aliskiren and Disease-Models--Animal

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

Topics: Amides; Animals; Anti-Inflammatory Agents; Disease Models, Animal; Drug Repositioning; Endomyocardial Fibrosis; Fibrosis; Fumarates; Humans; Nephritis, Interstitial; Oxidative Stress

Aliskiren, the first orally effective direct renin inhibitor, is an effective antihypertensive agent with distinctive properties including placebo-like tolerability, pharmacologic effects that persist after drug discontinuation, and a unique mechanism of action. When combined with agents that inhibit the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers, additional blood pressure reduction reflects more complete RAAS blockade. Concern that marked elevation in plasma renin concentration following aliskiren administration might lead to RAAS-induced paradoxical blood pressure increases appears unfounded, based upon analyses of patients participating in clinical trials. Studies in animals and humans indicate that aliskiren accumulates in renal tissue, blocks the intrarenal RAAS, and interferes with deleterious cellular effects of angiotensin II by mechanisms that may include enzymatic blockade of renin and prorenin at the site of the (pro)renin receptor. In patients with diabetic nephropathy, adding aliskiren to losartan resulted in an additional 20% reduction in urinary protein excretion. In patients with heart failure, aliskiren reduced brain natriuretic peptide levels when added to other RAAS inhibitors, suggesting an additional hemodynamic effect. The ASPIRE HIGHER clinical trials program is assessing whether the promising pharmacologic properties of aliskiren translate into long-term clinical benefits.

Topics: Amides; Animals; Antihypertensive Agents; Disease Models, Animal; Fumarates; Humans; Hypertension; Rats; Renin

To study the effect of direct renin inhibitor (aliskiren) on the renal function during acute and chronic partial ureteral obstruction (PUO) in rat solitary kidney.. Sixty male Sprague-Dawley rats were randomly allocated into three groups (20 rats each); sham, PUO and aliskiren groups. Right nephrectomy was performed in all groups. Rats in PUO and aliskiren groups were subjected to left PUO and received no treatment and aliskiren (10 mg/kg, orally, once per day till sacrification), respectively. Blood samples were then collected for biochemical measurements. Ten rats from each group were sacrificed after two weeks, while the remaining rats were sacrificed after four weeks. Left kidneys were harvested for histopathological examination, BCL-2, interleukin (IL)-6, transforming growth factor (TGF)-β1, collagen I and fibronectin relative gene expression and assessment of glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (NO) activity.. After two and four weeks of PUO, aliskiren significantly recompensed the rise of serum creatinine (Scr) and blood urea nitrogen (BUN). Aliskiren also revealed significantly better histopathological results regarding cortical and medullary necrosis, regeneration and inflammatory cell infiltration. Aliskiren group showed statistically significant up-regulation of BCL-2 and down-regulation of IL-6, TGF-β1, collagen I and fibronectin relative gene expression. Aliskiren significantly increased GSH and SOD activity and reduced MDA and NO activity. Moreover, aliskiren administration for four weeks after PUO significantly yielded more renoprotective effect compared to its administration for two weeks.. Aliskiren ameliorates the deterioration of the renal function during acute and chronic PUO in a solitary kidney.

Topics: Amides; Animals; Creatinine; Disease Models, Animal; Fumarates; Gene Expression Regulation; Kidney Function Tests; Male; Rats; Rats, Sprague-Dawley; Renin; Solitary Kidney; Time Factors; Ureteral Obstruction

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Hypertension is characterized by persistent elevated blood pressure levels, one of the leading causes of death in the world. Renovascular hypertension represents the most common cause of secondary hypertension, and its progress is associated with overactivation of the renin angiotensin aldosterone system (RAAS), causing systemic and local changes. Aliskiren is a renin-inhibiting drug that optimizes RAAS suppression. In this sense, the objective of the present study was to analyze the morphophysiology of the left kidney in Wistar rats with renovascular hypertension after treatment with Aliskiren. Parameters such as systolic blood pressure, urinary creatinine and protein excretion, renal cortex structure and ultrastructure, fibrosis and tissue inflammation were analyzed. Our results showed that the hypertensive animals treated with Aliskiren presented a reestablishment of blood pressure, expression of renin, and renal function, as well as a remodeling of morphological alterations through the reduction of fibrosis. The treatment regulated the laminin expression and decreased pro-inflammatory cytokines, restoring the integrity of the glomerular filtration barrier. Therefore, our findings suggest that Aliskiren has a renoprotective effect acting on the improvement of the morphology, physiology and pathology of the renal cortex of animals with renovascular hypertension.

Topics: Amides; Animals; Antihypertensive Agents; Disease Models, Animal; Fibrosis; Fumarates; Hypertension, Renovascular; Inflammation; Kidney; Rats; Renin-Angiotensin System

Aliskiren (ALS) is well known for its antihypertensive properties. However, the potential underlying the molecular mechanism and the anti-hypertrophic effect of ALS have not yet been fully elucidated. The aim of the present study was to investigate the role of ALS in mammalian target of rapamycin (mTOR) and apoptosis signaling using in vivo and in vitro models of cardiac hypertrophy. A rat model of cardiac hypertrophy was induced by isoproterenol treatment (5 mg·kg-1·day-1) for 4 weeks, with or without ALS treatment at 20 mg·kg-1·day-1. The expression of hypertrophic, fibrotic, and apoptotic markers was determined by RT-qPCR. The protein expression of apoptotic markers mTOR and p-mTOR was assessed by western blot analysis. The proliferation of H9C2 cells was monitored using the MTS assay. Cell apoptosis was analyzed using flow cytometry. In vivo, isoproterenol-treated rats exhibited worse cardiac function, whereas ALS treatment reversed these dysfunctions, which were associated with changes in p-mTOR, Bcl-2, Bax, and cleaved caspase-3 expression, as well as the number of apoptotic cells. In vitro, H9C2 cardiomyocyte viability was significantly inhibited and cardiac hypertrophy was induced by Ang II administration, but ALS reversed Ang II-induced H9C2 cardiomyocyte hypertrophy and death. Furthermore, Ang II triggered the activation of the mTOR and apoptosis pathways in hypertrophic cardiomyocytes that were inhibited by ALS treatment. These results indicated that ALS alleviated cardiac hypertrophy through inhibition of the mTOR and apoptosis pathways in cardiomyocytes.

Topics: Amides; Angiotensin II; Animals; Apoptosis; Blotting, Western; Cardiomegaly; Disease Models, Animal; Fibrosis; Flow Cytometry; Fumarates; Isoproterenol; Male; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; TOR Serine-Threonine Kinases

The present study was designed to evaluate the anti-inflammatory effects of different doses of aliskiren in two animal models of inflammation.. Sixty-six Wistar rats were allocated into five groups: the first group (six rats) was treated with the vehicle only, without induction of paw edema and granulomatous inflammation, and served as a negative control; the second group (12 rats) was allocated into two subgroups and treated with the vehicle only, with induction of paw edema and granulomatous inflammation, and served as a positive control; the third group (36 rats) was allocated into six subgroups and treated with different doses of aliskiren (15, 30, and 60 mg/kg) in both models; the fourth group (12 rats) was treated with dexamethasone (1 mg/kg) in both models of inflammation. Serum concentrations of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), vascular cell adhesion molecule-1 (VCAM-1), and high sensitivity C-reactive protein (hs-CRP) were measured. Skin samples were also sent for histopathological examination.. Aliskiren, in a dose-dependent pattern, significantly decreased inflammation in rat models of inflammation, by attenuating the percentage of exudate, granuloma, and paw edema. Furthermore, it significantly reduced serum concentrations of TNF-α, VCAM-1, and hs-CRP and restored the serum concentration of IL-10. Additionally, significant improvement was seen in the histopathological findings.. In the current study, aliskiren was successful in decreasing inflammation in both models. These findings suggest that aliskiren is a good candidate for the treatment of inflammatory diseases.

Topics: Amides; Animals; Anti-Inflammatory Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Edema; Female; Formaldehyde; Fumarates; Inflammation; Male; Rats; Rats, Wistar; Skin

Topics: Amides; Animals; Anticonvulsants; Avoidance Learning; Brain; Carbamazepine; Disease Models, Animal; Drug Interactions; Epilepsy, Temporal Lobe; Fumarates; Mice; Pentylenetetrazole; Phenobarbital; Seizures

(Pro)renin receptor [(P)RR] has multiple functions, but its regulation and role in the pathogenesis in glomerulonephritis (GN) are poorly defined. The aims of the present study were to determine the effects of direct renin inhibition (DRI) and demonstrate the role of (P)RR on the progression of crescentic GN. The anti-glomerular basement membrane nephritis rat model developed progressive proteinuria (83.64 ± 10.49 mg/day) and glomerular crescent formation (percent glomerular crescent: 62.1 ± 2.3%) accompanied by increased macrophage infiltration and glomerular expression of monocyte chemoattractant protein (MCP)-1, (P)RR, phospho-extracellular signal-regulated kinase (ERK)1/2, Wnt4, and active β-catenin. Treatment with DRI ameliorated proteinuria (20.33 ± 5.88 mg/day) and markedly reduced glomerular crescent formation (20.9 ± 2.6%), induction of macrophage infiltration, (P)RR, phospho-ERK1/2, Wnt4, and active β-catenin. Furthermore, primary cultured parietal epithelial cells stimulated by recombinant prorenin showed significant increases in cell proliferation. Notably, while the ERK1/2 inhibitor PD98059 or (P)RR-specific siRNA treatment abolished the elevation in cell proliferation, DRI treatment did not abrogate this elevation. Moreover, cultured mesangial cells showed an increase in prorenin-induced MCP-1 expression. Interestingly, (P)RR or Wnt4-specific siRNA treatment or the β-catenin antagonist XAV939 inhibited the elevation of MCP-1 expression, whereas DRI did not. These results suggest that (P)RR regulates glomerular crescent formation via the ERK1/2 signaling and Wnt/β-catenin pathways during the course of anti-glomerular basement membrane nephritis and that DRI mitigates the progression of crescentic GN through the reduction of (P)RR expression but not inhibition of prorenin binding to (P)RR.

Topics: Amides; Animals; beta Catenin; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Fumarates; Glomerulonephritis; Male; Mesangial Cells; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Phosphorylation; Rats, Inbred WKY; Receptors, Cell Surface; Vacuolar Proton-Translocating ATPases; Wnt Signaling Pathway; Wnt4 Protein

Topics: Amides; Animals; Anticonvulsants; Avoidance Learning; Behavior, Animal; Brain; Disease Models, Animal; Drug Interactions; Fumarates; Male; Memory, Long-Term; Mice; Motor Activity; Pentylenetetrazole; Reaction Time; Renin; Seizures; Time Factors

Our aim is to investigate the potentially preventive effects of Aliskiren in a carrageenan-induced lung pleurisy model and to compare the standard anti-inflammatory agents, indomethacin and dexamethasone. The pleurisy model was induced through the injection of carrageenan (0.2 ml-%2) into the pleural cavity. After the experiment, serum and lung tissues were collected and biochemical, molecular and pathological examinations were performed. In our study, pleural inflammation decreased superoxide dismutase activity and the glutathione level and increased the malondialdehyde level in the lung of rats, while Aliskiren increased the superoxide dismutase activity and glutathione level and decreased the malondialdehyde level. In addition, carrageenan-induced pleurisy caused a significant increase in pro-inflammatory cytokines mRNA expressions (TNF-α, IL-1β, and NF-KB), while Aliskiren administration decreased their expressions as well as the standard treatments, indomethacin and dexamethasone, did. Aliskiren administration at the 200 mg/kg dose protected the lungs in the pathological evaluation, especially against inflammatory cell infiltration and edematous lesions. It appears that Aliskiren protects the lung from carrageenan-induced pleurisy damage by regulating inflammation and antioxidant-oxidant balance via Renin Angiotensin Aldosterone System inhibition.

Topics: Amides; Animals; Anti-Inflammatory Agents; Carrageenan; Disease Models, Animal; Fumarates; Glutathione; Interleukin-1beta; Lung; Male; Malondialdehyde; NF-kappa B; Oxidative Stress; Pleurisy; Rats, Wistar; Real-Time Polymerase Chain Reaction; Renin-Angiotensin System; Tumor Necrosis Factor-alpha

Aliskiren, a renin inhibitor, has been shown to have cardioprotective and blood pressure (BP) lowering effects. We aimed to determine the effects of nanoparticle-loaded aliskiren on BP, nitric oxide synthase activity (NOS) and structural alterations of the heart and aorta developed due to spontaneous hypertension in rats. Twelve week-old male spontaneously hypertensive rats (SHR) were divided into the untreated group, group treated with powdered or nanoparticle-loaded aliskiren (25 mg/kg/day) and group treated with nanoparticles only for 3 weeks by gavage. BP was measured by tail-cuff plethysmography. NOS activity, eNOS and nNOS protein expressions, and collagen content were determined in both the heart and aorta. Vasoactivity of the mesenteric artery and wall thickness, inner diameter, and cross-sectional area (CSA) of the aorta were analyzed. After 3 weeks, BP was lower in both powdered and nanoparticle-loaded aliskiren groups with a more pronounced effect in the latter case. Only nanoparticle-loaded aliskiren increased the expression of nNOS along with increased NOS activity in the heart (by 30%). Moreover, nanoparticle-loaded aliskiren decreased vasoconstriction of the mesenteric artery and collagen content (by 11%), and CSA (by 25%) in the aorta compared to the powdered aliskiren group. In conclusion, nanoparticle-loaded aliskiren represents a promising drug with antihypertensive and cardioprotective effects.

Topics: Amides; Animals; Antihypertensive Agents; Biomarkers; Blood Pressure; Cardiovascular System; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Carriers; Fumarates; Heart; Hypertension; Nanoparticles; Nitric Oxide; Polyesters; Rats; Rats, Inbred SHR

The intrarenal renin angiotensin system (RAS) is activated in polycystic kidney disease. We have recently shown in the Pkd1 mouse that Gen 2 antisense oligonucleotide (ASO), which suppresses angiotensinogen (Agt) synthesis, is efficacious in slowing kidney cyst formation compared with lisinopril. The aim of this current study was to determine 1) if unilateral nephrectomy accelerates cystogenesis in Pkd1 mice (as previously shown in cilia knockout mice) and 2) whether Agt ASO can slow the progression in this accelerated cystic mouse model. Adult Pkd1 conditional floxed allele mice expressing cre were administered tamoxifen, resulting in global knockout of Pkd1. Three weeks after tamoxifen injection, mice underwent left unilateral nephrectomy. Mice were then treated with Agt ASO (75 mg/kg per week) or aliskiren (20 mg/kg per day)+Agt ASO or control for 8 wk. Unilateral nephrectomy accelerated kidney cyst formation compared with nonnephrectomized mice. Both Agt ASO and Aliskiren+Agt ASO treatments significantly reduced plasma and urinary Agt levels. Blood pressure was lowest in Aliskiren+Agt ASO mice among all treatment groups, and the control group had the highest blood pressure. All mice developed significant kidney cysts at 8 wk after nephrectomy, but Agt ASO and Aliskiren+Agt ASO groups had fewer kidney cysts than controls. Renal pAkt, pS6 levels, and apoptosis were significantly suppressed in those receiving Agt ASO compared with controls. These results indicate that suppressing Agt using an ASO slowed the progression of accelerated cystic kidney disease induced by unilateral nephrectomy in Pkd1 mice by suppressing intrarenal RAS, mammalian target of rapamycin pathway, and cell proliferation.

Topics: Amides; Angiotensinogen; Animals; Apoptosis; Cell Proliferation; Disease Models, Animal; Disease Progression; ErbB Receptors; Female; Fumarates; Genetic Predisposition to Disease; Kidney; Male; Mice, Knockout; Nephrectomy; Oligonucleotides, Antisense; Phenotype; Polycystic Kidney, Autosomal Dominant; Renin; Renin-Angiotensin System; Time Factors; TOR Serine-Threonine Kinases; TRPP Cation Channels

Psoriasis is a complex inflammatory and hyperproliferative skin disease. The pathogenesis and mechanisms involved are not completely understood, which makes treatment a difficult issue. Angiotensin II, the most active peptide of the renin-angiotensin system, seems to be involved in processes related to psoriasis pathogenesis, such as inflammation and cell proliferation. The aim of this study was to investigate the influence of renin inhibition on inflammation parameters and keratinocyte proliferation in a mouse model of chronic skin inflammation induced by croton oil. Aliskiren had anti-inflammatory effects by reducing levels of tumor necrosis factor-α and interleukin -6, and by inhibiting myeloperoxidase activity. Aliskiren also showed antiproliferative activity by reducing epidermal hyperplasia and proliferating cell nuclear antigen levels. Aliskiren treatment did not induce alterations in the cardiovascular system, normal skin thickness, and organ weight. These results suggest that aliskiren could be a valuable tool to be incorporated in the treatment of hyperproliferative and inflammatory skin disorders such as psoriasis.

Topics: Amides; Angiotensin II; Animals; Anti-Inflammatory Agents; Antihypertensive Agents; Cardiovascular System; Disease Models, Animal; Female; Fumarates; Inflammation; Keratinocytes; Mice; Psoriasis; Renin; Renin-Angiotensin System; Skin Diseases

The renin-angiotensin system (RAS), which plays an important role in the progression of heart failure, is efficiently blocked by the inhibition of renin, the rate-limiting enzyme in the RAS cascade. In the present study, we investigated the cardioprotective effects of TAK-272 (SCO-272, imarikiren), a novel, orally effective direct renin inhibitor (DRI), and compared its efficacy with that of aliskiren, a DRI that is already available in the market. TAK-272 was administered to calsequestrin transgenic (CSQ-tg) heart failure mouse model that show severe symptoms and high mortality. The CSQ-tg mice treated with 300 mg/kg, the highest dose tested, of TAK-272 showed significantly reduced plasma renin activity (PRA), cardiac hypertrophy, and lung congestion. Further, TAK-272 reduced cardiomyocyte injury accompanied by an attenuation of the increase in NADPH oxidase 4 and nitric oxide synthase 3 expressions. TAK-272 also prolonged the survival of CSQ-tg mice in a dose-dependent manner (30 mg/kg: P = 0.42, 100 mg/kg: P = 0.12, 300 mg/kg: P < 0.01). Additionally, when compared at the same dose level (300 mg/kg), TAK-272 showed strong and sustained PRA inhibition and reduced the heart weight and plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration, a heart failure biomarker, while aliskiren showed a significant weaker PRA inhibition and failed to demonstrate any cardioprotective effects. Our results showed that TAK-272 is an orally active and persistent renin inhibitor, which reduced the mortality of CSQ-tg mice and conferred protection against cardiac hypertrophy and injury. Thus, TAK-272 treatment could provide a new therapeutic approach for heart failure.

Topics: Amides; Animals; Benzimidazoles; Cardiovascular Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Fumarates; Heart; Heart Failure; Hypertrophy; Lung Diseases; Mice, Inbred C57BL; Mice, Inbred DBA; Mice, Transgenic; Morpholines; Piperidines; Protective Agents; Random Allocation; Renin

Because of the presence of the blood-brain barrier, brain renin-angiotensin system activity should depend on local (pro)renin synthesis. Indeed, an intracellular form of renin has been described in the brain, but whether it displays angiotensin (Ang) I-generating activity (AGA) is unknown. Here, we quantified brain (pro)renin, before and after buffer perfusion of the brain, in wild-type mice, renin knockout mice, deoxycorticosterone acetate salt-treated mice, and Ang II-infused mice. Brain regions were homogenized and incubated with excess angiotensinogen to detect AGA, before and after prorenin activation, using a renin inhibitor to correct for nonrenin-mediated AGA. Renin-dependent AGA was readily detectable in brain regions, the highest AGA being present in brain stem (>thalamus=cerebellum=striatum=midbrain>hippocampus=cortex). Brain AGA increased marginally after prorenin activation, suggesting that brain prorenin is low. Buffer perfusion reduced AGA in all brain areas by >60%. Plasma renin (per mL) was 40× to 800× higher than brain renin (per gram). Renin was undetectable in plasma and brain of renin knockout mice. Deoxycorticosterone acetate salt and Ang II suppressed plasma renin and brain renin in parallel, without upregulating brain prorenin. Finally, Ang I was undetectable in brains of spontaneously hypertensive rats, while their brain/plasma Ang II concentration ratio decreased by 80% after Ang II type 1 receptor blockade. In conclusion, brain renin levels (per gram) correspond with the amount of renin present in 1 to 20 μL of plasma. Brain renin disappears after buffer perfusion and varies in association with plasma renin. This indicates that brain renin represents trapped plasma renin. Brain Ang II represents Ang II taken up from blood rather than locally synthesized Ang II.

Topics: Amides; Angiotensin II; Angiotensinogen; Animals; Blood Pressure; Blood-Brain Barrier; Brain; Desoxycorticosterone Acetate; Disease Models, Animal; Fumarates; Hypertension; Mice; Mice, Knockout; Random Allocation; Rats; Rats, Inbred SHR; Reference Values; Renin-Angiotensin System

The local renin-angiotensin system (RAS) has been reported to have an important role in the pathogenesis and progression of metabolic bone diseases, including osteoarthritis (OA). Aliskiren is the first in a new class of orally effective direct renin inhibitors and is approved for the treatment of hypertension in humans. However, its efficacy in patients with OA is unknown. A rat model of OA was induced to investigate the potential efficacy of aliskiren. Effects of aliskiren on the cartilage structure were detected by safranin O staining and its effects on the widths of the proliferation zone and hypertrophic zone (HZ) of chondrocytes were analyzed by Masson's staining. Tartate‑resistant acid phosphatase staining was used to evaluate the effects of aliskiren on osteoclasts in the chondrocytes. Relative histological analyses were performed. Additionally, the expression levels of factors associated with osteoclast differentiation (receptor activator of nuclear factor κB ligand and osteoprotegerin), articular cartilage destruction [tumor necrosis factor‑α (TNF‑α) and matrix metalloproteinase 9] and osteoblast differentiation [runt related transcription factor 2 (Runx2)], along with RAS components (renin, renin‑receptor, angiotensin type 1 receptor (AT1R), AT2R, angiotensin converting enzyme (ACE) and angiotensin II (Ang II)] were detected in samples from the proximal tibias. Aliskiren did not fully suppress the inflammatory reaction in OA model animals and had marginal regulatory effects on biochemical bone markers induced by OA. However, aliskiren attenuated cartilage destruction, abnormal cartilage cellularity and the expansion of the HZ of chondrocytes, and significantly attenuated the expression of interleukin‑1, TNF‑α, Runx2 and procollagen type I N‑terminal propeptide. These chondroprotective properties were accompanied by reductions in the levels of RAS components (renin, Ang II, ACE and AT1R), indicating that aliskiren exerts multiple effects of on bone formation, osteoblast differentiation and articular cartilage protection via the RAS. OA activates the local bone RAS, inhibits bone formation and stimulates bone resorption. Aliskiren, a renin inhibitor, demonstrated chondroprotective efficacy in a rat model of OA through suppression of the local RAS.

Topics: Amides; Animals; Biomarkers; Cartilage, Articular; Chondrocytes; Core Binding Factor Alpha 1 Subunit; Disease Models, Animal; Fumarates; Immunohistochemistry; Matrix Metalloproteinase 9; Osteoarthritis; Osteoclasts; Protective Agents; ras Proteins; Rats; Renin-Angiotensin System; Tumor Necrosis Factor-alpha

In addition to its role in regulation of blood pressure, fluid and electrolyte homeostasis, the renin-angiotensin system (RAS) components were expressed in many other tissues suggesting potential roles in their functions.. The present study aims to evaluate the protective effect aliskiren, when used alone or in combination with azilsartan against high fat diet-induced liver disease in rats.. Thirty-two Wistar male rats, weighing 150-200 gm were allocated evenly into four groups and treated as follow: group I, rats were fed a specially formulated high-fat diet for 8 weeks to induce non-alcoholic liver disease and considered as control group; groups II, III and IV, the rats were administered azilsartan (0.5 mg/kg), aliskiren (25 mg/kg) or their combination orally via gavage tube once daily, and maintained on high fat diet for 8 weeks. The possible treatment outcome was evaluated through measuring serum levels of glucose, insulin, lipid profile, TNF-α, IL-1β and liver enzymes. Additionally, the liver tissue contents of glycogen and lipids and histological changes were also evaluated.. The results showed that azilsartan significantly improves the studied markers greater than aliskiren, and their combination o has no additive or synergistic effects on the activity of each one of them.. Both azilsartan and aliskiren protects the rats against high-fat diet induced NAFLD with predominant effects for the former, and their combination showed no beneficial synergistic or additive effects.

Topics: Amides; Animals; Benzimidazoles; Diet, High-Fat; Disease Models, Animal; Drug Therapy, Combination; Fumarates; Liver; Male; Non-alcoholic Fatty Liver Disease; Oxadiazoles; Rats; Rats, Wistar

Angiotensin II is thought to participate in aneurysm formation, because of its ability to induce and perpetuate inflammation in the aortic wall. Because activation of renin is the first step of the renin-angiotensin system, renin inhibition could inhibit all components of this system effectively. Therefore, we examined the hypothesis that direct inhibition of renin activity could decrease the expansion of aortic aneurysm using a rabbit model. Aortic dilatation was induced by incubation with elastase around the rabbit abdominal aorta. Continuous administration of a direct renin inhibitor, aliskiren, was started at 1 week before incubation with elastase and continued for 5 weeks. Treatment with aliskiren markedly inhibited tissue renin activation and resulted in a significant reduction in angiotensin I and II production in the aneurysm wall. Consequently, the inhibition of renin activity prevented the expansion of experimental aortic aneurysm associated with preservation of the medial layer, independent of its blood pressure-lowering effect. Administration of aliskiren led to the inhibition of activation of NF-κB (nuclear factor-κB), AP-1 (activator protein-1), and CREB (cAMP response element-binding protein), which are thought to cooperatively regulate the inflammatory gene expression profile associated with aneurysm formation. As a result, treatment with aliskiren inhibited macrophage accumulation through suppression of MCP-1 (monocyte chemoattractant protein-1) and CCL4 (C-C motif chemokine ligand 4) expression, and TNF-α (tumor necrosis factor-α) production and activation of MMP-2 (matrix metalloproteinase-2) and MMP-9 (matrix metalloproteinase-9) were also suppressed in the aneurysm wall. In addition, inhibition of (pro)renin receptor elevation was also observed after treatment with aliskiren. Direct inhibition of renin activity using aliskiren prevented the progression of aortic aneurysm, suggesting it as a therapeutic option to treat abdominal aortic aneurysm.

Topics: Amides; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Blotting, Western; Disease Models, Animal; Disease Progression; Fumarates; Gene Expression Regulation; Immunoenzyme Techniques; Immunohistochemistry; Rabbits; Real-Time Polymerase Chain Reaction; Renin; Renin-Angiotensin System; RNA; Ultrasonography

Aliskiren, a direct renin inhibitor is expected to achieve sufficient suppression of renin-angiotensin system. We evaluated the effect of aliskiren on the electrical and structural remodeling in a canine atrial fibrillation (AF) model. Twenty-eight dogs were divided into three groups: (1) pacing control group (n = 12), with continuous atrial rapid pacing for 3 or 6 weeks, (2) pacing + aliskiren group (n = 12), with oral aliskiren (30 mg/kg/day), and (3) sham group (n = 4), no pacing nor drug administration. Electrophysiological properties and AF inducibility were evaluated every week. After the protocol, the left atrial tissue was sampled for the further histological and mRNA analysis. The electrical remodeling, AF inducibility, the left atrial enlargement and interstitial fibrosis were observed in pacing control group and were more prominent in the 6-week protocol (vs. 3 week, p < 0.05). The mRNA expressions of matricellular proteins exhibited upregulation in 3-week pacing control, but these upregulations became insignificant in 6 weeks. In contrast, collagen type 3 exhibited significant upregulation in 6 week but not in 3-week protocol. These changes were suppressed in the pacing + aliskiren group. Aliskiren suppressed the atrial remodeling in a canine AF model. This effect was accompanied by the suppression of tissue fibrosis.

Topics: Amides; Animals; Atrial Fibrillation; Cardiac Pacing, Artificial; Disease Models, Animal; Dogs; Echocardiography; Female; Fibrosis; Fumarates; Gene Expression; Heart Atria; Hemodynamics; Renin; Renin-Angiotensin System

Fat embolism (FE) and the consequent FE syndrome occurring after trauma or surgery can lead to serious pulmonary injury, including ARDS and death. Current treatment of FE syndrome is limited to supportive therapy. We have shown in a rat model that the renin angiotensin system plays a significant role in the pathophysiology of FE because drugs interfering with the renin angiotensin system, captopril and losartan reduce the histopathologic pulmonary damage. The purpose of the current study was to determine if inhibition of renin by aliskiren, an FDA-approved drug for treating hypertension, would produce effective protection in the same model.. The FE model used intravenous injection of the neutral fat triolein in unanesthetized rats. Intraperitoneal injections of saline or aliskiren at either 50 or 100 mg/kg were performed 1 hour after FE induction via triolein. Rats were euthanized at 48 hours, and various histologic stains were used to examine the lungs.. (1) Fibrosis: rats treated with triolein showed significant fibrotic changes with increased collagen and myofibroblast activation (p < 0.0001 for both trichrome and α-smooth muscle actin staining). Aliskiren blocked this inflammatory and profibrotic process to a level indistinguishable from the controls (p < 0.0001 for both trichrome and α-smooth muscle actin staining). (2) Fat: rats treated with triolein showed a statistically significant increase in fat (p = 0.0006). Subsequent aliskiren administration at both doses reduced the size, distribution, and amount of fat droplets (low dose, p = 0.0095; high dose, p = 0.0028). (3) Vessel patency: the low dose of aliskiren blocked the reduction of lumen patency observed after triolein administration (p = 0.0058).. Aliskiren protected the lungs of rats from gross and histopathologic FE-induced pulmonary damage at 48 hours. Clinical implications include the use of aliskiren both prophylactically (before certain orthopedic procedures) and therapeutically (after severe trauma) to prevent the consequent severe pulmonary pathologic sequelae.

Topics: Amides; Animals; Disease Models, Animal; Embolism, Fat; Fumarates; Male; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Triolein

Tacrolimus (Tac) and Cyclosporine A (CyA) calcineurin inhibitors (CNIs) are 2 effective immunosuppressants which are essential to prevent allograft rejection. Calcineurin inhibitors are known to be nephrotoxic. However, the precise mechanism of nephrotoxicity is not fully understood. In this study, we investigated the in vivo effects of CNIs on the local renal renin-angiotensin system in the collecting duct (CD).. Three-week-old mice were treated with either vehicle, CyA (2 mg/kg per day), Tac (0.075 mg/kg per day), CyA + Aliskiren (25 mg/kg per day), or Tac + Aliskiren for 3 weeks. Serum creatinine was measured. Renin and vascular endothelial growth factor (VEGF) contents in CD were evaluated with flow cytometry and multiphoton microscopy. The diameter of vessels was assessed with multiphoton microscopy, and the amount of renal collagen was determined by real-time polymerase chain reaction and Masson staining.. The elevated level of serum creatinine in CNI groups was abolished by Aliskiren. Flow cytometric analysis found elevated renin content in principal cells, which was prevented by Aliskiren. This result was further confirmed with multiphoton microscopy. The VEGF content in CD correlated with reduced capillary diameter and with the formation of fibrotic islands.. Calcineurin inhibitors induce production of renin in the CD that may contribute to decreased renal blood flow. In turn, CD responds with increased VEGF production, resulting in disproportional vessel growth, further worsening the local hypoxia and striped fibrosis surrounding the CDs. Aliskiren, a direct renin inhibitor blocks these effects and improves CNI-induced nephropathy by decreasing renin production in the CDs. Our data suggest that Aliskiren may be used for the prevention of CNI nephrotoxicity.

Topics: Amides; Animals; Biomarkers; Calcineurin Inhibitors; Capillaries; Collagen Type I; Creatinine; Cyclosporine; Cytoprotection; Disease Models, Animal; Fibrosis; Flow Cytometry; Fumarates; Immunosuppressive Agents; Kidney Diseases; Kidney Tubules, Collecting; Male; Mice, Inbred C57BL; Microscopy, Fluorescence, Multiphoton; Real-Time Polymerase Chain Reaction; Renal Circulation; Renin; Renin-Angiotensin System; Tacrolimus; Time Factors; Up-Regulation; Vascular Endothelial Growth Factor A

Obesity-related kidney disease is related to caloric excess promoting deleterious cellular responses. Accumulation of saturated free fatty acids in tubular cells produces lipotoxicity involving significant cellular dysfunction and injury. The objectives of this study were to elucidate the role of renin-angiotensin system (RAS) activation in saturated fatty acid-induced endoplasmic reticulum (ER) stress in cultured human proximal tubule epithelial cells (HK2) and in mice fed with a high-fat diet. Treatment with saturated fatty acid palmitic acid (PA; 0.8 mM) for 24 h induced ER stress in HK2, leading to an unfolded protein response as reflected by increased expressions of the ER chaperone binding immunoglobulin protein (BiP) and proapoptotic transcription factor C/EBP homologous protein (CHOP) protein as evaluated by immunoblotting. PA treatment also induced increased protein expression of inositol requiring protein 1α (IRE1α), phosphorylated eukaryotic initiation factor-α (eIF2α), and activating transcription factor 4 (ATF4) as well as activation of caspase-3. PA treatment was associated with increased angiotensin II levels in cultured medium. The angiotensin II type 1 receptor (AT1R) blocker valsartan or renin inhibitor aliskiren dramatically suppressed PA-induced upregulation of BiP, CHOP, IRE1α, p-eIF2α, and ATF4 in HK2 cells. In contrast, valsartan or aliskiren did not prevent ER stress induced by tunicamycin. C57BL/6 mice fed with a high-fat diet for 14 wk exhibited increased protein expressions of BiP and CHOP compared with control mice, which were significantly attenuated by the valsartan treatment. Increased angiotensin II levels in serum and urine were observed in mice fed with a high-fat diet when compared with controls. It is suggested that the intrarenal RAS activation may play an important role in diabetic kidney injury via mediating ER stress induced by saturated fatty acid.

Topics: Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Apoptosis; Blood Glucose; Cell Line; Cell Survival; Diet, High-Fat; Disease Models, Animal; Dose-Response Relationship, Drug; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Fumarates; Gene Expression Regulation; Heat-Shock Proteins; Humans; Kidney Diseases; Kidney Tubules, Proximal; Male; Mice, Inbred C57BL; Palmitic Acid; Renin-Angiotensin System; RNA, Messenger; Signal Transduction; Transcription Factor CHOP; Tunicamycin; Unfolded Protein Response; Valsartan

This study determined whether angiotensinogen (AGT) has angiotensin II-independent effects using multiple genetic and pharmacological manipulations.. All study mice were in low-density lipoprotein receptor -/- background and fed a saturated fat-enriched diet. In mice with floxed alleles and a neomycin cassette in intron 2 of the AGT gene (hypoAGT mice), plasma AGT concentrations were >90% lower compared with their wild-type littermates. HypoAGT mice had lower systolic blood pressure, less atherosclerosis, and diminished body weight gain and liver steatosis. Low plasma AGT concentrations and all phenotypes were recapitulated in mice with hepatocyte-specific deficiency of AGT or pharmacological inhibition of AGT by antisense oligonucleotide administration. In contrast, inhibition of AGT cleavage by a renin inhibitor, aliskiren, failed to alter body weight gain and liver steatosis in low-density lipoprotein receptor -/- mice. In mice with established adiposity, administration of AGT antisense oligonucleotide versus aliskiren led to equivalent reductions of systolic blood pressure and atherosclerosis. AGT antisense oligonucleotide administration ceased body weight gain and further reduced body weight, whereas aliskiren did not affect body weight gain during continuous saturated fat-enriched diet feeding. Structural comparisons of AGT proteins in zebrafish, mouse, rat, and human revealed 4 highly conserved sequences within the des(angiotensin I)AGT domain. des(angiotensin I)AGT, through adeno-associated viral infection in hepatocyte-specific AGT-deficient mice, increased body weight gain and liver steatosis, but did not affect atherosclerosis.. AGT contributes to body weight gain and liver steatosis through functions of the des(angiotensin I)AGT domain, which are independent of angiotensin II production.

Topics: Amides; Amino Acid Sequence; Angiotensin II; Angiotensinogen; Animals; Atherosclerosis; Blood Pressure; Conserved Sequence; Dependovirus; Diet, High-Fat; Disease Models, Animal; Fatty Liver; Fumarates; Genetic Vectors; Genotype; Hepatocytes; Hypertension; Liver; Male; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Oligonucleotides, Antisense; Phenotype; Protein Binding; Protein Interaction Domains and Motifs; Receptors, LDL; Renin; Signal Transduction; Time Factors; Transduction, Genetic; Weight Gain

Aliskiren has been found to reduce chronic injury and steatosis in the liver of methionine-choline-deficient (MCD) diet-fed mice. This study investigated whether aliskiren has an anti-steatotic effect in HFD-fed mice, which are more relevant to human patients with non-alcoholic fatty liver disease than MCD mice. Mice fed with 4-week normal chow or HFD randomly received aliskiren (50 mg/kg/day) or vehicle via osmotic minipumps for further 4 weeks. Aliskiren reduced systemic insulin resistance, hepatic steatosis, epididymal fat mass and increased gastrocnemius muscle glucose transporter type 4 levels with lower tissue angiotensin II levels in the HFD-fed mice. In addition, aliskiren lowered nuclear peroxisome proliferator-activated receptor gamma and its down-signaling molecules and increased cytochrome P450 4A14 and carnitine palmitoyltransferase 1A (CPT1a) in liver. In epididymal fat, aliskiren inhibited expressions of lipogenic genes, leading to decrease in fat mass, body weight, and serum levels of leptin and free fatty acid. Notably, in the gastrocnemius muscle, aliskiren increased phosphorylation of insulin receptor substrate 1 and Akt. Based on these beneficial effects on liver, peripheral fat and skeletal muscle, aliskiren is a promising therapeutic agent for patients with NAFLD.

Topics: Adipose Tissue; Amides; AMP-Activated Protein Kinases; Animals; Carnitine O-Palmitoyltransferase; Cytochrome P450 Family 4; Diet, High-Fat; Disease Models, Animal; Epididymis; Fumarates; Insulin; Insulin Resistance; Lipid Metabolism; Liver; Male; Mice; Muscle, Skeletal; Non-alcoholic Fatty Liver Disease; Oxidative Stress; Phosphorylation; PPAR gamma; Proto-Oncogene Proteins c-akt; Signal Transduction

There has been controversy about the role of Toll-like receptor 2 (TLR2) in renal injury following ureteric obstruction. Although inhibition of the renin angiotensin system (RAS) reduces TLR2 expression in mice, the exact relationship between TLR2 and RAS is not known. The aim of this study was to determine whether the RAS modulates TLR2.. We used 8-week-old male wild type (WT) and TLR2-knockout (KO) mice on a C57Bl/6 background. Unilateral ureteral obstruction (UUO) was induced by complete ligation of the left ureter. Angiotensin (Ang) II (1,000 ng/kg/min) and the direct renin inhibitor aliskiren (25 mg/kg/day) were administrated to mice using an osmotic minipump. Molecular and histologic evaluations were performed.. Ang II infusion increased mRNA expression of TLR2 in WT mouse kidneys (p < 0.05). The expression of renin mRNA in TLR2-KO UUO kidneys was significantly higher than that in WT UUO kidneys (p < 0.05). There were no differences in tissue injury score or mRNA expression of monocyte chemotactic protein 1 (MCP-1), osteopontin (OPN), or transforming growth factor β (TGF-β) between TLR2-KO UUO and WT UUO kidneys. However, aliskiren decreased the tissue injury score and mRNA expression of TLR2, MCP-1, OPN, and TGF-β in WT UUO kidneys (p < 0.05). Aliskiren-treated TLR2-KO UUO kidneys showed less kidney injury than aliskiren-treated WT UUO kidneys.. TLR2 deletion induced activation of the RAS in UUO kidneys. Moreover, inhibition of both RAS and TLR2 had an additive ameliorative effect on UUO injury of the kidney.

Topics: Amides; Angiotensin II; Animals; Disease Models, Animal; Fibrosis; Fumarates; Kidney; Male; Mice, Inbred C57BL; Mice, Knockout; Nephritis, Interstitial; Renin; Renin-Angiotensin System; RNA, Messenger; Toll-Like Receptor 2; Ureteral Obstruction

The aim of this study was to evaluate the effects of aliskiren, direct renin inhibitor, as an antioxidant and tissue protective agent and evaluate the molecular, biochemical, and histopathological changes in experimental ischemia and ischemia/reperfusion injury in rat ovaries. Forty-eight female rats were randomly divided into eight groups: in Group 1, only sham operation was performed. Group 2 received 100 mg/kg aliskiren and sham operated. In Group 3, 3 h-period of bilateral ovarian ischemia was applied. Group 4 received a 3-h period of ischemia followed by 3 h of reperfusion. Groups 5 and 6 received 50 and 100 mg/kg, respectively, of aliskiren and bilateral ovarian ischemia was applied (after a 3-h period of ischemia, both ovaries were surgically removed). To Groups 7 and 8, 50 and 100 mg/kg of aliskiren were administered, respectively, and the induction of ischemia was performed. At the end of a 3-h period of ischemia, bilateral vascular clips were removed, and 3 h of reperfusion continued. After the experiments, IL-1β, IL-6, TNF-α, and iNOS mRNA expressions and SOD, GSH, MDA, renin, and angiotensin-II levels were determined and histopathological changes were examined in rat ovaries. Aliskiren treatment normalized excessive changes in cytokine and oxidative stress markers in both ischemia and ischemia/reperfusion injury. Histopathologically, treatment with aliskiren ameliorated the development of ischemia and/or ischemia/reperfusion tissue injury. This study concluded that aliskiren treatment is effective in reversing ischemia and/or ischemia/reperfusion induced ovary damage via the improvement of oxidative stress, reduction of inflammation, and suppression of the renin-angiotensin aldosterone system.

Topics: Amides; Animals; Disease Models, Animal; Female; Fumarates; Ischemia; Ovarian Diseases; Protective Agents; Random Allocation; Rats; Rats, Wistar; Renin-Angiotensin System; Reperfusion Injury

The critical role of CaMKIIδ isoforms in cardiac hypertrophy is well documented.. This study was aimed to investigate the possible inhibitory effects of aliskiren (ALS) and/or carvedilol (CAV) on CaMKIIδ isoforms expression in experimental cardiac hypertrophy.. Male Wistar albino rats were subcutaneously injected with isoproterenol (ISO) (5 mg/kg/day) for 4 weeks to induce cardiac hypertrophy. Hypertrophied rats were daily treated with either ALS (10 mg/kg) and/or CAV (10 mg/kg). At the end of the treatment, rats were killed; blood and hearts were collected for assessing different biochemical parameters.. ISO treatment significantly increased heart weight to body weight (HW/BW) ratio, serum creatine kinase MB (CK-MB) and troponin T (Tn-T) levels, and plasma renin activity (PRA) as compared to control rats. Additionally, ISO treatment produced a significant increase in the expression of myocardial CaMKIIδ2 and CaMKIIδ3 that were associated with significant elevation in myocardial caspase-3 protein expression. Histopathological examination of rats exposed to ISO treatment showed severe myocardial cell degeneration. ALS and/or CAV treatment significantly reduced the altered HW/BW ratio, serum CK-MB and Tn-T levels, PRA, and caspase-3 protein expression in hypertrophied rats, with maximal improvement in the combination group. These biochemical findings were supported by the histopathological examination of the heart tissue. Additionally, treatment with ALS and CAV significantly inhibited ISO-induced increase in CaMKIIδ2 and CaMKIIδ3 expression levels.. The present study indicated that ALS and CAV treatment ameliorated ISO-induced hypertrophy via inhibiting the expression and the activity of CaMKIIδ isoforms and the associated myocardial apoptosis.

Topics: Amides; Animals; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Carbazoles; Cardiomegaly; Carvedilol; Creatine Kinase, MB Form; Disease Models, Animal; Drug Therapy, Combination; Fumarates; Heart; Isoproterenol; Male; Myocardium; Organ Size; Propanolamines; Protein Isoforms; Rats, Wistar; Real-Time Polymerase Chain Reaction; Renin; Renin-Angiotensin System; Troponin T

Atrial fibrillation (AF) contributing to the increasing mortality risk is the most common disease in clinical practice. Owing to the side effects and relative inefficacy of current antiarrhythmic drugs, some research focuses on renin-angiotensin-aldosterone system (RAS) for finding out the new treatment of AF. The purpose of this study is to confirm whether aliskiren as a proximal inhibitor of renin, which completely inhibits RAS, has beneficial effects on atrial structural remodeling in AF. In this study, rapid atrial pacing was induced at 500 beats per minute for 2 weeks in a canine model. A different dose of aliskiren was given orally for 2 weeks before rapid atrial pacing. HE staining and Masson's staining were used for analysis of myocardial fibrosis. TGF-β1, signal pathways, and pro-inflammatory cytokines were shown for the mechanism of structural remodeling after the treatment of aliskiren. Serious atrial fibrosis was induced by rapid atrial pacing, followed by the elevated TGF-β1, upregulated MEK and ERK1/2, and increased inflammatory factors. Aliskiren could apparently improve myocardial fibrosis by reducing the expression of TGF-β1, inhibiting MEK and ERK1/2 signal pathways, and decreasing IL-18 and TLR4 in both serum and atrial tissue. In conclusion, aliskiren could prevent atrial structural remodeling from rapid atrial pacing for 2 weeks. Aliskiren may play a potential beneficial role in the treatment of AF induced by rapid atrial pacing.

Topics: Action Potentials; Amides; Animals; Anti-Arrhythmia Agents; Atrial Fibrillation; Atrial Remodeling; Cardiac Pacing, Artificial; Cytokines; Disease Models, Animal; Dogs; Extracellular Signal-Regulated MAP Kinases; Female; Fibrosis; Fumarates; Heart Atria; Heart Rate; Inflammation Mediators; Male; MAP Kinase Kinase 1; Renin; Signal Transduction; Transforming Growth Factor beta1

Pulmonary fibrosis is a progressive lung disorder with high mortality rate and limited successful treatment. This study was designed to assess the potential anti-oxidant and anti-fibrotic effects of aliskiren (Alsk) during bleomycin (BLM)-induced pulmonary fibrosis. Male Wistar rats were used as control untreated or treated with the following: a single dose of 2.5 mg/kg of BLM endotracheally and BLM and Alsk (either low dose 30 mg/kg/day or high dose 60 mg/kg/day), and another group was given Alsk 60 mg/kg/day alone. Alsk was given by gavage. Alsk anti-oxidant and anti-fibrotic effects were assessed. BLM significantly increased relative lung weight and the levels of lactate dehydrogenase and total and differential leucocytic count in bronchoalveolar lavage that was significantly ameliorated by high-dose Alsk treatment. As markers of oxidative stress, BLM caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease of superoxide dismutase and glutathione transferase enzymes. High-dose Alsk treatment restored these markers toward normal values. Alsk counteracted the overexpression of advanced glycation end products, matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinases-1 in lung tissue induced by BLM. Fibrosis assessed by measuring hydroxyproline content, which markedly increased in the BLM group, was also significantly reduced by Alsk. These were confirmed by histopathological and immunohistochemical examination which revealed that Alsk attenuates signs of pulmonary fibrosis and decreased the overexpressed MMP-9 and transforming growth factor β1. Collectively, these findings indicate that Alsk has a potential anti-fibrotic effect beside its anti-oxidant activity.

Topics: Amides; Animals; Antioxidants; Biomarkers; Bleomycin; Cytoprotection; Disease Models, Animal; Dose-Response Relationship, Drug; Fumarates; Glycation End Products, Advanced; Hydroxyproline; Lipid Peroxidation; Lung; Male; Matrix Metalloproteinase 9; Oxidative Stress; Pulmonary Fibrosis; Rats, Wistar; Tissue Inhibitor of Metalloproteinase-1; Transforming Growth Factor beta1

The influence of intracellular renin on the inward calcium current in isolated smooth muscle cells from SHR mesenteric arteries was investigated. Measurements of calcium current were performed using the whole cell configuration of pCLAMP. The results indicated that: 1) renin (100nM) dialyzed into smooth muscle cells, increased the inward calcium current; 2) verapamil (10-9M) administered to the bath inhibited the effect of renin on the inward calcium current; 3) concurrently with the increase of calcium current a depolarization of 6.8+/-2.1mV (n=16)(P<0.05) was found in cells dialyzed with renin; 4) intracellular dialysis of renin (100nM) into smooth muscle cells isolated from mesenteric arteries of normal Wystar Kyoto rats showed no significant change on calcium current; 5) aliskiren (10-9M) dialyzed into the cell together with renin (100nM) abolished the effect of the enzyme on the calcium current in SHR; 6) Ang II (100nM) dialyzed into the smooth muscle cell from mesenteric artery of SHR in absence of renin, decreased the calcium current-an effect greatly reduced by valsartan (10-9M) added to the cytosol; 7) administration of renin (100nM) plus angiotensinogen (100nM) into the cytosol of muscles cells from SHR rats reduced the inward calcium current; 8) extracellular administration of Ang II (100nM) increased the inward calcium current in mesenteric arteries of SHR.. intracellular renin in vascular resistance vessels from SHR due to internalization or expression, contributes to the regulation of vascular tone and control of peripheral resistance-an effect independently of Ang II. Implications for hypertension and vascular remodeling are discussed.

Topics: Amides; Angiotensin II; Animals; Calcium; Calcium Signaling; Disease Models, Animal; Fumarates; Humans; Hypertension; Mesenteric Arteries; Myocytes, Smooth Muscle; Rats; Renin; Vascular Remodeling; Verapamil

To examine the effects of aliskiren, a small-molecule renin inhibitor, on cancer cachexia and to explore the underlying mechanisms. A cancer cachexia model was established by subcutaneously injecting C26 mouse colon carcinoma cells into isogenic BALB/c mice. Aliskiren was administered intragastrically [10 mg/kg body weight (BW)] on day 5 (as a preventive strategy, AP group) or on day 12 (as a therapeutic strategy, AT group) after C26 injection. Mice that received no C26 injection (healthy controls, HC group) or only C26 injection but not aliskiren (cancer, CA group) were used as controls. BW, tumor growth, whole body functions, and survival were monitored daily in half of the mice in each group, whereas serum, tumors, and gastrocnemius muscles were harvested from the other mice after sacrifice on day 20 for further analysis. Aliskiren significantly alleviated multiple cachexia‑associated symptoms, including BW loss, tumor burden, muscle wasting, muscular dysfunction, and shortened survival. On the molecular level, aliskiren antagonized cachexia‑induced activation of the renin‑angiotensin system (RAS), systematic and muscular inflammation, oxidative stress, and autophagy‑lysosome as well as ubiquitin‑proteasome stimulation. In addition, early administration of aliskiren before cachexia development (AP group) resulted in more robust effects in alleviating cachexia or targeting underlying mechanisms than administration after cachexia development (AT group). Aliskiren exhibited potent anti‑cachexia activities. These activities were achieved through the targeting of at least four mechanisms underlying cachexia development: RAS activation, increase in systematic inflammation, upregulation of oxidative stress, and stimulation of autophagy-lysosome pathway (ALP) and ubiquitin-proteasome pathway (UPP).

Topics: Amides; Animals; Autophagy; Cachexia; Cell Line, Tumor; Colonic Neoplasms; Disease Models, Animal; Fumarates; Humans; Mice; Muscle, Skeletal; Muscular Atrophy; Oxidative Stress; Renin; Renin-Angiotensin System

This study aimed to analyze the hemodynamic and cardiac effects of direct renin inhibitor (DRI) treatment and swimming training in hypertensive rats.. Seventy-seven rats were divide into eight groups: sedentary normotensive (SN), trained normotensive (TN), sedentary normotensive treated with DRI (SN_DRI), trained normotensive treated with DRI (TN_DRI), sedentary hypertensive (SH), trained hypertensive (TH), sedentary hypertensive treated with DRI (SH_DRI), trained hypertensive treated with DRI (TH_DRI). Swimming training occurred for up to 60 min, five times a week for four weeks. The hypertensive animals were treated with 20 mg ċ kg(-1) ċ day(-1) L-NAME for four weeks. Groups treated with DRI received 10 mg ċ kg(-1) ċ day(-1) of aliskiren for four weeks. After the treatment period, all the animals underwent femoral artery catheterization surgery for direct measurement of cardiovascular variables.. The SH group presented hypertension (136.4 ± 5.0 mmHg) compared to the SN (107.1 ± 1.7 mmHg). The TH group showed lower mean arterial pressure (MAP) than the SH (121.1 ± 1.3 mmHg), but the treatment with DRI did not attenuate hypertension (128.2 ± 4.9 mmHg). The analysis of collagen areas demonstrated that treatment with DRI may attenuate cardiac remodeling in situations of hypertension, in the condition of treatment alone or combined with physical training.. Both interventions in combination may be more effective at reducing cardiovascular risk in hypertensive subjects.

Topics: Amides; Animals; Blood Pressure; Disease Models, Animal; Enzyme Inhibitors; Fumarates; Heart; Hypertension; Male; NG-Nitroarginine Methyl Ester; Physical Conditioning, Animal; Rats; Rats, Wistar; Renin; Risk Factors; Swimming

Ureteral obstruction is associated with reduced expression of renal aquaporins (AQPs), urinary concentrating defects, and an enhanced inflammatory response, in which the renin-angiotensin system (RAS) may play an important role. We evaluated whether RAS blockade by a direct renin inhibitor, aliskiren, would prevent the decreased renal protein expression of AQPs in a unilateral ureteral obstruction (UUO) model and what potential mechanisms may be involved. UUO was performed for 3 days (3UUO) and 7 days (7UUO) in C57BL/6 mice with or without aliskiren injection. In 3UUO and 7UUO mice, aliskiren abolished the reduction of AQP2 protein expression but not AQP1, AQP3, and AQP4. mRNA levels of renal AQP2 and vasopressin type 2 receptor were decreased in obstructed kidneys of 7UUO mice, which were prevented by aliskiren treatment. Aliskiren treatment was also associated with a reduced inflammatory response in obstructed kidneys of UUO mice. Aliskiren significantly decreased mRNA levels of several proinflammatory factors, such as transforming growth factor-β and tumor necrosis factor-α, seen in obstructed kidneys of UUO mice. Interestingly, mRNA and protein levels of the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome components apoptosis-associated speck-like protein containing a caspase recruitment domain, caspase-1, and IL-1β were dramatically increased in obstructed kidneys of 7UUO mice, which were significantly suppressed by aliskiren. In primary cultured inner medullary collecting duct cells, IL-1β significantly decreased AQP2 expression. In conclusions, RAS blockade with the direct renin inhibitor aliskiren increased water channel AQP2 expression in obstructed kidneys of UUO mice, at least partially by preventing NLRP3 inflammasome activation in association with ureteral obstruction.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Aquaporin 2; Carrier Proteins; Cells, Cultured; Cytoprotection; Disease Models, Animal; Fumarates; Inflammasomes; Inflammation Mediators; Kidney; Kidney Diseases; Male; Mice, Inbred C57BL; NLR Family, Pyrin Domain-Containing 3 Protein; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Renin; Renin-Angiotensin System; RNA, Messenger; Time Factors; Up-Regulation; Ureteral Obstruction

Aliskiren is the first orally active inhibitor of renin to be approved for clinical use as an antihypertensive agent. A number of studies show a link between aliskiren and intravascular thrombosis.. The goal of the present study was to investigate the impact of aliskiren on arterial thrombosis in normotensive and renovascular hypertensive rats. The contribution of each coagulation and fibrinolytic parameters in the mode of aliskiren action was determined. Six weeks after clipping of the left renal artery rats developed hypertension which was confirmed by the "tail cuff" method. Animals were treated with aliskiren (10, 30 and 100mg/kg/day) per os for 10 days. Arterial thrombosis was induced by electrical stimulation of the common carotid artery.. It was found that aliskiren in a dose-dependent manner decreased weight of the arterial thrombus in normotensive and hypertensive rats. It has been shown that this result was not associated with the effects on blood pressure, TF, PT, APTT, fibrinogen and hematological parameters. It was found that aliskiren caused increase of t-PA activity and decrease of its inhibitor activity.. The presented results indicate that aliskiren inhibits hemostasis in the arterial thrombosis in rats. The antithrombotic effect is related with improvement of the fibrinolytic balance, and also depends on antiplatelet action.

Topics: Amides; Animals; Antihypertensive Agents; Blood Coagulation; Blood Coagulation Factors; Blood Pressure; Disease Models, Animal; Fumarates; Hemostasis; Hypertension; Male; Plasminogen Activator Inhibitor 1; Platelet Aggregation; Rats; Thrombosis; Tissue Plasminogen Activator

This study aimed to investigate the possible protective effects of aliskiren against doxorubicin (DXR)-induced cardiorenal injury and to identify the mechanisms involved. Intraperitoneal administration of DXR (15 mg/kg, body weight, as a single dose) caused significant induction in the levels of angiotensin I, caspase-3, lactate dehydrogenase (LDH), lipid peroxidation malondialdehyde (MDA), urea, and creatinine. Concomitant decline in the levels of albumin and total protein in plasma, reduction in reduced glutathione (GSH), and antiperoxidative enzyme superoxide dismutase (SOD) levels followed by ultrastructural alterations in the myocardial and renal tissues were also observed. Oral administration of aliskiren (100 mg/kg, for a period of 14 days) significantly prevented all these DXR-induced adverse effects and maintained the rats near to normal status. However, telmisartan (10 mg/kg) pretreatment has shown slight protection in DXR-induced renal injury as evidenced by broadening of podocyte foot process and narrowing of slit pore diameter. The results of aliskiren were compared with telmisartan which was used as reference in this study. These results suggested that aliskiren has protective effects against acute model of DXR-induced cardiotoxicity and nephrotoxicity, implying that plasma renin activity plays a role in DXR-induced cardio-renal injury.

Topics: Administration, Oral; Amides; Animals; Antihypertensive Agents; Cardiotoxicity; Disease Models, Animal; Doxorubicin; Fumarates; Injections, Intraperitoneal; Kidney Diseases; Myocardium; Rats; Rats, Wistar; Renin

The renin-angiotensin-aldosterone system (RAAS) plays pivotal roles in the pathogenesis of chronic kidney disease (CKD) progression. Aliskiren, a direct renin inhibitor, inhibits the rate-limiting step of the RAAS without any alternative pathway. It is proven to reduce albuminuria in CKD patients treated with angiotensin blockade. However, there are few reports which evaluate the advantage of aliskiren as the first-line drug against CKD progression in RAAS-activated hypertensive patients.. Tsukuba hypertensive mice (THM), double transgenic mice carrying both the human renin and human angiotensinogen genes, were fed a high-salt diet and treated with hydraladine, ramipril and aliskiren for 10 weeks. Blood pressure and urinary albumin excretion were measured every 2 weeks during the experimental period. We evaluated renal histological changes and gene expression. Plasma angiotensin concentration was measured to evaluate the RAAS inhibitory effect.. High-salt-loaded THM showed severe hypertension and renal injury. All antihypertensive drugs suppressed blood pressure and prevented renal disease progression. RAAS blockade showed a higher renoprotective effect than hydraladine despite an equivalent blood pressure lowering effect. Aliskiren exhibited even stronger renoprotection than ramipril. Plasma angiotensin concentration was increased in THM fed both normal salt and high salt. Hydraladine did not alter the plasma angiotensin concentration. Ramipril significantly decreased angiotensin II concentration. Aliskiren treatment almost completely suppressed angiotensin I and resulted in lower angiotensin II concentration than ramipril treatment.. Aliskiren prevents renal disease progression by suppressing both angiotensin I and II in RAAS-activated pathology. Our data suggest the application of a renin inhibitor for preventing kidney disease progression in CKD patients.

Topics: Albuminuria; Amides; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Cytoprotection; Disease Models, Animal; Disease Progression; Down-Regulation; Fumarates; Humans; Hydralazine; Hypertension; Kidney; Kidney Diseases; Mice; Mice, Transgenic; Ramipril; Renin; Renin-Angiotensin System; Sodium Chloride, Dietary; Time Factors

We tested the hypothesis that direct renin inhibition with aliskiren protects against myocardial ischemia/reperfusion (I/R) injury in spontaneously hypertensive rats (SHR), and examined the mechanism by which this occurs.. Male SHR were treated (orally, 4 weeks) with saline or aliskiren (30 or 60 mg kg(-1) day(-1)) and subjected to 30 minutes of left anterior descending coronary artery occlusion followed by 6 or 24 hours of reperfusion. Only the higher dose significantly lowered systolic blood pressure, the lower dose causing a smaller apparent lowering that was nonsignificant. Despite this difference in blood pressure-lowering effect, both doses increased the ejection fraction and fractional shortening and reduced myocardial infarct size equally. I/R decreased cardiac expression of phosphatidylinositol 3-kinase (PI3K), phospho-Akt and phospho-endothelial nitric oxide synthase (phospho-eNOS), but increased expression of inducible nitric oxide synthase (iNOS); these changes were all abrogated by aliskiren. Moreover, aliskiren decreased superoxide anion generation and increased cyclic guanosine-3',5'-monophosphate, an index of bioactive nitric oxide, in myocardium. It also decreased the expression of myocardial matrix metalloproteinase-2, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinases-1 (TIMP-1) following I/R. In a Langendorff heart preparation, the detrimental cardiac effects of I/R were abrogated by aliskiren, and these protective effects were abolished by NOS or PI3K inhibition. In a parallel study, although specific iNOS inhibition reduced plasma malondialdehyde and myocardial superoxide anion generation, it did not affect the deleterious effects of I/R on myocardial structure and function.. Direct renin inhibition protects against myocardial I/R injury through activation of the PI3K-Akt-eNOS pathway.

Topics: Amides; Animals; Antihypertensive Agents; Blood Pressure; Cyclic GMP; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Activation; Fumarates; Hypertension; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Myocardial Contraction; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Rats, Sprague-Dawley; Renin; Signal Transduction; Stroke Volume; Superoxides; Tissue Inhibitor of Metalloproteinase-1; Ventricular Function, Left

Aliskiren is a direct renin inhibitor developed to treat hypertension. Several clinical studies have suggested that aliskiren has beneficial effects on cardiovascular diseases beyond its antihypertensive effect. In the present study, we examined whether aliskiren limits the progression of AAA (abdominal aortic aneurysm), VH (ventricular hypertrophy) and atherosclerosis in an AngII (angiotensin II)-infused mouse model. ApoE-/- (apolipoprotein-E-deficient) mice were infused subcutaneously with AngII (1000 ng/kg of body weight per day; 4 weeks) to induce AAA and VH. At the completion of the AngII infusion, mice were randomly allocated to three groups to receive vehicle control, low-dose aliskiren (10 mg/kg of body weight per day) or high-dose aliskiren (50 mg/kg of body weight per day) for 4 weeks. Suprarenal aortic diameter assessed by ultrasound was significantly smaller in mice administered aliskiren at days 42 and 56. Aliskiren also significantly reduced the normalized heart weight, ventricular myocyte cell width and aortic arch atherosclerosis. Aliskiren lowered PRR (pro-renin receptor) expression and MAPK (mitogen-activated protein kinase) activity in the suprarenal aorta and heart. Aortic infiltration of T-lymphocytes and macrophages was reduced by aliskiren. In conclusion, aliskiren limits the progression of AAA, VH and atherosclerosis in an AngII-infused mouse model.

Topics: Amides; Angiotensin II; Animals; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Apolipoproteins E; Atherosclerosis; Blood Pressure; Disease Models, Animal; Fumarates; Hypertension; Hypertrophy; Mice; Mice, Inbred C57BL; Mice, Knockout

Dual renin-angiotensin system (RAS) blockade in diabetic nephropathy is no longer feasible because of the profit/side effect imbalance. (Pro)renin receptor [(P)RR] blockade with handle region peptide (HRP) has been reported to exert beneficial effects in various diabetic models in a RAS-independent manner. To what degree (P)RR blockade adds benefits on top of RAS blockade is still unknown. In the present study, we treated diabetic TGR(mREN2)27 rats, a well-established nephropathy model with high prorenin levels [allowing continuous (P)RR stimulation in vivo], with HRP on top of renin inhibition with aliskiren. Aliskiren alone lowered blood pressure and exerted renoprotective effects, as evidenced by reduced glomerulosclerosis, diuresis, proteinuria, albuminuria, and urinary aldosterone levels as well as diminished renal (P)RR and ANG II type 1 receptor expression. It also suppressed plasma and tissue RAS activity and suppressed cardiac atrial natriuretic peptide and brain natriuretic peptide expression. HRP, when given on top of aliskiren, did not alter the effects of renin inhibition on blood pressure, RAS activity, or aldosterone. However, it counteracted the beneficial effects of aliskiren in the kidney, induced hyperkalemia, and increased plasma plasminogen activator-inhibitor 1, renal cyclooxygenase-2, and cardiac collagen content. All these effects have been linked to (P)RR stimulation, suggesting that HRP might, in fact, act as a partial agonist. Therefore, the use of HRP on top of RAS blockade in diabetic nephropathy is not advisable.

Topics: Aldosterone; Amides; Animals; Blood Pressure; Cyclooxygenase 2; Diabetes Mellitus, Experimental; Disease Models, Animal; Female; Fumarates; Kidney; Male; Oligopeptides; Plasminogen Activator Inhibitor 1; Potassium; Prorenin Receptor; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Streptozocin

The purpose of this study was to investigate the effect of the renin inhibitor, aliskiren, on retinal ischemia-reperfusion injury. Retinal ischemia was induced by increasing intraocular pressure to 130 mmHg. At 7 days after ischemia, retinal damage was evaluated by measuring the retinal thickness and the number of retinal ganglion cells. Western blot was used to measure changes in the (pro)renin receptor expression. Retinal mRNA expressions of prorenin, angiotensinogen and angiotensin II type 1 receptor (AT1-R) were measured by real-time polymerase chain reaction. Rats were treated with the renin inhibitor, aliskiren. Although the number of retinal ganglion cells and the inner retinal thickness were significantly decreased at 7 days after ischemia, treatment with aliskiren significantly inhibited retinal ischemic injury. Administration of aliskiren increased mRNA expression of prorenin in the retina at 3 h after the reperfusion. The expression of the (pro)renin receptor was not changed after ischemia-reperfusion injury with or without aliskiren. Although there was an increase in the retinal expression of AT1-R at 3 h after the reperfusion, aliskiren administration suppressed this expression. A renin inhibitor attenuated subsequent ischemic damage in the rat retina via the inhibition of the prorenin-induced angiotensin generation.

Topics: Amides; Angiotensinogen; Animals; Blotting, Western; Cell Survival; Disease Models, Animal; Electroretinography; Fumarates; Infusion Pumps, Implantable; Intraocular Pressure; Male; Prorenin Receptor; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Receptor, Angiotensin, Type 1; Receptors, Cell Surface; Renin; Renin-Angiotensin System; Reperfusion Injury; Retina; Retinal Diseases; Retinal Ganglion Cells; RNA, Messenger

Dysfunction of renin-angiotensin system (RAS) contributes to the pathogenesis of diabetic retinopathy (DR). Prorenin, the precursor of renin is highly elevated in ocular fluid of diabetic patients with proliferative retinopathy. Prorenin may exert local effects in the eye by binding to the so-called (pro)renin receptor ((P)RR). Here we investigated the combined effects of the renin inhibitor aliskiren and the putative (P)RR blocker handle-region peptide (HRP) on diabetic retinopathy in streptozotocin (STZ)-induced diabetic transgenic (mRen2)27 rats (a model with high plasma prorenin levels) as well as prorenin stimulated cytokine expression in cultured Müller cells. Adult (mRen2)27 rats were randomly divided into the following groups: (1) non-diabetic; (2) diabetic treated with vehicle; (3) diabetic treated with aliskiren (10 mg/kg per day); and (4) diabetic treated with aliskiren+HRP (1 mg/kg per day). Age-matched non-diabetic wildtype Sprague-Dawley rats were used as control. Drugs were administered by osmotic minipumps for three weeks. Transgenic (mRen2)27 rat retinas showed increased apoptotic cell death of both inner retinal neurons and photoreceptors, increased loss of capillaries, as well as increased expression of inflammatory cytokines. These pathological changes were further exacerbated by diabetes. Aliskiren treatment of diabetic (mRen2)27 rats prevented retinal gliosis, and reduced retinal apoptotic cell death, acellular capillaries and the expression of inflammatory cytokines. HRP on top of aliskiren did not provide additional protection. In cultured Müller cells, prorenin significantly increased the expression levels of IL-1α and TNF-α, and this was completely blocked by aliskiren or HRP, their combination, (P)RR siRNA and the AT1R blocker losartan, suggesting that these effects entirely depended on Ang II generation by (P)RR-bound prorenin. In conclusion, the lack of effect of HRP on top of aliskiren, and the Ang II-dependency of the ocular effects of prorenin in vitro, argue against the combined application of (P)RR blockade and renin inhibition in diabetic retinopathy.

Topics: Amides; Animals; Apoptosis; Blood Pressure; Cytokines; Diabetic Retinopathy; Disease Models, Animal; Fumarates; Gliosis; Inflammation Mediators; Mice, Transgenic; Oligopeptides; Prorenin Receptor; Rats; Receptors, Cell Surface; Renin; Retinal Ganglion Cells

Aliskiren, a direct renin inhibitor, is a novel antihypertensive drug. To study whether aliskiren can reverse chronic kidney disease, we administered it to renin transgenic mice, a strain characterized by elevated blood pressure and a slow decline of renal function, mimicking well the progression of hypertensive chronic kidney disease. Ten-month-old transgenic mice were treated either with aliskiren or placebo for 28 days. Age-matched wild-type mice treated or not with aliskiren were considered as normotensive controls. Aliskiren reduced blood pressure to wild-type levels from as early as day 14. Proteinuria and cardiac hypertrophy and fibrosis were also normalized. Renal interstitial fibrosis and inflammation were significantly ameliorated in aliskiren-treated mice (shown by the decrease of proinflammatory and profibrotic markers), and the phenotypes of tubular epithelial cells and podocytes were restored as evidenced by the reappearance of cellular proteins characteristic of normal phenotype of these cells. Profibrotic p38 and Erk mitogen-activated protein kinases were highly activated in placebo-treated transgenic animals. Aliskiren treatment cancelled this activation. This nephroprotection was not attributed to the antihypertensive activity of aliskiren, because blood pressure normalization after treatment with hydralazine failed to induce the regression of renal fibrosis. Direct inhibition of renin can restore renal function and structure in aged hypertensive animals with existing proteinuria. This finding suggests that, in addition to antihypertensive action, aliskiren can be also used to treat chronic kidney disease.

Topics: Amides; Animals; Disease Models, Animal; Fibrosis; Fumarates; Hypertension; Kidney; Kidney Diseases; Mice; Mice, Transgenic; Renin

Diabetes-induced organ damage is significantly associated with the activation of the renin-angiotensin system (RAS). Recently, several studies have demonstrated a change in the RAS from an extracellular to an intracellular system, in several cell types, in response to high ambient glucose levels. In cardiac myocytes, intracellular angiotensin (ANG) II synthesis and actions are ACE and AT1 independent, respectively. However, a role of this system in diabetes-induced organ damage is not clear.. To determine a role of the intracellular ANG II in diabetic cardiomyopathy, we induced diabetes using streptozotocin in AT1a receptor deficient (AT1a-KO) mice to exclude any effects of extracellular ANG II. Further, diabetic animals were treated with a renin inhibitor aliskiren, an ACE inhibitor benazeprilat, and an AT1 receptor blocker valsartan.. AT1a-KO mice developed significant diastolic and systolic dysfunction following 10 wks of diabetes, as determined by echocardiography. All three drugs prevented the development of cardiac dysfunction in these animals, without affecting blood pressure or glucose levels. A significant down regulation of components of the kallikrein-kinin system (KKS) was observed in diabetic animals, which was largely prevented by benazeprilat and valsartan, while aliskiren normalized kininogen expression.. These data indicated that the AT1a receptor, thus extracellular ANG II, are not required for the development of diabetic cardiomyopathy. The KKS might contribute to the beneficial effects of benazeprilat and valsartan in diabetic cardiomyopathy. A role of intracellular ANG II is suggested by the inhibitory effects of aliskiren, which needs confirmation in future studies.

Topics: Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Benzazepines; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Cardiomyopathies; Disease Models, Animal; Down-Regulation; Fumarates; Kallikreins; Kininogens; Kinins; Mice; Mice, Knockout; Myocytes, Cardiac; Receptor, Angiotensin, Type 1; Renin; Renin-Angiotensin System; Tetrazoles; Ultrasonography; Valine; Valsartan

Diminishing the activity of the renin-angiotensin system (RAS) plays a pivotal role in the treatment of heart failure. In addition to angiotensin converting enzyme (ACE) inhibitors and angiotensin-receptor blockers, direct renin inhibition has emerged as a potential adjunctive treatment to conventional RAS blockade. We sought to determine the effectiveness of this strategy after myocardial infarction (MI) in the setting of preexisting hypertension, a common premorbid condition in patients with ischemic heart disease.. Ten-week-old female heterozygous hypertensive (mRen-2)27 transgenic rats (Ren-2), were randomized to one of five groups (n = 8 per group); sham, MI, MI + aliskiren, MI + lisinopril and MI + combination lisinopril and aliskiren. Cardiac function was assessed by echocardiography and in vivo cardiac catheterization. Untreated MI animals developed heart failure with hypotension, dilation, reduced ejection fraction (EF), and raised left ventricular end-diastolic pressure (LVEDP). Treatment with single agent treatment had only modest effect on cardiac function though combination therapy was associated with significant improvements in EF and LVEDP when compared to untreated MI animals (P < 0.05). Histologic analysis demonstrated increase extracellular matrix deposition and cardiomyocyte hypertrophy in the noninfarct region of all MI groups when compared with sham operated animals (P < 0.05) that was reduced by ACE inhibitor monotherapy and combination treatment but not by aliskiren alone.. In a hypertensive rat model that underwent experimental MI, EF, and LVEDP, key functional indices of heart failure, were improved by treatment with combination ACE and direct renin inhibition when compared with either agent used alone.

Topics: Amides; Angiotensin-Converting Enzyme Inhibitors; Animals; Cardiac Catheterization; Disease Models, Animal; Drug Therapy, Combination; Echocardiography; Female; Fumarates; Heart Failure; Hypertension; Lisinopril; Myocardial Infarction; Myocardium; Random Allocation; Rats; Rats, Transgenic; Recovery of Function; Renin; Renin-Angiotensin System; Stroke Volume; Ventricular Function, Left; Ventricular Pressure; Ventricular Remodeling

Angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers can improve insulin resistance and vascular dysfunction in insulin-resistant rats; however, there are few reports on the effects of direct renin inhibitors on these conditions. We investigated the effects of a direct renin inhibitor, aliskiren, on insulin resistance, aortic endothelial dysfunction and vascular remodeling in fructose-fed hypertensive rats. Male Wistar-Kyoto rats were divided into four groups (n=6 per group) and studied for 8 weeks: Group Con: standard chow diet; group Fru: high-fructose diet (60% fructose); Group FruA: high-fructose diet with concurrent aliskiren treatment (100 mg kg(-1) per day); and Group FruB: high-fructose diet with subsequent aliskiren treatment 4 weeks later. Blood was collected for biochemical assays, and isolated rings of the thoracic aorta were obtained for analysis of vascular reactivity, vascular structure and lipid peroxide. Rats fed with high-fructose diets developed significant systolic hypertension, decreased plasma nitrite (NO(2); nitric oxide metabolite) levels and increased plasma glucose, insulin, triglyceride, total cholesterol and aortic lipid peroxide levels, and aortic wall thickness compared with control rats. Aliskiren treatment, either concurrent or subsequent, elevated plasma NO(2) levels and reduced systolic hypertension, insulin resistance, dyslipidemia, aortic lipid peroxide levels and aortic wall hypertrophy in FHR. The peak endothelium-dependent aortic relaxations were significantly higher in rats that received aliskiren treatment than in those that did not. In conclusion, our findings suggest that aliskiren prevents and ameliorates insulin resistance, aortic endothelial dysfunction and oxidative vascular remodeling in fructose-fed hypertensive rats.

Topics: Amides; Animals; Aorta, Thoracic; Dietary Carbohydrates; Disease Models, Animal; Endothelium, Vascular; Fructose; Fumarates; Hypertension; Insulin Resistance; Lipid Peroxides; Male; Nitrites; Oxidative Stress; Rats; Rats, Inbred WKY; Renin; Vasodilation

To test the hypothesis that aliskiren improves the metabolic phenotype in a genetic mouse model of the metabolic syndrome (the caveolin-1 (cav-1) knock out (KO) mouse).. Eleven-week-old cav-1 KO and genetically matched wild-type (WT) mice were randomized to three treatment groups: placebo (n=8/group), amlodipine (6 mg/kg/day, n=18/ group), and aliskiren (50 mg/kg/day, n=18/ group). After three weeks of treatment, all treatment groups were assessed for several measures of insulin resistance (fasting insulin and glucose, HOMA-IR, and the response to an intraperitoneal glucose tolerance test (ipGTT)) as well as for triglyceride levels and the blood pressure response to treatment.. Treatment with aliskiren did not affect the ipGTT response but significantly lowered the HOMA-IR and insulin levels in cav-1 KO mice. However, treatment with amlodipine significantly degraded the ipGTT response, as well as the HOMA-IR and insulin levels in the cav-1 KO mice. Aliskiren also significantly lowered triglyceride levels in the cav-1 KO but not in the WT mice. Moreover, aliskiren treatment had a significantly greater effect on blood pressure readings in the cav-1 KO vs. WT mice, and was marginally more effective than amlodipine.. Our results support the hypothesis that aliskiren reduces insulin resistance as indicated by improved HOMA-IR in cav-1 KO mice whereas amlodipine treatment resulted in changes consistent with increased insulin resistance. In addition, aliskiren was substantially more effective in lowering blood pressure in the cav-1 KO mouse model than in WT mice and marginally more effective than amlodipine.

Topics: Amides; Animals; Antihypertensive Agents; Blood Glucose; Blood Pressure; Caveolin 1; Disease Models, Animal; Fumarates; Glucose Tolerance Test; Insulin; Insulin Resistance; Male; Metabolic Syndrome; Mice; Mice, Knockout; Random Allocation; Renin; Triglycerides

The present study was designed to investigate the potential of aliskiren, a direct renin inhibitor, in chronic constriction injury (CCI)-induced neuropathic pain in rats. Neuropathic pain was induced by placing four loose ligatures around the sciatic nerve. Acetone drop, von Frey hair, pin-prick and hot plate tests were performed to assess cold allodynia, mechanical allodynia, mechanical and heat hyperalgesia, respectively. The levels of Tumor necrosis factor-alpha (TNF-α) were measured in the sciatic nerve as an inflammatory marker. CCI was associated with the development of cold allodynia, mechanical allodynia, mechanical and heat hyperalgesia along with a rise in the levels of Tumor necrosis factor-alpha (TNF-α). Administration of aliskiren (25 or 50 mg/kg intraperitoneal (i.p.)) for 14 days in CCI-subjected rats significantly attenuated CCI-induced pain-related behavior and rise in TNF-α level. It may be concluded that aliskiren-mediated anti-inflammatory actions may be responsible for its beneficial effects in neuropathic pain in rats.

Topics: Amides; Animals; Constriction; Disease Models, Animal; Female; Fumarates; Hyperalgesia; Male; Neuralgia; Rats; Rats, Sprague-Dawley; Sciatic Nerve; Tumor Necrosis Factor-alpha

A substantial amount of evidence links the renin-angiotensin system with thrombosis. For example, ACE inhibitors and angiotensin receptor blockers possess independent of the hemodynamic changes, antithrombotic activity. Aliskiren direct renin inhibitor belongs to a new very promising antihypertensive drug that effectively inhibits the renin-angiotensin system. The aim of study was to determine the influence of aliskiren on stasis-induced venous thrombosis in renovascular hypertensive and normotensive rats. The involvement of nitric oxide and prostacyclin in the potential antithrombotic action was also elucidated. Six weeks after clipping of the left renal artery rats developed hypertension which was confirmed by the "tail cuff" method. Hypertensive and normotensive rats were treated with aliskiren (10, 30 and 100mg/kg/day) per os for 10days. Venous thrombosis was induced by stasis of vena cava inferior. Aliskiren at the highest dose induced a significant decrease in systolic blood pressure in hypertensive, but did not change this parameter in normotensive rats. Oral administration of aliskiren resulted in dose-dependent decrease of venous thrombus weight in hypertensive and normotensive rats. The antithrombotic activity of aliskiren was abolished both by NO synthase inhibitor and prostacyclin synthesis inhibitor. Aliskiren decreased collagen-induced platelet aggregation, increased plasma level of tissue plasminogen activator activity whereas no changes in plasminogen activator inhibitor activity and coagulation parameters were found. We showed that aliskiren prevents the development of venous thrombosis by enhanced fibrinolysis and the blood platelet inhibition via nitric oxide and/or prostacyclin-dependent mechanism.

Topics: Administration, Oral; Amides; Animals; Biomarkers; Blood Platelets; Blood Pressure; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epoprostenol; Fibrinolysis; Fibrinolytic Agents; Fumarates; Hypertension, Renovascular; Hypoglycemic Agents; Kidney; Ligation; Male; Nitric Oxide; Nitric Oxide Synthase; Plasminogen Activator Inhibitor 1; Platelet Activation; Rats; Rats, Wistar; Renal Artery; Tissue Plasminogen Activator; Venous Thrombosis

This study revealed that low-dose aliskiren treatment could attenuate proteinuria by interrupting the renin-angiotensin system in mice with lupus nephritis, and the beneficial effect was beyond blood pressure control. An in and ex vivo fluorescence imaging (using a non-invasion in vivo imaging system) showed intense labeling of renin in the kidneys of female MRL/lpr mice. In the study, Alzet mini-osmotic pumps were implanted into 6-week-old female MRL/lpr mice. Pumps were filled with either phosphate-buffered saline or a solution of aliskiren dissolved in phosphate-buffered saline (20 mg/kg/day) and replaced at 28-day intervals. Mice were sacrificed at four and eight weeks. To label cells for DNA synthesis, bromodeoxyuridine (BrdU) (50 mg/kg) was injected intraperitoneally an hour prior to sacrifice. The level of renin inhibition was adequate, as aliskiren-treated mice demonstrated higher renal renin mRNA expression than controls (p < 0.05). Although there were no significant differences in the systolic blood pressure (control versus aliskiren-treated: 127.20 ± 4.44 mmHg versus 103.80 ± 7.40 mmHg, p > 0.05) and heart rate (control versus aliskiren-treated: 680.50 ± 11.71 versus 647.80 ± 13.90, p > 0.05) of both groups after eight weeks, there was significant reduction of inflammatory cytokines (transforming growth factor-beta1, regulated on activation normal T cell expressed, monocyte chemoattractant protein-1 and osteopontin, p < 0.05), reduction of innate immunity (toll-like receptor 7, p < 0.05), as well as a reduction of glomerular proliferation and inflammation (BrdU-, CD45-, CD3- and F4/80-positive glomerular cells, p < 0.01) after aliskiren infusion, which might translate into an improvement in proteinuria (control versus aliskiren-treated: 493.7 versus 843.7 mg/g, p < 0.01) or weight gain (control versus aliskiren-treated: 5.65 ± 1.61 versus 8.67 ± 0.97%, p < 0.05).

Topics: Amides; Animals; Blood Pressure; Disease Models, Animal; Female; Fumarates; Lupus Nephritis; Mice; Mice, Inbred Strains; Proteinuria; Renal Agents; Renin

Aliskiren is a direct renin inhibitor used in the treatment for arterial hypertension. It can also augment nitric oxide (NO) production, which plays a crucial role in the pathogenesis of portal hypertension and modulation of porto-systemic collaterals. This study investigated the effects of aliskiren on portal pressure and porto-systemic collaterals of portal vein-ligated (PVL) rats.. Sham-operated and PVL rats received aliskiren (50 mg/kg per day) or distilled water (control) treatment for 10 days. The mean arterial pressure and portal pressure were measured by catheterization of the right femoral artery and mesenteric vein, while the superior mesenteric arterial blood flow was measured by Doppler technique. The left adrenal vein and superior mesentery artery were dissected for mRNA study. The PVL rats also underwent preincubation with (i) Krebs solution (control); (ii) 10(-4) M aliskiren; or (iii) 10(-4) M aliskiren plus nonselective NO inhibitor N(ω)-nitro-L-arginine (10(-4) M), followed by the addition of arginine vasopressin (AVP) to evaluate the collateral vascular responsiveness.. Aliskiren had systemic arterial pressure- and portal pressure-lowering effects in PVL rats. Superior mesentery arterial resistance also decreased. The constitutive NO synthase was enhanced in the left adrenal vein and superior mesentery artery after aliskiren treatment. Aliskiren attenuated the collateral vasoconstrictive effects of AVP, but the vasodilatory effects were abolished after nonselective NO synthase inhibition.. Chronic aliskiren use reduces portal pressure in portal hypertensive rats partly due to the modulation of splanchnic and collateral NO synthase.

Topics: Amides; Animals; Antihypertensive Agents; Blood Pressure; Collateral Circulation; Disease Models, Animal; Dose-Response Relationship, Drug; Fumarates; Hypertension, Portal; Male; Nitric Oxide; Nitric Oxide Synthase; Portal Pressure; Portal System; Rats; Rats, Sprague-Dawley; Renin

We have demonstrated previously that overactivity of the renin-angiotensin system (RAS) is associated with whole body and skeletal muscle insulin resistance in obese Zucker (fa/fa) rats. Moreover, this obesity-associated insulin resistance is reduced by treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor (type 1) blockers. However, it is currently unknown whether specific inhibition of renin itself, the rate-limiting step in RAS functionality, improves insulin action in obesity-associated insulin resistance. Therefore, the present study assessed the effect of chronic, selective renin inhibition using aliskiren on glucose tolerance, whole body insulin sensitivity, and insulin action on the glucose transport system in skeletal muscle of obese Zucker rats. Obese Zucker rats were treated for 21 days with either vehicle or aliskiren (50 mg/kg body wt ip). Renin inhibition was associated with a significant lowering (10%, P < 0.05) of resting systolic blood pressure and induced reductions in fasting plasma glucose (11%) and free fatty acids (46%) and homeostatic model assessment for insulin resistance (13%). Glucose tolerance (glucose area under the curve) and whole body insulin sensitivity (inverse of the glucose-insulin index) during an oral glucose tolerance test were improved by 15% and 16%, respectively, following chronic renin inhibition. Moreover, insulin-stimulated glucose transport activity in isolated soleus muscle of renin inhibitor-treated animals was increased by 36% and was associated with a 2.2-fold greater Akt Ser(473) phosphorylation. These data provide evidence that chronic selective inhibition of renin activity leads to improvements in glucose tolerance and whole body insulin sensitivity in the insulin-resistant obese Zucker rat. Importantly, chronic renin inhibition is associated with upregulation of insulin action on skeletal muscle glucose transport, and it may involve improved Akt signaling. These data support the strategy of targeting the RAS to improve both blood pressure regulation and insulin action in conditions of insulin resistance.

Topics: Amides; Animals; Biological Transport; Blood Pressure; Body Weight; Disease Models, Animal; Fatty Acids, Nonesterified; Female; Fumarates; Glucose; Insulin; Insulin Resistance; Muscle, Skeletal; Obesity; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Zucker; Renin; Signal Transduction

Chronic renal ischemia leads to renal fibrosis and atrophy. Activation of the renin-angiotensin-aldosterone system is one of the main mechanisms driving chronic renal ischemic injury. The aim of the present study was to define the effect of aliskiren in chronic ischemia of the kidney. Two-kidney, one-clip mice were used to study chronic renal ischemia. Aliskiren significantly lowered the blood pressure in mice with renal artery constriction (92.1±1.1 vs. 81.0±1.8 mm Hg, P<0.05). Renin expression was significantly increased in ischemic kidneys when treated with aliskiren. In addition, (Pro)renin receptor expression was decreased by aliskiren in ischemic kidneys. Aliskiren treatment significantly increased klotho expression and reduced the expression of fibrogenic cystokines, caspase-3 and Bax in ischemic kidneys. Histological examination revealed that aliskiren significantly reduced the nephrosclerosis score (4.5±1.9 vs. 7.3±0.4, P<0.05). Immunofluorescence staining also showed that aliskiren decreased the deposition of interstitial collagen I in ischemic kidneys. In conclusion, direct renin inhibition significantly reduced renal fibrosis and apoptosis following chronic renal ischemia.

Topics: Amides; Animals; Antihypertensive Agents; Caspase 3; Collagen Type I; Disease Models, Animal; Female; Fibrosis; Fumarates; Glucuronidase; Ischemia; Kidney; Kidney Failure, Chronic; Klotho Proteins; Mice; Mice, Inbred Strains; Renal Artery; Renin; Surgical Instruments

Alterations in the circadian arterial pressure rhythm predict cardiovascular mortality. We examined the circadian arterial pressure rhythm and the effect of renin-angiotensin system blockade in congenic mRen2.Lewis hypertensive rats, a renin-dependent model of hypertension derived from the backcross of transgenic hypertensive [mRen-2]27 rats with Lewis normotensive ones.. Twenty-nine mRen2.Lewis hypertensive rats were randomly assigned to drink tap water (vehicle; n = 9), valsartan (30 mg/kg/day; n = 10), or valsartan (30 mg/kg/day) combined with aliskiren given subcutaneously (50 mg/kg/day; n = 10) for 2 weeks. Arterial pressure, heart rate, and locomotive activity were recorded with chronically implanted radiotelemetry probes. The awake/asleep ratio was calculated as [awake mean arterial pressure (MAP) mean - asleep MAP mean)] / (awake MAP mean) x 100. Plasma renin activity (PRA) and concentration (PRC), and plasma and kidney angiotensin II (Ang II) were measured by radioimmunoassay (RIAs).. Untreated hypertensive rats showed an inverse arterial pressure rhythm, higher at day and lower at night, accompanied by normal rhythms of heart rate and locomotive activity. Treatment with valsartan or aliskiren and valsartan normalized the elevated arterial pressure and the arterial pressure rhythm, with the combination therapy being more effective in reducing MAP and in restoring the awake/asleep ratio. While PRA and PRC increased with the treatments, the addition of aliskiren to valsartan partially reversed the increases in plasma Ang II levels. Valsartan and the aliskiren and valsartan combination markedly reduced the renal cortical content of Ang II.. The altered circadian arterial pressure rhythm in this renin-dependent hypertension model uncovers a significant role of Ang II in the desynchronization of the circadian rhythm of arterial pressure, heart rate, and locomotive activity.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Animals; Antihypertensive Agents; Blood Pressure; Circadian Rhythm; Disease Models, Animal; Drug Therapy, Combination; Fumarates; Heart Rate; Male; Motor Activity; Random Allocation; Rats; Rats, Inbred Lew; Rats, Transgenic; Receptors, Angiotensin; Renin; Tetrazoles; Valine; Valsartan

Increasing evidence indicates that locally blocking renin-angiotensin system activity exerts a beneficial effect on glomerulonephritis (GN) progression leading to irreversible glomerulosclerosis. This is the first study on the pharmacological effect of the renal delivery of aliskiren, a direct renin inhibitor, in a progressive model of anti-Thy-1 GN.. Local blockade of renin activity was accomplished by subrenal capsular implantation of a collagen sponge with aliskiren. The pharmacological effect was evaluated by semiquantitative and quantitative analysis of immunohistological findings and by analysis of glomerular microcirculation using an intravital microscope system.. Quantitative mesangial matrix analysis showed that local treatment with aliskiren significantly suppressed mesangial matrix expansion and ameliorated the glomerular sclerotic index in the progressive model of ATS GN. Immunofluorescent studies revealed that renin expression at the juxtaglomerular region was enhanced in the ATS + aliskiren group, and pathological expressions of α-smooth muscle cell actin and type I collagen in ATS GN were remarkably decreased by local treatment with aliskiren. Furthermore, local delivery of aliskiren significantly improved glomerular blood flow levels.. This study revealed that renally delivered aliskiren has a renoprotective effect on potentially progressive glomerulosclerosis.

Topics: Actins; Amides; Animals; Antibodies, Monoclonal; Collagen Type I; Disease Models, Animal; Disease Progression; Fumarates; Glomerulonephritis; Infusion Pumps, Implantable; Injections, Intravenous; Kidney; Male; Mesangial Cells; Pilot Projects; Rats; Rats, Wistar; Renin

Chronic activation of the renin-angiotensin-aldosterone system is a major contributing factor to the pathogenesis and progression of cardiovascular and renal diseases.. To evaluate the role of renin-angiotensin-aldosterone system blockade with aliskiren, a direct renin inhibitor, in the development and progression of dilated cardiomyopathy in the Syrian cardiomyopathic hamster (SCH) model, we treated 1-month-old SCH with aliskiren (10 mg·kg·d) over a 4-month period. For comparative purposes, we also evaluated the effects of the angiotensin receptor blocker valsartan (10 mg·kg·d) and the combination of both drugs. Age-matched golden hamsters were used as controls. Left ventricular end-diastolic volume and end-systolic volume, ejection fraction, and diastolic function were determined by echocardiography. Systolic blood pressure (SBP) was also measured in the left femoral artery by sphygmomanometry.. Results indicate that at 2 months of age, SBP is higher in SCH than in controls, and administration for 1 month of aliskiren, valsartan, or the combination of these drugs normalized SBP in SCH to a similar extent. In 5-month-old SCH, aliskiren improved ejection fraction (from 48.6% ± 5.8% to 69.4% ± 3.2%, n = 5, P < 0.05), left ventricular end-systolic volume (from 0.28 ± 0.06 to 0.10 ± 0.01 mL/100 g body weight), left ventricular end-diastolic volume (from 0.61 ± 0.05 to 0.34 ± 0.02 mL/100 g body weight), and normalized diastolic function (E:A ratio increases from 0.93 ± 0.13 to 1.70 ± 0.03, n = 5, P < 0.05). Similar results were observed with valsartan or the combination of aliskiren and valsartan.. Our results indicate that in this animal model, aliskiren is as effective as valsartan, or the combination of both drugs, in improving diastolic function and in preventing the development of dilated cardiomyopathy. These findings suggest that aliskiren may be used as a monotherapy in heart failure management. Clinical studies, however, are needed to assess the effectiveness of this drug in patients with heart failure.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Animals; Blood Pressure; Cardiomyopathy, Dilated; Cricetinae; Disease Models, Animal; Disease Progression; Drug Therapy, Combination; Fumarates; Male; Renin; Renin-Angiotensin System; Tetrazoles; Valine; Valsartan; Ventricular Dysfunction, Left

Doxorubicin (DXR) is one of the most effective antineoplastic agents. However, the optimal clinical use of this agent is limited because of marked cardiomyopathy and congestive heart failure. Renin angiotensin system (RAS) plays an important role in the development of cardiac hypertrophy, reperfusion injury and congestive heart failure. Aliskiren (ALK) is a direct inhibitor of renin and does not affect other systems involved in cardiovascular regulation. This study was designed to explore the possible protective effects of ALK (30 and 100 mg/kg, per oral [p.o.] respectively for 42 days) in chronic model of DXR (1.25 mg/kg, intraperitoneally (i.p.) sixteen equal cumulative doses) induced cardiomyopathy in rats. DXR treatment significantly (P<0.01) increased the activities of serum creatine kinase (CK-MB), lactate dehydrogenase (LDH), cardiomyocyte caspase-3 and catalase (CAT). ALK (100 mg/kg) treatment prevented the animals significantly (P<0.01) from rise in the above indices. Furthermore ALK (100 mg/kg) significantly restores the DXR-induced decrease in antioxidant defense, reduced glutathione (GSH) and superoxide dismutase (SOD). Transmission electron microscopic studies showed that DXR caused apoptosis in myocardium, manifested as condensation of chromatin network at the margins and rupture of nuclear membrane which was well protected by ALK (100 mg/kg) treatment. The present study indicates that ALK protected rats from DXR-induced cardiomyopathy.

Topics: Amides; Animals; Antibiotics, Antineoplastic; Antioxidants; Apoptosis; Cardiomyopathies; Chronic Disease; Disease Models, Animal; Dose-Response Relationship, Drug; Doxorubicin; Fumarates; Microscopy, Electron, Transmission; Myocardium; Oxidative Stress; Rats; Rats, Wistar; Renin; Renin-Angiotensin System

Aliskiren is the first in a new class of orally active direct renin inhibitors, approved for the treatment of hypertension. However, the efficacy of aliskiren in diabetic cardiovascular complications remains to be defined. This study aimed to test the hypothesis that aliskiren may enhance the beneficial effects of pioglitazone against cardiovascular injury associated with diabetic nephropathy.. Diabetic nephropathy was induced in rats by unilateral nephrectomy followed by streptozotocin injection. Diabetic nephropathic rats were orally given vehicle, pioglitazone, aliskiren, or combined pioglitazone and aliskiren for four weeks to compare their effects on cardiovascular injury, particularly myocardial fibrosis.. Pioglitazone treatment significantly attenuated cardiac lipid peroxidation, oxidative injury and myocardial fibrosis in diabetic nephropathic rats. This was associated with up-regulation of transforming growth factor-β1 and matrix metalloproteinase-2 genes, along with down-regulation of tissue inhibitor of metalloproteinase-2 gene in cardiac tissue. The combination of aliskiren with pioglitazone exerted greater beneficial effect than monotherapy with either drug, on all the aforementioned parameters.. Our findings suggested that aliskiren enhanced the protective effects of pioglitazone against myocardial fibrosis, in experimental diabetic nephropathy. Thus, the combination of aliskiren and pioglitazone may be a potential therapeutic strategy for cardiovascular injury associated with diabetic nephropathy.

Topics: Amides; Animals; Antihypertensive Agents; Cardiomyopathies; Diabetic Nephropathies; Disease Models, Animal; Drug Therapy, Combination; Fibrosis; Fumarates; Gene Expression Regulation; Hypoglycemic Agents; Lipid Peroxidation; Male; Matrix Metalloproteinase 2; Myocardium; Nephrectomy; Oxidative Stress; Pioglitazone; Rats; Rats, Wistar; Streptozocin; Thiazolidinediones; Tissue Inhibitor of Metalloproteinase-2; Transforming Growth Factor beta1

The complex pathophysiological interactions between heart and kidney diseases are collectively known as cardiorenal syndrome. The renin-angiotensin system (RAS) may have a pivotal role in the development of cardiorenal syndrome. The aim of this study was to elucidate the RAS activity responsible for adverse post-infarction remodeling and prognosis in mice with renal failure. To establish the type IV cardiorenal syndrome model, 5/6 nephrectomy (NTX) was performed in a surgical procedure, followed by the induction of myocardial ischemia (MI) by a coronary artery ligation 4 weeks later. NTX and MI resulted in deteriorated left ventricular remodeling and RAS activation, which was improved by an aliskiren that appeared to be independent of renal function and blood pressure (BP). Moreover, MI induced in renin and angiotensinogen double-transgenic (Tg) mice showed comparable effects to MI plus NTX mice, including advanced ventricular remodeling and enhancement of RAS, oxidative stress, and monocytes chemoattractant protein (MCP)-1. Aliskiren suppressed these changes in the MI-induced Tg mice. In in vitro study, Nox2 expression was elevated by the stimulation of plasma from NTX mice in isolated neonatal cardiomyocytes. However, Nox2 upregulation was negated when we administered plasma from aliskiren-treated-NTX mice or isolated cardiomyocytes from AT1-deficient mice. Primary mononuclear cells also showed an upregulation in the expression of Nox2 and MCP-1 by stimulation with plasma from NTX mice. Our data suggest that renal disorder results in ventricular dysfunction and deteriorates remodeling after MI through excessive RAS activation. Moreover, renin inhibition improved the changes caused by cardiorenal syndrome.

Topics: Amides; Analysis of Variance; Animals; Atrial Natriuretic Factor; Chemokine CCL2; Disease Models, Animal; Fumarates; Humans; Hypertension; Kaplan-Meier Estimate; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardial Infarction; Myocardium; Nephrectomy; Oxidative Stress; Renal Insufficiency, Chronic; Renin; Renin-Angiotensin System; Ventricular Remodeling

The direct renin inhibitor aliskiren is known to exhibit a strong antihypertensive effect. However, the organoprotective potential of aliskiren beyond its antihypertensive properties is less clear. This study investigates the antifibrotic nephroprotective effects of aliskiren in a nonhypertensive mouse model for progressive renal fibrosis.. COL4A3(-/-) mice received aliskiren via osmotic minipumps. Placebo-treated animals served as controls. Therapy was initiated in 6-week-old animals already showing renal damage (proteinuria ~1 g/l, starting renal fibrosis) and lasted for 4 weeks. Six animals were sacrificed after 9.5 weeks; serum urea and proteinuria were measured. Kidneys were further investigated using histological, immunohistological, and western blot techniques. Survival until end-stage renal failure was monitored in the remaining animals.. COL4A3(-/-) mice did not develop hypertension. Aliskiren serum levels were in the therapeutic range (288 ± 44 ng/ml). Therapy significantly prolonged lifespan until death from renal failure by 18% compared with placebo-treated controls (78.6 ± 8.2 vs. 66.6 ± 4.9 days, P < 0.05). Similarly, therapy reduced the amount of proteinuria and serum urea. Compared with placebo-treated controls, the accumulation of extracellular matrix and renal scarring and the levels of transforming growth factor-β (TGFβ) and connective tissue growth factor (CTGF) were decreased in treated mice.. Despite the late onset of therapy, our results indicate nephroprotective effects of the renin inhibitor aliskiren beyond its antihypertensive property in this animal model of progressive renal fibrosis. In addition to the recognized antihypertensive action of aliskiren, its antifibrotic, antiproteinuric effects demonstrated in the present study indicate that aliskiren may have potential as an important therapeutic option for chronic fibrotic diseases in humans.

Topics: Amides; Angiotensin-Converting Enzyme Inhibitors; Animals; Antihypertensive Agents; Autoantigens; Collagen Type IV; Connective Tissue Growth Factor; Disease Models, Animal; Extracellular Matrix; Fibrosis; Fumarates; Kidney; Mice; Proteinuria; Transforming Growth Factor beta1; Uremia

Cyp1a1-Ren2 transgenic rats [strain name: TGR(Cyp1a1Ren2)], administered indole-3-carbinol (I3C) develop angiotensin (ANG) II-dependent hypertension due to hepatic expression of the Ren2 renin gene. Although AT1 receptor blockade prevents the development of hypertension and normalizes the elevated arterial blood pressure of Cyp1-Ren2 rats, little information is available regarding the blood pressure and renal functional responses to direct inhibition of renin in this high circulating renin model of ANG II-dependent hypertension. This study was performed to determine the effects of acute direct renin inhibition with aliskiren on blood pressure and renal hemodynamics in Cyp1a1-Ren2 rats with ANG II-dependent malignant hypertension.. Mean arterial pressure (MAP) and renal hemodynamics were measured in pentobarbital-anesthetized male Cyp1a1-Ren2 rats during control conditions and after administration of the renin inhibitor, aliskiren (10 mg/kg, intravenous).. Rats induced with I3C had higher MAP (194 ± 7 versus 141 ± 2 mm Hg, P < 0.001), lower renal plasma flow (RPF; 2.47 ± 0.23 versus 4.17 ± 0.35 mL/min/g, P < 0.001) and lower glomerular filtration rate (GFR; 1.01 ± 0.07 versus 1.34 ± 0.06 mL/min/g, P = 0.01) than noninduced Cyp1a1-Ren2 rats (n = 5). Aliskiren administration decreased MAP (194 ± 7 to 136 ± 2 mm Hg, P < 0.001) and increased RPF (2.47 ± 0.23 versus 4.31 ± 0.20 mL/min/g, P < 0.001) in hypertensive but not in normotensive rats, without altering GFR.. Acute renin inhibition with aliskiren normalizes MAP and RPF in Cyp1a1-Ren2 rats with malignant hypertension. The normalization of MAP and RPF after acute renin inhibition indicates that renin generated by expression of the Ren2 gene is responsible for the maintenance of malignant hypertension and the associated reduction in renal hemodynamic function in Cyp1a1-Ren2 rats.

Topics: Amides; Angiotensin II; Animals; Blood Pressure; Cytochrome P-450 CYP1A1; Disease Models, Animal; Fumarates; Glomerular Filtration Rate; Hypertension, Malignant; Kidney; Male; Rats; Rats, Transgenic; Regional Blood Flow; Renin; Vascular Resistance

The hypertensive double-transgenic (dTG) rat strain, expressing human renin and angiotensinogen, develops severe hypertension and organ damage and 50% of individuals die by 7 weeks of age. Here, we characterise a variation of this model in which animals present stable hypertension.. The effect of renin-angiotensin system blockers on blood pressure was determined with adult dTG rats treated with enalapril from 3 to 12 weeks of age. Tissue expression levels of renin and angiotensinogen were determined in dTG rats and rhesus monkeys by quantitative PCR.. Upon withdrawal from enalapril, mean arterial pressure (MAP) rose to 160-180 mmHg, with 95% of the female dTG rats surviving for 6 to 12 months, In Sprague-Dawley (SD) rats and rhesus monkeys, renin mRNA was absent or weakly expressed in most tissues, except for the kidneys and adrenals. In dTG rats, human renin expression was high in many additional tissues. The expression of human angiotensinogen in dTG rats followed a similar tissue pattern to SD and rhesus monkey angiotensinogen. Oral dosing of aliskiren, enalapril or losartan provided a similar maximal reduction in MAP and duration of efficacy in telemetrised dTG rats.. Enalapril-pretreated dTG rats are suitable for long-term MAP monitoring and sequential evaluation of human renin inhibitors.

Topics: Amides; Angiotensinogen; Animals; Blood Pressure; Disease Models, Animal; Enalapril; Female; Fumarates; Gene Expression Regulation; Heart Rate; Humans; Hypertension; Macaca mulatta; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; RNA, Messenger; Tissue Distribution

The role of the renin-angiotensin system in cognitive impairment is unclear. This work was undertaken to test our hypothesis that renin-angiotensin system may contribute to cognitive decline and brain damage caused by chronic cerebral ischemia. C57BL/6J mice were subjected to bilateral common carotid artery stenosis with microcoil to prepare mice with chronic cerebral hypoperfusion, a model of subcortical vascular dementia. The effects of aliskiren, a direct renin inhibitor, or Tempol, a superoxide scavenger, on brain damage and working memory in these mice were examined. Chronic cerebral hypoperfusion significantly increased brain renin activity and angiotensinogen expression in C57BL/6J mice, which was attributed to the increased renin in activated astrocytes and microvessels and the increased angiotensinogen in activated astrocytes in white matter. Aliskiren pretreatment significantly inhibited brain renin activity and ameliorated brain p67(phox)-related NADPH oxidase activity, oxidative stress, glial activation, white matter lesion, and spatial working memory deficits in C57BL/6J mice with bilateral common carotid artery stenosis. To elucidate the role of oxidative stress in brain protective effects of aliskiren, we also examined the effect of Tempol in the same mice with bilateral common carotid artery stenosis. Tempol pretreatment mimicked the brain protective effects of aliskiren in this mouse model. Posttreatment of mice with aliskiren or Tempol after bilateral common carotid artery stenosis also prevented cognitive decline. In conclusion, chronic cerebral hypoperfusion induced the activation of the brain renin-angiotensin system. Aliskiren ameliorated brain damage and working memory deficits in the model of chronic cerebral ischemia through the attenuation of oxidative stress. Thus, direct renin inhibition seems to be a promising therapeutic strategy for subcortical vascular dementia.

Topics: Amides; Angiotensinogen; Animals; Antihypertensive Agents; Blood Pressure; Brain Damage, Chronic; Brain Ischemia; Cognition Disorders; Cyclic N-Oxides; Dementia, Vascular; Disease Models, Animal; Fumarates; Hypertension; Male; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Oxidative Stress; Renin; Renin-Angiotensin System; Risk Factors; Spin Labels

The blood pressure-lowering effect of the renin inhibitor aliskiren equals that of angiotensin-converting enzyme (ACE) inhibitors and angiotensin (Ang) II type 1 (AT1) receptor blockers. Whether aliskiren offers end-organ protection remains to be investigated. Here, we compared the cardiac effects of aliskiren, the AT1 receptor blocker irbesartan and the ACE inhibitor captopril in spontaneously hypertensive rats (SHR) at equi-hypotensive doses.. SHR were treated for 1-3 weeks with vehicle, aliskiren, captopril or irbesartan (100, 3 and 15 mg/kg per day, respectively) using an osmotic minipump, and compared to vehicle-treated Wistar-Kyoto (WKY) controls. All drugs lowered (but not normalized) mean arterial pressure in SHR equi-effectively, as monitored by radiotelemetry, without altering heart rate. All drugs also reduced the increased cardiomyocyte area in SHR, and tended to normalize the elevated brain natriuretic peptide plasma levels. In the Langendorff set-up, all drugs normalized the diminished endothelium-dependent vasodilator response to bradykinin in SHR. Moreover, aliskiren and irbesartan, but not captopril, decreased the enhanced coronary Ang II response in SHR. Aliskiren reduced plasma renin activity and the plasma and tissue angiotensin levels at 1 week of treatment; yet, after 3 weeks of aliskiren treatment only the cardiac angiotensin levels remained suppressed, whereas no tissue angiotensin reductions were seen with captopril or irbesartan.. For a given decrease in blood pressure, aliskiren improves coronary endothelial function and decreases cardiac hypertrophy in SHR to at least the same degree as ACE inhibition and AT1 receptor blockade. In addition, aliskiren diminishes the enhanced Ang II response in the coronary circulation of SHR and offers superior long-term cardiac angiotensin suppression.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensins; Animals; Biphenyl Compounds; Blood Pressure; Captopril; Disease Models, Animal; Dose-Response Relationship, Drug; Fumarates; Heart; Heart Ventricles; Hypertension; Hypertrophy; Irbesartan; Male; Natriuretic Peptide, Brain; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Renin; Tetrazoles

The relationship between angiotensin II (ANG II) and endothelin-1 (ET-1) is known to be complex; both peptides can initiate and potentiate the gene expression of each other. This pilot study investigated the effects of the AT(1) receptor blocker losartan or the direct renin inhibitor aliskiren on mean arterial pressure (MAP) and albuminuria and the renal ANG II and ET-1 levels. 3-month-old male Ren-2 transgenic rats (TGR) were treated either with losartan (5 mg kg(-1) day(-1)) or aliskiren (10 mg kg(-1) day(-1)) for 10 weeks. At the end of the experiment, rats were decapitated and cortical and papillary parts of kidneys were separated. Plasma and tissue ANG II levels were measured by RIA and tissue ET-1 concentrations by ELISA. In all four groups of animals ET-1 levels were lowest in renal cortex and more than 100-fold higher in the papilla. Cortical and papillary ET-1 concentrations in untreated TGR significantly exceeded those of control HanSD rats and were significantly depressed by both drugs. In both strains, papillary ANG II concentrations were moderately but significantly higher than cortical ANG II, TGR exhibited higher ANG II levels both in cortex and papilla as compared to control HanSD rats. Aliskiren and losartan at the doses used depressed similarly the levels of ANG II in cortex and papilla and reduced ET-1 significantly in the renal cortex and papilla below control levels in HanSD rats. Albuminuria, which was more than twice as high in TGR as in HanSD rats, was normalized with aliskiren and reduced by 28% with losartan, although MAP was reduced to a similar degree by both drugs. Despite similar reductions of MAP and renal ET-1 and ANG II levels aliskiren appears to be more effective than losartan, at the doses used, in reducing albuminuria in heterozygous hypertensive Ren-2 rats.

Topics: Albuminuria; Amides; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Animals; Antihypertensive Agents; Blood Pressure; Disease Models, Animal; Down-Regulation; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Fumarates; Hypertension; Kidney; Losartan; Male; Mice; Pilot Projects; Radioimmunoassay; Rats; Rats, Transgenic; Renin; Time Factors

The effects of the human renin inhibitor aliskiren on blood pressure (BP), end-organ damage, proteinuria, and tissue and plasma angiotensin (ANG) II levels in young and adult heterozygous Ren-2 transgenic rats (TGR) were evaluated and compared with the effect of the ANG type 1 (AT(1)) receptor blocker losartan during treatment and after 12 days after the withdrawal of drug treatments. BP was monitored by telemetry from the age of 32 days on (young rats) and at 100 days (adult rats). Aliskiren (10 mg·kg(-1)·day(-1) in osmotic minipumps) or losartan (5 mg·kg(-1)·day(-1) in drinking water) treatment was applied for 28 days in young rats and for 70 days in adult rats. In young untreated TGR, severe hypertension rapidly evolved. Adult untreated TGR exhibited stable established hypertension. Both aliskiren and losartan fully prevented the development of hypertension and cardiac hypertrophy in young TGR and normalized BP and cardiac hypertrophy in adult TGR. After cessation of aliskiren treatment in both young and adult TGR BP and cardiac hypertrophy were persistently reduced, while after losartan withdrawal BP and cardiac hypertrophy rapidly increased. In adult aliskiren-treated rats proteinuria was significantly reduced compared with losartan (the effect persisting after withdrawal of treatment), and this decrease strongly correlated with normalization of glomerular size in these animals. In conclusion, aliskiren and losartan had similar antihypertensive effects during chronic treatment, but the antihypertensive and organoprotective effects of aliskiren were persistent even after the 12-day washout period. The durable effect on proteinuria can possibly be attributed to the normalization of glomerular morphology.

Topics: Amides; Angiotensin II; Animals; Antihypertensive Agents; Blood Pressure; Cardiomegaly; Disease Models, Animal; Fumarates; Heart Rate; Hypertension; Kidney Glomerulus; Losartan; Male; Proteinuria; Rats; Rats, Transgenic; Renin; Time Factors

Sca-1 and VEGFR-2 positive pro-angiogenic cells (PAC) predict outcome of patients with vascular disease. Activation of the renin-angiotensin-aldosterone system impairs PAC function. The effects of the direct renin inhibitor aliskiren on PAC numbers and function are not known. Treatment of C57Bl/6 mice and Apo E(-/-) mice on high-cholesterol diet with aliskiren, 25 mg/kg/day s.c. for 3-6 weeks, reduced systolic and diastolic blood pressure by -11.5 and -13.7% compared to vehicle. Aliskiren increased Sca-1/VEGFR-2 positive PAC in the blood (159 ± 14%) and spleen-derived DiLDL/lectin positive PAC (180 ± 21%). Migratory capacity of PAC was increased to 165 ± 16%. In cultured human PAC, aliskiren dose-dependently increased the number of colony forming units to 152 ± 9% (1 μmol/l) and 187 ± 7% (10 μmol/l), which was prevented by the eNOS inhibitor LNMA. H₂O₂-induced apoptosis of cultured human PAC was reduced to 77 ± 23%. In Apo E(-/-) mice, aliskiren reduced atherosclerotic plaque area in the aortic sinus by 58 ± 4%. Circulating Sca-1/VEGFR-2 positive PAC were upregulated to 180 ± 25% and migratory capacity of PAC was increased to 127 ± 7%. Aliskiren reduced vascular NADPH oxidase activity to 41.6 ± 6.7%. Despite similar blood pressure lowering, treatment with hydralazine (25 mg/kg/day) did not significantly influence atherogenesis or PAC. Treatment of C57Bl/6 mice with a lower dose of aliskiren (15 mg/kg/day) did not affect blood pressure but increased cultured DiLDL/lectin positive PAC to 229 ± 30% and their migratory capacity to 214 ± 24%. Aliskiren increased number and function of PAC in mice and prevented atherosclerotic lesion formation. The effects were observed independent of blood pressure lowering.

Topics: Amides; Angiogenesis Inducing Agents; Animals; Antigens, Ly; Apolipoproteins E; Apoptosis; Atherosclerosis; Blood Pressure; Cell Movement; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Fumarates; Humans; Infusions, Subcutaneous; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Neovascularization, Physiologic; Oxidative Stress; Renin; Stem Cells; Time Factors; Vascular Endothelial Growth Factor Receptor-2

Renin initiates angiotensin II formation and has no other known functions. We observed that transgenic rats (TGR) overexpressing the human renin gene (hREN) developed moderate obesity with increased body fat mass and glucose intolerance compared with nontransgenic Sprague-Dawley (SD) rats. The metabolic changes were not reversed by an angiotensin-converting enzyme inhibitor, a direct renin inhibitor, or by (pro)renin receptor blocker treatment. The obese phenotype in TGR(hREN) originated from higher food intake, which was partly compensated by increases in resting energy expenditure, total thermogenesis (postprandial and exercise activity), and lipid oxidation during the first 8 weeks of life. Once established, the difference in body weight between TGR(hREN) and SD rats remained constant over time. When restricted to the caloric intake of SD, TGR(hREN) developed an even lower body weight than nontransgenic controls. We did not observe significant changes in the cocaine and amphetamine-regulated transcript, pro-opiomelanocortin, both anorexigenic, or neuropeptide Y, orexigenic, mRNA levels in TGR(hREN) versus SD controls. However, the mRNA level of the agouti-related peptide, orexigenic, was significantly reduced in TGR(hREN) versus SD controls at the end of the study, which indicates a compensatory mechanism. We suggest that the human renin transgene initiates a process leading to increased and early appetite, obesity, and metabolic changes not related to angiotensin II. The mechanisms are independent of any currently known renin-related effects.

Topics: Adipocytes; Amides; Angiotensin II; Animals; Cells, Cultured; Disease Models, Animal; Energy Metabolism; Fumarates; Humans; Leptin; Lipid Metabolism; Male; Obesity; Phenotype; Rats; Rats, Sprague-Dawley; Rats, Transgenic; Renin; Thermogenesis

Renin is the rate-limiting enzyme in renin-angiotensin system (RAS) activation. We sought to determine the impact of renin inhibition on whole-body insulin sensitivity and skeletal muscle RAS, oxidative stress, insulin signaling, and glucose transport in the transgenic TG(mRen2)27 rat (Ren2), which manifests increased tissue RAS activity, elevated serum aldosterone, hypertension, and insulin resistance. Young (aged 6-9 wk) Ren2 and age-matched Sprague Dawley control rats were treated with aliskiren [50 mg/kg . d, ip] or placebo for 21 d and administered an ip glucose tolerance test. Insulin metabolic signaling and 2-deoxyglucose uptake in soleus muscle were examined in relation to tissue renin-angiotensin-aldosterone system [angiotensin (Ang) II, mineralocorticoid receptor (MR), and Ang type I receptor (AT(1)R)] and measures of oxidative stress as well as structural changes evaluated by light and transmission electron microscopy. Ren2 rats demonstrated systemic insulin resistance with decreased skeletal muscle insulin metabolic signaling and glucose uptake. This was associated with increased Ang II, MR, AT(1)R, oxidative stress, and reduced tyrosine insulin receptor substrate-1 phosphorylation, protein kinase B/(Akt) phosphorylation and glucose transporter-4 immunostaining. The Ren2 also demonstrated perivascular fibrosis and mitochondrial remodeling. Renin inhibition improved systemic insulin sensitivity, insulin metabolic signaling, and glucose transport along with normalization of Ang II, AT(1)R, and MR levels, oxidative stress markers, fibrosis, and mitochondrial structural abnormalities. Our data suggest that renin inhibition improves systemic insulin sensitivity, skeletal muscle insulin metabolic signaling, and glucose transport in Ren2 rats. This is associated with reductions in skeletal muscle tissue Ang II, AT(1)R, and MR expression; oxidative stress; fibrosis; and mitochondrial abnormalities.

Topics: Amides; Angiotensin II; Animals; Animals, Genetically Modified; Disease Models, Animal; Fumarates; Gene Expression Regulation; Glucose; Glucose Transporter Type 4; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Muscle, Skeletal; Oxidative Stress; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Reactive Nitrogen Species; Receptor, Angiotensin, Type 1; Receptors, Mineralocorticoid; Renin

The renin-angiotensin-aldosterone system (RAS) plays a central role in atherosclerosis. To investigate the effects of a direct renin inhibitor aliskiren on vascular inflammation, we conducted leukocyte adhesion assays in vivo and in vitro using a novel real-time imaging system.. Aliskiren (10 mg/kg/d) or PBS was administered to C57BL/6 mice (6-7 weeks of age; Oriental Yeast, Tokyo, Japan) for 2 weeks via an osmotic pump. Blood pressure was not significantly changed in the 2 groups throughout the experimental period. A perivascular cuff injury was then introduced to the femoral artery and real-time intravital microscopic observation was conducted 24 hours after injury. The number of adherent leukocytes was elevated in the injured mice without aliskiren (43.8+/-9.3/10(-2) mm(2)), whereas that was significantly reduced in the mice with aliskiren (18.4+/-4.4, P<0.05). Treatment of human umbilical vein endothelial cells (HUVECs) with aliskiren significantly reduced the adhesion of THP-1 cells to TNF-alpha-activated HUVECs (P<0.05). Interestingly, TNF-alpha-induced renin activity and angiotensin II production in HUVECs were also blunted by aliskiren. Furthermore, exogenous renin and angiotensin II abrogated the aliskiren-mediated reduction of THP-1 cell adhesion to HUVECs.. Our in vivo and in vitro findings indicate a pivotal role for renin inhibition in vascular inflammation independent of blood pressure.

Topics: Amides; Animals; Blotting, Western; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Femoral Artery; Fumarates; Humans; In Vitro Techniques; Mice; Mice, Inbred C57BL; Oxidative Stress; Random Allocation; Reactive Oxygen Species; Renin; Renin-Angiotensin System; Reverse Transcriptase Polymerase Chain Reaction; Sensitivity and Specificity; Tumor Necrosis Factor-alpha

We compared the effect n-3 polyunsaturated fatty acids (PUFAs) with direct renin inhibition on electrophysiological remodeling in angiotensin II-induced cardiac injury. We treated double-transgenic rats expressing the human renin and angiotensinogen genes (dTGRs) from week 4 to 7 with n-3 PUFA ethyl-esters (Omacor; 25-g/kg diet) or a direct renin inhibitor (aliskiren; 3 mg/kg per day). Sprague-Dawley rats were controls. We performed electrocardiographic, magnetocardiographic, and programmed electrical stimulation. Dietary n-3 PUFAs increased the cardiac content of eicosapentaenoic and docosahexaenoic acid. At week 7, mortality in dTGRs was 31%, whereas none of the n-3 PUFA- or aliskiren-treated dTGRs died. Systolic blood pressure was modestly reduced in n-3 PUFA-treated (180+/-3 mm Hg) compared with dTGRs (208+/-5 mm Hg). Aliskiren-treated dTGRs and Sprague-Dawley rats were normotensive (110+/-3 and 119+/-6 mm Hg, respectively). Both n-3 PUFA-treated and untreated dTGRs showed cardiac hypertrophy and increased atrial natriuretic peptide levels. Prolonged QRS and QT(c) intervals and increased T-wave dispersion in dTGRs were reduced by n-3 PUFAs or aliskiren. Both treatments reduced arrhythmia induction from 75% in dTGRs to 17% versus 0% in Sprague-Dawley rats. Macrophage infiltration and fibrosis were reduced by n-3 PUFAs and aliskiren. Connexin 43, a mediator of intermyocyte conduction, was redistributed to the lateral cell membranes in dTGRs. n-3 PUFAs and aliskiren restored normal localization to the intercalated disks. Thus, n-3 PUFAs and aliskiren improved electrical remodeling, arrhythmia induction, and connexin 43 expression, despite a 70-mm Hg difference in blood pressure and the development of cardiac hypertrophy.

Topics: Amides; Angiotensinogen; Animals; Animals, Genetically Modified; Antihypertensive Agents; Arrhythmias, Cardiac; Blood Pressure; Cardiac Pacing, Artificial; Cardiomegaly; Connexin 43; Dietary Fats; Disease Models, Animal; Electrocardiography; Electrophysiology; Fatty Acids, Omega-3; Fumarates; Humans; Hypertension; Magnetocardiography; Male; Rats; Rats, Sprague-Dawley; Renin; Up-Regulation

Hypertension is associated with increased risk of cardiovascular diseases. Antihypertensive treatment, particularly blockade of the renin-angiotensin system, contributes to prevent atherosclerosis-mediated cardiovascular events. Direct comparison of different antihypertensive treatments on atherosclerosis and particularly plaque stabilization is sparse. ApoE(-/-) mice with vulnerable (2-kidney, 1-clip renovascular hypertension model) or stable (1-kidney, 1-clip renovascular hypertension model) atherosclerotic plaques were used. Mice were treated with aliskiren (renin inhibitor), irbesartan (angiotensin-receptor blocker), atenolol (beta-blocker), or amlodipine (calcium channel blocker). Atherosclerosis characteristics were assessed. Hemodynamic and hormonal parameters were measured. Aliskiren and irbesartan significantly prevented atherosclerosis progression in 2-kidney, 1-clip mice. Indeed, compared with untreated animals, plaques showed thinner fibrous cap (P<0.05); smaller lipid core (P<0.05); decreased media degeneration, layering, and macrophage content (P<0.05); and increased smooth muscle cell content (P<0.05). Interestingly, aliskiren significantly increased the smooth muscle cell compared with irbesartan. Despite similar blood pressure lowering, only partial plaque stabilization was attained by atenolol and amlodipine. Amlodipine increased plaque smooth muscle cell content (P<0.05), whereas atenolol decreased plaque inflammation (P<0.05). This divergent effect was also observed in 1-kidney, 1-clip mice. Normalizing blood pressure by irbesartan increased the plasma renin concentration (5932+/-1512 ng/mL per hour) more than normalizing it by aliskiren (16085+/-5628 ng/mL per hour). Specific renin-angiotensin system blockade prevents atherosclerosis progression. First, evidence is provided that direct renin inhibition mediates atherosclerotic plaque stabilization. In contrast, beta-blocker and calcium channel blocker treatment only partially stabilize plaques differently influencing atherogenesis. Angiotensin II decisively mediates plaque vulnerability. The plasma renin concentration measurement by an indirect method did not confirm the excessive increase of plasma renin concentration reported in the literature during aliskiren compared with irbesartan or amlodipine treatment.

Topics: Amides; Amlodipine; Animals; Antihypertensive Agents; Apolipoproteins E; Atenolol; Atherosclerosis; Biphenyl Compounds; Blood Pressure; Cholesterol; Disease Models, Animal; Disease Progression; Female; Fumarates; Heart Rate; Irbesartan; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Renin; Renin-Angiotensin System; Tetrazoles