procedures, and vutrisiran for the treatment of hereditary transthyretin-related amyloidosis with polyneuropathy were also reviewed. Finally, we briefly discuss recent clinical trials suggesting that FXIa inhibitors may have the potential to uncouple thrombosis from hemostasis and attenuate/prevent thromboembolic events with minimal disruption of hemostasis.

Polypill Strategy in Secondary Cardiovascular Prevention

BACKGROUND

A polypill that includes key medications associated with improved outcomes (aspirin, angiotensin-converting-enzyme [ACE] inhibitor, and statin) has been proposed as a simple approach to the secondary prevention of cardiovascular death and complications after myocardial infarction.

METHODS

In this phase 3, randomized, controlled clinical trial, we assigned patients with myocardial infarction within the previous 6 months to a polypill-based strategy or usual care. The polypill treatment consisted of aspirin (100 mg), ramipril (2.5, 5, or 10 mg), and atorvastatin (20 or 40 mg). The primary composite outcome was cardiovascular death, nonfatal type 1 myocardial infarction, nonfatal ischemic stroke, or urgent revascularization. The key secondary end point was a composite of cardiovascular death, nonfatal type 1 myocardial infarction, or nonfatal ischemic stroke.

RESULTS

A total of 2499 patients underwent randomization and were followed for a median of 36 months. A primary-outcome event occurred in 118 of 1237 patients (9.5%) in the polypill group and in 156 of 1229 (12.7%) in the usual-care group (hazard ratio, 0.76; 95% confidence interval [CI], 0.60 to 0.96; P = 0.02). A key secondary-outcome event occurred in 101 patients (8.2%) in the polypill group and in 144 (11.7%) in the usual-care group (hazard ratio, 0.70; 95% CI, 0.54 to 0.90; P = 0.005). The results were consistent across prespecified subgroups. Medication adherence as reported by the patients was higher in the polypill group than in the usual-care group. Adverse events were similar between groups.

CONCLUSIONS

Treatment with a polypill containing aspirin, ramipril, and atorvastatin within 6 months after myocardial infarction resulted in a significantly lower risk of major adverse cardiovascular events than usual care. (Funded by the European Union Horizon 2020; SECURE ClinicalTrials.gov number, NCT02596126; EudraCT number, 2015-002868-17.).

A Pair of "ACEs"

The emergence of the COVID-19 viral pandemic has generated a renewed interest in pharmacologic agents that target the renin angiotensin system (RAS). Angiotensin-converting enzyme 1 (ACE1) inhibitors decrease the synthesis of angiotensin II (Ang II) from its precursor angiotensin I and inhibit the breakdown of bradykinin, while Ang II receptor blockers antagonize the action of Ang II at the receptor level downstream. The actions of both classes of drugs lead to vasodilation, a blunting of sympathetic drive and a reduction in aldosterone release, all beneficial effects in hypertension and congestive heart failure. ACE2 cleaves the vasoconstrictor Ang II to produce the anti-inflammatory cytoprotective angiotensin 1-7 (Ang 1-7) peptide, which functions through the G protein-coupled receptor MAS to counteract the pathophysiologic effects induced by Ang II via its receptors, including vasoconstriction, inflammation, hypercoagulation, and fibrosis. SARS-CoV-2 enters human cells by binding ACE2 on the cell surface, decreases ACE2 activity, competes for ACE2 receptor-binding sites, and shifts the RAS toward an overexpression of Ang II, accounting for many of the deleterious effects of the virus. Thus, there is great interest in developing recombinant ACE2 as a therapeutic for prevention or treatment of COVID-19. Notably, ACE2 is highly expressed in the oral cavity, and saliva and dorsum of the tongue are major reservoirs of SARS-CoV-2. Cost-effective methods to debulk the virus in the oral cavity may aid in the prevention of viral spread. Here we review the pharmacology of targeted small molecule inhibitors of the RAS and discuss novel approaches to employing ACE2 as a therapeutic for COVID-19.

Efficacy of tripterygium glycosides combined with ARB on diabetic nephropathy: a meta-analysis

The purpose of this meta-analysis was to evaluate the beneficial and adverse effects of tripterygium glycosides (TGs) combined with angiotensin II receptor blocker (ARB) on diabetic nephropathy (DN). We searched for randomized controlled trials (RCTs) in PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang Data, Chinese Biomedical Literature Database, China Science and Technology Journal Database up to June 2017. Weighted mean difference (WMD) and standardized mean difference (SMD) were used for continuous variables and all variables were expressed by 95% confidence interval (CI). Twenty-three studies with 1810 DN patients were included in this meta-analysis. TG combined with ARB statistically significantly improved 24-h urinary total protein (24-h UTP) (SMD = −1.46; 95% CI = −1.84 to −1.09; P<0.00001), urinary albumin excretion rate (UAER) (SMD = −6.9; 95% CI = −9.65 to −4.14, P<0.00001), serum creatinine (SCr) (WMD = −7.65.14; 95% CI = −12.99 to −2.31; P=0.005) and albumin (Alb) (WMD = 5.7; 95% CI = 4.44 to 6.96; P<0.00001) more than did ARB alone. TG combined with ARB statistically significantly affected the level of serum glutamic pyruvic transaminase (SGPT) (WMD = 1.08; 95% CI = 0.04 to 2.12, P=0.04) more than did ARB alone. Compared with ARB alone, TG combined with ARB showed no significant difference in improving blood urea nitrogen (BUN) and hemoglobin A1c (HbA1c). Minor side effects from the combined treatment were observed and mainly focused on the abnormal liver function. TG combined with ARB offers a novel concept in treating DN, more high-quality RCTs are needed for better understanding and applying the combined treatment in DN.

Reversion of cardiovascular remodelling in renovascular hypertensive 2K-1C rats by renin-angiotensin system inhibitors

OBJECTIVES

Evaluate whether the RAS dual blockade would induce additional beneficial effects on cardiovascular remodelling when compared to monotherapy in renal hypertensive two kidneys-one clip (2K-1C) rats.

METHODS

Hypertensive 2K-1C and normotensive (2K) rats were treated for 14 days with submaximal doses of losartan (LOS), enalapril (ENA), losartan plus enalapril (LOS + ENA) or vehicle (water). Blood pressure and some parameters of cardiovascular remodelling were evaluated.

RESULTS

Systolic blood pressure (SBP) was higher in 2K-1C (209 ± 3 mm Hg, P < .05) than in 2K (113 ± 1 mm Hg) rats. There was an additional effect in 2K-1C treated with LOS + ENA (153 ± 9 mm Hg) on lowering SBP when compared to LOS (184 ± 12 mm Hg) or ENA (177 ± 9 mm Hg). None of the treatments had effect on SBP in 2K rats. In 2K-1C, cardiomyocyte hypertrophy was reduced by all treatments, although the cardiac hypertrophy indexes remained unchanged. 2K-1C aortas presented medial thickening that was partially reduced by the treatments. Intimal hyperplasia observed in 2K-1C (15.56 ± 0.89 µm vs 8.24 ± 0.80 µm) was reversed by ENA (9.52 ± 0.45 µm) or LOS + ENA (8.17 ± 0.53 µm). Collagen deposition was increased in 2K-1C hearts (1.77 ± 0.16 vs 1.28 ± 0.09) and aortas (8.1 ± 0.6 vs 5.2 ± 0.2). Treatment with LOS reduced (1.12 ± 0.14%) and ENA (0.81 ± 0.11%) or LOS + ENA (0.86 ± 0.11%) additionally diminished collagen only in 2K-1C hearts.

CONCLUSIONS

Submaximal doses of ACEi and/or ARB have inhibitory actions on cardiac remodelling and vascular hypertrophy not entirely dependent on their effects on blood pressure normalization in renovascular hypertensive rats. Combined therapy produced additional reduction in blood pressure than monotherapy despite a similar inhibition on cardiovascular remodelling.

Strategies and Challenges in Clinical Trials Targeting Human Aging

Interventions that target fundamental aging processes have the potential to transform human health and health care. A variety of candidate drugs have emerged from basic and translational research that may target aging processes. Some of these drugs are already in clinical use for other purposes, such as metformin and rapamycin. However, designing clinical trials to test interventions that target the aging process poses a unique set of challenges. This paper summarizes the outcomes of an international meeting co-ordinated by the NIH-funded Geroscience Network to further the goal of developing a translational pipeline to move candidate compounds through clinical trials and ultimately into use. We review the evidence that some drugs already in clinical use may target fundamental aging processes. We discuss the design principles of clinical trials to test such interventions in humans, including study populations, interventions, and outcomes. As examples, we offer several scenarios for potential clinical trials centered on the concepts of health span (delayed multimorbidity and functional decline) and resilience (response to or recovery from an acute health stress). Finally, we describe how this discussion helped inform the design of the proposed Targeting Aging with Metformin study.

Long-term antihypertensive effects of far-infrared ray irradiated from wooden board in spontaneously hypertensive rats

Background

Far-infrared ray (FIR) has been widely used in promoting health and has been shown to exert beneficial effects in vascular function. The non-thermal effect of FIR has been found to play a significant role in the protective effect on some vascular-related diseases, but its protective effects and use against hypertension have not been clearly presented.

Methods

In the present study, by using a wooden board coated with FIR-irradiated materials, we evaluated the long-term antihypertensive effect on spontaneously hypertensive rats (SHRs) in the environment in contact with the FIR-irradiated wooden board. SHRs were placed on the wooden board with or without FIR radiation for 4 weeks.

Results

The systolic blood pressure (BP) of SHRs undergoing different treatments was measured weekly using a tail-cuff method. FIR radiation significantly reduced the systolic BP of the SHRs along with a decreasing plasma level of angiotensin II and an increasing plasma level of bradykinin. In addition, long-term contact of FIR did not significantly affect the BP in normotensive Wistar Kyoto rats (WKYs).

Conclusions

Our results provided the evidence based on which FIR radiation could be considered an effective non-pharmacological choice for preventing hypertension.

What Physicians Need to Know About Renal Function in Outpatients with Heart Failure

The majority of outpatients with heart failure (HF) have chronic kidney disease (CKD) as an important comorbidity. Both glomerular filtration rate and abnormal urinary albumin excretion are major predictors of outcome in HF patients. Despite this, patients with renal dysfunction have been systematically excluded from the large randomized HF trials. There is lack of evidence for optimal treatment in these cardiorenal patients and treatment nihilism may account in part for their bad prognosis. Identifying and monitoring the progression of renal disease and making an effort to preserve renal function should be an important task in the management of all patients with HF. In this review, the current understanding of the pathophysiology of renal dysfunction in outpatients with HF will be summarized. Furthermore, important principles of the identification and management of cardiorenal patients will be described in order to make the physician more capable of managing outpatients with HF and renal dysfunction.

Angiotensin-converting enzyme-induced activation of local angiotensin signaling is required for ascending aortic aneurysms in fibulin-4-deficient mice

Aortic aneurysms are life-threatening and often associated with defects in connective tissues and mutations in smooth muscle cell (SMC) contractile proteins. Despite recent advances in understanding altered signaling in aneurysms of Marfan syndrome, the underlying mechanisms and options for pharmacological treatment for other forms of aneurysms are still under investigation. We previously showed in mice that deficiency in the fibulin-4 gene in vascular SMCs (Fbln4(SMKO)) leads to loss of the SMC contractile phenotype, hyperproliferation, and ascending aortic aneurysms. We report that abnormal up-regulation of angiotensin-converting enzyme (ACE) in SMCs and subsequent activation of angiotensin II (AngII) signaling are involved in the onset of aortic aneurysms in Fbln4(SMKO) mice. In this model, aneurysm formation was completely prevented by inhibition of the AngII pathway with losartan or captopril within a narrow therapeutic window during the first month of life, even though the altered mechanical properties of blood vessel walls were not reversed by the pharmacological treatment. The therapeutic effects of losartan in Fbln4(SMKO) mice do not require the AngII receptor type 2 (Agtr2) but likely require both type 1a (Agtr1a) and 1b (Agtr1b) receptors. The results indicate that fibulin-4 is a vascular matrix component required for regulation of local angiotensin signaling and development and maintenance of the SMC phenotype.

Telmisartan ameliorates glutamate-induced neurotoxicity: roles of AT(1) receptor blockade and PPARγ activation

Sartans (Angiotensin II AT(1) Receptor Blockers, ARBs) are powerful neuroprotective agents in vivo and protect against IL-1β neurotoxicity in vitro. The purpose of this research was to determine the extent of sartan neuroprotection against glutamate excitotoxicity, a common cause of neuronal injury and apoptosis. The results show that sartans are neuroprotective, significantly reducing glutamate-induced neuronal injury and apoptosis in cultured rat primary cerebellar granule cells (CGCs). Telmisartan was the most potent sartan studied, with an order of potency telmisartan > candesartan > losartan > valsartan. Mechanisms involved reduction of pro-apoptotic caspase-3 activation, protection of the survival PI3K/Akt/GSK-3β pathway and prevention of glutamate-induced ERK1/2 activation. NMDA receptor stimulation was essential for glutamate-induced cell injury and apoptosis. Participation of AT(1A) receptor was supported by glutamate-induced upregulation of AT(1A) gene expression and AT(1) receptor binding. Conversely, AT(1B) or AT(2) receptors played no role. Glutamate-induced neuronal injury and the neuroprotective effect of telmisartan were decreased, but not abolished, in CGCs obtained from AT(1A) knock-out mice. This indicates that although AT(1) receptors are necessary for glutamate to exert its full neurotoxic potential, part of the neuroprotective effect of telmisartan is independent of AT(1) receptor blockade. PPARγ activation was also involved in the neuroprotective effects of telmisartan, as telmisartan enhanced PPARγ nuclear translocation and the PPARγ antagonist GW9662 partially reversed the neuroprotective effects of telmisartan. The present results substantiate the therapeutic use of sartans, in particular telmisartan, in neurodegenerative diseases and traumatic brain disorders where glutamate neurotoxicity plays a significant role.

Effects of aqueous leaf extract of Asystasia gangetica on the blood pressure and heart rate in male spontaneously hypertensive Wistar rats

Background

Asystasia gangentica (A. gangetica) belongs to the family Acanthaceae. It is used to treat hypertension, rheumatism, asthma, diabetes mellitus, and as an anthelmintic in South Africa, India, Cameroun, Nigeria, and Kenya respectively. It has also been reported to inhibit the angiotensin I converting enzyme (ACE) in-vitro. Therefore, the aim of this study is to investigate the in-vivo effect of aqueous leaf extract (ALE) of A. gangetica on the blood pressure (BP) and heart rate (HR) in anaesthetized male spontaneously hypertensive rats (SHR); and to elucidate possible mechanism(s) by which it acts.

Methods

The ALE of A. gangetica (10–400 mg/kg), angiotensin I human acetate salt hydrate (ANG I, 3.1–100 μg/kg) and angiotensin II human (ANG II, 3.1–50 μg/kg) were administered intravenously. The BP and HR were measured via a pressure transducer connecting the femoral artery to a Powerlab and a computer for recording.

Results

A. gangetica significantly (p<0.05), and dose-dependently reduced the systolic, diastolic, and mean arterial BP. The significant (p<0.05) reductions in HR were not dose-dependent. Both ANG I and ANG II increased the BP dose-dependently. Co-infusion of A. gangetica (200 mg/kg) with either ANG I or ANG II significantly (p<0.05) suppressed the hypertensive effect of both ANG I and ANG II respectively, and was associated with reductions in HR.

Conclusions

A. gangetica ALE reduced BP and HR in the SHR. The reduction in BP may be a result of actions of the ALE on the ACE, the ANG II receptors and the heart rate.

Lisinopril Indifferently Improves Heart Rate Variability During Day and Night Periods in Spontaneously Hypertensive Rats

The aim of this work was to investigate the effect of 10 weeks of lisinopril treatment to spontaneously hypertensive rats (SHRs) on day/night variations of blood pressure, heart rate and autonomic cardio-regulation parameters. Male SHR with surgically implanted radio-telemetry implant that provided direct measurements of arterial pressure and electrocardiogram wave were used. Animals were allocated to two groups (n=5 each). The first group was treated with lisinopril (20 mg/kg by gavage) daily for 10 weeks (treated group); whereas the second was gavaged daily with tap water (untreated group). Arterial blood pressure, ECG and other telemetry parameters were recorded at the start and at the end of 10-week treatment. Collected data were analyzed using specialized software and were statistically tested. In addition to the expected lowering of blood pressure, spectral analysis of R-R intervals revealed that lisinopril treatment for 10 weeks significantly caused 2-3 fold increase in heart rate variability (HRV) during both active and inactive periods. However, R-R interval durations demonstrated variable distribution patterns during those periods. The cause of observed distribution pattern of R-R intervals during active and inactive periods may be of significance to better understand HRV changes and warrants further investigations.

An update on telmisartan/hydrochlorothiazide combinations for the management of hypertensive patients with additional cardiovascular risk factors

International hypertension guidelines endorse the use of combination therapy to achieve blood pressure control in the majority of patients. Angiotensin AT1 receptor blockers, in combination with diuretics, are among the preferred combinations, with telmisartan plus hydrochlorothiazide (HCTZ) being an effective and well-tolerated combination. This article provides an up-to-date review of the existing data on telmisartan/HCTZ combination for the management of hypertension in patients with additional cardiovascular risk factors, including reports emerging from a number of recent clinical trials and secondary analyses of older trials. The accumulated evidence from clinical trials demonstrates that telmisartan/HCTZ combinations are effective and well tolerated in patients with mild-to-severe hypertension, including subgroups of patients with cardiovascular risk factors such as advanced age, obesity, chronic kidney disease, diabetes mellitus and treatment-resistant hypertension.

The direct renin inhibitor aliskiren improves vascular remodelling in transgenic rats harbouring human renin and angiotensinogen genes

In the present study, we tested the hypothesis that chronic treatment with the direct rennin inhibitor aliskiren improves the remodelling of resistance arteries in dTGR (double-transgenic rats). dTGR (5 weeks) were treated with aliskiren (3 mg/kg of body mass per day) or ramipril (1 mg/kg of body mass per day) for 14 days and compared with age-matched vehicle-treated dTGR. BP (blood pressure) was similarly reduced in both aliskiren-treated and ramipril-treated rats compared with control dTGR (167±1 and 169±2 mmHg compared with 197±4 mmHg respectively; P<0.05). The M/L (media-to-lumen) ratio assessed on pressurized preparations was equally reduced in aliskiren-treated and ramipril-treated rats compared with controls (6.3±0.5 and 6.4±0.2% compared with 9.8±0.4% respectively; P<0.05). Endothelium-dependent and -independent relaxations were similar among the groups. L-NAME (NG-nitro-L-arginine methyl ester) significantly reduced acetylcholine-induced dilation in drug-treated dTGR. This effect was significantly more prominent in aliskiren-treated rats. eNOS (endothelial NO synthase) expression showed a 2-fold increase only in aliskiren-treated dTGR as compared with controls (P<0.01) and ramipril-treated dTGR (P<0.05). Plasma nitrite, as an index of NO production, was significantly increased in dTGR treated with either aliskiren or ramipril compared with controls. Only aliskiren induced a 2-fold increase in plasma nitrite, which was significantly greater than that induced by ramipril (P<0.05). gp91phox expression and ROS (reactive oxygen species) production in aorta were significantly and similarly reduced by both drugs. In conclusion, equieffective hypotensive doses of aliskiren or ramipril reduced the M/L ratio of mesenteric arteries and improved oxidative stress in dTGR. However, only aliskiren increased further NO production in the vasculature. Hence, in dTGR, direct renin inhibition induces favourable effects similar to that induced by ACE (angiotensin-converting enzyme) inhibition in improving vascular remodelling through different mechanisms.

Endogenous angiotensin II-induced p44/42 mitogen-activated protein kinase activation mediates sodium appetite but not thirst or neurohypophysial secretion in male rats

The renin-angiotensin-aldosterone system makes a critical contribution to body fluid homeostasis, and abnormalities in this endocrine system have been implicated in certain forms of hypertension. The peptide hormone angiotensin II (AngII) regulates hydromineral homeostasis and blood pressure by acting on both peripheral and brain targets. In the brain, AngII binds to the angiotensin type 1 receptor (AT1R) to stimulate thirst, sodium appetite and both arginine vasopressin (AVP) and oxytocin (OT) secretion. The present study used an experimental model of endogenous AngII to examine the role of p44/42 mitogen-activated protein kinase (MAPK) as a signalling mechanism to mediate these responses. Animals were given a combined treatment of furosemide and a low dose of captopril (furo/cap), comprising a diuretic and an angiotensin-converting enzyme inhibitor, respectively, to elevate endogenous AngII levels in the brain. Furo/cap induced p44/42 MAPK activation in key brain areas that express AT1R, and this effect was reduced with either a centrally administered AT1R antagonist (irbesartan) or a p44/42 MAPK inhibitor (U0126). Additionally, furo/cap treatment elicited water and sodium intake, and irbesartan markedly reduced both of these behaviours. Central injection of U0126 markedly attenuated furo/cap-induced sodium intake but not water intake. Furthermore, p44/42 MAPK signalling was not necessary for either furo/cap- or exogenous AngII-induced AVP or OT release. Taken together, these results indicate that p44/42 MAPK is required for AngII-induced sodium appetite but not thirst or neurohypophysial secretion. This result may allow for the discovery of more specific downstream targets of p44/42 MAPK to curb sodium appetite, known to exacerbate hypertension, at the same time as leaving thirst and neurohypophysial hormone secretion undisturbed.

Can losartan and blood pressure control peri arteriovenous fistula creation ameliorate the early associated left ventricular hypertrophic response a randomised placebo controlled trial

Background

Haemodialysis results in a left ventricular hypertrophic response. It is unclear whether tight blood pressure control or particular medications might attenuate this response. We sought to determine, in a pre-dialysis cohort on atenolol, whether Losartan might attenuate left ventricular hypertrophy post arteriovenous fistula creation in end stage kidney disease.

Materials and methods

Placebo controlled double blind randomisation of 26 patients to fixed dose atenolol plus fixed dose losartan or placebo occurred 1 day prior to fistula creation. Pre-randomisation echocardiography was repeated at 1 week and 1-month. Measurement was undertaken of blood pressure, heart rate, brain natriuretic peptide, serum creatinine and estimated glomerular filtration rate. The primary pre-specified endpoint was the change in left ventricular mass at 1 month. Non-parametric statistical comparison was performed within and between groups.

Results

There was no difference in left ventricular mass between our groups 1-month post fistula creation. In the entire cohort, change in left ventricular mass was driven by changes in blood pressure and volume loading. Blood pressure changes correlated with left ventricular mass changes seen shortly post arteriovenous fistula creation, suggesting blood pressure control during this time period may be an important part of the management of end stage kidney disease.

Conclusions

We did not see an advantage with the use of losartan with respect to diminution of the LVM response. However, our demonstrated change in LVM was relatively small compared to previous literature and suggests a possible role for beta blockade as a neurohormonal modulator around the time of arteriovenous fistula creation.

Trial registration

Clinical trials.gov (NCT00602004).

Cardio-cerebrovascular protective effects of valsartan in high-risk hypertensive patients with coronary artery disease (from the Kyoto Heart Study)

The objective was to examine whether previous coronary artery disease (CAD) influences the add-on effects of the angiotensin II receptor blocker (ARB) valsartan on cardio-cerebrovascular morbidity and mortality in high-risk hypertensive patients who participated in the Kyoto Heart Study. The primary end point was the same as in the main study: a composite of new-onset and/or worsening of cardiovascular and cerebrovascular events. Median follow-up was 3.27 years. According to the presence of previous CAD at baseline, the study population was divided into 2 groups (with CAD, n = 707; without CAD, n = 2,324) in which primary end-point events occurred more frequently in patients with CAD than in patients without CAD (15.1% vs 5.6%, hazard ratio [HR] 2.68, 95% confidence interval [CI] 2.11 to 3.42). Add-on valsartan significantly decreased the occurrence of the primary end-point events in patients with CAD (11.3% vs 19.0%, HR 0.59, 95% CI 0.41 to 0.85) and without CAD (3.7% vs 7.6%, HR 0.49, 95% CI 0.34 to 0.70) compared to non-ARB treatment. In the presence of previous CAD, patients with valsartan add-on treatment had a significantly lower prevalence of angina pectoris and stroke than those with non-ARB treatment, whereas the valsartan add-on effects on angina and stroke were not significant in the absence of CAD. Changes in blood pressure during the follow-up period did not differ significantly between study subgroups. In conclusion, in the presence or absence of previous CAD, valsartan add-on treatment prevented more cardio-cerebrovascular events than conventional non-ARB treatment in high-risk hypertensive patients. In addition, valsartan add-on treatment conferred not only an antianginal effect but also stroke prevention exclusively in hypertensive patients with CAD compared to those without CAD.

Angiotensin-converting enzyme 2 regulates renal atrial natriuretic peptide through angiotensin-(1-7)

Deficiency of ACE2 (angiotensin-converting enzyme 2), which degrades Ang (angiotensin) II, promotes the development of glomerular lesions. However, the mechanisms explaining why the reduction in ACE2 is associated with the development of glomerular lesions have still to be fully clarified. We hypothesized that ACE2 may regulate the renoprotective actions of ANP (atrial natriuretic peptide). The aim of the present study was to investigate the effect of ACE2 deficiency on the renal production of ANP. We evaluated molecular and structural abnormalities, as well as the expression of ANP in the kidneys of ACE2-deficient mice and C57BL/6 mice. We also exposed renal tubular cells to AngII and Ang-(1-7) in the presence and absence of inhibitors and agonists of RAS (renin-angiotensin system) signalling. ACE2 deficiency resulted in increased oxidative stress, as well as pro-inflammatory and profibrotic changes. This was associated with a down-regulation of the gene and protein expression on the renal production of ANP. Consistent with a role for the ACE2 pathway in modulating ANP, exposing cells to either Ang-(1-7) or ACE2 or the Mas receptor agonist up-regulated ANP gene expression. This work demonstrates that ACE2 regulates renal ANP via the generation of Ang-(1-7). This is a new mechanism whereby ACE2 counterbalances the renal effects of AngII and which explains why targeting ACE2 may be a promising strategy against kidney diseases, including diabetic nephropathy.

Telmisartan ameliorates lipopolysaccharide-induced innate immune response through peroxisome proliferator-activated receptor-γ activation in human monocytes

OBJECTIVE

Angiotensin II type 1 receptor (AT1) blockers (ARBs) reduce the bacterial endotoxin lipopolysaccharide (LPS)-induced innate immune response in human circulating monocytes expressing few AT1. To clarify the mechanisms of anti-inflammatory effects of ARBs with different peroxisome proliferator-activated receptor-γ (PPARγ)-activating potencies, we focused our study on telmisartan, an ARB with the highest PPARγ-stimulating activity.

METHODS

Human circulating monocytes and monocytic THP-1 (human acute monocytic leukemia cell line) cells were exposed to 50 ng/ml LPS with or without pre-incubation with telmisartan. AT1 mRNA and protein expressions were determined by real-time PCR and membrane receptor binding assay, respectively. The expression of pro-inflammatory factors was determined by real-time PCR, western blot analysis and ELISA. PPARγ activation was measured by electrophoretic mobility shift assay and its role was determined by pharmacological inhibition and PPARγ gene silencing.

RESULTS

In human monocytes, telmisartan significantly attenuated the LPS-induced expression of pro-inflammatory factors, the release of pro-inflammatory cytokines and prostaglandin E2, nuclear factor-κB activation and reactive oxygen species formation. In THP-1 cells, telmisartan significantly reduced LPS-induced tumor necrosis factor-α, inhibitor of κB-α, monocyte chemotactic protein-1 (MCP-1) and lectin-like oxidized low-density lipoprotein receptor-1 gene expression and MCP-1-directed migration. Telmisartan also stimulated the expression of the PPARγ target genes cluster of differentiation 36 and ATP-binding cassette subfamily G member 1 in monocytes. The anti-inflammatory effects of telmisartan were prevented by both PPARγ antagonism and PPARγ gene silencing. Anti-inflammatory effects of ARBs correlated with their PPARγ agonist potency.

CONCLUSION

Our observations demonstrate that in human monocytes, ARBs inhibit the LPS-induced pro-inflammatory response to a major extent through the PPARγ activation pathway and may be beneficial for the treatment of cardiovascular and metabolic disorders in which inflammation plays a major role.

Differential pharmacology and benefit/risk of azilsartan compared to other sartans

Azilsartan, an angiotensin II type 1 (AT₁) receptor blocker (ARB), was recently approved by regulatory authorities for treatment of hypertension and is the 8th ARB to join the clinical market. This article discusses the medical reasons for introducing a new AT₁ receptor blocker and reviews the experimental and clinical studies that have compared the functional properties of azilsartan to those of other ARBs. The main question addressed is: Does azilsartan have distinguishing features that should motivate choosing it over any of the other sartans for use in clinical practice? Based on studies conducted to date in hypertensive patients without serious comorbidities, azilsartan appears to be characterized by a superior ability to control 24-hour systolic blood pressure (BP) relative to other widely used ARBs including valsartan, olmesartan, and candesartan, and presumably others as well (eg, losartan). Compared to these other ARBs, azilsartan may increase the BP target control and response rate by an absolute value of 8%–10%. Greater antihypertensive effects of azilsartan might be due in part to its unusually potent and persistent ability to inhibit binding of angiotensin II to AT₁ receptors. Preclinical studies have indicated that azilsartan may also have potentially beneficial effects on cellular mechanisms of cardiometabolic disease and insulin sensitizing activity that could involve more than just blockade of AT₁ receptors and/or reduction in BP. However, the clinical relevance of these additional actions is unknown. Given that the general ability of antihypertensive drugs to protect against target organ damage is largely mediated by their ability to decrease BP, the enhanced antihypertensive effects of azilsartan should serve to justify clinical interest in this ARB relative to other molecules in the class that have a lower capacity to reduce BP.

Comparative efficacy and safety of combination aliskiren/amlodipine and amlodipine monotherapy in African Americans with stage 2 hypertension

Initial multiple drug therapy for hypertension achieves greater and quicker reductions and higher blood pressure (BP) control rates than monotherapy. This 8-week, prospective, multicenter, randomized, double-blind study compared the efficacy and safety of the initial combination of aliskiren/amlodipine with amlodipine monotherapy in African Americans with stage 2 hypertension. After a 1- to 4-week washout, patients received aliskiren/amlodipine 150/5 mg or amlodipine 5 mg for 1 week and then were force-titrated to aliskiren/amlodipine 300/10 mg or amlodipine 10 mg for 7 weeks. At week 8, greater reductions in mean sitting systolic BP were obtained with aliskiren/amlodipine (n = 220) than with amlodipine (n = 223) (least squares mean change [standard error of the mean], -34.1 [1.14] mm Hg vs -28.9 [1.12] mm Hg; P<.001). Ambulatory and central BP measures were consistent with clinic BP findings, although these were conducted in a small subset of patients (n = 94 in ambulatory BP monitoring substudy and n = 136 for central BP). More patients achieved goal BP (<140/90 mm Hg) with aliskiren/amlodipine than with amlodipine at week 8 (57.3% vs 48.0%; P = .051). Both treatment groups had similar adverse event rates (35.0% and 32.7%, respectively). The most common adverse events were peripheral edema (7.7% with aliskiren/amlodipine and 9.0% with amlodipine), headache, fatigue, and nausea. The combination of aliskiren/amlodipine reduced peripheral, ambulatory, and central BP more than amlodipine alone with similar tolerability in African Americans with stage 2 hypertension.

Fosinopril and losartan regulate klotho gene and nicotinamide adenine dinucleotide phosphate oxidase expression in kidneys of spontaneously hypertensive rats

BACKGROUND/AIMS

Klotho, a newly identified antiaging gene, predominantly detected in the kidney, has pleiotropic protective effects on kidney diseases. Several studies have confirmed the association between Klotho and oxidative stress. The present studies were performed to explore effects of fosinopril (Fos) and losartan (Los) on Klotho and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression in kidneys of spontaneously hypertensive rats (SHR).

METHODS

Twenty-four male 22-week-old SHR were randomly divided into three groups: model group, Fos group and Los group. Wistar-Kyoto rats were taken as control. After 8 weeks, urinary N-acetyl-β-D-glucosaminidase (NAGase), 24 h urinary protein (Upro), serum creatinine (Scr), blood urea nitrogen (BUN) and renal pathological changes were detected. Renal mRNA and protein expression of Klotho and three subunits of NADPH oxidase protein expression were evaluated.

RESULTS

As compared to the model group, NAGase, Upro, Scr and BUN were decreased; the typical renal pathological damage was relieved in the Fos or Los group. Fos or Los inhibited the reduction of Klotho expression, and reduced the elevation of NADPH oxidase expression.

CONCLUSION

Abnormal expression of Klotho and NADPH oxidase plays important roles in progression of hypertensive renal damage. Fos and Los can increase Klotho expression, and inhibit NADPH oxidase expression, which may be one of the mechanisms of their protective effects in hypertensive renal damage.

Oxidative stress and endothelial dysfunction: therapeutic implications

In a previous issue of Annals of Medicine, we presented evidence in support of the concept that an abnormally increased production of reactive oxygen species plays a central role in the genesis and progression of cardiovascular disease. While a number of preclinical lines of evidence support this concept, and despite the results of many studies suggesting a beneficial impact of antioxidant drugs on endothelial function, large clinical trials have failed to demonstrate a benefit of antioxidants on cardiovascular outcomes. Studies exploring the possibility that classical antioxidants such as vitamin C, vitamin E, selenium, or folic acid may improve the prognosis of patients with cardiac disease have substantially reported neutral-and occasionally negative-results. In contrast, medications such as statins, ACE inhibitors, certain β-blockers, or angiotensin I receptor blockers, which possess indirect 'ancillary' antioxidant properties, have been associated with beneficial effects in both preclinical studies and large clinical trials. The reasons for the failure of the 'direct' approach to antioxidant therapy, and for the success of the therapy with these drugs, are discussed in the present review.

Potential benefits of aliskiren beyond blood pressure reduction

There is now clear evidence that reducing blood pressure (BP) with a broad range of agents, including angiotensin converting enzyme inhibitors and angiotensin receptor blockers, improves cardiovascular and renal outcomes. There is also evidence suggesting that these drugs have beneficial effects that are independent of BP lowering. Aliskiren is a direct renin inhibitor that interrupts the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step. Unlike angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, aliskiren produces a sustained reduction in plasma renin activity and reduces plasma levels of angiotensin II and aldosterone. Preclinical data and clinical trials in high-risk patients using surrogate markers increasingly suggest that aliskiren can reduce the progression of end-organ damage beyond that afforded by BP control. With its unique mechanism of action, combining aliskiren with another RAAS-blocking agent that has a different mechanism of action may provide more comprehensive blockade of the RAAS, potentially conferring additional clinical benefits. Evaluation of these end-organ effects in humans is underway in clinical trials designed to assess the effects of aliskiren alone and in combination with other antihypertensive agents on cardiovascular and renal outcomes.

Effect of ACE inhibition on glomerular permselectivity and tubular albumin concentration in the renal ablation model

Despite the central role of tubular plasma proteins that characterize progressive kidney diseases, protein concentrations along the nephron in pathological conditions have not been quantified so far. We combined experimental techniques and theoretical analysis to estimate glomerular and tubular levels of albumin in the experimental model of 5/6 nephrectomy (Nx) in the rat, with or without angiotensin-converting enzyme (ACE) inhibition. We measured glomerular permselectivity by clearance of fluorescent Ficoll and albumin and used theoretical analysis to estimate tubular albumin. As expected, 5/6 Nx induced an elevation of the fractional clearance of the largest Ficoll molecules (radii >56 Å, P < 0.05), increasing the importance of the shunt pathway of the glomerular membrane and the albumin excretion rate (119 ± 41 vs. 0.6 ± 0.2 mg/24 h, P < 0.01). ACE inhibition normalized glomerular permselectivity and urinary albumin (0.5 ± 0.3 mg/24 h). Theoretical analysis indicates that with 5/6 Nx, an increased albumin filtration overcomes proximal tubule reabsorption, with a massive increase in average albumin concentration along the tubule, reaching the highest value of >2,500 μg/ml at the end of the collecting duct. ACE inhibition improved glomerular permselectivity, limiting albumin filtration under proximal tubule reabsorption capacity, with low albumin concentration along the entire nephron, averaging <13 μg/ml at the end of the collecting duct. These results reinforce our understanding of the mechanisms of renal disease progression and the effects of angiotensin II antagonism. They also suggest that evaluation of tubular protein concentration levels could help to identify patients at risk of kidney disease progression and to improve clinical management.

Enhanced angiotensin II-mediated central sympathoexcitation in streptozotocin-induced diabetes: role of superoxide anion

Studies have shown that the superoxide mechanism is involved in angiotensin II (ANG II) signaling in the central nervous system. We hypothesized that ANG II activates sympathetic outflow by stimulation of superoxide anion in the paraventricular nucleus (PVN) of streptozotocin (STZ)-induced diabetic rats. In α-chloralose- and urethane-anesthetized rats, microinjection of ANG II into the PVN (50, 100, and 200 pmol) produced dose-dependent increases in renal sympathetic nerve activity (RSNA), arterial pressure (AP), and heart rate (HR) in control and STZ-induced diabetic rats. There was a potentiation of the increase in RSNA (35.0 ± 5.0 vs. 23.0 ± 4.3%, P < 0.05), AP, and HR due to ANG II type I (AT(1)) receptor activation in diabetic rats compared with control rats. Blocking endogenous AT(1) receptors within the PVN with AT(1) receptor antagonist losartan produced significantly greater decreases in RSNA, AP, and HR in diabetic rats compared with control rats. Concomitantly, there were significant increases in mRNA and protein expression of AT(1) receptor with increased superoxide levels and expression of NAD(P)H oxidase subunits p22(phox), p47(phox), and p67(phox) in the PVN of rats with diabetes. Pretreatment with losartan (10 mg·kg(-1)·day(-1) in drinking water for 3 wk) significantly reduced protein expression of NAD(P)H oxidase subunits (p22(phox) and p47(phox)) in the PVN of diabetic rats. Pretreatment with adenoviral vector-mediated overexpression of human cytoplasmic superoxide dismutase (AdCuZnSOD) within the PVN attenuated the increased central responses to ANG II in diabetes (RSNA: 20.4 ± 0.7 vs. 27.7 ± 2.1%, n = 6, P < 0.05). These data support the concept that superoxide anion contributes to an enhanced ANG II-mediated signaling in the PVN involved with the exaggerated sympathoexcitation in diabetes.