A single dose of angiotensin-(1-7) resolves eosinophilic inflammation and protects the lungs from a secondary inflammatory challenge.

OBJECTIVE: Angiotensin-(1-7) [Ang-(1-7)] is a pro-resolving mediator. It is not known whether the pro-resolving effects of Ang-(1-7) are sustained and protect the lung from a subsequent inflammatory challenge. This study sought to investigate the impact of treatment in face of a second allergic or lipopolysaccharide (LPS) challenge. METHODS: Mice, sensitized and challenged with ovalbumin (OVA), received a single Ang-(1-7) dose at the peak of eosinophilic inflammation, 24 h after the final OVA challenge. Subsequently, mice were euthanized at 48, 72, 96, and 120 h following the OVA challenge, and cellular infiltrate, inflammatory mediators, lung histopathology, and macrophage-mediated efferocytic activity were evaluated. The secondary inflammatory stimulus (OVA or LPS) was administered 120 h after the last OVA challenge, and subsequent inflammatory analyses were performed. RESULTS: Treatment with Ang-(1-7) resulted in elevated levels of IL-10, CD4+Foxp3+, Mres in the lungs and enhanced macrophage-mediated efferocytic capacity. Moreover, in allergic mice treated with Ang-(1-7) and then subjected to a secondary OVA challenge, inflammation was also reduced. Similarly, in mice exposed to LPS, Ang-(1-7) effectively prevented the lung inflammation. CONCLUSION: A single dose of Ang-(1-7) resolves lung inflammation and protect the lung from a subsequent inflammatory challenge highlighting its potential therapeutic for individuals with asthma.

Angiotensin-(1-7) Treatment Early in Life Prevents Cardiac Hypertrophy in Adult Hypertensive Rats.

ABSTRACT: Angiotensin (Ang)-(1-7) is a cardioprotective peptide of the renin-angiotensin system. Prepuberty has been considered as a later susceptible window of development, and stressful factors in this life phase can induce chronic diseases in adulthood. We aimed to investigate whether the treatment with Ang-(1-7) during the prepuberty could attenuate the development of hypertension and cardiac injury in adult spontaneously hypertensive rats (SHRs). SHRs were treated with Ang-(1-7) (24 µg/kg/h) from age 4 to 7 weeks. Systolic blood pressure was measured by tail-cuff plethysmography up to 17th week. Thereafter, echocardiography was performed, and the rats were euthanized for the collection of tissues and blood. Ang-(1-7) did not change the systolic blood pressure but reduced the septal and posterior wall thickness, and cardiomyocyte hypertrophy and fibrosis in SHR. In addition, Ang-(1-7) reduced the gene expression of atrial natriuretic peptide and brain natriuretic peptide, increased the metalloproteinase 9 expression, and reduced the extracellular signal-regulated kinases 1/2 phosphorylation. Ang-(1-7) also prevented the reduction of Mas receptor but did not change the protein expression of angiotensin-converting enzyme, angiotensin-converting enzyme 2, AT1, and AT2. The treatment with Ang-(1-7) decreased the malondialdehyde (MDA) levels and increased superoxide dismutase-1 and catalase activities and protein expression of catalase. Our findings demonstrate that the treatment of SHR with Ang-(1-7) for 3 weeks early in life promotes beneficial effects in the heart later in life, even without altering blood pressure, through mechanisms involving the reduction of oxidative stress and ERK1/2 phosphorylation. In addition, this study supports the prepuberty as an important programming window.

NaHS restores the vascular alterations in the renin-angiotensin system induced by hyperglycemia in rats.

Hyperglycemia (HG) impairs the renin-angiotensin system (RAS), which may contribute to vascular dysfunction. Besides, hydrogen sulfide (H2S) exerts beneficial cardiovascular effects in metabolic diseases. Therefore, our study aimed to determine the effects of chronic administration of sodium hydrosulfide (NaHS; inorganic H2S donor) and DL-Propargylglycine [DL-PAG; cystathionine-×¥-lyase (CSE) inhibitor] on the RAS-mediated vascular responses impairments observed in thoracic aortas from male diabetic Wistar rats. For that purpose, neonatal rats were divided into two groups that received: 1) citrate buffer (n = 12) or 2) streptozotocin (STZ, 70 mg/kg; n = 48) on the third postnatal day. After 12 weeks, diabetic animals were divided into 4 subgroups (n = 12 each) that received daily i.p. injections during 4 weeks of: 1) non-treatment; 2) vehicle (PBS, 1 mL/kg); 3) NaHS (5.6 mg/kg); and 4) DL-PAG (10 mg/kg). After treatments (16 weeks), blood glucose, angiotensin-(1-7) [Ang-(1-7)], and angiotensin II (Ang II) levels, vascular responses to Ang-(1-7) and Ang II, and the expression of angiotensin AT1, AT2, and Mas receptors, angiotensin converting enzyme (ACE) and ACE type 2 (ACE2) were determined. HG induced: 1) increased blood glucose levels and expression of angiotensin II AT1 receptor; 2) impaired Ang-(1-7) and Ang II mediated vascular responses; 3) decreased angiotensin levels and expression of angiotensin II AT2 and angiotensin-(1-7) Mas receptors, and ACE2; and 4) no changes in ACE expression. Interestingly, NaHS, but not DL-PAG, reversed HG-induced impairments, except for blood glucose level changes. These results suggest that NaHS restores vascular function in streptozotocin-induced HG through RAS modulation.

Peptide inhibitors of angiotensin-I converting enzyme based on angiotensin (1-7) with selectivity for the C-terminal domain.

The renin-angiotensin system (RAS) is a key regulator of human arterial pressure. Several of its effects are modulated by angiotensin II, an octapeptide originating from the action of angiotensin-I converting enzyme (ACE) on the decapeptide angiotensin-I. ACE possess two active sites (nACE and cACE) that have their own kinetic and substrate specificities. ACE inhibitors are widely used as the first-line treatment for hypertension and other heart-related diseases, but because they inactivate both ACE domains, their use is associated with serious side effects. Thus, the search for domain-specific ACE inhibitors has been the focus of intense research. Angiotensin (1-7), a peptide that also belongs to the RAS, acts as a substrate of nACE and an inhibitor of cACE. We have synthetized 15 derivatives of Ang (1-7), sequentially removing the N-terminal amino acids and modifying peptides extremities, to find molecules with improved selectivity and inhibition properties. Ac-Ang (2-7)-NH2 is a good ACE inhibitor, resistant to cleavage and with improved cACE selectivity. Molecular dynamics simulations provided a model for this peptide's selectivity, due to Val3 and Tyr4 interactions with ACE subsites. Val3 has an important interaction with the S3 subsite, since its removal greatly reduced peptide-enzyme interactions. Taken together, our findings support ongoing studies using insights from the binding of Ac-Ang (2-7)-NH2 to develop effective cACE inhibitors.

Angiotensin-(1-9) in hypertension.

Angiotensin-(1-9) [Ang-(1-9)] is a peptide of the non-canonical renin-angiotensin system (RAS) synthesized from angiotensin I by the monopeptidase angiotensin-converting enzyme type 2 (ACE2). Using osmotic minipumps, infusion of Ang-(1-9) consistently reduces blood pressure in several rat hypertension models. In these animals, hypertension-induced end-organ damage is also decreased. Several pieces of evidence suggest that Ang-(1-9) is the endogenous ligand that binds and activates the type-2 angiotensin II receptor (AT2R). Activation of AT2R triggers different tissue-specific signaling pathways. This phenomenon could be explained by the ability of AT2R to form different heterodimers with other G protein-coupled receptors. Because of the antihypertensive and protective effects of AT2R activation by Ang-(1-9), associated with a short half-life of RAS peptides, several synthetic AT2R agonists have been synthesized and assayed. Some of them, particularly CGP42112, C21 and novokinin, have demonstrated antihypertensive properties. Only two synthetic AT2R agonists, C21 and LP2-3, have been tested in clinical trials, but none of them like an antihypertensive. Therefore, Ang-(1-9) is a promising antihypertensive drug that reduces hypertension-induced end-organ damage. However, further research is required to translate this finding successfully to the clinic.

Treatment with Angiotensin-(1-7) Prevents Development of Oral Papilloma Induced in K-ras Transgenic Mice.

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant cancer affecting the oral cavity. It is characterized by high morbidity and very few therapeutic options. Angiotensin (Ang)-(1-7) is a biologically active heptapeptide, generated predominantly from AngII (Ang-(1-8)) by the enzymatic activity of angiotensin-converting enzyme 2 (ACE 2). Previous studies have shown that Ang-(1-7) counterbalances AngII pro-tumorigenic actions in different pathophysiological settings, exhibiting antiproliferative and anti-angiogenic properties in cancer cells. However, the prevailing effects of Ang-(1-7) in the oral epithelium have not been established in vivo. Here, we used an inducible oral-specific mouse model, where the expression of a tamoxifen-inducible Cre recombinase (CreERtam), which is under the control of the cytokeratin 14 promoter (K14-CreERtam), induces the expression of the K-ras oncogenic variant KrasG12D (LSLK-rasG12D). These mice develop highly proliferative squamous papilloma in the oral cavity and hyperplasia exclusively in oral mucosa within one month after tamoxifen treatment. Ang-(1-7) treated mice showed a reduced papilloma development accompanied by a significant reduction in cell proliferation and a decrease in pS6 positivity, the most downstream target of the PI3K/Akt/mTOR signaling route in oral papilloma. These results suggest that Ang-(1-7) may be a novel therapeutic target for OSCC.

Combined Administration of Andrographolide and Angiotensin- (1-7) Synergically Increases the Muscle Function and Strength in Aged Mice.

BACKGROUND: Sarcopenia is a progressive and generalized skeletal muscle disorder characterized by muscle weakness, loss of muscle mass, and decline in the capacity of force generation. Aging can cause sarcopenia. Several therapeutic strategies have been evaluated to prevent or alleviate this disorder. One of them is angiotensin 1-7 [Ang-(1-7)], an anti-atrophic peptide for skeletal muscles that regulates decreased muscle mass for several causes, including aging. Another regulator of muscle mass and function is andrographolide, a bicyclic diterpenoid lactone that decreases the nuclear factor kappa B (NF-κB) signaling and attenuates the severity of some muscle diseases. OBJECTIVE: Evaluate the effect of combined administration of Ang-(1-7) with andrographolide on the physical performance, muscle strength, and fiber´s diameter in a murine model of sarcopenia by aging. METHODS: Aged male mice of the C57BL/6J strain were treated with Andrographolide, Ang-(1-7), or combined for three months. The physical performance, muscle strength, and fiber´s diameter were measured. RESULTS: The results showed that aged mice (24 months old) treated with Ang-(1-7) or Andrographolide improved their performance on a treadmill test, muscle strength, and their fiber´s diameter compared to aged mice without treatment. The combined administration of Ang-(1-7) with andrographolide to aged mice has an enhanced synergically effect on physical performance, muscle strength, and fiber´s diameter. CONCLUSION: Our results indicated that in aged mice, the effects of andrographolide and Ang-(1-7) on muscle function, strength, and fiber´s diameter are potentiated.

Angiotensin-(1-7)/MasR axis promotes migration of monocytes/macrophages with a regulatory phenotype to perform phagocytosis and efferocytosis.

Nonphlogistic migration of macrophages contributes to the clearance of pathogens and apoptotic cells, a critical step for the resolution of inflammation and return to homeostasis. Angiotensin-(1-7) [Ang-(1-7)] is a heptapeptide of the renin-angiotensin system that acts through Mas receptor (MasR). Ang-(1-7) has recently emerged as a novel proresolving mediator, yet Ang-(1-7) resolution mechanisms are not fully determined. Herein, Ang-(1-7) stimulated migration of human and murine monocytes/macrophages in a MasR-, CCR2-, and MEK/ERK1/2-dependent manner. Pleural injection of Ang-(1-7) promoted nonphlogistic mononuclear cell influx alongside increased levels of CCL2, IL-10, and macrophage polarization toward a regulatory phenotype. Ang-(1-7) induction of CCL2 and mononuclear cell migration was also dependent on MasR and MEK/ERK. Of note, MasR was upregulated during the resolution phase of inflammation, and its pharmacological inhibition or genetic deficiency impaired mononuclear cell recruitment during self-resolving models of LPS pleurisy and E. coli peritonitis. Inhibition/absence of MasR was associated with reduced CCL2 levels, impaired phagocytosis of bacteria, efferocytosis, and delayed resolution of inflammation. In summary, we have uncovered a potentially novel proresolving feature of Ang-(1-7), namely the recruitment of mononuclear cells favoring efferocytosis, phagocytosis, and resolution of inflammation. Mechanistically, cell migration was dependent on MasR, CCR2, and the MEK/ERK pathway.

Oral Treatment with Angiotensin-(1-7) Attenuates the Kidney Injury Induced by Gentamicin in Wistar Rats.

BACKGROUND: Acute Kidney Injury (AKI), a common disease of the urinary system, can be induced by high doses of gentamicin (GM). The renin-angiotensin system exerts a key role in the progression of the AKI since elevated intrarenal levels of Ang II, and ACE activity is found in this condition. However, it is unknown whether oral administration of angiotensin (Ang)-(1-7), a heptapeptide that evokes opposite effects of Ang II, may attenuate the renal injuries induced by gentamicin. OBJECTIVES: To evaluate the effects of Ang-(1-7) on GM-induced renal dysfunction in rats. METHODS: AKI was induced by subcutaneous administration of GM (80 mg/Kg) for 5 days. Simultaneously, Ang-(1-7) included in hydroxypropyl ß-cyclodextrin (HPßCD) was administered by gavage [46 µg/kg HPßCD + 30 µg/kg Ang-(1-7)]. At the end of the treatment period (sixth day), the rats were housed in metabolic cages for renal function evaluation. Thereafter, blood and kidney samples were collected. RESULTS: Ang-(1-7) attenuated the increase of the plasmatic creatinine and proteinuria caused by GM but did not change the glomerular filtration rate nor tubular necrosis. Ang-(1-7) attenuated the increased urinary flow and the fractional excretion of H2O and potassium observed in GM rats but intensified the elevated excretion of sodium in these animals. Morphological analysis showed that Ang-(1-7) also reduced the tubular vacuolization in kidneys from GM rats. CONCLUSION: Ang-(1-7) promotes selective beneficial effects in renal injuries induced by GM.

Alamandine but not angiotensin-(1-7) produces cardiovascular effects at the rostral insular cortex.

Experiments aimed to evaluate the tissue distribution of Mas-related G protein-coupled receptor D (MrgD) revealed the presence of immunoreactivity for the MrgD protein in the rostral insular cortex (rIC), an important area for autonomic and cardiovascular control. To investigate the relevance of this finding, we evaluated the cardiovascular effects produced by the endogenous ligand of MrgD, alamandine, in this brain region. Mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were recorded in urethane anesthetized rats. Unilateral microinjection of equimolar doses of alamandine (40 pmol/100 nL), angiotensin-(1-7), angiotensin II, angiotensin A, and Mas/MrgD antagonist d-Pro7-Ang-1-7 (50 pmol/100 nL), Mas antagonist A779 (100 pmol/100 nL), or vehicle (0.9% NaCl) were made in different rats (n = 4-6/group) into rIC. To verify the specificity of the region, a microinjection of alamandine was also performed into intermediate insular cortex (iIC). Microinjection of alamandine in rIC produced an increase in MAP (Δ = 15 ± 2 mmHg), HR (Δ = 36 ± 4 beats/min), and RSNA (Δ = 31 ± 4%), but was without effects at iIC. Strikingly, an equimolar dose of angiotensin-(1-7) at rIC did not produce any change in MAP, HR, and RSNA. Angiotensin II and angiotensin A produced only minor effects. Alamandine effects were not altered by A-779, a Mas antagonist, but were completely blocked by the Mas/MrgD antagonist d-Pro7-Ang-(1-7). Therefore, we have identified a brain region in which alamandine/MrgD receptor but not angiotensin-(1-7)/Mas could be involved in the modulation of cardiovascular-related neuronal activity. This observation also suggests that alamandine might possess unique effects unrelated to angiotensin-(1-7) in the brain.

Oral Angiotensin-(1-7) Peptide Modulates Intestinal Microbiota Improving Metabolic Profile in Obese Mice.

BACKGROUND: Obesity is a serious health problem that dysregulate Renin-Angiotensin System (RAS) and intestinal microbiota. OBJECTIVE: The present study aimed to evaluate the Angiotensin-(1-7) [ANG-(1-7)] oral formulation effects on obese mice intestinal microbiota. METHODS: Mice were divided into four groups: obese and non-obese treated with ANG-(1-7) and obese and non-obese without ANG-(1-7) during four weeks. RESULTS: We observed a significant decrease in the fasting plasma glucose, total cholesterol, triglycerides, and Low-density lipoprotein levels and increased High-density lipoprotein in animals treated with ANG-(1-7). The histological analysis showed intestinal villi height reduction in mice treated with ANG-(1-7). Additionally, increased Bacteroidetes and decreased Firmicutes (increased Bacteroidetes/ Firmicutes ratio) and Enterobacter cloacae populations were observed in the High-Fat Diet + ANG-(1-7) group. Receptor toll-like 4 (TLR4) intestinal mRNA expression was reduced in the HFD+ANG-(1-7) group. Finally, the intestinal expression of the neutral amino acid transporter (B0AT1) was increased in animals treated with ANG-(1-7), indicating a possible mechanism associated with tryptophan uptake. CONCLUSION: The results of the present study suggest for the first time an interaction between oral ANG-(1-7) and intestinal microbiota modulation.

Angiotensin-(1-7) prevents T3-induced cardiomyocyte hypertrophy by upregulating FOXO3/SOD1/catalase and downregulating NF-ĸB.

Clinical studies have shown a correlation between thyroid disorders and cardiac diseases. High levels of triiodothyronine (T3) induce cardiac hypertrophy, a risk factor for cardiac complications and heart failure. Previous results have demonstrated that angiotensin-(1-7) is able to block T3-induced cardiac hypertrophy; however, the molecular mechanisms involved in this event have not been fully elucidated. Here, we evidenced the contribution of FOXO3 signaling to angiotensin-(1-7) effects. Angiotensin-(1-7) treatment increased nuclear FOXO3 levels and reduced p-FOXO3 levels (inactive form) in isolated cardiomyocytes. Knockdown of FOXO3 by RNA silencing abrogated the antihypertrophic effect of angiotensin-(1-7). Increased expression of antioxidant enzymes superoxide dismutase 1 (SOD1 and catalase) and lower levels of reactive oxygen species and nuclear factor-κB (NF-κB) were observed after angiotensin-(1-7) treatment in vitro. Consistent with these results, transgenic rats overexpressing angiotensin-(1-7) displayed increased nuclear FOXO3 and SOD1 levels and reduced NF-κB levels in the heart. These results provide a new molecular mechanism responsible for the antihypertrophic effect of angiotensin-(1-7), which may contribute to future therapeutic targets.

Effect of angiotensin II and angiotensin-(1-7) on proliferation of stem cells from human dental apical papilla.

The effects of the renin-angiotensin system (RAS) on stem cells isolated from human dental apical papilla (SCAPs) are completely unknown. Therefore, the aim of this study was to identify RAS components expressed in SCAPs and the effects of angiotensin (Ang) II and Ang-(1-7) on cell proliferation. SCAPs were collected from third molar teeth of adolescents and maintained in cell culture. Messenger RNA expression and protein levels of angiotensin-converting enzyme (ACE), ACE2, and Mas, Ang II type I (AT1) and type II (AT2) receptors were detected in SCAPs. Treatment with either Ang II or Ang-(1-7) increased the proliferation of SCAPs. These effects were inhibited by PD123319, an AT2 antagonist. While Ang II augmented mTOR phosphorylation, Ang-(1-7) induced ERK1/2 phosphorylation. In conclusion, SCAPs produce the main RAS components and both Ang II and Ang-(1-7) treatments induced cell proliferation mediated by AT2 activation through different intracellular mechanisms.

Relevance of angiotensin-(1-7) and its receptor Mas in pneumonia caused by influenza virus and post-influenza pneumococcal infection.

Resolution failure of exacerbated inflammation triggered by Influenza A virus (IAV) prevents return of pulmonary homeostasis and survival, especially when associated with secondary pneumococcal infection. Therapeutic strategies based on pro-resolving molecules have great potential against acute inflammatory diseases. Angiotensin-(1-7) [Ang-(1-7)] is a pro-resolving mediator that acts on its Mas receptor (MasR) to promote resolution of inflammation. We investigated the effects of Ang-(1-7) and the role of MasR in the context of primary IAV infection and secondary pneumococcal infection and evaluated pulmonary inflammation, virus titers and bacteria counts, and pulmonary damage. Therapeutic treatment with Ang-(1-7) decreased neutrophil recruitment, lung injury, viral load and morbidity after a primary IAV infection. Ang-(1-7) induced apoptosis of neutrophils and efferocytosis of these cells by alveolar macrophages, but had no direct effect on IAV replication in vitro. MasR-deficient (MasR-/-) mice were highly susceptible to IAV infection, displaying uncontrolled inflammation, increased viral load and greater lethality rate, as compared to WT animals. Ang-(1-7) was not protective in MasR-/- mice. Interestingly, Ang-(1-7) given during a sublethal dose of IAV infection greatly reduced morbidity associated with a subsequent S. pneumoniae infection, as seen by decrease in the magnitude of neutrophil influx, number of bacteria in the blood leading to a lower lethality. Altogether, these results show that Ang-(1-7) is highly protective against severe primary IAV infection and protects against secondary bacterial infection of the lung. These effects are MasR-dependent. Mediators of resolution of inflammation, such as Ang-(1-7), should be considered for the treatment of pulmonary viral infections.

Alamandine through MrgD receptor induces antidepressant-like effect in transgenic rats with low brain angiotensinogen.

Alamandine (Ala1-Arg2-Val3-Tyr4-Ile5-His6-Pro7), a heptapeptide hormone of the renin-angiotensin system (RAS), exerts its effects through the Mas-related G-protein coupled receptor of the type D, MrgD, which is expressed in different tissues, including the brain. In the present study, we tested the hypothesis that alamandine could attenuate the depression-like behavior observed in transgenic rats with low brain angiotensinogen, TGR (ASrAOGEN)680. Transgenic rats exhibited a significant increase in the immobility time in forced swim test, a phenotype reversed by intracerebroventricular infusion of alamandine. Pretreatment with D-Pro7-Ang-(1-7), a Mas/MrgD receptor antagonist, prevented the antidepressant-like effect induced by this peptide demonstrating, for the first time, that alamandine through MrgD receptor, can modulate depression-like behavior in TGR (ASrAOGEN)680. This result shows an action of alamandine which strengthens the importance of the counter-regulatory arms of the RAS in fight and treatment of neuropsychiatric diseases.

Angiotensin-(1-7) Prevents Lipopolysaccharide-Induced Autophagy via the Mas Receptor in Skeletal Muscle.

Skeletal muscle atrophy, which occurs in lipopolysaccharide (LPS)-induced sepsis, causes a severe muscle function reduction. The increased autophagy contributes to sepsis-induced skeletal muscle atrophy in a model of LPS injection, increasing LC3II/LC3I ratio, autophagy flux, and autophagosomes. Angiotensin-(1-7) (Ang-(1-7)) has anti-atrophic effects via the Mas receptor in skeletal muscle. However, the impact of Ang-(1-7) on LPS-induced autophagy is unknown. In this study, we determined the effect of Ang-(1-7) on sepsis-induced muscle autophagy. C57BL6 wild-type (WT) mice and mice lacking the Mas receptor (KO Mas) were injected with LPS together with the systemic administration of Ang-(1-7) to determine autophagy in skeletal muscle. We also evaluated autophagy and p38 and c-Jun N-terminal kinase (JNK)activation. Our results show that Ang-(1-7) prevents LPS-induced autophagy in the diaphragm, tibialis anterior, and gastrocnemius of WT mice, which is demonstrated by a decrease in the LC3II/LC3I ratio and mRNA levels of lc3b and ctsl. This effect was lost in KO Mas mice, suggesting the role of the Mas receptor. The results in C2C12 cells show that Ang-(1-7) reduces several LPS-dependent effects, such as autophagy (LC3II/LC3I ratio, autophagic flux, and autophagosomes), activation of p38 and JNK, B-cell lymphoma-2 (BCL2) phosphorylation, and disassembly of the Beclin1/BCL2 complex. In conclusion, Ang-(1-7)/Mas receptor reduces LPS-induced autophagy in skeletal muscle. In vitro assays indicate that Ang-(1-7) prevents LPS-induced autophagy and modifies the MAPK signaling and the disassembly of a complex involved at the beginning of autophagy.

Different reactive species modulate the hypotensive effect triggered by angiotensins at CVLM of 2K1C hypertensive rats.

Hypertension is associated with increased central activity of the renin-angiotensin system (RAS) and oxidative stress. Here, we evaluated whether reactive species and neurotransmitters could contribute to the hypotensive effect induced by angiotensin (Ang) II and Ang-(1-7) at the caudal ventrolateral medulla (CVLM) in renovascular hypertensive rats (2K1C). Therefore, we investigated the effect of Ang II, Ang-(1-7), and the Ang-(1-7) antagonist A-779 microinjected before and after CVLM microinjection of the nitric oxide (NO)-synthase inhibitor, (L-NAME), vitamin C (Vit C), bicuculline, or kynurenic acid in 2K1C and SHAM rats. Baseline values of the mean arterial pressure (MAP) in 2K1C rats were higher than in SHAM rats. CVLM microinjection of Ang II, Ang-(1-7), l-NAME, or bicuculline induced decreases in the MAP in SHAM and 2K1C rats. In addition, Vit C and A-779 produced decreases in the MAP only in 2K1C rats. Kynurenic acid increased the MAP in both SHAM and 2K1C rats. Only the Ang-(1-7) effect was increased by l-NAME and reduced by bicuculline in SHAM rats. L-NAME also reduced the A-779 effect in 2K1C rats. Only the Ang II effect was abolished by CVLM Vit C and enhanced by CVLM kynurenic acid in SHAM and 2K1C rats. Overall, the superoxide anion and glutamate participated in the hypotensive effect of Ang II, while NO and GABA participated in the hypotensive effect of Ang-(1-7) in CVLM. The higher hypotensive response of A-779 in the CVLM of 2K1C rats suggests that Ang-(1-7) contributes to renovascular hypertension.

Angiotensin-(1-9) prevents vascular remodeling by decreasing vascular smooth muscle cell dedifferentiation through a FoxO1-dependent mechanism.

The renin-angiotensin system, one of the main regulators of vascular function, controls vasoconstriction, inflammation and vascular remodeling. Antagonistic actions of the counter-regulatory renin-angiotensin system, which include vasodilation, anti-proliferative, anti-inflammatory and anti-remodeling effects, have also been described. However, little is known about the direct effects of angiotensin-(1-9), a peptide of the counter-regulatory renin-angiotensin system, on vascular smooth muscle cells. Here, we studied the anti-vascular remodeling effects of angiotensin-(1-9), with special focus on the control of vascular smooth muscle cell phenotype. Angiotensin-(1-9) decreased blood pressure and aorta media thickness in spontaneously hypertensive rats. Reduction of media thickness was associated with decreased vascular smooth muscle cell proliferation. In the A7r5 VSMC cell line and in primary cultures of rat aorta smooth muscle cells, angiotensin-(1-9) did not modify basal proliferation. However, angiotensin-(1-9) inhibited proliferation, migration and contractile protein decrease induced by platelet derived growth factor-BB. Moreover, angiotensin-(1-9) reduced Akt and FoxO1 phosphorylation at 30 min, followed by an increase of total FoxO1 protein content. Angiotensin-(1-9) effects were blocked by the AT2R antagonist PD123319, Akt-Myr overexpression and FoxO1 siRNA. These data suggest that angiotensin-(1-9) inhibits vascular smooth muscle cell dedifferentiation by an AT2R/Akt/FoxO1-dependent mechanism.

Antiepileptic effects of long-term intracerebroventricular infusion of angiotensin-(1-7) in an animal model of temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is the most frequent type of epilepsy and is often refractory to pharmacological treatment. In this scenario, extensive research has identified components of the renin-angiotensin system (RAS) as potential therapeutic targets. Therefore, the aim of the present study was to evaluate the effects of long-term treatment with angiotensin-(1-7) [Ang-(1-7)] in male Wistar rats with TLE induced by pilocarpine (PILO). Rats with TLE were submitted to intracerebroventricular (icv) infusion of Ang-(1-7) (200 ng/kg/h) for 28 days, starting at the first spontaneous motor seizure (SMS). Body weight, food intake, and SMS were evaluated daily. Behavioral tests and hippocampal protein levels were also evaluated at the end of the treatment. Ang-(1-7) treatment reduced the frequency of SMS and attenuated low anxiety levels, increased locomotion/exploration, and reduced body weight gain that was induced by TLE. Moreover, Ang-(1-7) positively regulated the hippocampal levels of antioxidant protein catalase and antiapoptotic protein B-cell lymphoma 2 (Bcl-2), as well as mammalian target of rapamycin (mTOR) phosphorylation, which were reduced by TLE. The hippocampal up-regulation of angiotensin type 1 receptor induced by TLE was also attenuated by Ang-(1-7), while the Mas receptor (MasR) was down-regulated compared with epilepsy. These data show that Ang-(1-7) presents an antiepileptic effect, increasing neuroprotection markers and reducing SMS frequency, body weight, and behavior impairments found in TLE. Therefore, Ang-(1-7) is a promising coadjutant therapeutic option for the treatment of TLE.