Zebrafish Model to Study Angiotensin II-Mediated Pathophysiology.
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ABSTRACT:
SUBMITTER: Joshi B
PROVIDER: S-EPMC8614710 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Hypertension is associated with an increased risk of thrombosis that appears to involve an interaction between the renin-angiotensin system and hemostasis. In this study we determined whether angiotensin II-mediated thrombosis occurs in arterioles and/or venules and assessed the involvement of type 1 (AT?), type 2 (AT?), and type 4 (AT?) angiotensin II receptors, as well as receptors for endothelin 1 and bradykinin 1 and 2 in angiotensin II-enhanced microvascular thrombosis. Thrombus development in mouse cremaster microvessels was quantified after light/dye injury using the time of onset of the thrombus and time to blood flow cessation. Wild-type and AT? receptor-deficient mice were implanted with an angiotensin II-loaded ALZET pump for 2 weeks. Angiotensin II administration in both wild-type and ATAT? receptor-deficient mice significantly accelerated thrombosis in arterioles. Genetic deficiency and pharmacological antagonism of AT? receptors did not alter the thrombosis response to angiotensin II. Isolated murine platelets aggregated in response to low (picomolar) but not high (nanomolar) concentrations of angiotensin II. The platelet aggregation response to angiotensin II depended on AT? receptors. Antagonism of AT? receptors in vivo significantly prolonged the onset of angiotensin II-enhanced thrombosis, whereas an AT? receptor antagonist prolonged the time to flow cessation. Selective antagonism of either endothelin 1 or bradykinin 1 receptors largely prevented both the onset and flow cessation responses to chronic angiotensin II infusion. Our findings indicate that angiotensin II induced hypertension is accompanied by enhanced thrombosis in arterioles, and this response is mediated by a mechanism that involves AT?, AT?, bradykinin 1, and endothelin 1 receptor-mediated signaling.
| S-EPMC3023299 | biostudies-literature
Project description:Background/aimsAngiotensin II in the failing heart initially helps to maintain cardiac output and blood pressure, but ultimately accelerates its deterioration. In this study, we established a model of arrhythmia-induced heart failure (HF) in zebrafish and investigated the role of renin-angiotensin-aldosterone system (RAAS) modulation by using an angiotensin II type 1 receptor blocker, fimasartan, through the assessment of cellular and physiologic responses, morbidity, and mortality.MethodsHF was induced in zebrafish larvae by exposure to 20 μM terfenadine. Morphologic, physiologic, and functional parameters were assessed in the presence or absence of fimasartan treatment.ResultsZebrafish exposed to terfenadine showed marked dilatation of the ventricle and reduced systolic function. Treatment with terfenadine was associated with 10-fold higher expression of atrial natriuretic peptide (p < 0.001 vs. vehicle), increased p53 mRNA expression, and chromatin fragmentation in the TUNEL assay, all of which were significantly reduced by fimasartan treatment. Moreover, fimasartan improved fractional shortening (terfenadine + fimasartan 16.9% ± 3.1% vs. terfenadine + vehicle 11.4% ± 5.6%, p < 0.05) and blood flow (terfenadine + fimasartan 479.1 ± 124.1 nL/sec vs. terfenadine + vehicle 273.0 ± 109.0 nL/sec, p < 0.05). Finally, treatment with fimasartan remarkably reduced mortality (terfenadine + fimasartan 36.0% vs. terfenadine + vehicle 96.0%, p < 0.001).ConclusionFimasartan effectively protected against the progression of HF in zebrafish by improving hemodynamic indices, which improved survival. A reduction in apoptotic cell death and an improvement in hemodynamics may be the mechanisms behind these effects. Further human studies are warranted to evaluate the possible role of fimasartan in the treatment of HF.
| S-EPMC7652659 | biostudies-literature
Project description:The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT1R) is believed to mediate most functions of ANG II in the system. AT1R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT1R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT1R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.
| S-EPMC6335102 | biostudies-literature
Project description:Hypertension is the leading cause of cardiovascular diseases, and angiotensin II is one of the major components of the mechanisms that contribute to the development of hypertension. However, the precise mechanisms for the development of hypertension are unknown. Our recent study showing that angiotensin II-induced vascular smooth muscle cell growth depends on cytochrome P450 1B1 led us to investigate its contribution to hypertension caused by this peptide. Angiotensin II was infused via miniosmotic pump into rats (150 ng/kg per minute) or mice (1000 μg/kg per day) for 13 days resulting in increased blood pressure, increased cardiac and vascular hypertrophy, increased vascular reactivity to vasoconstrictor agents, increased vascular reactive oxygen species production, and endothelial dysfunction in both species. The increase in blood pressure and associated pathophysiological changes were minimized by the cytochrome P450 1B1 inhibitor 2,3',4,5'-tetramethoxystilbene in both species and was markedly reduced in Cyp1b1(-/-) mice. These data suggest that cytochrome P450 1B1 contributes to angiotensin II-induced hypertension and associated pathophysiological changes. Moreover, 2,3',4,5'-tetramethoxystilbene, which prevents both cytochrome P450 1B1-dependent and -independent components of angiotensin II-induced hypertension and inhibits associated pathophysiological changes could be clinically useful in the treatment of hypertension and associated cardiovascular and inflammatory diseases.
| S-EPMC2946077 | biostudies-literature
Project description:The sympathetic nervous system interacts with the renin-angiotensin-aldosterone system (RAAS) contributing to cardiovascular diseases. In this study, we sought to determine if renal denervation (RDN) inhibits aldosterone expression and associated cardiovascular pathophysiological changes in angiotensin II (Ang II)-induced hypertension. Bilateral RDN or SHAM operation was performed before chronic 14-day Ang II subcutaneous infusion (200ng/kg/min) in male Sprague-Dawley rats. Bilateral RDN blunted Ang II-induced hypertension and ameliorated the mesenteric vascular dysfunction. Cardiovascular hypertrophy in response to Ang II was significantly attenuated by RDN as shown by histopathology and transthoracic echocardiography. Moreover, Ang II-induced vascular and myocardial inflammation and fibrosis were suppressed by RDN with concurrent decrease in fibronectin and collagen deposition, macrophage infiltration, and MCP-1 expression. Interestingly, RDN also inhibited Ang II-induced aldosterone expression in the plasma, kidney and heart. This was associated with the reduction of calcitonin gene-related peptide (CGRP) in the adrenal gland. Ang II promoted aldosterone secretion which was partly attenuated by CGRP in the adrenocortical cell line, suggesting a protective role of CGRP in this model. Activation of transforming growth factor-? (TGF-?)/Smad and mitogen-activated protein kinases (MAPKs) signaling pathway was both inhibited by RDN especially in the heart. These results suggest that the regulation of the renal sympathetic nerve in Ang II-induced hypertension and associated cardiovascular pathophysiological changes is likely mediated by aldosterone, with CGRP involvement.
| S-EPMC5356522 | biostudies-literature
Project description:Clinical trials and animal studies have revealed a role for the renin-angiotensin system in the enhanced thrombus development that is associated with hypertension. Because T lymphocytes have been implicated in the vascular dysfunction and blood pressure elevation associated with increased angiotensin II (Ang II) levels, we evaluated the role of the adaptive immune system in mediating the enhanced thrombosis during Ang II-induced hypertension. Light/dye-induced thrombosis was induced in cremaster arterioles of wild-type, immunodeficient Rag-1(-/-), CD8(+), or CD4(+) lymphocyte-deficient and NADPH oxidase (gp91(phox))-deficient mice implanted with an Ang II-loaded pump for 2 weeks. Chronic Ang II infusion enhanced arteriolar thrombosis in wild-type mice but not in Rag-1(-/-), CD4(+) T-cell-deficient, or gp91(phox-/-) mice. CD8(+) T-cell(-/-) mice exhibited partial protection. Adoptive transfer of T cells derived from wild-type or gp91(phox-/-) mice into Rag-1(-/-) restored the prothrombotic phenotype induced by Ang II. T lymphocytes (CD4(+) and, to a lesser extent, CD8(+)) play a major role in mediating the accelerated microvascular thrombosis associated with Ang II-induced hypertension. NADPH oxidase-derived reactive oxygen species, produced by cells other than T lymphocytes, also appear critical for the Ang II-enhanced, T cell-dependent thrombosis response.
| S-EPMC3199307 | biostudies-literature
Project description:Background and purposeMitochondrial dysfunction plays a role in the progression of cardiovascular diseases including heart failure. 3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins), which inhibit ROS synthesis, show cardioprotective effects in chronic heart failure. However, the beneficial role of statins in mitochondrial protection in heart failure remains unclear.Experimental approachRats were treated with angiotensin II (1.5 mg·kg-1 ·day-1 ) or co-administered simvastatin (oral, 10 mg·kg-1 ) for 14 days; and then administration was stopped for the following 14 days. Cardiac structure/function was examined by wheat germ agglutinin staining and echocardiography. Mitochondrial morphology and the numbers of lipid droplets, lysosomes, autophagosomes, and mitophagosomes were determined by transmission electron microscopy. Human cardiomyocytes were stimulated, and intracellular ROS and mitochondrial membrane potential (ΔΨm ) changes were measured by flow cytometry and JC-1 staining, respectively. Autophagy and mitophagy-related and mitochondria-regulated apoptotic proteins were identified by immunohistochemistry and western blotting.Key resultsSimvastatin significantly reduced ROS production and attenuated the disruption of ΔΨm . Simvastatin induced the accumulation of lipid droplets to provide energy for maintaining mitochondrial function, promoted autophagy and mitophagy, and inhibited mitochondria-mediated apoptosis. These findings suggest that mitochondrial protection mediated by simvastatin plays a therapeutic role in heart failure prevention by modulating antioxidant status and promoting energy supplies for autophagy and mitophagy to inhibit mitochondrial damage and cardiomyocyte apoptosis.Conclusion and implicationsMitochondria play a key role in mediating heart failure progression. Simvastatin attenuated heart failure, induced by angiotensin II, via mitochondrial protection and might provide a new therapy to prevent heart failure.
| S-EPMC6780047 | biostudies-literature
Project description:Most of the patients affected by neuronopathic forms of Mucopolysaccharidosis type II (MPS II), a rare lysosomal storage disorder caused by defects in iduronate-2-sulfatase (IDS) activity, exhibit early neurological defects associated with white matter lesions and progressive behavioural abnormalities. While neuronal degeneration has been largely described in experimental models and human patients, more subtle neuronal pathogenic defects remain still underexplored. In this work, we discovered that the axon guidance receptor Deleted in Colorectal Cancer (Dcc) is significantly dysregulated in the brain of ids mutant zebrafish since embryonic stages. In addition, thanks to the establishment of neuronal-enriched primary cell cultures, we identified defective proteasomal degradation as one of the main pathways underlying Dcc upregulation in ids mutant conditions. Furthermore, ids mutant fish-derived primary neurons displayed higher levels of polyubiquitinated proteins and P62, suggesting a wider defect in protein degradation. Finally, we show that ids mutant larvae display an atypical response to anxiety-inducing stimuli, hence mimicking one of the characteristic features of MPS II patients. Our study provides an additional relevant frame to MPS II pathogenesis, supporting the concept that multiple developmental defects concur with early childhood behavioural abnormalities.
| S-EPMC11021486 | biostudies-literature
Project description:Activation of the nuclear hormone receptor peroxisome proliferator-activated receptor delta (PPARdelta) has been shown to improve insulin resistance, adiposity, and plasma HDL levels. However, its antiatherogenic role remains controversial. Here we report atheroprotective effects of PPARdelta activation in a model of angiotensin II (AngII)-accelerated atherosclerosis, characterized by increased vascular inflammation related to repression of an antiinflammatory corepressor, B cell lymphoma-6 (Bcl-6), and the regulators of G protein-coupled signaling (RGS) proteins RGS4 and RGS5. In this model, administration of the PPARdelta agonist GW0742 (1 or 10 mg/kg) substantially attenuated AngII-accelerated atherosclerosis without altering blood pressure and increased vascular expression of Bcl-6, RGS4, and RGS5, which was associated with suppression of inflammatory and atherogenic gene expression in the artery. In vitro studies demonstrated similar changes in AngII-treated macrophages: PPARdelta activation increased both total and free Bcl-6 levels and inhibited AngII activation of MAP kinases, p38, and ERK1/2. These studies uncover crucial proinflammatory mechanisms of AngII and highlight actions of PPARdelta activation to inhibit AngII signaling, which is atheroprotective.
| S-EPMC2393800 | biostudies-other
Project description:Glomerular permeability and subsequent albuminuria are early clinical markers for glomerular injury in hypertensive nephropathy. Albuminuria predicts mortality and cardiovascular morbidity. AT1 receptor blockers protect from albuminuria, cardiovascular morbidity and mortality. A blood pressure independent, molecular mechanism for angiotensin II (Ang II) dependent albuminuria has long been postulated. Albuminuria results from a defective glomerular filter. Nephrin is a major structural component of the glomerular slit diaphragm and its endocytosis is mediated by β-arrestin2. Ang II stimulation increases nephrin-β-arrestin2 binding, nephrin endocytosis and glomerular permeability in mice. This Ang II effect is mediated by AT1-receptors. AT1-receptor mutants identified G-protein signaling to be essential for this Ang II effect. Gαq knockdown and phospholipase C inhibition block Ang II mediated enhanced nephrin endocytosis. Nephrin Y1217 is the critical residue controlling nephrin binding to β-arrestin under Ang II stimulation. Nephrin Y1217 also mediates cytoskeletal anchoring to actin via nck2. Ang II stimulation decreases nephrin nck2 binding. We conclude that Ang II weakens the structural integrity of the slit diaphragm by increased nephrin endocytosis and decreased nephrin binding to nck2, which leads to increased glomerular permeability. This novel molecular mechanism of Ang II supports the use of AT1-receptor blockers to prevent albuminuria even in normotensives.
| S-EPMC5177899 | biostudies-literature