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.

Pharmacological characterisation of the mechanisms underlying the relaxant effect of adrenomedullin in the rat carotid artery.

OBJECTIVES: We investigated the mechanisms underlying the relaxant effect of adrenomedullin (AM) in the rat carotid artery and verified the expression of AM system components in this tissue. METHODS: The carotid artery was isolated from male Wistar rats and immunohistochemical, Western immunoblotting, real-time polymerase chain reaction and functional assays were conducted. KEY FINDINGS: Protein and mRNA expression of AM, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP)1, 2, 3 were detected in carotid segments from male Wistar rats. Immunohistochemical assays showed that AM and CRLR receptors are expressed in the endothelium and smooth muscle cells. Functional assays showed that AM concentration dependently relaxed carotid rings with intact endothelium. Endothelial removal reduced, but not abolished, the relaxation induced by AM. AM22-52 (selective antagonist for AM receptors) and calcitonin gene-related peptide (CGRP)8-37 (selective CGRP receptor antagonist) reduced AM-induced relaxation in endothelium-intact rings. Pre-incubation of endothelium-intact rings with N-nitro-L-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or Rp-8-Bromo-?-phenyl-1,N2-ethenoguanosine 3',5'cyclic monophosphorothioate reduced AM-induced relaxation. Inhibition of cyclooxygenase-1 and protein kinase A (PKA) reduced AM-induced relaxation. The relaxation induced by AM was attenuated by the K(+) channel blockers apamin and glibenclamide. AM increased nitrate levels and 6-keto-prostaglandin F1α (stable product of prostacyclin) in the rat carotid. In endothelium-denuded rings, AM22-52 , glibenclamide and PKA inhibition by H89 reduced AM-induced relaxation. CONCLUSIONS: The novelty of this work is that it first demonstrated functionally that AM-induced relaxation is mediated by AM and CGRP receptors located on the endothelium and AM receptors located on smooth muscle of rat carotid arteries. AM-induced relaxation involves the nitric oxide-cGMP pathway, a vasodilator prostanoid, the opening of K(+) channels and the activation of PKA.

Effects of elevated perfusion pressure and pulsatile flow on human saphenous veins isolated from diabetic and non-diabetic patients.

OBJECTIVE: This study was carried out to determine high pressure and pulsatile flow perfusion effects on human saphenous vein (HSV) segments obtained from diabetic and non-diabetic patients. METHODS: The veins were perfused with oxygenated Krebs solution for 3 h, with a pulsatile flow rate of 100 mL/min and pressures of 250 × 200 or 300 × 250 mmHg. After perfusion, veins were studied by light microscopy; nitric oxide synthase (NOS) isoforms, CD34 and nitrotyrosine immunohistochemistry and tissue nitrite/nitrate (NO(x)) and malondialdehyde (MDA) quantification. RESULTS: Light microscopy revealed endothelial denuding areas in all HSV segments subjected to 300 × 250 mmHg perfusion pressure, but the luminal area was similar. The percentage of luminal perimeter covered by endothelium decreased as perfusion pressures increased, and significant differences were observed between groups. The endothelial nitric oxide synthase (eNOS) isoform immunostaining decreased significantly in diabetic patients' veins independent of the perfusion pressure levels. The inducible NOS (iNOS), neuronal NOS (nNOS) and nitrotyrosine immunostaining were similar. Significant CD34 differences were observed between the diabetic 300 × 250 mmHg perfusion pressure group and the non-diabetic control group. Tissue nitrite/nitrate and MDA were not different among groups. CONCLUSIONS: Pulsatile flow and elevated pressures for 3 h caused morphological changes and decreased the eNOS expression in the diabetic patients' veins.

Ethanol consumption increases the expression of endothelial nitric oxide synthase, inducible nitric oxide synthase and metalloproteinases in the rat kidney.

OBJECTIVES: The effects of longterm ethanol consumption on the levels of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS) and metalloproteinase-2 (MMP-2) were studied in rat kidney. METHODS: Male Wistar rats were treated with 20% ethanol (v/v) for 6 weeks. Nitrite and nitrate generation was measured by chemiluminescence. Protein and mRNA levels of eNOS and iNOS were assessed by immunohistochemistry and quantitative real-time polymerase chain reaction, respectively. MMP-2 activity was determined by gelatin zymography. Histopathological changes in kidneys and indices of renal function (creatinine and urea) and tissue injury (mitochondrial respiration) were also investigated. RESULTS: Chronic ethanol consumption did not alter malondialdehyde levels in the kidney. Ethanol consumption induced a significant increase in renal nitrite and nitrate levels. Treatment with ethanol increased mRNA expression of both eNOS and iNOS. Immunohistochemical assays showed increased immunostaining for eNOS and iNOS after treatment with ethanol. Kidneys from ethanol-treated rats showed increased activity of MMP-2. Histopathological investigation of kidneys from ethanol-treated animals revealed tubular necrosis. Indices of renal function and tissue injury were not altered in ethanol-treated rats. CONCLUSIONS: Ethanol consumption increased renal metalloproteinase expression/activity, which was accompanied by histopathological changes in the kidney and elevated NO generation. Since iNOS-derived NO and MMPs contribute to progressive renal injury, the increased levels of NO and MMPs observed in ethanol-treated rats might contribute to progressive renal damage.

Chronic ethanol consumption induces histopathological changes and increases nitric oxide generation in the rat liver.

In the present work we evaluated the effect of ethanol consumption in histopathological liver changes and several biochemical biomarkers employed in the detection of hepatic dysfunction. Male Wistar rats were treated with ethanol 20% (vol/vol) for 6 weeks. Histopathological investigation of livers from ethanol-treated animals revealed steatosis. Indices of hepatic function (transaminases) and mitochondrial respiration were not altered in ethanol-treated rats. Chronic ethanol consumption did not alter malondialdehyde (MDA) levels in the liver. Ethanol consumption induced a significant increase on hepatic nitrite and nitrate levels. Treatment with ethanol increased both mRNA expression and immunostaining of iNOS, but not eNOS. Finally, ethanol consumption did not alter hepatic levels of metalloproteinase (MMP)-2 and MMP-9. We conclude that alterations on biochemical biomarkers (nitrite and nitrate levels) and histopathology occurred in ethanol-treated rats, supporting the practice of including both types of evaluation in toxicity studies to detect potential ethanol-related hepatic effects. In our model of ethanol consumption, histopathological liver changes were accompanied by elevation in nitrite and nitrate levels indicating increased nitric oxide (NO) generation. Since iNOS-derived NO contributes to hepatic injury, the increased levels of NO described in our study might contribute to a progressive hepatic damage. Therefore, increases in NO generation may be an early indicator of ethanol-induced liver damage.

Chronic alcoholism associated with diabetes impairs erectile function in rats.

OBJECTIVE: To investigate the effects of chronic ethanol consumption and diabetes on nitric oxide (NO)-mediated relaxation of cavernosal smooth muscle (CSM). MATERIAL AND METHODS: Male Wistar rats were divided into four groups: control, isocaloric, diabetic and ethanol-diabetic. The CSMs were mounted in organ chambers for measurement of isometric tension. Contraction of the strips was induced by electrical field stimulation (EFS, 1-32 Hz) and phenylephrine. We also evaluated the effect of ethanol consumption on the relaxation induced by acetylcholine (ACh; 0.01-1000 micromol/L), sodium nitroprusside (SNP, 0.01-1000 micromol/L) or EFS (1-32 Hz) in strips pre-contracted with phenylephrine (10 micromol/L). Immunoexpression of endothelial NO synthase (eNOS) and inducible NOS (iNOS) was also accessed. RESULTS: The endothelium-dependent relaxation induced by ACh was decreased in CSM from ethanol-diabetic rats when compared with the controls, with a mean (sem) of 21 (4) vs 37 (2)%. Similarly, the potency and maximal responses induced by SNP were reduced in the ethanol-diabetic [3.97 (0.38) and 85 (1)%, respectively] and diabetic groups [3.78 (0.56) and 81 (2)%, respectively] when compared with the controls [5.3 (0.22) and 90 (3)%, respectively] and isocaloric [5.3 (0.19) and 92 (1)%, respectively] groups. Noradrenergic nerve-mediated contractions of CSM in response to EFS were increased in rats from ethanol-diabetic and diabetic groups when compared with the control and isocaloric groups. Conversely, there were no differences in EFS-induced relaxation among the groups. The immunostaining assays showed overexpression of eNOS and iNOS in the CSM from diabetic and ethanol-diabetic rats when compared with the control and isocaloric rats. CONCLUSION: There was an impairment of relaxation of CSM from ethanol-diabetic and diabetic rats that involved a decrease in the NO-cyclic guanosine monophosphate signalling pathway by endothelium-dependent mechanisms accompanied by a change in the CSM contractile sensitivity.

Mechanisms underlying the vascular actions of endothelin 1, angiotensin II and bradykinin in the rat carotid.

The carotid artery has a pivotal role in the body since it supplies the head and neck with oxygenated blood. Alterations in the functional and structural integrity of these vessels can decrease blood flow to the brain. For this reason, it is important to understand how the carotid artery responds to various stimuli. The organ bath is a traditional experimental set-up that has been used extensively to investigate the (patho)physiology and pharmacology of in vitro tissue preparations including the rat carotid artery. Molecular biology developed from related fields such as biochemistry, genetics and biophysics is now considered an important tool for understanding physiological pathways in a variety of tissues. Several local and systemic factors regulate carotid reactivity, including vaso-active peptides, such as endothelin 1 (ET-1), angiotensin II (Ang II) and bradykinin (BK). These vaso-active peptides play a fundamental role in controlling the functional and structural integrity of the arterial wall and may be important in physiological processes and in pathological mechanisms underlying vascular diseases. In the rat carotid, these peptides induce vasoconstriction or relaxation by the release of endothelium-derived relaxing factors, such as nitric oxide and prostacyclin. Identification of such signal transduction processes is essential for understanding the mechanisms that regulate vascular smooth muscle cell function, both physiologically and pathophysiologically. The present review discusses the mechanisms of action, distribution of ET-1, Ang II and BK and their receptors in the rat carotid. With this purpose, data obtained in functional studies using classical pharmacological approaches as well as data obtained in molecular biology experiments are discussed.

Chronic ethanol consumption induces cavernosal smooth muscle dysfunction in rats.

OBJECTIVES: To investigate the effects of chronic ethanol consumption on nitric oxide (NO)-mediated relaxation in rat cavernosal smooth muscle (CSM). METHODS: Male wistar rats were divided into 2 groups: control and ethanol. CSM obtained from both groups were mounted in organ chambers for measurement of isometric tension. Contraction of the strips was induced by electrical field stimulation (EFS, 1-32 Hertz) and phenylephrine. We also evaluated the effect of ethanol consumption on the relaxation induced by acetylcholine (0.01-1000 micromol L(-1)), sodium nitroprusside (SNP, 0.01-1000 micromol L(-1)), or EFS (1-32 Hz) in strips precontracted with phenylephrine (10 micromol L(-1)). Blood ethanol, serum testosterone levels, and basal nitrate generation were determined. Immunoexpression of endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) was also accessed. RESULTS: Ethanol intake for 4 weeks significantly increased noradrenergic nerve-mediated contractions of CSM in response to EFS. The endothelium-dependent relaxation induced by acetylcholine decreased after the ethanol treatment. Ethanol consumption decreased serum testosterone levels but did not affect the nitrate levels on rat CSM. The mRNA and protein levels for eNOS and iNOS receptors were increased in CSM from ethanol-treated rats. CONCLUSIONS: Ethanol consumption reduces endothelium-dependent relaxation induced by acetylcholine, but does not affect SNP or EFS-induced relaxation, suggesting that ethanol disrupts the endothelial function. Despite the overexpression of eNOS and iNOS in ethanol-treated rats, the impaired relaxation induced by acetylcholine may suggest that chronic ethanol consumption induces endothelial dysfunction.

Results of novel strategies for treatment of Wilms' tumor.

OBJECTIVE: To evaluate treatment outcomes in Wilms' tumor (WT). MATERIALS AND METHODS: We studied 53 children with median age of 2 years with WT, stages I-19, II-14, III-12, IV-6 and V-2. Treatment consisted of surgical excision plus adjuvant (40 children) or neoadjuvant and adjuvant chemotherapy (unresectable tumor, n=8, or caval tumor extension, n=5). Chemotherapy and radiotherapy followed protocols of Brazilian Wilms' Tumor Study Group excepting 16 cases with stage I disease that received a short duration postoperative treatment with vincristine (VCR - 11 doses) and dactinomycin (AMD - 4 doses). Relapsed WT was treated with multiagent regimens including cisplatin/carboplatin, cyclophosphamide, ifosfamide and etoposide. One patient with resistant relapsed WT was treated by high-dose conditioning chemotherapy with stem cell rescue. RESULTS: Overall and disease-free survival rates at 5 years were respectively 88.2 +/- 5.0% and 76.7 +/- 6.6%. Short duration therapy for stage I tumor showed a disease-free survival rate of 100% in a median time of 101 months (range 14 to 248 months). Overall and disease-free survival of 10 patients with recurrent WT at 5 years was 42.8%. The child treated with high-dose chemotherapy plus stem cell transplant is alive without evidence of disease 84 months from relapse. CONCLUSION: The postoperative chemotherapy in stage I disease can be reduced without compromising the cure rate. The treatment of unfavorable stage III and IV disease or relapsed tumor remains a challenge.

Results of novel strategies for treatment of Wilms' tumor

OBJECTIVE: To evaluate treatment outcomes in Wilms' tumor (WT). MATERIALS AND METHODS: We studied 53 children with median age of 2 years with WT, stages I-19, II-14, III-12, IV-6 and V-2. Treatment consisted of surgical excision plus adjuvant (40 children) or neoadjuvant and adjuvant chemotherapy (unresectable tumor, n = 8, or caval tumor extension, n = 5). Chemotherapy and radiotherapy followed protocols of Brazilian Wilms' Tumor Study Group excepting 16 cases with stage I disease that received a short duration postoperative treatment with vincristine (VCR - 11 doses) and dactinomycin (AMD - 4 doses). Relapsed WT was treated with multiagent regimens including cisplatin/carboplatin, cyclophosphamide, ifosfamide and etoposide. One patient with resistant relapsed WT was treated by high-dose conditioning chemotherapy with stem cell rescue. RESULTS: Overall and disease-free survival rates at 5 years were respectively 88.2 ± 5.0 percent and 76.7 ± 6.6 percent. Short duration therapy for stage I tumor showed a disease-free survival rate of 100 percent in a median time of 101 months (range 14 to 248 months). Overall and disease-free survival of 10 patients with recurrent WT at 5 years was 42.8 percent. The child treated with high-dose chemotherapy plus stem cell transplant is alive without evidence of disease 84 months from relapse. CONCLUSION: The postoperative chemotherapy in stage I disease can be reduced without compromising the cure rate. The treatment of unfavorable stage III and IV disease or relapsed tumor remains a challenge.