Nebivolol Prevents Up-Regulation of Nox2/NADPH Oxidase and Lipoperoxidation in the Early Stages of Ethanol-Induced Cardiac Toxicity.

Changes in redox state are described in the early stages of ethanol-induced cardiac toxicity. Here, we evaluated whether nebivolol would abrogate ethanol-induced redox imbalance in the heart. Male Wistar rats were treated with a solution of ethanol (20% v/v) for 3 weeks. Treatment with nebivolol (10 mg/kg/day; p.o. gavage) prevented the increase of both superoxide (O2•-) and thiobarbituric acid reactive substances (TBARS) in the left ventricle of rats chronically treated with ethanol. Neither ethanol nor nebivolol affected the expression of Nox4, p47phox, or Rac-1. Nebivolol prevented ethanol-induced increase of Nox2 expression in the left ventricle. Superoxide dismutase (SOD) activity as well as the concentration of reduced glutathione (GSH) was not altered by ethanol or nebivolol. Augmented catalase activity was detected in the left ventricle of both ethanol- and nebivolol-treated rats. Treatment with nebivolol, but not ethanol increased eNOS expression in the left ventricle. No changes in the activity of matrix metalloproteinase (MMP)2 or in the expressions of MMP2, MMP9, and tissue inhibitor metalloproteinase (TIMP)1 were detected after treatment with ethanol or nebivolol. However, ethanol increased the expression of TIMP2, and this response was prevented by nebivolol. Our results provided novel insights into the mechanisms underlying the early stages of the cardiac injury induced by ethanol consumption. We demonstrated that Nox2/NADPH oxidase-derived ROS play a role in ethanol-induced lipoperoxidation and that this response was prevented by nebivolol. In addition, we provided evidence that MMPs are not activated in the early stages of ethanol-induced cardiac toxicity.

Treatment with nitrite prevents reactive oxygen species generation in the corpora cavernosa and restores intracavernosal pressure in hypertensive rats.

Hypertension is a risk factor for erectile dysfunction (ED) and both conditions are associated with oxidative stress. Given that nitrite is described to display antioxidant effects, we hypothesized that treatment with nitrite would exert antioxidant effects attenuating both reactive oxygen species (ROS) generation in the corpora cavernosa (CC) and ED induced by hypertension. Two kidney, one clip (2K1C) hypertension was induced in male Wistar rats. Treatment with sodium nitrite (15 mg/kg/day, p.o., gavage) was initiated two weeks after surgery to induce hypertension and maintained for four weeks. Nitrite abrogated both the decrease in intracavernosal pressure and endothelial dysfunction of the CC induced by hypertension. Treatment with nitrite decreased hypertension-induced ROS generation in the CC assessed in situ using the fluorescent dye dihidroethidium (DHE) and with the lucigenin assay. Western immunoblotting analysis revealed that nitrite prevented the increase in Nox1 expression in the CC from 2K1C rats. Decreased concentrations of hydrogen peroxide (H2O2) were found in the CC from hypertensive rats and treatment with nitrite prevented this response. Treatment with nitrite increased the fluorescence of DAF-2DA in the CC from sham-operated rats and restored nitric oxide (NO) levels in the CC from 2K1C rats. In summary, we found novel evidence that nitrite reversed the decrease in intracavernosal pressure induced by 2K1C hypertension. This response was partially attributed to the antioxidant effect of nitrite that blunted ROS generation and endothelial dysfunction in the CC. In addition, nitrite-derived NO may have promoted direct protective actions against hypertension-induced CC dysfunction.

Perivascular adipose tissue contributes to lethal sepsis-induced vasoplegia in rats.

It is well established that sepsis induces vascular hyporesponsiveness to vasoconstrictors. Perivascular adipose tissue (PVAT) displays anti-contractile action in various blood vessels. We hypothesized that sepsis would increase the anti-contractile effect of PVAT aggravating sepsis-induced vasoplegia. Male Wistar Hannover rats were subjected to lethal sepsis by cecal ligation and puncture (CLP) method. Aorta or PVAT were collected for functional or biochemical assays 6 h after CLP surgery. Functional experiments showed that sepsis increased the anti-contractile action of PVAT in both endothelium-intact and endothelium-denuded aortas. Carboxy-PTIO, L-NAME and ODQ reversed the hypocontractility mediated by PVAT in aortas from septic rats. Inhibition of nNOS and iNOS with 7-nitroindazole and 1400 W attenuated PVAT-mediated hypocontractility during sepsis. Similar results were found in the presence of indomethacin and Ro1138452, a selective prostacyclin IP receptor antagonist. However, neither tiron nor catalase affected phenylephrine-induced contraction in aortas from septic rats. Increased levels of superoxide anion (O2•-) and 6-keto-prostaglandin F1α (stable product of prostacyclin) were detected in PVAT from septic rats. In situ quantification of reactive oxygen species and nitric oxide (NO) using fluorescent dyes revealed increased levels of both in PVAT from septic rats. The novelty of our study is that PVAT contributes to sepsis-induced vasoplegia by releasing NO and prostacyclin. These findings suggested that signaling pathways in PVAT may be considered as potential novel pharmacological therapeutic targets during sepsis-induced vasoplegia.

Chronic ethanol consumption induces micturition dysfunction and alters the oxidative state of the urinary bladder.

Oxidative stress is pointed out as a major mechanism by which ethanol induces functional and structural changes in distinctive tissues. We evaluated whether ethanol consumption would increase oxidative stress and cause micturition dysfunction. Male C57BL/6J mice were treated with 20% ethanol (v/v) for 10 weeks. Our findings showed that chronic ethanol consumption reduced micturition spots and urinary volume in conscious mice, whereas in anaesthetized animals cystometric analysis revealed reduced basal pressure and increased capacity, threshold pressure, and maximum voiding. Treatment with ethanol reduced the contraction induced by carbachol in isolated bladders. Chronic ethanol consumption increased the levels of oxidant molecules and thiobarbituric acid reactive species in the mouse bladder. Upregulation of Nox2 was detected in the bladder of ethanol-treated mice. Increased activity of both superoxide dismutase and catalase were detected in the mouse bladder after treatment with ethanol. Conversely, decreased levels of reduced glutathione were detected in the bladder of ethanol-treated mice. The present study first demonstrated that chronic ethanol consumption induced micturition dysfunction and that this response was accompanied by increased levels of oxidant molecules in the mousebladder. These findings suggest that ethanol consumption is a risk factor for vesical dysfunction.

Chronic ethanol consumption increases reactive oxygen species generation and the synthesis of pro-inflammatory proteins in the heart through TNFR1-dependent mechanisms.

We evaluated the role of tumor necrosis factor (TNF)-α receptor 1 (TNFR1) on ethanol-induced cardiac dysfunction. Male C57BL/6J wild-type (WT) or TNFR1-deficient mice (TNFR1-/-) were treated with ethanol (20% v/v) for 10 weeks. Increased protein expression of TNFR1 and NFκB p65 was detected in the left ventricle (LV) of WT mice chronically treated with ethanol. Echocardiographic analysis showed that ethanol consumption increased left ventricular posterior wall end-diastolic diameter and left ventricular posterior wall end-systolic diameter in WT, but not TNFR1-/- mice. Increased levels of TNF-α, interleukin (IL)-6, superoxide anion (O2-), thiobarbituric acid reactive substances (TBARS) as well as increased nitrotyrosine immunostaining were detected in the LV from WT, but not TNFR1-/- mice. Conversely, treatment with ethanol decreased nitrate/nitrite (NOx) concentration in the LV. Histopathological analysis showed that ethanol did not induce inflammatory infiltrates, necrosis or edema in the LV. No differences in the ventricular expression of iNOS, Nox2 or COX-2 as well as in the activity of superoxide dismutase (SOD), myeloperoxidase (MPO) and N-acetyl-beta-D-glucosaminidase (NAG) were found after treatment with ethanol. Our study provided novel evidence that ethanol consumption augmented the production of reactive oxygen species (ROS) and the synthesis of pro-inflammatory proteins in the LV through TNFR1-dependent mechanisms. These findings provided novel mechanistic insights about the contribution of TNFR1 in the initial steps of the cardiac damage induced by ethanol.

Tumor necrosis factor-α receptor 1 contributes to ethanol-induced vascular reactive oxygen species generation and hypertension.

We evaluated the contribution of tumor necrosis factor-α receptor 1 (TNFR1) to ethanol-induced hypertension and vascular oxidative stress and the possible role of perivascular adipose tissue (PVAT) in such responses. Male C57BL/6 wild-type (WT) or TNFR1-deficient mice (TNFR1-/-) were treated with ethanol (20% vol/vol) for 12 weeks. Ethanol induced an increase in blood pressure in WT mice and TNFR1-/- at 4 and 5 weeks of treatment, respectively. Treatment with ethanol increased tumor necrosis factor-α and interleukin-6 levels in aortas with or without PVAT (PVAT+ and PVAT-, respectively) from WT mice, but not TNFR1-/-. Ethanol increased superoxide anion (O2-) generation, thiobarbituric acid reactive substance concentration, and the activity of superoxide dismutase and catalase in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1-/-. Conversely, ethanol consumption decreased the concentration of nitrate/nitrite in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1-/-. Treatment with ethanol increased myeloperoxidase activity in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1-/-. The major finding of our study is that TNFR1 contributes to ethanol-induced hypertension and oxidative stress in the vasculature. Additionally, TNFR1 plays a role in ethanol-induced increase in proinflammatory cytokines and neutrophils migration. However, PVAT does not counteract or aggravate the effects induced by ethanol.

Reactive oxygen species derived from NAD(P)H oxidase play a role on ethanol-induced hypertension and endothelial dysfunction in rat resistance arteries.

Chronic ethanol consumption is a risk factor for cardiovascular diseases. We studied whether NAD(P)H oxidase-derived reactive oxygen species (ROS) play a role in ethanol-induced hypertension, vascular dysfunction, and protein expression in resistance arteries. Male Wistar rats were treated with ethanol (20 % v/v) for 6 weeks. Ethanol treatment increased blood pressure and decreased acetylcholine-induced relaxation in the rat mesenteric arterial bed (MAB). These responses were attenuated by apocynin (30 mg/kg/day; p.o. gavage). Ethanol consumption increased superoxide anion (O2-) generation and decreased nitrate/nitrite (NO x ) concentration in the rat MAB and apocynin prevented these responses. Conversely, ethanol did not affect the concentration of hydrogen peroxide (H2O2) and reduced glutathione (GSH) or the activity of superoxide dismutase (SOD) and catalase (CAT) in the rat MAB. Ethanol increased interleukin (IL)-10 levels in the rat MAB but did not affect the levels of tumor necrosis factor (TNF)-α, IL-6, or IL-1ß. Ethanol increased the expression of Nox2 and the phosphorylation of SAPK/JNK, but reduced eNOS expression in the rat MAB. Apocynin prevented these responses. However, ethanol treatment did not affect the expression of Nox1, Nox4, p38MAPK, ERK1/2, or SAPK/JNK in the rat MAB. Ethanol increased plasma levels of TBARS, TNF-α, IL-6, IL-1ß, and IL-10, whereas it decreased NO x levels. The major finding of our study is that NAD(P)H oxidase-derived ROS play a role on ethanol-induced hypertension and endothelial dysfunction in resistance arteries. Moreover, ethanol consumption affects the expression and phosphorylation of proteins that regulate vascular function and NAD(P)H oxidase-derived ROS play a role in such responses.