Endothelin-1-induced oxidative stress in DOCA-salt hypertension involves NADPH-oxidase-independent mechanisms

2006 ◽  
Vol 110 (2) ◽  
pp. 243-253 ◽  
Author(s):  
Glaucia E. Callera ◽  
Rita C. Tostes ◽  
Alvaro Yogi ◽  
Augusto C. I. Montezano ◽  
Rhian M. Touyz

We have demonstrated recently [Callera, Touyz, Teixeira, Muscara, Carvalho, Fortes, Schiffrin and Tostes (2003) Hypertension 42, 811–817] that increased vascular oxidative stress in DOCA (deoxycorticosterone acetate)-salt rats is associated with activation of the ET (endothelin) system via ETA receptors. The exact source of ET-1-mediated oxidative stress remains unclear. The aim of the present study was to investigate whether ET-1 increases generation of ROS (reactive oxygen species) in DOCA-salt hypertension through NADPH-oxidase-dependent mechanisms. Xanthine oxidase, eNOS (endothelial nitric oxide synthase) and COX-2 (cyclo-oxygenase-2) were also examined as potential ET-1 sources of ROS as well as mitochondrial respiration. DOCA-salt and control UniNX (uninephrectomized) rats were treated with the ETA antagonist BMS182874 (40 mg·day−1·kg−1 of body weight) or vehicle. Plasma TBARS (thiobarbituric acid-reacting substances) were increased in DOCA-salt compared with UniNX rats. Activity of NADPH and xanthine oxidases in aorta, mesenteric arteries and heart was increased in DOCA-salt rats. BMS182874 decreased plasma TBARS levels without influencing NADPH and xanthine oxidase activities in DOCA-salt rats. Increased p22phox protein expression and increased p47phox membrane translocation in arteries from DOCA-salt by rats were not affected by BMS182874 treatment. Increased eNOS and COX-2 expression, also observed in aortas from DOCA-salt rats, was unaltered by BMS182874. Increased mitochondrial generation of ROS in DOCA-salt rats was normalized by BMS182874. ETA antagonism also increased the expression of mitochondrial MnSOD (manganese superoxide dismutase) in DOCA-salt rats. In conclusion, activation of NADPH oxidase does not seem to be the major source of oxidative stress induced by ET-1/ETA in DOCA-salt hypertension, which also appears to be independent of increased activation of xanthine oxidase or eNOS/COX-2 overexpression. Mitochondria may play a role in ET-1-driven oxidative stress, as evidenced by increased mitochondrial-derived ROS in this model of hypertension.

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Srinivas Sriramula ◽  
Huijing Xia ◽  
Eric Lazartigues

Elevated reactive oxygen species (ROS) in the central nervous system (CNS) through NADPH oxidase and diminished Nitric oxide (NO) levels are involved in the pathogenesis of hypertension. We previously reported that central Angiotensin Converting Enzyme 2 (ACE2) overexpression prevents the development of hypertension induced by DOCA-salt in a transgenic mouse model (syn-hACE2; SA) with human ACE2 targeted selectively to neurons in the CNS. While baseline blood pressure (BP; telemetry) was not different among genotypes, DOCA-salt treatment (1mg/g body wt DOCA, 1% saline in drinking water for 3 weeks) resulted in significantly lower BP level in SA mice (122 ±3 mmHg, n=12) compared to non-transgenic (NT) littermates (138 ±3 mmHg, n=8). To elucidate the mechanisms involved in this response, we investigated the paraventricular nucleus (PVN) expression of Nox-2 (catalytic subunit of NADPH oxidase), 3-nitrotyrosine, and endothelial nitric oxide synthase (eNOS) and anti-oxidant enzymes superoxide dismutase (SOD) and catalase in the hypothalamus. DOCA-salt treatment resulted in decreased catalase (95.2 ±5.6 vs. 113.8 ±17.6 mmol/min/ml, p<0.05) and SOD (4.1 ±0.4 vs. 5.9 ±0.2 U/ml, p<0.01) activities in hypothalamic homogenates of NT mice, which was prevented by ACE2 overexpression (141.8 ±9.9 vs. 142.1 ±9.2 mmol/min/ml and 5.9 ±0.3 vs. 7.9 ±0.2 U/ml, respectively). NT mice treated with DOCA-salt showed increased oxidative stress as indicated by increased expression of Nox-2 (61 ±5 % increase, n=9, p<0.001 vs. NT) and 3-nitrotyrosine (89 ±32 % increase, n=9, p<0.01 vs. NT) in the PVN which was attenuated in SA mice. Furthermore, DOCA-salt hypertension resulted in decreased phosphorylation of eNOS-ser1177 in the PVN (33 ±5 % decrease, n=9, p<0.05 vs NT) and this decrease was prevented by ACE2 overexpression. Taken together, these data provide evidence that brain ACE2 regulates the balance between NO and ROS levels, thereby preventing the development of DOCA-salt hypertension.


2015 ◽  
pp. 303-312 ◽  
Author(s):  
M. VOKURKOVÁ ◽  
H. RAUCHOVÁ ◽  
L. ŘEZÁČOVÁ ◽  
I. VANĚČKOVÁ ◽  
J. ZICHA

Enhanced production of superoxide radicals by nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase in the brain and/or kidney of salt hypertensive Dahl rats has been proposed to participate in the pathogenesis of this form of experimental hypertension. Most information was obtained in young Dahl salt-sensitive (DS) rats subjected to high salt intake prior to sexual maturation. Therefore, the aim of our study was to investigate whether salt hypertension induced in adult DS rats is also accompanied with a more pronounced oxidative stress in the brain or kidney as compared to Dahl salt-resistant (DR) controls. NADPH oxidase activity as well as the content of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes (oxidative index), which indicate a degree of lipid peroxidation, were evaluated in two brain regions (containing either hypothalamic paraventricular nucleus or rostral ventrolateral medulla) as well as in renal medulla and cortex. High salt intake induced hypertension in DS rats but did not modify blood pressure in DR rats. DS and DR rats did not differ in NADPH oxidase-dependent production of ROS, TBARS content or oxidative index in either part of the brain. In addition, high-salt diet did not change significantly any of these brain parameters. In contrast, the enhanced NADPH oxidase-mediated ROS production (without significant signs of increased lipid peroxidation) was detected in the renal medulla of salt hypertensive DS rats. Our findings suggest that there are no signs of enhanced oxidative stress in the brain of adult Dahl rats with salt hypertension induced in adulthood.


Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Rong Jin ◽  
Zifang Song ◽  
Shiyong Yu ◽  
Daniel J Daunis ◽  
Brittany S Hopkins ◽  
...  

Rationale: Although CD40/CD40 ligand (CD40L) signaling has been implicated in clinical and experimental ischemic strokes, the underlying mechanisms are largely unclear. Objective: We investigated how CD40 participates in the cellular and molecular events underlying the postischemic inflammation and oxidative stress that may contribute to the tissue damage during cerebral ischemia. Methods and Results: Wild-type (WT, n=164) and CD40 knockout mice (n=132) were subjected to middle cerebral artery occlusion (MCAO, 60 minutes) followed by reperfusion. We found that ischemia/reperfusion induced CD40 expression in the brain in a time-dependent manner, primarily localized to the microvascular endothelial cells in the early phase (6h) and then to the activated microglia in the later time (24h). The adhesion and infiltration of neutrophils as well as the activation and expansion of microglia induced by ischemia/reperfusion were inhibited in CD40-/- mice, which were time-dependently correlated with suppressing nuclear factor-kB activation and proinflammatory cytokines (IL-1β, TNFα) and adhesion molecules (E- and P-selectin, ICAM-1,MCP-1). Infarct volumes and mortality were reduced in CD40-/- mice at 72h after ischemia/reperfusion. Treatment with an inhibitor of either NADPH oxidase or COX-2, the known enzymes that contributes to the tissue damage, reduced ischemic brain injury in wild-type mice, but not in CD40-/- mice. In contrast, treatment with an inhibitor of inducible nitric oxide synthase (iNOS) further reduced tissue injury in CD40-/- mice. Consistently, ischemia/reperfusion-induced upregulation of NADPH oxidase (Nox2, and Nox4) and COX-2, but not iNOS, were attenuated in CD40-/- mice. Conclusions: The findings unveil an essential role for CD40 in the regulation of early molecular and cellular events leading to postischemic inflammation. Inhibition of CD40 signaling may be a valuable therapeutic approach to counteract the deleterious effects of postischemic inflammation.


2008 ◽  
Vol 295 (1) ◽  
pp. H281-H288 ◽  
Author(s):  
Emilie C. Viel ◽  
Karim Benkirane ◽  
Danesh Javeshghani ◽  
Rhian M. Touyz ◽  
Ernesto L. Schiffrin

Vascular superoxide anion (O2•−) levels are increased in DOCA-salt hypertensive rats. We hypothesized that the endothelin (ET)-1-induced generation of ROS in the aorta and resistance arteries of DOCA-salt rats originates partly from xanthine oxidase (XO) and mitochondria. Accordingly, we blocked XO and the mitochondrial oxidative phosphorylation chain to investigate their contribution to ROS production in mesenteric resistance arteries and the aorta from DOCA-salt rats. Systolic blood pressure rose in DOCA-salt rats and was reduced after 3 wk by apocynin [NAD(P)H oxidase inhibitor and/or radical scavenger], allopurinol (XO inhibitor), bosentan (ETA/B receptor antagonist), BMS-182874 (BMS; ETA receptor antagonist), and hydralazine. Plasma uric acid levels in DOCA-salt rats were similar to control unilaterally nephrectomized (UniNx) rats, reduced with allopurinol and bosentan, and increased with BMS. Levels of thiobarbituric acid-reacting substances were increased in DOCA-salt rats versus UniNx rats, and BMS, bosentan, and hydralazine prevented their increase. Dihydroethidium staining showed reduced O2•− production in mesenteric arteries and the aorta from BMS- and bosentan-treated DOCA-salt rats compared with untreated DOCA-salt rats. Increased O2•− derived from XO was reduced or prevented by all treatments in mesenteric arteries, whereas bosentan and BMS had no effect on aortas from DOCA-salt rats. O2•− generation decreased with in situ treatment by tenoyltrifluoroacetone and CCCP, inhibitors of mitochondrial electron transport complexes II and IV, respectively, whereas rotenone (mitochondrial complex I inhibitor) had no effect. Our findings demonstrate the involvement of ETA receptor-modulated O2•− derived from XO and from mitochondrial oxidative enzymes in arteries from DOCA-salt rats.


Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Gaizun Hu ◽  
Osamu Ito ◽  
Rong Rong ◽  
Bin Xu ◽  
Akihiro Sakuyama ◽  
...  

Clinical trials have demonstrated renoprotective effects of atorvastatin (ATV) and pitavastatin (PTV), which belong to the strong statins, are more potent than other statins. We reported previously that ATV attenuated the development of hypertension in SHR with increasing the endothelial and neuronal NO synthases (eNOS, nNOS) expressions in the kidney, whereas ATV inhibited the eNOS phosphorylation at serin1177 (J Hypertes 28: 2278-2288, 2010). To clarify the mechanisms of renoprotective effects of PTV, the present study examined the effects of PTV on blood pressure, renal functions, NOS and oxidative stress in the kidney of SHR. Five-week-old, male SHR were given orally PTV (2mg/kg/day) or vehicle for 8 weeks. The systolic blood pressure (SBP) was measured. The NOS expression and eNOS phosphorylation were analyzed by Western blot. The NADPH oxidase activity was measured by the lucigenin-enhanced chemiluminescence method. PTV attenuated the progression of hypertension (220 ± 8 vs. 177± 4 mmHg, P<0.01) and albuminuria (684 ± 66 vs. 398 ± 42 mg/day, P<0.01) without changing plasma total cholesterol or creatinine. PTV increased the eNOS and nNOS expressions in the outer and inner medulla of the kidney (eNOS; by 182% and 186%, nNOS; by 315% and 194%, P<0.01). PTV significantly stimulated the eNOS phosphorylation at serin1177 in the inner medulla and inhibited the eNOS phosphorylation at threonine495 in the outer and inner medulla. PTV decreased hydrogen peroxide (13.4 ± 2.1 vs. 6.1 ± 1.2 nmol/day, P<0.05) and thiobarbituric acid reactive substances (TBARS) (236.6 ± 12.4 vs. 198.3 ± 10.6 nmol/day, P<0.05) in the urine and the NADPH oxidase activity (42681± 2515 vs. 32381 ± 1995 c.p.m/mg protein, P<0.01) in the renal cortex. These results indicate that PTV attenuates the development of hypertension and albuminuria in SHR with increasing the eNOS and nNOS expressions, changing the eNOS phosphorylation to an active form and mitigating oxidative stress in the kidney. The antihypertensive and renoprotective effects of PTV may be mediated in part by an upregulation of NO system and down-regulation of oxidative stress in the kidney.


2001 ◽  
Vol 94 (2) ◽  
pp. 303-312 ◽  
Author(s):  
Masaya Kudo ◽  
Mitsuo Aono ◽  
Yoonki Lee ◽  
Gary Massey ◽  
Robert D. Pearlstein ◽  
...  

Background Volatile anesthetics decrease ischemic brain injury. Mechanisms for this protection remain under investigation. The authors hypothesized that volatile anesthetics serve as antioxidants in a neuronal-glial cell culture system. Methods Primary cortical neuronal-glial cultures were prepared from fetal rat brain. Cultures were exposed to iron, H2O2, or xanthine-xanthine oxidase for 30 min in serum-free media containing dissolved isoflurane (0-3.2 mm), sevoflurane (0-3.6 mm), halothane (0-4.1 mm), n-hexanol, or known antioxidants. Cell damage was assessed by release of lactate dehydrogenase (LDH) and trypan blue exclusion 24 h later. Lipid peroxidation was measured by the production of thiobarbituric acid-reactive substances in a cell-free lipid system. Iron and calcium uptake and mitochondrial depolarization were measured after exposure to iron in the presence or absence of isoflurane. Results Deferoxamine reduced LDH release caused by H2O2 or xanthine-xanthine oxidase, but the volatile anesthetics had no effect. Iron-induced LDH release was prevented by the volatile anesthetics (maximum effect for halothane = 1.2 mm, isoflurane = 1.2 mm, and sevoflurane = 2.1 mm aqueous phase). When corrected for lipid solubility, the three volatile anesthetics were equipotent against iron-induced LDH release. In the cell-free system, there was no effect of the anesthetics on thiobarbituric acid-reactive substance formation in contrast to Trolox, which provided complete inhibition. Isoflurane (1.2 mm) reduced mean iron uptake by 46% and inhibited mitochondrial depolarization but had no effect on calcium uptake. Conclusions Volatile anesthetics reduced cell death induced by oxidative stress only in the context of iron challenge. The likely reason for protection against iron toxicity is inhibition of iron uptake and therefore indirect reduction of subsequent intracellular oxidative stress caused by this challenge. These data argue against a primary antioxidant effect of volatile anesthetics.


Author(s):  
Rukiye Nalan Tiftik ◽  
Meryem Temiz-Reşitoğlu ◽  
Demet Sinem Güden ◽  
Gülsen Bayrak ◽  
İsmail Ün ◽  
...  

It has been clearly indicated that osteoarthritis (OA) is an inflammatory and degenerative disease that could be promoted by Rho-kinase (ROCK); however, little is known about the role of ROCK/inhibitor κB alpha (IκB-α)/nuclear factor-κB (NF-κB) p65 pathway activation in interleukin-1β (IL-1β) induced inflammatory response and oxidative stress in primary human chondrocytes. To test this hypothesis, we focused on determining ROCK-II, IκB-α, p-IκB-α, NF-κB p65, p-NF-κB p65, IL-6, tumor necrosis factor alpha (TNF-α), cyclooxygenase-2 (COX-2), p22phox, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subtype 4 (NOX4) protein expression, ROCK-II activity, NADPH oxidase levels, and total antioxidant capacity (TAC) in the presence and absence of ROCK-inhibitor fasudil. IL-1β (2 ng·mL–1, 24 h) increased the expression of ROCK-II, p-IκB-α, NF-κB p65, p-NF-κB p65, IL-6, TNF-α, COX-2, and p22phox proteins, and decreased the expression of IκB-α, and the NOX4 protein level did not alter. ROCK activity and NADPH oxidase levels were increased, whereas the TAC was decreased by IL-1β. Fasudil (10−5–10−7 M) reversed all these changes induced by IL-1β. These results demonstrate that ROCK/IκB-α/NF-κB p65 pathway activation contributes to the IL-1β-induced inflammatory response and oxidative stress, and thus, ROCK inhibition might be a beneficial treatment option for OA patients mainly based on its anti-inflammatory and antioxidant effects.


2012 ◽  
Vol 302 (1) ◽  
pp. F85-F94 ◽  
Author(s):  
Lucienne S. Lara ◽  
Michael McCormack ◽  
Laura C. Semprum-Prieto ◽  
Sylvia Shenouda ◽  
Dewan S. A. Majid ◽  
...  

Augmentation of intrarenal angiotensinogen (AGT) synthesis, secretion, and excretion is associated with the development of hypertension, renal oxidative stress, and tissue injury during ANG II-dependent hypertension. High salt (HS) exacerbates hypertension and kidney injury, but the mechanisms remain unclear. In this study, we determined the consequences of HS intake alone compared with chronic ANG II infusion and combined HS plus ANG II on the stimulation of urinary AGT (uAGT), renal oxidative stress, and renal injury markers. Sprague-Dawley rats were subjected to 1) a normal-salt diet [NS, n = 5]; 2) HS diet [8% NaCl, n = 5]; 3) ANG II infusion in NS rats [ANG II 80 ng/min, n = 5]; 4) ANG II infusion in HS rats [ANG II+HS, n = 5]; and 5) ANG II infusion in HS rats treated with ANG II type 1 receptor blocker (ARB) [ANG II+HS+ARB, n = 5] for 14 days. Rats fed a HS diet alone did not show changes in systolic blood pressure (SBP), proteinuria, cell proliferation, or uAGT excretion although they did exhibit mesangial expansion, collagen deposition, and had increased NADPH oxidase activity accompanied by increased peroxynitrite formation in the kidneys. Compared with ANG II rats, the combination of ANG II infusion and a HS diet led to exacerbation in SBP (175 ± 10 vs. 221 ± 8 mmHg; P < 0.05), proteinuria (46 ± 7 vs. 127 ± 7 mg/day; P < 0.05), and uAGT (1,109 ± 70 vs.. 7,200 ± 614 ng/day; P < 0.05) associated with greater collagen deposition, mesangial expansion, interstitial cell proliferation, and macrophage infiltration. In both ANG II groups, the O2− levels were increased due to increased NADPH oxidase activity without concomitant increases in peroxynitrite formation. The responses in ANG II rats were prevented or ameliorated by ARB treatment. The results indicate that HS independently stimulates ROS formation, which may synergize with the effect of ANG II to limit peroxynitrite formation, leading to exacerbation of uAGT and greater injury during ANG II salt hypertension.


2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Emőke Šteňová ◽  
Martina Bakošová ◽  
Lucia Lauková ◽  
Peter Celec ◽  
Barbora Vlková

Rheumatoid arthritis (RA) as a chronic inflammatory disease is associated with oxidative stress. Drugs targeting tumor necrosis factor-alpha (TNF-α) ameliorate inflammation and symptoms of RA in most patients. Whether markers of oxidative stress can be used for monitoring of treatment effects is unknown. The aim of our study was to analyze the effects of anti-TNF-α treatment on oxidative stress in plasma and saliva of patients with RA. Samples were collected from 26 patients with RA at baseline as well as 3 and 6 months after starting the anti-TNF-α treatment. Thiobarbituric acid-reacting substances (TBARS), advanced oxidation protein products (AOPP), advanced glycation end products (AGEs), and fructosamine were quantified using spectrophotometry and spectrofluorometry in plasma. TBARS were measured also in saliva. The disease activity score (DAS28) was used to assess the clinical status of patients. No significant dynamic changes were found except plasma TBARS that decreased continuously. At 6 months after starting the treatment, plasma TBARS were lower by 39% in comparison to baseline ( p = 0.006 ). Salivary concentrations of TBARS did not reflect the dynamics in plasma. Although a trend was observed ( r = 0.33 ), a significant correlation between plasma TBARS and DAS28 was not found. Our results indicate that anti-TNF-α treatment decreases plasma TBARS as a marker of lipid peroxidation. However, the lack of a significant correlation with DAS28 suggests that it cannot be used for monitoring of treatment. Other markers of oxidative stress and antioxidant capacity with lower biological variability should be tested in future studies.


1995 ◽  
Vol 79 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Z. Radak ◽  
K. Asano ◽  
M. Inoue ◽  
T. Kizaki ◽  
S. Oh-Ishi ◽  
...  

A superoxide dismutase derivative (SM-SOD) that circulates and is bound to albumin with a half-life of 6 h was injected intraperitoneally into rats before exhaustive treadmill running to study its antioxidant scavenging capacity in the plasma and soleus and tibialis muscles. The exercise induced a marked increase in xanthine oxidase activity in plasma and an increase in thiobarbituric acid-reactive substances in the plasma as well as in the soleus and tibialis muscles of nonadministered rats immediately after the exercise. The immunoreactive content and activity of both SOD isoenzymes (Cu,Zn-SOD and Mn-SOD) of the nonadministered rats increased in the soleus and tibialis muscles immediately after running. SM-SOD treatment definitely attenuated the degree of the increase in thiobarbituric acid-reactive substances and xanthine oxidase in all samples examined immediately after exercise. Glutathione peroxidase activity significantly increased in the soleus muscle of nonadministered rats 1 day after running, whereas catalase activity remained unchanged throughout the experimental period. These results suggest that a single bout of exhaustive exercise induces oxidative stress in skeletal muscle of rats and that this oxidative stress can be attenuated by exogenous SM-SOD.


Sign in / Sign up

Export Citation Format

Share Document