Deoxycorticosterone Acetate Salt Research Articles

Genetic Deletion of β-Arrestin 2 From the Subfornical Organ and Other Periventricular Nuclei in the Brain Alters Fluid Homeostasis and Blood Pressure.

ANG (angiotensin II) elicits dipsogenic and pressor responses via activation of the canonical Gαq (G-protein component of the AT1R [angiotensin type 1 receptor])-mediated AT1R in the subfornical organ. Recently, we demonstrated that ARRB2 (β-arrestin 2) global knockout mice exhibit a higher preference for salt and exacerbated pressor response to deoxycorticosterone acetate salt. However, whether ARRB2 within selective neuroanatomical nuclei alters physiological responses to ANG is unknown. Therefore, we hypothesized that ARRB2, specifically in the subfornical organ, counterbalances maladaptive dipsogenic and pressor responses to the canonical AT1R signaling. Male and female Arrb2FLOX mice received intracerebroventricular injection of either adeno-associated virus (AAV)-Cre-GFP (green fluorescent protein) to induce brain-specific deletion of ARRB2 (Arrb2ICV-Cre). Arrb2FLOX mice receiving ICV-AAV-GFP were used as control (Arrb2ICV-Control). Infection with ICV-AAV-Cre primarily targeted the subfornical organ with few off targets. Fluid intake was evaluated using the 2-bottle choice paradigm with 1 bottle containing water and 1 containing 0.15 mol/L NaCl. Arrb2ICV-Cre mice exhibited a greater pressor response to acute ICV-ANG infusion. At baseline conditions, Arrb2ICV-Cre mice exhibited a significant increase in saline intake compared with controls, resulting in a saline preference. Furthermore, when mice were subjected to water-deprived or sodium-depleted conditions, which would naturally increase endogenous ANG levels, Arrb2ICV-Cre mice exhibited elevated saline intake. Overall, these data indicate that ARRB2 in selective cardiovascular nuclei in the brain, including the subfornical organ, counterbalances canonical AT1R responses to both exogenous and endogenous ANG. Stimulation of the AT1R/ARRB axis in the brain may represent a novel strategy to treat hypertension.

Inhibiting the MAPK pathway improves heart failure with preserved ejection fraction induced by salt-sensitive hypertension

Heart failure (HF) preserved ejection fraction (HFpEF) accounts for almost 50% of HF, and hypertension is one of the pathogenies. The MAPK signaling pathway is closely linked to heart failure and hypertension; however, its function in HEpEF resulting from salt-sensitive hypertension is not well understood. In this work, a salt-sensitive hypertension-induced HEpEF model was established based on deoxycorticosterone acetate-salt (DOCA-salt) hypertension mice. The impact of the MAPK inhibitor (Doramapimod) on HEpEF induced by salt-sensitive hypertension was assessed through various measures, such as blood pressure, transthoracic echocardiography, running distance, and histological analysis, to determine its therapeutic effectiveness on cardiac function. In addition, the effects of high salt on myogenic cells were also evaluated in vitro using qRTPCR. The LV ejection fractions (LVEF) in DOCA-salt hypertension mice were over 50%, indicating that the salt-sensitive hypertension-induced HFpEF model was successful. RNA-seq revealed that the MAPK signaling pathway was upregulated in the HFpEF model compared with the normal mice, accompanied by hypertension, impaired running distance, restricted cardiac function, increased cross-sectional and fibrosis area, and upregulation of heart failure biomarkers, including GAL-3, LDHA and BNP. The application of Doramapimod could improve blood pressure, cardiomyocyte hypertrophy, and myocardial fibrosis, as well as decrease the aforementioned heart failure biomarkers. The qRTPCR results showed similar findings to these observations. Our findings suggest that the use of a MAPK inhibitor (Doramapimod) could be a potential treatment for salt-sensitive hypertension-induced HFpEF.

Bioactive Peptides from Ruditapes philippinarum Attenuate Hypertension and Cardiorenal Damage in Deoxycorticosterone Acetate-Salt Hypertensive Rats.

Hypertension is a common disease that affects human health and can lead to damage to the heart, kidneys, and other important organs. In this study, we investigated the regulatory effects of bioactive peptides derived from Ruditapes philippinarum (RPP) on hypertension and organ protection in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We found that RPPs exhibited significant blood pressure-lowering properties. Furthermore, the results showed that RPPs positively influenced vascular remodeling and effectively maintained a balanced water-sodium equilibrium. Meanwhile, RPPs demonstrated anti-inflammatory potential by reducing the serum levels of inflammatory cytokines (TNF-α, IL-2, and IL-6). Moreover, we observed the strong antioxidant activity of RPPs, which played a critical role in reducing oxidative stress and alleviating hypertension-induced damage to the aorta, heart, and kidneys. Additionally, our study explored the regulatory effects of RPPs on the gut microbiota, suggesting a possible correlation between their antihypertensive effects and the modulation of gut microbiota. Our previous studies have demonstrated that RPPs can significantly reduce blood pressure in SHR rats. This suggests that RPPs can significantly improve both essential hypertension and DOAC-salt-induced secondary hypertension and can ameliorate cardiorenal damage caused by hypertension. These findings further support the possibility of RPPs as an active ingredient in functional anti-hypertensive foods.

Dectin1 contributes to hypertensive vascular injury by promoting macrophage infiltration through activating the Syk/NF-κB pathway

Vascular injury is an early manifestation leading to end-organ damage in hypertension pathogenesis, which involves a macrophage-associated immune response. Dendritic cell-associated C-type lectin-1 (Dectin1) is a pivotal player in regulating inflammation-mediated cardiovascular disease. However, its role in hypertension-induced vascular damage and the underlying mechanisms remain unclear. We hypothesized that Dectin1 might accelerate angiotensin II (Ang II)- or deoxycorticosterone acetate–salt (DOCA-salt)-induced vascular injury through proinflammatory actions in macrophages. Macrophage Dectin1 was upregulated in mouse aortic tissues stimulated with Ang II. In the peripheral blood, Ang II also increased CD11b+F4/80+ macrophages in mice. In our constructed Dectin1 knockout mice, Dectin1 deletion protected against Ang II-induced EB extravasation and aortic wall thickness. Deficiency of Dectin1 or its pharmacological inhibition considerably improved fibrosis and inflammation responses, accompanied by a reduction in M1 macrophage polarization as well as proinflammatory cytokines and chemokines induced by Ang II or DOCA-salt. Through the bone marrow (BM) transplantation assay, these effects were verified in the wild type mice reconstituted with Dectin1-deficient BM cells. Mechanistically, Ang II promoted Dectin1 homodimerization, thereby triggering the spleen tyrosine kinase/nuclear factor kappa B pro-inflammatory cascade to induce the expression of inflammatory factors and chemokines in vivo and in vitro. In conclusion, Dectin1 has an essential role in the pathogenic procedure of Ang II-stimulated or DOCA-salt-induced vascular damage in mice and represents a promising therapeutic target for cardiovascular diseases.

Tryptophan Metabolites Target Transmembrane and Immunoglobulin Domain-Containing 1 Signaling to Augment Renal Tubular Injury

Chronic kidney disease (CKD) is characterized by the accumulation of uremic toxins and renal tubular damage. Tryptophan-derived uremic toxins [indoxyl sulfate (IS) and kynurenine (Kyn)] are well-characterized tubulotoxins. Emerging evidence suggests that transmembrane and immunoglobulin domain-containing 1 (TMIGD1) protects tubular cells and promotes survival. However, the direct molecular mechanism(s) underlying how these two opposing pathways crosstalk remains unknown. We posited that IS and Kyn mediate tubular toxicity through TMIGD1 and the loss of TMIGD1 augments tubular injury. Results from the current study showed that IS and Kyn suppressed TMIGD1 transcription in tubular cells in a dose-dependent manner. The wild-type CCAAT enhancer-binding protein β (C/EBPβ) enhanced, whereas a dominant-negative C/EBPβ suppressed, TMIGD1 promoter activity. IS down-regulated C/EBPβ in primary human renal tubular cells. The adenine-induced CKD, unilateral ureteric obstruction, and deoxycorticosterone acetate salt unilateral nephrectomy models showed reduced TMIGD1 expression in the renal tubules, which correlated with C/EBPβ expression. C/EBPβ levels negatively correlated with the IS and Kyn levels. Inactivation of TMIGD1 in mice significantly lowered acetylated tubulin, decreased tubular cell proliferation, caused severe tubular damage, and worsened renal function. Thus, the current results demonstrate that TMIGD1 protects renal tubular cells from renal injury in different models of CKD and uncovers a novel mechanism of tubulotoxicity of tryptophan-based uremic toxins.

Qiliqiangxin capsule improves cardiac remodeling in rats with DOCA-salt-induced diastolic dysfunction.

The aim of this study was to investigate the protective effect and mechanism of action (MOA) of Qiliqiangxin capsule (QL) in the deoxycorticosterone acetate (DOCA) salt-induced rat heart failure with preserved ejection fraction (HFpEF) model. Nono-nephrectomy sixty Sprague Dawley (SD) rats received DOCA salt injection and 1% saline in drinking water for 4 weeks and were randomly divided into four groups on average: Model group (n=15), Sac/Val group (Sacubitril Valsartan 0.02 g/kg, n=15), QL-L group (Qiliqiangxin 0.25 g/kg, n=15) and QL-H group (Qiliqiangxin 1 g/kg, n=15). Another Normal group was set (n=15). Blood pressure, N-terminal pro-brain natriuretic peptide (NT-proBNP), cardiac index, echocardiography, and hemodynamics were measured to evaluate heart function. Masson and Wheat germ agglutinin (WGA) staining was performed to observe the fibrosis deposition and the cross-sectional area (CSA) of cardiomyocytes. The concentration levels of the serum cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-2, IL-6, and IL-10 inflammatory factors, were detected by ELISA; matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9), transforming growth factor-β1 (TGF-β1), nuclear factor-κB (NF-κB), Smad homologue 2 (Smad2) and Smad homologue 3 (Smad3) expression were detected by Western-blot. Compared with the Model group, QL treatment significantly ameliorated the heart function in DOCA salt-induced rat HFpEF model, showing a decrease in cardiac index, an increase of the EF and E/A ratio, a reduction in the left ventricular anterior/posterior wall (LVAW/LVPW), in the time contraction of isovolumic diastolic time (IVRT), -dP/dt Max, and Tau, and the decrease of serum NT-ProBNP. Masson and WGA staining indicated that QL inhibited the fibrosis deposition and the myocardial hypertrophy compared with the Model group, which was consistent in reducing the protein expression levels of cardiac remodeling such as TGF-β1, MMP2, MMP9, Smad2, and Smad3. Moreover, QL treatment inhibited the expression of NF-κB in the heart tissues and decreased the serum concentration of pro-inflammatory cytokines TNF-α and IL-2, instead, increasing the IL-10 concentration. QL improved the cardiac function and inhibited the myocardial fibrosis in DOCA salt-induced rat HFpEF by improving diastolic dysfunction, preventing left ventricular hypertrophy, and ameliorating the inflammatory responses model in DOCA salt-induced rat HFpEF model.

P2Y2 receptor decreases blood pressure by inhibiting ENaC.

Stimulating the Gq-coupled P2Y2 receptor (P2ry2) lowers blood pressure. Global knockout of P2ry2 increases blood pressure. Vascular and renal mechanisms are believed to participate in P2ry2 effects on blood pressure. To isolate the role of the kidneys in P2ry2 effects on blood pressure and to reveal the molecular and cellular mechanisms of this action, we test here the necessity of the P2ry2 and the sufficiency of Gq-dependent signaling in renal principal cells to the regulation of the epithelial Na+ channel (ENaC), sodium excretion, and blood pressure. Activating P2ry2 in littermate controls but not principal cell-specific P2ry2-knockout mice decreased the activity of ENaC in renal tubules. Moreover, deletion of P2ry2 in principal cells abolished increases in sodium excretion in response to stimulation of P2ry2 and compromised the normal ability to excrete a sodium load. Consequently, principal cell-specific knockout of P2ry2 prevented decreases in blood pressure in response to P2ry2 stimulation in the deoxycorticosterone acetate-salt (DOCA-salt) model of hypertension. In wild-type littermate controls, such stimulation decreased blood pressure in this model of hypertension by promoting a natriuresis. Pharmacogenetic activation of Gq exclusively in principal cells using targeted expression of Gq-designer receptors exclusively activated by designer drugs and clozapine N-oxide decreased the activity of ENaC in renal tubules, promoting a natriuresis that lowered elevated blood pressure in the DOCA-salt model of hypertension. These findings demonstrate that the kidneys play a major role in decreasing blood pressure in response to P2ry2 activation and that inhibition of ENaC activity in response to P2ry2-mediated Gq signaling lowered blood pressure by increasing renal sodium excretion.

CD1d-Dependent Natural Killer T Cells Mediate Hypertension and Vascular Injury Through Interleukin-17A.

Background Different T-lymphocyte subsets, including CD1d-dependent natural killer T (NKT) cells, play distinct roles in hypertension, highlighting the importance of identifying key immune cells for its treatment. This study aimed to determine the unknown effects of CD1d-dependent NKT cells on hypertension and vascular injury. Methods and Results Hypertension models were induced in male CD1d knockout (CD1dko), wild-type, and adoptive bone marrow transfer mice by angiotensin II (Ang II) or deoxycorticosterone acetate salt. Blood pressure was measured by the tail-cuff system and radiotelemetry. Vascular injury was assessed by histologic studies or aortic ring assay. Inflammation was detected by flow cytometry, quantitative real-time polymerase chain reaction, or ELISA. Results showed that Ang II infusion significantly reduced CD1d expression and NKT cell numbers in the aorta of mice. CD1dko mice exhibited worsened blood pressure elevation, vascular injury, and inflammatory response induced by Ang II or deoxycorticosterone acetate salt. However, these effects were markedly reversed in wild-type mice treated with NKT cell-specific activator. Adoptive transfer of CD1dko bone marrow cells to wild-type mice also significantly worsened Ang II-induced responses. Mechanistically, CD1dko increased Ang II-induced interleukin-6 production and activated signal transducer and activator of transcription 3 and orphan nuclear receptor γ, subsequently inducing interleukin-17A production. Neutralizing interleukin-17A partially reversed Ang II-induced hypertension and vascular injury in CD1dko mice. In addition, levels of NKT cells were lower in the blood of patients with hypertension (n=57) compared with normotensive individuals (n=87). Conclusions These findings reveal a previously unknown role for CD1d-dependent NKT cells in hypertension and vascular injury, indicating that NKT cell activation could be a promising therapeutic target for hypertension.

Complement component C3 as a new target to lower albuminuria in hypertensive kidney disease.

Complement activation may drive hypertension through its effects on immunity and tissue integrity. We examined expression of C3, the central protein of the complement cascade, in hypertension. Increased C3 expression was found in kidney biopsies and micro-dissected glomeruli of patients with hypertensive nephropathy. Renal single cell RNA sequence data from normotensive and hypertensive patients confirmed expression of C3 in different cellular compartments of the kidney. In angiotensin II (Ang II) induced hypertension renal C3 expression was up-regulated. C3-/- mice revealed a significant lower albuminuria in the early phase of hypertension. However, no difference was found for blood pressure, renal injury (histology, glomerular filtration rate, inflammation) and cardiac injury (fibrosis, weight, gene expression) between C3-/- and wildtype mice after Ang II infusion. Also, in deoxycorticosterone acetate (DOCA) salt hypertension, a significantly lower albuminuria was found in the first weeks of hypertension in C3 deficient mice but no significant difference in renal and cardiac injury. Down-regulation of C3 by C3 targeting GalNAc (n-acetylgalactosamine) small interfering RNA (siRNA) conjugate decreased C3 in the liver by 96% and lowered albuminuria in the early phase but showed no effect on blood pressure and end-organ damage. Inhibition of complement C5 by siRNA showed no effect on albuminuria. Increased C3 expression is found in the kidneys of hypertensive mice and men. Genetic and therapeutic knockdown of C3 improved albuminuria in the early phase of hypertension but did not ameliorate arterial blood pressure nor renal and cardiac injury.

Use of the Peregrine Catheter Infusion System to develop novel targeted renal nerve ablation therapies in hypertensive sheep

Background and Objective: Clinical trials have shown that catheter-based total (efferent and afferent) renal denervation (TRDN) can effectively lower arterial pressure in patients with treatment-resistant hypertension (HTN). The Peregrine catheter infusion system deploys microneedles from the renal artery lumen into the renal artery adventitia to inject the neurolytic agent ethanol. The objective of this study was to utilize this catheter to develop novel renal denervation therapies in a large animal model. In this study our aim was to demonstrate that TRDN lowers arterial pressure in the deoxycorticosterone acetate and high salt diet (DOCA-salt) sheep model of HTN. This will establish the utility of this catheter to deliver the afferent nerve neurolytic agent, capsaicin. Our group has shown that selective afferent renal denervation (ARDN) lowers arterial pressure to the same degree as TRDN in DOCA-salt HTN rats. Our long-term goal is to translate these findings to the DOCA-salt sheep model and eventually humans. Methods: Adult Domestic sheep weighing 60-80 kg were implanted with a subcutaneous silicone pellet containing DOCA (350mg/kg) and given access to salted (0.2% NaCl) drinking water and (180mEq Na+/kg) feed. Stellar radio telemeters were implanted for continuous measurement of MAP. 30 days following induction of DOCA-salt HTN, the Peregrine catheter infusion system was used to perform bilateral TRDN. One month after TRDN, animals were terminated and kidneys were harvested to verify denervation efficacy. Preliminary Results: 30 days following implantation of DOCA, 24hr MAP increased ~25mmHg from a baseline of 99mmHg to 123mmHg (n=2). 30 days following TRDN, 24hr MAP decreased to near control levels of 105mmHg. Conclusion and Future Directions: These preliminary results demonstrate that TRDN with the Peregrine catheter lowers MAP in DOCA-salt HTN sheep. The mechanism underlying this response is still being investigated. Sheep studies are underway to utilize the Peregrine catheter to perform ARDN by injection of capsaicin into the renal artery adventitia. The goal is to conduct a translational study to move catheter-based ARDN into clinical trials. If catheter-based ARDN lowers MAP to the same degree as TRDN, efferent renal nerves could be preserved to maintain MAP and blood volume in response to hemorrhagic or septic shock. Supported by NHLBI R01 HL116476. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Integrin CD11b Contributes to Hypertension and Vascular Dysfunction Through Mediating Macrophage Adhesion and Migration.

Leukocyte adhesion to endothelium is an early inflammatory response and is mainly controlled by the β2-integrins. However, the role of integrin CD11b/CD18 in the pathogenesis of hypertension and vascular dysfunction is unclear. Hypertension was established by angiotensin II (490 ng/kg·per min) or deoxycorticosterone acetate salt. Hypertensive responses were studied in CD11b-deficient (CD11b-/-) mice, bone marrow transplanted and wild-type (WT) mice that were administered anti-CD11b neutralizing antibody or agonist leukadherin-1. Blood pressure was monitored with tail-cuff method and radiotelemetry. Blood and vascular inflammatory cells were assessed by flow cytometry. Aortic remodeling and function were examined using histology and aortic ring analysis. Cell adhesion and migration were evaluated in vitro. The relationship between circulating CD11b+ immune cells and hypertension was analyzed in patients with hypertension. We found that CD11b and CD18 expression as well as the CD45+CD11b+CD18+ myeloid cells were highly increased in the aorta of angiotensin II-infused mice. Ablation or pharmacological inhibition of CD11b in mice significantly alleviated hypertension, aortic remodeling, superoxide generation, vascular dysfunction, and the infiltration of CD11b+ macrophages through reducing macrophage adhesion and migration. These effects were confirmed in WT mice reconstituted with CD11b-deficient bone marrow cells. Conversely, angiotensin II-induced hypertensive response was exacerbated by CD11b agonist leukadherin-1. Notably, circulating CD45+CD11b+CD18+ myeloid cells and the ligand levels in hypertensive patients were significantly higher than in normotensive controls. We demonstrated a critical significance of CD11b+ myeloid cells in hypertension and vascular dysfunction. Targeting CD11b may represent a novel therapeutic option for hypertension.

PS-B09-13: PHARMACOLOGICAL INHIBITION OF INTERLEUKIN-18 REDUCES DEOXYCORTICOSTERONE/SALT-INDUCED HYPERTENSION AND RENAL INFLAMMATION

Objective: Circulating levels of the pro inflammatory cytokine, interleukin18 (IL18), are elevated in patients with hypertension and chronic kidney disease (CKD). Moreover, genetic deficiency of IL18 prevents the development of one kidney deoxycorticosterone acetate and high salt (DOCA/salt) induced blood pressure (BP) elevation and renal injury. Thus, the current study aimed to determine if pharmacological inhibition of IL18 is similarly protective against elevations in BP, renal inflammation and dysfunction in the DOCA/salt model of hypertension and CKD. Design and method: Male C57BL/6 mice were randomly assigned to receive either control IgG or anti IL18 neutralising monoclonal antibody (control IgG and mAb; 30 mg/kg, i.p., Novartis, bolus every 3 days). Three days after the first injection, mice were uninephrectomised and treated for a further 21 days with either DOCA (2.4 mg/d, s.c. pellet) with high salt (0.9% in drinking water), or a placebo pellet (s.c.) plus normal drinking water. BP was measured weekly (tail cuff, starting at baseline). Transdermal glomerular filtration rate (tGFR) measurements were recorded at baseline and at endpoint to determine kidney function. Kidneys were harvested at endpoint for histopathological staining, quantitative reverse transcription PCR (RT qPCR) and flow cytometry to assess fibrosis, inflammation and immune cell infiltration, respectively. Results: Baseline systolic BP was not different between mice treated with anti IL18 mAb (118 ± 2 mmHg) versus control IgG (122 ± 3 mmHg). However, anti IL18 mAb treatment significantly blunted hypertensive responses to DOCA/salt, with systolic BP only reaching 139 ± 6 mmHg compared to 159 ± 6 mmHg in control IgG treated animals (Figure; n = 11–12; P < 0.05). Anti IL18 mAb treatment also significantly reduced DOCA/salt induced leukocyte (CD45+) accumulation in the kidneys (0.9 ± 0.1x105 cells/kidney) compared to control IgG treatment (1.6 ± 0.3x105 cells/ kidney; n = 11–12; P < 0.05), which was largely attributed to reduced macrophage accumulation (CD11b+/F4/80+; n = 11–12; P < 0.05). A ∼30% decline in kidney function was observed in DOCA/salt-treated mice that received control IgG, which was associated with renal fibrosis and injury. Impaired kidney function decline (but not fibrosis and injury) appeared to be less severe in DOCA/salt treated mice that received anti IL18 mAb (n = 7). DOCA/salt treatment increased expression of genes associated with renal fibrosis (Col1al, Col3a1 and Col5a1), injury (Kim1 and Ngal) and inflammation (Ifng, Mrc1, II6, Ccl2 etc.). Surprisingly, DOCA/salt induced changes in gene expression were not prevented by anti IL18 mAb treatment. Conclusions: IL18 neutralisation affords protection against DOCA/salt induced hypertension and renal inflammation. Thus. IL18 may represent a potential therapeutic target to treat hypertension and CKD.

Investigation of the relationship between serum adropin levels, oxidative stress biomarkers, and blood pressure in DOCA-salt hypertensive rats

Background/Aim: Adropin is involved in the pathophysiology and development of cardiovascular diseases, such as hypertension. The aim of this study was to investigate the effects of adropin in serum, potential use as a biochemical biomarker of oxidative stress, and effects on blood pressure in deoxycorticosterone acetate (DOCA) salt hypertensive rats.
 Methods: Eighteen male Sprague-Dawley rats were divided into two groups: (1) Control (C) and (2) Hypertensive (H). Systolic and diastolic blood pressures (SBP and DBP, respectively), and mean blood pressure (MBP) were measured using the tail-cuff method. At the end of the study, serum endothelin-1 (ET-1), adropin, nitric oxide (NO), total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were also analyzed.
 Results: Significant increases in SBP, DBP, MBP, cardiac hypertrophy index (CHI), and left ventricular hypertrophy index (LVCI) in the H group compared with the C group were found. Serum levels of ET-1, TOS, and OSI were significantly higher in the H group and serum levels of NO, adropin, and TAS were lower than in the C group. A negative correlation between serum adropin levels and the variables SBP, DBP, MBP, TOS, OSI, CHI, and LVHI was found. Adropin levels were positively correlated positively with serum NO levels in both groups.
 Conclusion: Serum adropin levels decreased in hypertensive DOCA-salt rats. Lower serum adropin levels were found to be significantly associated with hypertension and may play a role in this disease. However, further comprehensive and diverse studies are needed.

ARRB2 (β-Arrestin-2) Deficiency Alters Fluid Homeostasis and Blood Pressure Regulation

GPCRs (G protein-coupled receptors) are implicated in blood pressure (BP) and fluid intake regulation. There is a developing concept that these effects are mediated by both canonical G protein signaling and noncanonical β-arrestin mediated signaling, but the contributions of each remain largely unexplored. Here, we hypothesized that β-arrestin contributes to fluid homeostasis and blood pressure (BP) regulation in deoxycorticosterone acetate (DOCA) salt hypertension, a prototypical model of salt-sensitive hypertension. Global β-arrestin1 (Arrb1) and β-arrestin2 (Arrb2) knockout mice were employed to evaluate drinking behavior, and BP was evaluated in Arrb2-knockout mice. Age- and sex-matched C57BL/6 mice served as controls. We measured intake of water and different sodium chloride solutions and BP employing a 2-bottle choice paradigm with and without DOCA. Without DOCA (baseline), Arrb2-knockout mice exhibited a significant elevation in saline intake with no change in water intake. With DOCA treatment, Arrb2-knockout mice exhibited a significant increase in both saline and water intake. Although Arrb2-knockout mice exhibited hypernatremia at baseline conditions, we did not find significant changes in total body sodium stores or sodium palatability. In a separate cohort, BP was measured via telemetry in Arrb2-knockout and C57BL/6 mice with and without DOCA. Arrb2-knockout did not exhibit significant differences in BP before DOCA treatment when provided water alone, or when provided a choice of water and saline. However, Arrb2-knockout exhibited an increased pressor response to DOCA-salt. These findings suggest that in salt-sensitive hypertension, ARRB2, but not ARRB1 (β-arrestin 1), might counterbalance the canonical signaling of GPCRs.

Elucidation of Anti-Hypertensive Mechanism by a Novel Lactobacillus rhamnosus AC1 Fermented Soymilk in the Deoxycorticosterone Acetate-Salt Hypertensive Rats.

Dietary intake of fermented soymilk is associated with hypotensive effects, but the mechanisms involved have not been fully elucidated. We investigated the anti-hypertensive effects of soymilk fermented by L. rhamnosus AC1 on DOCA-salt hypertension from the point of view of oxidative stress, inflammatory response and alteration of the gut microbiome. The antioxidant assays in vitro indicated the ethanol extract (EE) of L. rhamnosus AC1 fermented soymilk showed better antioxidative effects than the water extract (WE). Those extracts displayed a hypotensive effect using a tail-cuff approach to measuring blood pressure and improved nitric oxide (NO), angiotensin II (Ang II), tumor necrosis factor-α (TNF-α) and interleukin factor-6 (IL-6) on DOCA-salt hypertensive rats. Furthermore, cardiac and renal fibrosis were attenuated by those extracts. The gut microbiota analysis revealed that they significantly reduced the abundance of phylum Proteobacteria, its family Enterobacteriaceae and genus Escherichia-Shigella. Moreover, metabolomic profiling revealed several potential gut microbiota-related metabolites which appeared to involve in the development and recovery of hypertension. In conclusion, fermented soymilk is a promising nutritional intervention strategy to improve hypertension via reducing inflammation and reverting dysbiotic microbiota.

Improved method for surgical induction of chronic hypertension in mice.

ABSTRACTChronic hypertension can be induced in mice by one-kidney one-clip (1K1C) or two-kidney one-clip surgery, transgenic overexpression of angiotensinogen and renin, administration of deoxycorticosterone acetate-salt, supplying Nitro-L-arginine methyl-ester in the drinking water and Angiotensin-II infusion. Although each model has its own pros and cons, selection of a model that mimics human hypertensive disease accurately is essential to ensure rigor and reproducibility in hypertension research. 1K1C mice represent an efficient, budget-friendly, and translationally capable model; however, their use in preclinical research has remained largely hindered due to concerns about potential technical complexity and lack of reported information regarding procedure-related mortality rates. Here, we describe in detail an improved version of the 1K1C surgery in mice that has zero intraoperative mortality and excellent survival rates in a long-term setting and permits the development of stable chronic hypertension and its target organ complications. Key to this outcome is unilateral nephrectomy 1 week after renal artery clipping to decelerate the blood pressure (BP) increase, which allows the organism to adapt better to the BP rise. The technical and animal welfare improvements presented here may promote the acceptance of the 1K1C model.

Pharmacological Inhibition of Mammalian Target of Rapamycin Attenuates Deoxycorticosterone Acetate Salt-Induced Hypertension and Related Pathophysiology: Regulation of Oxidative Stress, Inflammation, and Cardiovascular Hypertrophy in Male Rats.

The present study aimed to explore the contribution of mammalian target of rapamycin (mTOR) in deoxycorticosterone acetate (DOCA) salt-induced hypertension and related pathophysiological changes in cardiovascular and renal tissues. DOCA salt loading resulted in an increase in systolic blood pressure, diastolic blood pressure, and mean blood pressure along with the activity of ribosomal protein S6, the effector protein of mTOR. Treatment with rapamycin, the selective inhibitor of mTOR, initiated at the fourth week of DOCA- salt administration normalized the systolic blood pressure and attenuated ribosomal protein S6 activity in the heart, aorta, and kidney. Cardiac and vascular hypertrophy, oxidative stress, and infiltration of macrophages (CD68+), the marker of inflammation, were also reduced in rapamycin-treated, DOCA-salt, hypertensive rats. In addition, renal hypertrophy and dysfunction were also reduced with rapamycin-treated hypertensive rats. Moreover, these pathophysiological changes in DOCA-salt hypertensive rats were associated with increased NADPH oxidase (NOX) activity, gp91phox (formerly NOX2) expression, ERK1/2, and p38 MAPK activities in the heart, aorta, and kidney were minimized by rapamycin. These data indicate that mTOR plays an important role in regulating blood pressure and the development of cardiovascular and renal pathophysiological changes, most likely due to increased NOX expression/activity, ERK1/2, and p38 MAPK activity with macrophages infiltration in the heart, kidney, and aorta. Pharmacological inhibition of mTOR and related signaling pathways could serve as a novel target for the treatment of hypertension.

Renal Denervation by Noninvasive Stereotactic Radiotherapy Induces Persistent Reduction of Sympathetic Activity in a Hypertensive Swine Model.

BackgroundWe have previously reported the feasibility of noninvasive stereotactic body radiotherapy (SBRT) as a novel approach for renal denervation.Methods and ResultsHerein, from a translational point of view, we assessed the antihypertensive effect and chronological evolution of SBRT‐induced renal nerve injury within 6 months in a hypertensive swine model. Hypertension was induced in swine by subcutaneous implantation of deoxycorticosterone acetate pellets in combination with a high‐salt diet. A single dose of 25 Gy with SBRT was delivered for renal denervation in 9 swine within 3.4±1.0 minutes. Blood pressure levels at baseline and 1 and 6 months post‐SBRT were comparable to control (n=5), whereas renal norepinephrine was significantly lower at 6 months (P<0.05). Abdominal computed tomography, performed before euthanasia and renal function assessment, remained normal. Standard semiquantitative histological assessment showed that compared with control (1.4±0.4), renal nerve injury was greater at 1 month post‐SBRT (2.3±0.3) and peaked at 6 months post‐SBRT (3.2±0.8) (P<0.05), along with a higher proportion of active caspase‐3–positive nerves (P<0.05). Moreover, SBRT resulted in continuous dysfunction of renal sympathetic nerves and low level of nerve regeneration in 6 months by immunohistochemistry analysis.ConclusionsSBRT delivering 25 Gy for renal denervation was safe and related to sustained reduction of sympathetic activity by aggravating nerve damage and inhibiting nerve regeneration up to 6 months; however, its translation to clinical trial should be cautious because of the negative blood pressure response in the deoxycorticosterone acetate–salt hypertensive swine model.

Novel Role of GPR35 (G-Protein-Coupled Receptor 35) in the Regulation of Endothelial Cell Function and Blood Pressure.

[Figure: see text].

Anti-Hypertensive Activity of Hydro Alcoholic Extract of Cìraka Cūraṇam on High Salt Loaded Wistar Albino Rats

Background: Hypertension is called as Silent killer. The most important risk factor for heart diseases and stroke and it may leads to premature death. Several medicinal plants have high effective in anti-hypertensive and anti-thrombotic activity without any side effects. Aim: To evaluate the anti-hypertensive activity of hydro alcoholic extract of Cìraka cūraṇam on deoxycorticosterone acetate (DOCA) salt induced wistar albino rats. Study design: Observational in-vivo study Place and duration of study: Animal house, Dept. of Pharmacology, Arulmigu Kalasalingam College of Pharmacy, Krishnankoil, Srivilliputtur,Tamilnadu. Materials and methods: Antihypertensive activity was conducted on wistar albino rats by determining serum Sodium and Potassium levels by using semi auto analyzer (RA-50, Bayer Diagnostics), using specific kits (Auto span, India) at 500 and 550 nm respectively and left carotid artery (for recording BP) was cannulated under aseptic conditions with polyethylene cannula filled with 1% heparin in normal saline. Rest procedure, which was stated under the 2K1C-model was followed and BP was observed in terms of mm of Hg. Results: The Cìraka cūraṇam possesses strong antihypertensive effect against DOCA-salt hypertensive rats, which is evidenced by a considerable decrease in blood pressures. Keywords: Anti-hypertensive activity, Cìraka cūraṇam, Wistar albino rats, Deoxycorticosterone acetate.