Activation AMPK in Hypothalamic Paraventricular Nucleus Improves Renovascular Hypertension Through ERK1/2-NF-κB Pathway.

Hypertension is a globally prevalent disease, but the pathogenesis remains largely unclear. AMP-activated protein kinase (AMPK) is a nutrition-sensitive signal of cellular energy metabolism, which has a certain influence on the development of hypertension. Previously, we found a down-regulation of the phosphorylated (p-) form of AMPK, and the up-regulation of the angiotensin II type 1 receptor (AT1-R) and that of p-ERK1/2 in the hypothalamic paraventricular nucleus (PVN) of hypertensive rats. However, the exact mechanism underlying the relationship between AMPK and AT1-R in the PVN during hypertension remains unclear. Thus, we hypothesized that AMPK modulates AT1-R through the ERK1/2-NF-κB pathway in the PVN, thereby inhibiting sympathetic nerve activity and improving hypertension. To examine this hypothesis, we employed a renovascular hypertensive animal model developed via two-kidney, one-clip (2K1C) and sham-operated (SHAM). Artificial cerebrospinal fluid (aCSF), used as vehicle, or 5-amino-1-ß-D-ribofuranosyl-imidazole-4-carboxamide (AICAR, an AMPK activator, 60 µg/day) was microinjected bilaterally in the PVN of these rats for 4 weeks. In 2K1C rats, there an increase in systolic blood pressure (SBP) and circulating norepinephrine (NE). Also, the hypertensive rats had lowered expression of p-AMPK and p-AMPK/AMPK, elevated expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R, increased NF-κB p65 activity in the PVN compared with the levels of these biomarkers in SHAM rats. Four weeks of bilateral PVN injection of AMPK activator AICAR, attenuated the NE level and SBP, increased the expression of p-AMPK and p-AMPK/AMPK, lessened the NF-κB p65 activity, decreased the expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R in the PVN of 2K1C rats. Data from this study imply that the activation of AMPK within the PVN suppressed AT1-R expression through inhibiting the ERK1/2-NF-κB pathway, decreased the activity of the sympathetic nervous system, improved hypertension.

Apelin-13: a novel approach to suppressing renin production in RVHT.

Renovascular hypertension (RVHT) is characterized by renal artery stenosis and overactivated renin-angiotensin system (RAS). Apelin, known for its negative modulation of RAS, has protective effects against cardiovascular diseases. The role and mechanisms of the primary active form of apelin, apelin-13, in RVHT are unclear. In this study, male Sprague-Dawley rats were divided into control, two-kidney one-clip (2K1C) model, and 2K1C with apelin-13 treatment groups. Renin expression was analyzed using immunohistochemistry and molecular techniques. Full-length (pro)renin receptor (fPRR) and soluble PRR (sPRR) levels were assessed via Western blotting, and cAMP levels were measured using ELISA. Plasma renin content, plasma renin activity (PRA), angiotensin II (ANG II), and sPRR levels were determined by ELISA. Human Calu-6 and mouse As4.1 cells were used to investigate renin production mechanisms. The 2K1C model exhibited increased systolic blood pressure, plasma renin content, PRA, sPRR, and ANG II levels, while apelin-13 treatment reduced these elevations. Apelin-13 inhibited cAMP production, renin mRNA expression, protein synthesis, and PRR/sPRR protein expression in renal tissue. In Calu-6 cells, cAMP-induced fPRR and site-1 protease (S1P)-derived sPRR expression, which was blocked by cAMP-responsive element-binding protein (CREB) inhibition. Apelin-13 suppressed cAMP elevation, CREB phosphorylation, fPRR/sPRR protein expression, and renin production. Recombinant sPRR (sPRR-His) stimulated renin production, which was inhibited by the PRR decoy peptide PRO20 and S1P inhibitor PF429242. These findings suggest that apelin-13 inhibits plasma renin expression through the cAMP/PKA/sPRR pathway, providing a potential therapeutic approach for RVHT. Understanding the regulation of renin production is crucial for developing effective treatments.NEW & NOTEWORTHY Our research elucidated that apelin-13 inhibits renin production through the cAMP/PKA/soluble (pro)renin receptor pathway, presenting a promising therapeutic approach for renovascular hypertension (RVHT) by targeting renin expression mechanisms. These findings underscore the potential of apelin-13 as a novel strategy to address RVHT.

Montelukast Ameliorates 2K1C-Hypertension Induced Endothelial Dysfunction and Associated Vascular Dementia.

BACKGROUND: Declined kidney function associated with hypertension is a danger for cognitive deficits, dementia, and brain injury. Cognitive decline and vascular dementia (VaD) are serious public health concerns, which highlights the urgent need for study on the risk factors for cognitive decline. Cysteinyl leukotriene (CysLT1) receptors are concerned with regulating cognition, motivation, inflammatory processes, and neurogenesis. OBJECTIVE: This research aims to examine the consequence of montelukast (specific CysLT1 antagonist) in renovascular hypertension 2-kidney-1-clip-2K1C model-triggered VaD in experimental animals. METHODS: 2K1C tactics were made to prompt renovascular hypertension in mature male rats. Morris water maze was employed to measure cognition. Mean arterial pressure (MAP), serum nitrite levels, aortic superoxide content, vascular endothelial activity, brain's oxidative stress (diminished glutathione, raised lipid peroxides), inflammatory markers (IL-10, IL-6, TNF-α), cholinergic activity (raised acetylcholinesterase), and cerebral injury (staining of 2, 3, 5- triphenylterazolium chloride) were also examined. RESULTS: Montelukast in doses of 5.0 and 10.0 mg kg-1 was used intraperitoneally as the treatment drug. Along with cognitive deficits, 2K1C-operated rats showed elevated MAP, endothelial dysfunction, brain oxidative stress, inflammation, and cerebral damage with diminished serum nitrite/nitrate. Montelukast therapy significantly and dose-dependently mitigated the 2K1Chypertension- provoked impaired behaviors, biochemistry, endothelial functions, and cerebral infarction. CONCLUSION: The 2K1C tactic caused renovascular hypertension and associated VaD, which was mitigated via targeted regulation of CysLT1 receptors by montelukast administration. Therefore, montelukast may be taken into consideration for the evaluation of its complete potential in renovascular-hypertension-induced VaD.

Caloric restriction improves inflammation in different tissues of the Wistar rats with obesity and 2K1C renovascular hypertension.

Renovascular hypertension (RHV) is the cause of high blood pressure due to left renal ischemia, and obesity and hypertension cause an inflammatory response. This work analyzed the inflammatory and tissue repair profile in renal, hepatic, and cardiac tissues in an animal model of RVH associated with a high-fat diet and caloric restriction. The expressions of RORγ-t, IL-17, T-bet, and TNF-α decreased and IFN-γ increased in the right kidney. In relation to the left kidney, caloric restriction decreased the expression of IFN-γ. In the liver, caloric restriction decreased RORγ-t, IL-17, and T-bet. Hypertension associated with obesity decreased the expression of IFN-γ, while caloric restriction increased. In the right kidney, hypertension and obesity, associated or not with caloric restriction, increased the area of collagen fibers. In the heart and liver, caloric restriction reduced the area of collagen fibers. Caloric restriction increased vascular endothelial growth factor, reduced levels of growth transformation factor-ß1 (TGF-ß), and increased collagen I in the left kidney. Hypertension/obesity, submitted or not having caloric restriction, increased TGF-ß in liver. The results suggest that caloric restriction has beneficial effects in lowering blood pressure and regulating tissue proinflammatory cytokines. However, there was no change in the structure and composition of tissue repair markers.

Antihypertensive and Antioxidant Effects of an Aqueous Extract of Asafetida in Renovascular Hypertensive Rats.

Recently, the effect of an aqueous extract of asafetida on acute angiotensin II hypertensive rats was evaluated. The present study evaluated the antihypertensive and antioxidant effects of asafetida on a rat model of renovascular hypertension (RVH) using four groups. RVH was induced by clipping the renal artery; the sham group underwent surgery but without clipping. The RVH rats received losartan (Los, an AT1 receptor antagonist) or asafetida by gavage for 4 weeks. On the 28th day, the femoral artery was cannulated, and the systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were recorded. Finally, the levels of superoxide dismutase (SOD) activity, malondialdehyde (MDA), and total thiol content in the kidney and heart tissues were measured. In RVH rats, SBP and MAP significantly increased compared with the control. Los and the extract significantly reduced the changes in SBP, MAP, and HR that were induced in the RVH rats (P <0.05-0.001). In RVH rats, levels of MDA significantly increased and the content of total thiol and SOD decreased in both the heart and kidney tissues. Los plus the extract significantly decreased MDA and increased total thiol and SOD in the heart and kidney tissues. We concluded that an aqueous extract of asafetida gum has antihypertensive and antioxidant effects in the RVH rat model. The effect of the extract is similar to that of Los, which suggests that this effect of asafetida is mediated via an effect on the angiotensin Type I receptor.

Differential effects of estrogen receptors in the rostral ventrolateral medulla in Goldblatt hypertension.

Previous studies have shown that 17ß-estradiol plays a cardioprotective role in the central nervous system (CNS) of male rats. The aim of the present study was to determine the influence of 17ß-estradiol on sympathetic vasomotor activity and blood pressure in a renovascular hypertensive Goldblatt two-kidney one-clip (2K-1C) male rat model. We also determined the influence of angiotensin II AT1 receptor on the expression of estrogen receptors (ERα, ERß, and G protein-coupled ER (GPER)) in the rostral ventrolateral medulla (RVLM) of Goldblatt rats. Experiments were performed in Goldblatt and age-matched control rats six weeks after clipping of renal artery to induce hypertension. Microinjection of 17ß-estradiol into the RVLM led to a greater reduction in mean arterial pressure and renal sympathetic nerve activity in controls than in 2K-1C rats. Microinjection of the GPER agonist G-1 into the RVLM led to a significantly greater increase in mean arterial pressure and renal sympathetic nerve activity in 2K-1C rats. Expression levels of estrogen receptors GPER and ERα, but not ERß, were significantly higher in the RVLM of 2K-1C rats than in that of the control rats. Chronic treatment with losartan significantly reduced the expression levels of estrogen receptors in the RVLM of 2K-1C rats. Taken altogether, the data suggest that the imbalance of actions between ERα and GPER, particularly with the predominance of GPER in the RVLM, contributes to sympathetic overactivation in male rats with Goldblatt hypertension. AT1-Angiotensin II receptor in the RVLM upregulated estrogen receptor expression in male Goldblatt rats.

Genistein alleviates renin-angiotensin system mediated vascular and kidney alterations in renovascular hypertensive rats.

Genistein is a bioflavonoid mainly found in soybean. This study evaluated the effect of genistein on vascular dysfunction and kidney damage in two-kidney, one-clipped (2K1C) hypertensive rats. Male Sprague-Dawley-2K1C hypertensive rats were treated with genistein (40 or 80 mg/kg) or losartan 10 mg/kg (n = 8/group). Genistein reduced blood pressure, attenuated the increase in sympathetic nerve-mediated contractile response and endothelial dysfunction in the mesenteric vascular beds and aorta of 2K1C rats. Increases in the intensity of tyrosine hydroxylase (TH) in the mesentery and plasma norepinephrine (NE) were alleviated in the genistein-treated group. Genistein also improved renal dysfunction, hypertrophy of the non-clipped kidney (NCK) and atrophy of the clipped kidney (CK) in 2K1C rats. Upregulation of angiotensin II receptor type I (AT1R), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit 4 (Nox4) and Bcl2-associated X protein (BAX) and downregulation of B-cell lymphoma 2 (Bcl2) protein found in CK were restored by genistein. It also suppressed the overexpression of AT1R, transforming growth factor beta I (TGF-ß1), smad2/3 and p-smad3 in NCK. Genistein reduced serum angiotensin converting enzyme (ACE) activity and plasma angiotensin II (Ang II) in 2K1C rats. Low levels of catalase activity as well as high levels of superoxide generation and malondialdehyde (MDA) in 2K1C rats were restored by genistein treatment. In conclusion, genistein suppressed renin-angiotensin system-mediated sympathetic activation and oxidative stress in 2K1C rats. It alleviated renal atrophy in CK via modulation of AT1R/NADPH oxidase/Bcl-2/BAX pathways and hypertrophy in NCK via AT1R/TGF-ß1/smad-dependent signalling pathways.

Bone marrow-derived mesenchymal stem cells transplantation ameliorates renal injury through anti-fibrotic and anti-inflammatory effects in chronic experimental renovascular disease.

BACKGROUND: Progressive renal fibrosis is an underlying pathological process of chronic kidney disease (CKD) evolution. This study aimed to evaluate the roles of bone-marrow-derived mesenchymal stem cells (MSC) in the remodeling of fibrotic kidney parenchyma in the two kidneys-one clip (2K1C) CKD animal model. METHODS: Wistar rats were allocated into three groups: Sham, 2K1C, and 2K1C þ MSC. MSCs (106) were transplanted into the renal subcapsular region two weeks after clipping the left renal artery. Six weeks after clipping, left kidney samples were analyzed using histological and western blotting techniques. ANOVA tests were performed and differences between groups were considered statistically significant if p < 0.05. RESULTS: Clipped kidneys of 2K1C rats displayed renal fibrosis, with excessive collagen deposition, glomerulosclerosis and renal basement membrane disruption. Clipped kidneys of 2K1C þ MSC rats showed preserved Bowman's capsule and tubular basement membranes, medullary tubules morphological reconstitution and reduced collagen deposits. Expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 were elevated, whereas tissue inhibitor of MMPs (TIMP)-1 and TIMP-2 levels were decreased in clipped kidneys of 2K1C rats. MSCs transplantation restored these expression levels. Moreover, MSCs suppressed macrophages and myofibroblasts accumulation, as well as TNF-a expression in clipped kidneys of 2K1C animals. MSCs transplantation significantly increased IL-10 expression. CONCLUSIONS: Transplanted MSCs orchestrate anti-fibrotic and anti-inflammatory events, which reverse renal fibrosis and promote renal morphological restoration. This study supports the notion that only one MSCs delivery into the renal subcapsular region represents a possible therapeutic strategy against renal fibrosis for CKD treatment.

RNA sequencing reveals induction of specific renal inflammatory pathways in a rat model of malignant hypertension.

In malignant hypertension, far more severe kidney injury occurs than in the "benign" form of the disease. The role of high blood pressure and the renin-angiotensin-aldosterone system is well recognized, but the pathogenesis of the renal injury of malignant hypertension (MH) remains incompletely understood. Using the rat model of two-kidney, one-clip renovascular hypertension in which some but not all animals develop MH, we performed a transcriptomic analysis of gene expression by RNA sequencing to identify transcriptional changes in the kidney cortex specific for MH. Differential gene expression was assessed in three groups: MH, non-malignant hypertension (NMH), and normotensive, sham-operated controls. To distinguish MH from NMH, we considered two factors: weight loss and typical renovascular lesions. Mean blood pressure measured intraarterially was elevated in MH (220 ± 6.5 mmHg) as well as in NMH (192 ± 6.4 mmHg), compared to controls (119 ± 1.7 mmHg, p < 0.05). Eight hundred eighty-six genes were exclusively regulated in MH only. Principal component analysis revealed a separated clustering of the three groups. The data pointed to an upregulation of many inflammatory mechanisms in MH including pathways which previously attracted relatively little attention in the setting of hypertensive kidney injury: Transcripts from all three complement activation pathways were upregulated in MH compared to NMH but not in NMH compared with controls; immunohistochemistry confirmed complement deposition in MH exclusively. The expression of chemokines attracting neutrophil granulocytes (CXCL6) and infiltration of myeloperoxidase-positive cells were increased only in MH rats. The data suggest that these pathways, especially complement deposition, may contribute to kidney injury under MH. KEY MESSAGES: The most severe hypertension-induced kidney injury occurs in malignant hypertension. In a rat model of malignant hypertension, we assessed transcriptional responses in the kidney exposed to high blood pressure. A broad stimulation of inflammatory mechanisms was observed, but a few specific pathways were activated only in the malignant form of the disease, notably activation of the complement cascades. Complement inhibitors may alleviate the thrombotic microangiopathy of malignant hypertension even in the absence of primary complement abnormalities.

Açaí Reverses Adverse Cardiovascular Remodeling in Renovascular Hypertension: A Comparative Effect With Enalapril.

ABSTRACT: This study aimed to determine if açai seed extract (ASE) could reverse pre-existing cardiovascular and renal injury in an experimental model of renovascular hypertension (2 kidney, 1 clip, 2K1C). Young male rats (Wistar) were used to obtain 2K1C and sham groups. Animals received the vehicle, ASE (200 mg/kg/d), or enalapril (30 mg/kg/d) in drinking water from the third to sixth week after surgery. We evaluated systolic blood pressure by tail plethysmography, vascular reactivity in the rat isolated mesenteric arterial bed (MAB), serum and urinary parameters, plasma inflammatory cytokines by ELISA, MAB expression of endothelial nitric oxide synthase and its active form peNOS by Western blot, plasma and MAB oxidative damage and antioxidant activity by spectrophotometry, and vascular and cardiac structural changes by histological analysis. ASE and enalapril reduced the systolic blood pressure, restored the endothelial and renal functions, and decreased the inflammatory cytokines and the oxidative stress in 2K1C rats. Furthermore, both treatments reduced vascular and cardiac remodeling. ASE substantially reduced cardiovascular remodeling and recovered endothelial dysfunction in 2K1C rats probably through its antihypertensive, antioxidant, and anti-inflammatory actions, supplying a natural resource for the treatment of renovascular hypertension.

Strength Training Reduces Cardiac and Renal Oxidative Stress in Rats with Renovascular Hypertension. / Treino de Força Reduz Stress Oxidativo Cardíaco e Renal em Ratos com Hipertensão Renovascular.

BACKGROUND: Strength training has beneficial effects on kidney disease, in addition to helping improve antioxidant defenses in healthy animals. OBJECTIVE: To verify if strength training reduces oxidative damage to the heart and contralateral kidney caused by the renovascular hypertension induction surgery, as well as to evaluate alterations in the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) endogenous antioxidant enzymes. METHODS: Eighteen male rats were divided into three groups (n=6/group): sham, hypertensive, and trained hypertensive. The animals were induced to renovascular hypertension through left renal artery ligation. Strength training was initiated four weeks after the induction of renovascular hypertension, continued for a 12-weeks period, and was performed at 70% of 1RM. After the training period, the animals were euthanized and the right kidney and heart were removed for quantitation of hydroperoxides, malondialdehyde and sulfhydryl groups, which are markers of oxidative damage. In addition, the activity of SOD, CAT, and GPx antioxidant enzymes was also measured. The adopted significance level was 5% (p < 0.05). RESULTS: After strength training, a reduction in oxidative damage to lipids and proteins was observed, as could be seen by reducing hydroperoxides and total sulfhydryl levels, respectively. Furthermore, an increased activity of superoxide dismutase, catalase, and glutathione peroxidase antioxidant enzymes was observed. CONCLUSION: Strength training is able to potentially reduce oxidative damage by increasing the activity of antioxidant enzymes. (Arq Bras Cardiol. 2021; 116(1):4-11).

FUNDAMENTO: O treino de força tem efeitos benéficos em doenças renais, além de ajudar a melhorar a defesa antioxidante em animais saudáveis. OBJETIVO: Verificar se o treino de força reduz o dano oxidativo ao coração e rim contralateral para cirurgia de indução de hipertensão renovascular, bem como avaliar as alterações na atividade das enzimas antioxidantes endógenas superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx). MÉTODOS: Dezoito ratos machos foram divididos em três grupos (n=6/grupo): placebo, hipertenso e hipertenso treinado. Os animais foram induzidos a hipertensão renovascular através da ligação da artéria renal esquerda. O treino de força foi iniciado quatro semanas após a indução da hipertensão renovascular, teve 12 semanas de duração e foi realizada a 70% de 1RM. Depois do período de treino, os animais foram submetidos a eutanásia e o rim esquerdo e o coração foram retirados para realizar a quantificação de peróxidos de hidrogênio, malondialdeído e grupos sulfidrílicos, que são marcadores de danos oxidativos. Além disso, foram medidas as atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. O nível de significância adotado foi de 5% (p < 0,05). RESULTADOS: Depois do treino de força, houve redução de danos oxidativos a lipídios e proteínas, como pode-se observar pela redução de peróxidos de hidrogênio e níveis sulfidrílicos totais, respectivamente. Além disso, houve um aumento nas atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. CONCLUSÃO: O treino de força tem o potencial de reduzir danos oxidativos, aumentando a atividades de enzimas antioxidantes. (Arq Bras Cardiol. 2021; 116(1):4-11).

Nrf1 Knock-Down in the Hypothalamic Paraventricular Nucleus Alleviates Hypertension Through Intervention of Superoxide Production-Removal Balance and Mitochondrial Function.

Oxidative stress in the hypothalamic paraventricular nucleus (PVN) contributes greatly to the development of hypertension. The recombinant nuclear respiratory factor 1 (Nrf1) regulates the transcription of several genes related to mitochondrial respiratory chain function or antioxidant expression, and thus may be involved in the pathogenesis of hypertension. Here we show that in the two-kidney, one-clip (2K1C) hypertensive rats the transcription level of Nrf1 was elevated comparing to the normotensive controls. Knocking down of Nrf1 in the PVN of 2K1C rats can significantly reduce their blood pressure and level of plasma norepinephrine (NE). Analysis revealed significant reduction of superoxide production level in both whole cell and mitochondria, along with up-regulation of superoxide dismutase 1 (Cu/Zn-SOD), NAD(P)H: quinone oxidoreductase 1 (NQO1), thioredoxin-dependent peroxiredoxin 3 (Prdx3), cytochrome c (Cyt-c) and glutathione synthesis rate-limiting enzyme (glutamyl-cysteine ligase catalytic subunit (Gclc) and modifier subunit (Gclm)), and down-regulation of cytochrome c oxidase subunit VI c (Cox6c) transcription after Nrf1 knock-down. In addition, the reduced ATP production and elevated mitochondrial membrane potential in the PVN of 2K1C rats were reinstated with Nrf1 knock-down, together with restored expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitochondrial transcription factor A (Tfam), coiled-coil myosin-like BCL2-interacting protein (Beclin1), and Mitofusin 1 (Mfn1), which are related to the mitochondrial biogenesis, fusion, and autophagy. Together, the results indicate that the PVN Nrf1 is associated with the development of 2K1C-induced hypertension, and Nrf1 knock-down in the PVN can alleviate hypertension through intervention of mitochondrial function and restorement of the production-removal balance of superoxide.

Treino de Força Reduz Stress Oxidativo Cardíaco e Renal em Ratos com Hipertensão Renovascular / Strength Training Reduces Cardiac and Renal Oxidative Stress in Rats with Renovascular Hypertension

Resumo Fundamento O treino de força tem efeitos benéficos em doenças renais, além de ajudar a melhorar a defesa antioxidante em animais saudáveis. Objetivo Verificar se o treino de força reduz o dano oxidativo ao coração e rim contralateral para cirurgia de indução de hipertensão renovascular, bem como avaliar as alterações na atividade das enzimas antioxidantes endógenas superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx). Métodos Dezoito ratos machos foram divididos em três grupos (n=6/grupo): placebo, hipertenso e hipertenso treinado. Os animais foram induzidos a hipertensão renovascular através da ligação da artéria renal esquerda. O treino de força foi iniciado quatro semanas após a indução da hipertensão renovascular, teve 12 semanas de duração e foi realizada a 70% de 1RM. Depois do período de treino, os animais foram submetidos a eutanásia e o rim esquerdo e o coração foram retirados para realizar a quantificação de peróxidos de hidrogênio, malondialdeído e grupos sulfidrílicos, que são marcadores de danos oxidativos. Além disso, foram medidas as atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. O nível de significância adotado foi de 5% (p < 0,05). Resultados Depois do treino de força, houve redução de danos oxidativos a lipídios e proteínas, como pode-se observar pela redução de peróxidos de hidrogênio e níveis sulfidrílicos totais, respectivamente. Além disso, houve um aumento nas atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. Conclusão O treino de força tem o potencial de reduzir danos oxidativos, aumentando a atividades de enzimas antioxidantes. (Arq Bras Cardiol. 2021; 116(1):4-11)

Abstract Background Strength training has beneficial effects on kidney disease, in addition to helping improve antioxidant defenses in healthy animals. Objective To verify if strength training reduces oxidative damage to the heart and contralateral kidney caused by the renovascular hypertension induction surgery, as well as to evaluate alterations in the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) endogenous antioxidant enzymes. Methods Eighteen male rats were divided into three groups (n=6/group): sham, hypertensive, and trained hypertensive. The animals were induced to renovascular hypertension through left renal artery ligation. Strength training was initiated four weeks after the induction of renovascular hypertension, continued for a 12-weeks period, and was performed at 70% of 1RM. After the training period, the animals were euthanized and the right kidney and heart were removed for quantitation of hydroperoxides, malondialdehyde and sulfhydryl groups, which are markers of oxidative damage. In addition, the activity of SOD, CAT, and GPx antioxidant enzymes was also measured. The adopted significance level was 5% (p < 0.05). Results After strength training, a reduction in oxidative damage to lipids and proteins was observed, as could be seen by reducing hydroperoxides and total sulfhydryl levels, respectively. Furthermore, an increased activity of superoxide dismutase, catalase, and glutathione peroxidase antioxidant enzymes was observed. Conclusion Strength training is able to potentially reduce oxidative damage by increasing the activity of antioxidant enzymes. (Arq Bras Cardiol. 2021; 116(1):4-11)

Experimental Renovascular Disease Induces Endothelial Cell Mitochondrial Damage and Impairs Endothelium-Dependent Relaxation of Renal Artery Segments.

BACKGROUND: Mitochondria modulate endothelial cell (EC) function, but may be damaged during renal disease. We hypothesized that the ischemic and metabolic constituents of swine renovascular disease (RVD) induce mitochondrial damage and impair the function of renal artery ECs. METHODS: Pigs were studied after 16 weeks of metabolic syndrome (MetS), renal artery stenosis (RAS), or MetS + RAS, and Lean pigs served as control (n = 6 each). Mitochondrial morphology, homeostasis, and function were measured in isolated primary stenotic-kidney artery ECs. EC functions were assessed in vitro, whereas vasoreactivity of renal artery segments was characterized in organ baths. RESULTS: Lean + RAS and MetS + RAS ECs showed increased mitochondrial area and decreased matrix density. Mitochondrial biogenesis was impaired in MetS and MetS + RAS compared with their respective controls. Mitochondrial membrane potential similarly decreased in MetS, Lean + RAS, and MetS + RAS groups, whereas production of reactive oxygen species increased in MetS vs. Lean, but further increased in both RAS groups. EC tube formation was impaired in MetS, RAS, and MetS + RAS vs. Lean, but EC proliferation and endothelial-dependent relaxation of renal artery segments were blunted in MetS vs. Lean, but further attenuated in Lean + RAS and MetS + RAS. CONCLUSIONS: MetS and RAS damage mitochondria in pig renal artery ECs, which may impair EC function. Coexisting MetS and RAS did not aggravate EC mitochondrial damage in the short time of our in vivo studies, suggesting that mitochondrial injury is associated with impaired renal artery EC function.

Fitness is improved by adjustments in muscle intracellular signaling in rats with renovascular hypertension 2K1C undergoing voluntary physical exercise.

AIM: To evaluate physical fitness and cardiovascular effects in rats with renovascular hypertension, two kidneys, one clip (2K1C) submitted to voluntary exercise (ExV). MAIN METHODS: 24 h after surgery (SHAM and 2K1C) rats were submitted to ExV for one week (adaptation). ExV adherent rats were separated into exercise (2K1C-EX and SHAM-EX) or sedentary (2K1C-SED and SHAM-SED) groups. After 4 weeks, exhaustion test, plasma lactate, cardiovascular parameters were evaluated and gastrocnemius muscle was removed for evaluation of gene expression of muscle metabolism markers (PGC1α; AMPK, SIRT-1, UCP-3; MCP-1; LDH) and of the redox process. KEY FINDINGS: ExV decreased blood lactate concentration and increased SOD and CAT activity and a SIRT-1 and UCP-3 gene expression in the gastrocnemius muscle of 2K1C-ExV rats compared to 2K1C-SED rats. Gene expressions of PGC1α, UCP-3, MCT-1, AMPK were higher in 2K1C-ExV rats compared to SHAM-SED rats. Blood pressure in 2K1C-ExV was lower compared to 2K1C-SED and higher in SHAM-SED rats. Reflex bradycardia in 2K1C-EX rats increased compared to 2K1C-SED and was similar to SHAM-SED. The variation in mean blood pressure induced by ganglion blocker hexamethonium and Ang II AT1 receptor antagonist, losartan in the 2K1C-ExV rats was smaller compared to the 2K1C-SED rats and it was similar to the SHAM-SED rats. SIGNIFICANCE: O ExV induced adaptive responses in 2K1C-ExV rats by decreasing sympathetic and Ang II activities and stimulating intracellular signaling that favors redox balance and reduced blood lactate concentration. These adaptive responses, then, contribute to reduced arterial pressure, improved baroreflex sensitivity and physical fitness of 2K1C rats.

Systemic administration of pentoxifylline attenuates the development of hypertension in renovascular hypertensive rats.

There is evidence to suggest that hypertension involves a chronic low-grade systemic inflammatory response; however, the underlying mechanisms are unclear. To further understand the role of inflammation in hypertension, we used a rat renovascular model of hypertension in which we administered the TNF-α synthesis inhibitor pentoxifylline (PTX, 30 mg/kg/day) in the drinking water for 60 days. In conscious rats, PTX administration significantly attenuated the development of hypertension (systolic blood pressure, PTX: 145 ± 8 vs. vehicle (Veh): 235 ± 11 mmHg, after 38 days of treatment, P < 0.05, N = 5/group). This attenuation in hypertension was coupled with a decrease in the low-frequency spectra of systolic blood pressure variability (PTX: 1.23 ± 0.2 vs Veh: 3.05 ± 0.8 arbitrary units, P < 0.05, N = 5/group). Furthermore, systemic PTX administration decreased c-Fos expression within the hypothalamic paraventricular nucleus (PTX: 17 ± 4 vs. Veh: 70 ± 13 cells, P < 0.01, N = 5, PVN) and increased the total number of microglial branches (PTX: 2129 ± 242 vs. Veh: 1415 ± 227 branches, P < 0.05, N = 4/group). Acute central injection of PTX (20 µg) under urethane anesthesia caused a small transient decrease in blood pressure but did not change renal sympathetic nerve activity. Surprisingly, we found no detectable basal levels of plasma TNF-α in either PTX- or vehicle-treated animals. These results suggest that inflammation plays a role in renovascular hypertension and that PTX might act both peripherally and centrally to prevent hypertension.

Correlations Between Interleukin-11 Expression and Hypertensive Kidney Injury in a Rat Model of Renovascular Hypertension.

BACKGROUND: Interleukin-11 (IL-11) is a pleiotropic cytokine of the interleukin-6 family. Recent studies revealed its crucial role in the development of cardiovascular fibrosis. In this study we examined IL-11 expression levels in the heart and the kidney exposed to high blood pressure in renovascular hypertensive rats and their correlations to fibrotic markers and kidney injury. METHODS: Two-kidney, one-clip renovascular hypertension (2K1C) was induced in rats. IL-11 expression was measured by real-time polymerase chain reaction in the left ventricle and the right kidney. The correlation of cardiac IL-11 expression with biomarkers of renal fibrosis was assessed. We further investigated IL-11 expression in 2K1C rats grouped into rats with malignant vs. nonmalignant hypertension (distinguishing criteria: weight loss, number of fibrinoid necrosis, and onion skin lesions). RESULTS: Thirty-five days after clipping, mean arterial pressure was significantly increased in 2K1C. Renal IL-11 expression was elevated in 2K1C. In the heart there was only a trend toward higher IL-11 expression in 2K1C. IL-11 in the kidney in 2K1C correlated with the expression of transforming growth factor (TGF)-ß1/2, collagens, fibronectin, osteopontin, as well as tissue inhibitors of metalloprotease 1/2. There were also correlations of IL-11 with tissue collagen expansion, number of activated fibroblasts and serum creatinine, but no correlation with mean arterial pressure. Renal expression of IL-11 was highest in rats with malignant hypertension. CONCLUSIONS: Renal IL-11 expression of renovascular hypertensive rats is markedly increased and correlates with profibrotic markers and loss of function and might therefore serve as a biomarker for the severity of hypertensive nephrosclerosis.

Dietary capsaicin-mediated attenuation of hypertension in a rat model of renovascular hypertension.

Background: Capsaicin, a pungent component of chili pepper, has been reported to decrease blood pressure (BP) and to cause vasorelaxation via nitric oxide (NO) production. However, it is still unclear how dietary capsaicin effects on renovascular hypertension. To examine this, we observed the effects of dietary capsaicin on BP in 2-kidney, 1-clip renovascular hypertension (2K1C) rats, and investigated the participation of NO in the mechanism.Methods: Rats with 2K1C or sham-operated rats (SHAM) were treated with 0.006% capsaicin diet (CAP) or control diet (CTL) for 6 weeks. Systolic BP (SBP) was measured by tail-cuff method once a week. In the end, mean arterial BP (MAP) was measured in the rats under anesthesia. These observations were performed also in the rats taking a NO synthase (NOS) inhibitor (LN). After rats were euthanized, thoracic aortas were collected and used for western blot analyses to evaluate the phosphorylated ratio of endothelial NOS (eNOS), protein kinase A (PKA) and B (Akt), in order to explore a mechanism of the effects on BP by dietary capsaicin.Results: SBP and MAP in 2K1C rats were significantly higher than in SHAM rats when fed CTL, but not when fed CAP. Those in 2K1C-CAP rats were significantly lower than in 2K1C-CTL rats. LN suppressed the effect of dietary capsaicin. The ratios of phosphorylated (p-) eNOS/eNOS and p-Akt/Akt, but not p-PKA/PKA, were significantly increased in rats fed CAP compared with rats fed CTL.Conclusion: Dietary capsaicin may alleviate 2K1C renovascular hypertension, probably via enhancing phosphorylation of Akt and eNOS.Abbreviations: 2K1C: 2-kidney, 1-clip hypertension model; Akt: protein kinase B; Ang II: angiotensin II; ANOVA: measures analysis of variance; BP: blood pressure; EC: endothelial cell; eNOS: endothelial nitric oxide synthase; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; L-NAME, LN: Nω-Nitro-L-arginine methyl ester hydrochloride; MA: mesenteric arteries; MAP: mean arterial blood pressure; NO: nitric oxide; PKA: protein kinase A; PVDF: polyvinylidene difluoride; SBP: Systolic blood pressure; SHR: spontaneously hypertensive rats; SN: sympathetic nervous; TRPV1: transient receptor potential vanilloid type 1; WKY: Wistar Kyoto rats.

Environmental Enrichment Promotes Antioxidant Effect in the Ventrolateral Medulla and Kidney of Renovascular Hypertensive Rats / O Enriquecimento Ambiental Promove Efeito Antioxidante no Bulbo Ventrolateral e Rins de Roedores com Hipertensão Renovascular

Abstract Background: Arterial hypertension is a precursor to the development of heart and renal failure, furthermore is associated with elevated oxidative markers. Environmental enrichment of rodents increases performance in memory tasks, also appears to exert an antioxidant effect in the hippocampus of normotensive rats. Objectives: Evaluate the effect of environmental enrichment on oxidative stress in the ventrolateral medulla, heart, and kidneys of renovascular hypertensive rats. Methods: Forty male Fischer rats (6 weeks old) were divided into four groups: normotensive standard condition (Sham-St), normotensive enriched environment (Sham-EE), hypertensive standard condition (2K1C-St), and hypertensive enriched environment (2K1C-EE). Animals were kept in enriched or standard cages for four weeks after all animals were euthanized. The level of significance was at p < 0.05. Results: 2K1C-St group presented higher mean arterial pressure (mmHg) 147.0 (122.0; 187.0) compared to Sham-St 101.0 (94.0; 109.0) and Sham-EE 106.0 (90.8; 117.8). Ventrolateral medulla from 2K1C-EE had higher superoxide dismutase (SOD) (49.1 ± 7.9 U/mg ptn) and catalase activity (0.8 ± 0.4 U/mg ptn) compared to SOD (24.1 ± 9.8 U/mg ptn) and catalase activity (0.3 ± 0.1 U/mg ptn) in 2K1C-St. 2K1C-EE presented lower lipid oxidation (0.39 ± 0.06 nmol/mg ptn) than 2K1C-St (0.53 ± 0.22 nmol/mg ptn) in ventrolateral medulla. Furthermore, the kidneys of 2K1C-EE (11.9 ± 2.3 U/mg ptn) animals presented higher superoxide-dismutase activity than those of 2K1C-St animals (9.1 ± 2.3 U/mg ptn). Conclusion: Environmental enrichment induced an antioxidant effect in the ventrolateral medulla and kidneys that contributes to reducing oxidative damage among hypertensive rats.

Resumo Fundamento: A hipertensão arterial é um precursor para o desenvolvimento da insuficiência cardíaca e renal e, além disso, está associada com o aumento dos marcadores oxidativos. O enriquecimento ambiental dos roedores melhora o desempenho em tarefas de memória, e também parece ter um efeito antioxidante sobre o hipocampo dos ratos normotensos. Objetivos: Avaliar o efeito do enriquecimento ambiental sobre o estresse oxidativo no bulbo ventrolateral, coração, e rins de ratos com hipertensão renovascular. Métodos: Quarenta ratos machos, tipo Fischer (6 semanas de idade), foram divididos em quatro grupos: normotensos em condições padrão (Sham-CP), normotensos em ambiente enriquecido (Sham-AE), hipertensos em condições padrão (2R1C-CP), e hipertensos em ambiente enriquecido (2R1C-AE). Os animais foram mantidos em gaiolas enriquecidas ou padrão durante quatro semanas e, por fim, todos os animais foram eutanasiados. O nível de significância foi p < 0,05. Resultados: O grupo 2R1C-CP apresentou pressão arterial média maior (mmHg) 147,0 (122,0; 187,0) quando comparado com os grupos Sham-CP 101,0 (94,0; 109,0) e Sham-AE 106,0 (90,8; 117,8). Observou-se maior atividade das enzimas superóxido dismutase (SOD) (49,1 ± 7,9 U/mg ptn) e da catalase (0,8 ± 0,4 U/mg ptn) no bulbo ventrolateral do grupo 2R1C-AE, em relação à atividade da SOD (24,1 ± 9,8 U/mg ptn) e da catalase (0,3 ± 0,1 U/mg ptn) no grupo 2R1C-CP. No grupo 2R1C-AE, a oxidação lipídica no bulbo ventrolateral foi menor (0,39 ± 0,06 nmol/mg ptn) quando comparado com o grupo 2R1C-CP (0,53 ± 0,22 nmol/mg ptn). Ademais, foi observada maior atividade das enzimas superóxido dismutase nos rins dos animais 2R1C-AE (11,9 ± 2,3 U/mg ptn) em relação aos animais 2R1C-CP (9,1 ± 2,3 U/mg ptn). Conclusão: O enriquecimento ambiental provocou efeito antioxidante no bulbo ventrolateral e nos rins, o que contribuiu para a redução do dano oxidante nos ratos hipertensos.

In renovascular hypertension, TNF-α type-1 receptors in the area postrema mediate increases in cardiac and renal sympathetic nerve activity and blood pressure.

AIMS: Neuroinflammation is a common feature in renovascular, obesity-related, and angiotensin II mediated hypertension. There is evidence that increased release of the pro-inflammatory cytokine tumour necrosis factor-α (TNF-α) contributes to the development of the hypertension, but the underlying neural mechanisms are unclear. Here, we investigated whether TNF-α stimulates neurons in the area postrema (AP), a circumventricular organ, to elicit sympathetic excitation, and increases in blood pressure (BP). METHODS AND RESULTS: In rats with renovascular hypertension, AP neurons that expressed TNF-α type-1 receptor (TNFR1) remained constantly activated (expressed c-Fos) and injection of TNFR1 neutralizing antibody into the AP returned BP (systolic: ∼151 mmHg) to normotensive levels (systolic: ∼108 mmHg). Nanoinjection of TNF-α (100 pg/50 nL) into the AP of anaesthetized normotensive rats increased BP (∼16 mmHg) and sympathetic nerve activity, predominantly to the heart (∼53%), but also to the kidneys (∼35%). These responses were abolished by prior injection of a TNFR1 neutralizing antibody (1 ng/50 nL) within the same site. TNFR1 were expressed in the somata of neurons activated by TNF-α that were retrogradely labelled from the rostral ventrolateral medulla (RVLM). CONCLUSION: These findings indicate that in renovascular hypertension, blocking TNFR1 receptors in the AP significantly reduces BP, while activation of TNFR1 expressing neurons in the AP by TNF-α increases BP in normotensive rats. This is mediated, in part, by projections to the RVLM and an increase in both cardiac and renal sympathetic nerve activity. These findings support the notion that proinflammatory cytokines and neuroinflammation are important pathological mechanisms in the development and maintenance of hypertension.