Suppression of inducible nitric oxide synthase and tumor necrosis factor-alpha level by lycopene is comparable to methylprednisolone in acute pancreatitis

BackgroundOxidative stress and inflammation may play a key role in the pathogenesis of acute pancreatitis (AP). Lycopene, a natural carotenoid, has antioxidant scavenger capacity and inhibits inflammation in many experimental models.AimThe study was designed to investigate whether lycopene can ameliorate l-arginine-induced pancreatitis in rats and to elucidate the underlying molecular mechanisms of these effects.MethodsForty-eight adult male Wistar rats were divided into: control group (vehicle, orally, 10 days), AP group (3 g/kg l-arginine, single i.p. injection, on day 10th of the experiment), lycopene group (50 mg/kg) and methylprednisolone group (30 mg/kg). Lycopene and methylprednisolone were given orally, once daily for 10 days prior to l-arginine injection. Rats were sacrificed 24 h after l-arginine injection. Inflammation/oxidative stress and pancreatic markers were assessed. Pancreatic histopathological studies were done.ResultsLycopene group showed a significant reduction in tumor necrosis factor alpha (TNF-α), myeloperoxidase activity, and down-regulation of inducible nitric oxide synthase (iNOS) gene expression. Pancreatic nitric oxide concentration was reduced and pancreatic GSH was increased in lycopene group. Serum α-amylase and lipase activities were reduced by lycopene treatment. The histology of pancreas was improved in lycopene group as well as methylprednisolone group.ConclusionLycopene prior treatment proved anti-inflammatory and antioxidant effects against AP rat model via different mechanisms.     

Nitric oxide synthase inhibitor increases hepatic injury with formation of oxidative DNA damage and microcirculatory disturbance in endotoxemic rats

BACKGROUND/AIMS: Nitric oxide plays important roles in the pathogenesis of endotoxin shock and multiple organ failure. Nitric oxide synthase inhibitors are used in patients to improve hemodynamics in endotoxin shock. However, the role of nitric oxide is controversial in hepatic injury with oxidative DNA damage in endotoxemia. This report investigated the role of nitric oxide on hepatic blood flow and liver injury in endotoxemic rats. METHODOLOGY: Under light ether anesthesia, male Wistar rats were given lipopolysaccharide (10 mg/kg) intravenously. Several hours (0-24 hr) later, the animals were used for experiments. In some experiments, NG-[1-iminoethyl]-L-ornithine, a potent inhibitor of nitric oxide synthase, was administered 5 mg/kg intraperitoneally every 3 hour after lipopolysaccharide injection. Hemodynamic changes, biochemical and histological analysis were determined. RESULTS: Lipopolysaccharide increased the activity of inducible nitric oxide synthase in the liver, lungs and spleen. Significant amounts of nitric oxide-hemoglobin complexes and nitrite plus nitrate appearing in the blood peaked at 8 hr after treatment. NG-[1-iminoethyl]-L-ornithine completely inhibited the generation of nitric oxide metabolites, but hardly affected formation of urinary 8-hydroxydeoxyguanosine and the systemic blood pressure in normal rats. NG-[1-iminoethyl]-L-ornithine increased 8-hydroxydeoxyguanosine formation and decreased the blood flow more in the superior mesenteric artery and hepatic microvascular blood flow in endotoxemic rats. Inhibition of nitric oxide synthase markedly caused deterioration of the lipopolysaccharide-induced liver injury indicated by hepatic enzymes and histological findings. CONCLUSIONS: These results suggested that suppresion of endogenous nitric oxide might aggravate hepatic injury, partly caused by decrease in hepatic blood flow accompanied with oxidative stress in endotoxemia.     

Diabetes Mellitus and Anal Sphincter Pressures: An Experimental Model in Rats

Purpose Symptoms of the gastrointestinal tract, frequent in patients with diabetes mellitus, which may be related to an increase in the production of free radicals, include alterations in the function of the sphincter anal musculature. Such alterations are characterized by a decrease of muscular tone associated with different degrees of fecal incontinence. This study was performed to show the alterations in the anal sphincter pressures of diabetic rats and to evaluate the role of nitric oxide and oxidative stress in this situation. Methods Male Wistar rats weighing 250 to 400 g were used. The animals were divided in two groups: control and diabetic. Diabetes was induced through intraperitoneal injection of streptozotocin and the anal pressures were gauged by anorectal manometry. Nitric oxide was evaluated through measures of nitrites and nitrates, and oxidative stress through the technique of chemoluminescence. Results There was a significant decrease in the sphincter anal pressure of diabetic animals 60 days after induction (P < 0.05). This pressure returned to basal values after administration of a nitric oxide synthase antagonist. The levels of nitrites and nitrates as well as of lipoperoxidation were significantly increased in the diabetic compared with the control group (P < 0.05). Conclusions In this study, hyperglycemia of diabetes mellitus caused an increase in the oxidative stress. Apparently the elevation of nitric oxide levels was one of the responsible factors for the decrease of anal sphincter pressures.     

吡咯列酮对雨蛙肽诱导急性胰腺炎氧化应激过程的作用

目的 探讨过氧化物酶体增殖物激活受体(PPAR)γ激动剂吡咯列酮在雨蛙肽诱导大鼠急性胰腺炎中对氧化应激产物的影响及保护作用.方法 30只雄性SD大鼠随机分为对照组、雨蛙肽+不同剂量吡咯列酮组、雨蛙肽组、雨蛙肽+吡咯列酮+GW9662组.每组6只.急性胰腺炎造模30 min后处死大鼠,光镜下观察胰腺组织病理学变化,测定各组大鼠胰腺组织质量与体重比,比色法检测胰腺组织髓过氧化物酶(MPO)活性、丙二醛(MDA)和一氧化氮合酶(NOS)及组织诱导型一氧化氮合酶(iNOS)含量.结果 与对照组比较,雨蛙肽组胰腺组织水肿严重胰腺净重/体重(0.0072比0.0042)],MPO活性、MDA、NOS及iNOS含量升高(P＜0.01).与雨蛙肽组比较,吡咯列酮20 mg/kg及40 mg/kg组胰腺损伤减轻,胰腺净重/体重、MPO活性、MDA和NOS及iNOS含量降低(P＜0.05);与吡咯列酮40 mg/kg组比较,PPARγ拮抗剂GW9662逆转了吡咯列酮的保护作用(P＜0.05).结论 在雨蛙肽诱导的大鼠急性胰腺炎发病中,胰腺腺泡细胞的氧化应激损伤起了重要的作用,PPARγ激动剂吡咯列酮预先干预,通过降低氧化应激过程,对雨蛙肽诱导的大鼠急性胰腺炎有一定的保护作用.     

Chronic Ingestion of a Potential Food Contaminant Induces Gastrointestinal Inflammation in Rats

Chronic ingestion of xenobiotics could be pathogenic in the gastrointestinal tract. Recently, we showed that acute low administration of a food contaminant (diquat) induced intestinal secretion involving mast cells and nitric oxide. This work aimed to determine in rats: (1) the influence of a low level (0.1 mg/kg/day per os) chronic ingestion of diquat on gastrointestinal immune cells, and (2) the participation of nitric oxide synthases (NOS) in these effects. Diquat increased both gastric and jejunal myeloperoxidase activities, tissue histamine in vitro release after stimulation by 48/80, and mast cell numbers. Diquat did not alter gastric NOS but increased intestinal inducible NOS (iNOS) activity. l-NAME prevented diquat-induced gastric and intestinal mastocytosis and gastric but not intestinal inflammation. l-NAME reduced gastric constitutive NOS (cNOS) activity and reestablished control iNOS activity. Chronic low level ingestion of diquat induces a low-grade gastric and intestinal inflammation with mastocytosis and enhancement of intestinal iNOS activity.     

Effects of Mast-Cell Stabilization in Cerulein-Induced Acute Pancreatitis in Rats

Summary Aim. In this study we aimed to clarify the role of mast cells in the development and progression of inflammation in cerulein-induced acute pancreatitis (AP) in rats. We have also examined the effects of ketotifen; a mast-cell stabilizing agent in the treatment of acute pancreatitis and its relation with nitric oxide (NO) synthesis. Methods. In the first part of the study we planned to examine the effects mast cell stabilization in acute pancreatitis, while the second part was focused on examining the relation between NO synthesis and the potential effects of ketotifen in AP. Wistar albino rats were randomly divided into 6 groups (n: 10). In the first part of the study, AP was induced by four subcutaneous (sc) injections of 20 μg/kg body weight of cerulein at hourly intervals in Groups A and B while Group C was treated with saline as the control group. Group B was pretreated with ketotifen 1 mg/kg (ip). In the second part, the study design was similar except for the inhibition of nitric oxide synthesis by N-nitro L-arginine methyl ester (L-NAME) 30 mg/kg (ip) in Groups D, E and F. Group D was treated with L-NAME and cerulein and Group E was treated with ketotifen, L-NAME and cerulein. Group F was treated with L-NAME and saline as the control group. Serum amylase activity and pancreatic myeloperoxidase activity (MPO) were measured. Pancreatic histology and mast-cell count in pancreatic tissue were evaluated. Results. Mast cell count was found to be increased in the pancreatic tissue in cerulein-induced AP. (2.93±0.26 vs 1.98±0.26; p<0.001). Ketotifen treatment significantly reduced cerulein induced edema (1.30±0.21 vs 0.70±0.15; p<0.001), neutrophil infiltration (1.50±0.16 vs 0.60±0.16; p<0.001) and attenuated the increase in amylase (4394.0±149.5 U/L vs 3350.5±216.9 U/L; p<0.05) and MPO activity (1.14±0.13 U/gr tissue vs 0.54±0.08 U/gr tissue; p<0.001). Mast-cell count in pancreatic tissue was also decreased significantly with ketotifen pretreatment (2.93±0.26 vs 1.70±0.21; p<0.05). Inhibition of NO synthesis with L-NAME treatment decreased the beneficial effects of ketotifen. Conclusion. It seems likely that mast cell activity may play an important role in the initiation and progression of acute pancreatitis. Ketotifen treatment may reduce the severity of AP in rats. The protective action of ketotifen in cerulein-induced acute pancreatitis is most probably owing to mast cell stabilization and stimulation of NO synthesis.     

Relaxin ameliorates hypertension and increases nitric oxide metabolite excretion in angiotensin II but not N(ω)-nitro-L-arginine methyl ester hypertensive rats

Previous findings suggest a potential therapeutic action of relaxin, the putative vasodilatory signal of normal pregnancy, in some forms of cardiovascular disease. However, the mechanisms underlying the beneficial effects of relaxin have not been fully elucidated. The purpose of this study was to determine whether the vasodilatory effects of relaxin are dependent on activation of NO synthase. We examined the effect of relaxin in male Sprague-Dawley rats given angiotensin II (Ang II; 200 ng/kg per minute SC by minipump), the NO synthase inhibitor N(ω)-nitro-l-arginine methyl ester (l-NAME; 1.5 mg/100 g IV followed by 150 mg/L in drinking water), or vehicle for 3 weeks. After 7 days of Ang II or l-NAME, mean arterial pressure was elevated compared with baseline. Relaxin was administered (4 μg/h, SC by minipump) for the next 2 weeks of Ang II, l-NAME, or vehicle treatment. Two-week relaxin treatment alone slightly reduced mean arterial pressure in normotensive rats. Three weeks of either Ang II or l-NAME treatment alone produced hypertension, albuminuria, mild glomerular sclerosis, reduced nitric oxide metabolite excretion, and increased oxidative stress (excretion of hydrogen peroxide and thiobarbituric acid reactive substances and renal cortex nitrotyrosine abundance). Relaxin reduced mean arterial pressure, albumin excretion, and oxidative stress markers and preserved glomerular structure and nitric oxide metabolite excretion in Ang II-treated rats; however, relaxin did not attenuate these changes in the rats treated with l-NAME. None of the treatments affected protein abundance of neuronal or endothelial NO synthase in the kidney cortex. These data suggest that the vasodilatory effects of relaxin are dependent on a functional NO synthase system and increased NO bioavailability possibly because of a reduction in oxidative stress.     

脂多糖对大鼠肺泡巨噬细胞分泌一氧化氮和氧化应激的影响

目的探讨细菌内毒素脂多糖（LPS）对SD大鼠肺泡巨噬细胞产生一氧化氮（NO）和氧化应激的影响。方法采用支气管肺泡灌洗和细胞差速贴壁的方法分离大鼠肺泡巨噬细胞（AM）,分别测定AM培养上清液NO含量、一氧化氮合酶（NOS）活性、丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性。结果在5,10,20,50mg/LLPS分别干预下,大鼠AM培养上清液NO含量、NOS活性和MDA含量均显著升高,SOD活性显著降低,并且具有浓度依赖性。结论LPS促进大鼠AM分泌NO,并诱导AM脂质过氧化损伤,这可能是内毒素诱发肺部炎症反应不易控制和急性肺损伤的机制之一。     

Pathogenic Role of Endothelial Nitric Oxide Synthase (eNOS/NOS-III) in Cerulein-Induced Rat Acute Pancreatitis

Nitric oxide (NO) is a potent pancreatic vasodilator, yet the pathogenic role of NO in acute pancreatitis remains controversial. NO is generated from L-arginine by NO synthase (NOS), classified into three isozymes: neuronal (nNOS), inducible (iNOS), and endothelial NOS (eNOS). The purpose of the present study was to investigate the role of NO/NOS isozymes in the pathogenesis of cerulein-induced acute pancreatitis in rats. Acute pancreatitis was induced in male Wistar rats by two subcutaneous injections of cerulein (20 μg/kg). N ^G-Nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) or aminoguanidine (a relatively selective iNOS inhibitor) was given orally, while tetrahydrobiopterin (BH₄), a critical cofactor for NOS, was administered intraperitoneally 30 min before the first cerulein injection. Cerulein given repeatedly twice produced acute pancreatitis, with concomitant increases in the serum amylase level, pancreas weight, myeloperoxidase activity, lipid peroxidation and microvascular permeability. Prior administration of L-NAME, but not aminoguanidine, significantly prevented these changes, in a dose-dependent manner, and this effect was antagonized by the coadministration of L-arginine, a precursor of NO. The expression of dimetric eNOS in the pancreas was markedly suppressed by cerulein injections, together with a decrease in NO production, but the response was partially but significantly reversed by the prior administration of BH₄. The increases in the serum amylase level and pancreas weight, as well as the lipid peroxidation induced by cerulein, were significantly attenuated by the administration of BH₄. L-NAME had no effect on pancreatic secretion induced by cerulein. These results suggest that the uncoupled eNOS, probably caused by the decrease in endogenous BH₄ availability, plays a deleterious role in the pathogenesis of cerulein-induced acute pancreatitis.     

Resveratrol, a Red Wine Constituent Polyphenol, Protects Gastric Tissue Against the Oxidative Stress in Cholestatic Rats

This experimental study was designed to determine the effects of resveratrol on the level of malondialdehyde (MDA), reduced glutathione (GSH), and nitric oxide (NO) in gastric tissue after bile duct ligation (BDL). Swiss albino rats were divided into three groups: Group 1, sham (n = 7); Group 2, BDL (BDL only group; n = 7); and Group 3, BDL plus resveratrol (n = 7). Animals in the resveratrol group were treated with 10 mg/kg resveratrol (i.p.) once a day throughout 28 days. In the resveratrol group, levels of MDA and NO in gastric tissue were significantly lower than in the BDL-only group (P < 0.001). The level of GSH in the resveratrol group was significantly higher than in the BDL-only group (P < 0.001). The present study demonstrates that intraperitoneal administration of resveratrol maintains antioxidant defenses and reduces oxidative gastric damage. This effect of resveratrol may be useful to preserve gastric tissue under oxidative stress due to cholestasis.     

The in vivo antioxidant effectiveness of alpha-tocopherol in oxidative stress induced by sodium nitroprusside in rat red blood cells

Reactive oxygen species avidly reacts with nitric oxide (NO) producing cytotoxic reactive nitrogen species capable of nitrating proteins and damaging other molecules which leads to the reduction of erythrocyte deformability. The aim of this investigation was to assess the importance of alpha-tocopherol (Vit-E) in the total antioxidant status of the erythrocytes in sodium nitroprusside (SNP), a nitric oxide donor, induced oxidative stress and its relation to erythrocyte deformability. Male Swiss Albino rats were used in 4 groups, comprising of 10 animals in each group. The first group was the control, and the other groups were administered SNP (10 mg/kg, i.p.), Vit-E (10 mg/kg, i.p.) + SNP, and SNP + L-NAME (10 mg/kg, i.p.), respectively. Relative filtration rate (RFR), relative filtration time (RFT) and relative resistance (Rrel) were determined as the indexes of erythrocyte deformability. In addition, malondialdehyde (MDA, as an index of lipid peroxidation) and nitric oxide levels and the antioxidant activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) were also determined in the red blood cells of all groups revealing the oxidant-antioxidant activity. RFT and the Rrel of the erythrocytes of the SNP-treated rats increased significantly (p<0.05) whereas the RFR of the erythrocytes decreased (p<0.05) in comparison to all groups reflecting the impaired deformability. This reduction in RFR was prevented with both L-NAME or Vit-E incubation. Vit-E has also reduced the Rrel of the erythrocyte which reveals that it has improved the erythrocyte deformability. Lipid peroxidation was suppressed by Vit-E and L-NAME significantly, where the red blood cell deformability was improved. Furthermore, SOD and CAT activities were significantly stimulated with SNP treatment (p<0.05), where as GSH-Px remained unchanged. In the contrary, GSH-Px activity was triggered significantly by Vit-E administration, whereas the SOD and CAT activities were reduced (p<0.05). As a result, these data reveal that Vit-E improves the erythrocyte deformability in SNP-induced oxidative stress by its antioxidant effects on the lipid peroxidation and antioxidant enzyme activities.     

Nitric oxide modulates pancreatic basal secretion and response to cerulein in the rat: Effects in acute pancreatitis

Nitric oxide synthase activity is detected in the pancreas, but the role of NO on pancreatic function has not been fully characterized. The aim of this study was to evaluate the role of NO in normal and diseased pancreatic function. Amylase and NO secretion were measured in vivo in rats and in vitro in dispersed acini, with and without NO synthesis blockade, by N^G-nitro-l-arginine methyl ester (l-NAME). Rats were subjected to cerulein-induced pancreatitis, and the effects of l-NAME or NO donors were assessed. l-NAME reduced amylase output to 60% of basal. This effect was reversed by l-arginine. The secretory response to optimal doses of cerulein induced a poor amylase secretion and a marked release of NO. High doses of cerulein in combination with l-NAME inhibited NO formation and amylase secretion. In dispersed acini, supramaximal cerulein concentrations induced NO release, but the amylase dose-response curve was not modified by NO inhibition. In acute pancreatitis, l-NAME increased amylasemia and tissue myeloperoxidase activities, whereas NO donors reduced amylasemia, lipasemia, and the histological damage score. The l-arginine/NO pathway facilitates basal and stimulated pancreatic secretion in vivo. NO donor drugs may improve the course of acute pancreatitis.     

Effects of ischemic postconditioning on reperfusion injury in rat liver grafts after orthotopic liver transplantation

Aim: The effects of ischemic postconditioning (IPostC) on ischemia reperfusion (IR) injury of liver grafts was examined in rats after orthotopic liver transplantation (OLT). Methods: Male Wistar rats were used as donors and recipients to establish a liver transplantation model. The animals were randomly divided into four groups: sham‐operated (SO, n = 6), IR (n = 6), IPostC1 (n = 6) and IPostC2 (n = 6). IPostC was achieved by several intermittent interruptions of blood flow in the early phase of reperfusion. Several parameters of hepatic damage, oxidative stress, neutrophil infiltration and the expression of TNF‐α and MIP‐2 were detected as well as microscopic examination. Nitric oxide release and liver NO synthases (endothelial NO synthase and inducible NO synthase) expression were also measured. Results: We observed that a significant reduction in alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase values in two IPostC groups when compared with IR group. The increases in hepatic malondialdehyde, and decreases in superoxide dismutase and reduced glutathione levels after orthotopic liver transplantation were significantly inhibited by IPostC. IR induced increase in hepatic myeloperoxidase content, TNF‐α and MIP‐2 expression were also lowered by IPostC. The increases in NO content and NOS protein expression were much more prominent in IPostC treated groups. Animals treated with IPostC presented minimal hemorrhage and reduced signs of liver injury. There was no significant difference between two IPostC treated groups. Conclusions: IPostC provided significant protection against IR injury to liver grafts. The protective effect of IPostC is closely related to the NO production following the increase in endothelial and inducible NO synthases expression and the suppression of tumor necrosis factor‐α and macrophage inflammatory protein‐2 overproduction.     

Calpain inhibitor I reduces colon injury caused by dinitrobenzene sulphonic acid in the rat

BACKGROUND AND AIMS: Inflammatory bowel disease is characterised by oxidative and nitrosative stress, leucocyte infiltration, upregulation of expression of intercellular adhesion molecule 1 (ICAM-1), and upregulation of P-selectin in the colon. The aim of the present study was to examine the effects of calpain inhibitor I in rats subjected to experimental colitis. METHODS: Colitis was induced in rats by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). RESULTS: Rats experienced haemorrhagic diarrhoea and weight loss. Four days after administration of DNAB, the mucosa of the colon exhibited large areas of necrosis. Neutrophil infiltration (determined by histology as well as by an increase in myeloperoxidase activity in the mucosa) was associated with upregulation of ICAM-1 and P-selectin as well as high tissue levels of malondialdehyde. Immunohistochemistry for nitrotyrosine and poly (ADP-ribose) polymerase (PARP) showed intense staining in the inflamed colon. Staining of sections of colon obtained from DNBS treated rats with an anti-cyclooxygenase 2 antibody showed diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in macrophages located within the inflamed colon of DNBS treated rats. Calpain inhibitor I (5 mg/kg daily intraperitoneally) significantly reduced the degree of haemorrhagic diarrhoea and weight loss caused by administration of DNBS. Calpain inhibitor I also caused a substantial reduction in (i) degree of colon injury, (ii) rise in myeloperoxidase activity (mucosa), (iii) increase in tissue levels of malondialdehyde, (iv) increase in staining (immunohistochemistry) for nitrotyrosine and PARP, as well as (v) upregulation of ICAM-1 and P-selectin caused by DNBS in the colon. CONCLUSION: Calpain inhibitor I reduces the degree of colitis caused by DNBS. We propose that calpain inhibitor I may be useful in the treatment of inflammatory bowel disease.     

Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

Background: Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients. Aims: To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity. Methods: Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission. Results: Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with Creactive protein at predicting pancreatitis severity. Conclusion: Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.     

Novel neuroprotective and hepatoprorective effects of citric acid in acute malathion intoxication

Objective: To study the effect of citric acid given alone or combined with atropine on brain oxidative stress, neuronal injury, liver damage, and DNA damage of peripheral blood lymphocytes induced in the rat by acute malathion exposure. Methods: Rats were received intraperitoneal(i.p.) injection of malathion 150 mg/kg along with citric acid(200 or 400 mg/kg, orally), atropine(1 mg/kg, i.p.) or citric acid 200 mg/kg+atropine 1 mg/kg and euthanized 4 h later. Results: Malathion resulted in increased lipid peroxidation(malondialdehyde) and nitric oxide concentrations accompanied with a decrease in brain reduced glutathione, glutathione peroxidase(GPx) activity, total antioxidant capacity(TAC) and glucose concentrations. Paraoxonase-1, acetylcholinesterase(ACh E) and butyrylcholinesterase activities decreased in brain as well. Liver aspartate aminotransferase and alanine aminotransferase activities were raised. The Comet assay showed increased DNA damage of peripheral blood lymphocytes. Histological damage and increased expression of inducible nitric oxide synthase(i NOS) were observed in brain and liver. Citric acid resulted in decreased brain lipid peroxidation and nitric oxide. Meanwhile, glutathione, GPx activity, TAC capacity and brain glucose level increased. Brain ACh E increased but PON1 and butyrylcholinesterase activities decreased by citric acid. Liver enzymes, the percentage of damaged blood lymphocytes, histopathological alterations and i NOS expression in brain and liver was decreased by citric acid. Meanwhile, rats treated with atropine showed decreased brain MDA, nitrite but increased GPx activity, TAC, ACh E and glucose. The drug also decreased DNA damage of peripheral blood lymphocytes, histopathological alterations and i NOS expression in brain and liver. Conclusions: The study demonstrates a beneficial effect for citric acid upon brain oxidative stress, neuronal injury, liver and DNA damage due to acute malathion exposure.     

Therapy with granulocyte colony-stimulating factor in the chronic stage, but not in the acute stage, improves experimental autoimmune myocarditis in rats via nitric oxide

We systematically investigated serial efficacy of granulocyte colony-stimulating factor (G-CSF) therapy upon experimental autoimmune myocarditis (EAM) in rats treated with and without the inhibition of nitric oxide (NO) with the analyses of tissue regeneration. G-CSF could mobilize multipotent progenitor cells of bone marrow into the peripheral blood and may improve ventricular function. A rat model of porcine myosin-induced EAM was used. After the immunization of myosin, G-CSF (10 μg/kg/day) or saline was injected intraperitoneally on days 0-21 in experiment 1 and on days 21-42 in experiment 2. Additional myosin-immunized rats were orally given 25 mg/kg/day of N^G-nitro-l-arginine methylester (l-NAME), an inhibitor of nitric oxide synthase (NOS), in each experiment (each group; n = 8-21). Serum cytokines and peripheral blood cell counts were measured in each group. In experiment 1, G-CSF treatment aggravated cardiac pathology associated with increased macrophage inflammatory protein-2 (MIP-2) and interleukin-6 (IL-6) levels and enhanced superoxide production. In experiment 2, G-CSF treatment reduced the severity of myocarditis with increased capillary density and improved left ventricular ejection fraction. In the rats with EAM treated with G-CSF associated with oral l-NAME treatment in experiment 2, the severity of myocarditis was not reduced. Myocardial c-kit⁺ cells were demonstrated only in G-CSF-treated group in experiment 2 but not in other groups. G-CSF has differential effects on EAM in rats associated with the modulation of cytokine network. The overwhelming superoxide production by G-CSF administration in the acute stage may worsen the disease. G-CSF therapy improved cardiac function via NO system in a rat model of myocarditis in the chronic stage, but not in the acute stage, possibly through the myocardial regeneration and acceleration of healing process.     

Effects of ozone oxidative preconditioning on nitric oxide generation and cellular redox balance in a rat model of hepatic ischaemia-reperfusion.

BACKGROUND: Many studies indicate that oxygen free-radical formation after reoxygenation of liver may initiate the cascade of hepatocellular injury. It has been demonstrated that controlled ozone administration may promote an oxidative preconditioning or adaptation to oxidative stress, preventing the damage induced by reactive oxygen species and protecting against liver ischaemia-reperfusion (I/R) injury. AIMS: In the present study, the effects of ozone oxidative preconditioning (OzoneOP) on nitric oxide (NO) generation and the cellular redox balance have been studied. Methods: Six groups of rats were classified as follows: (1). sham-operated; (2). sham-operated+l-NAME (N(omega)-nitro-l-arginine methyl ester); (3). I/R (ischaemia 90 min-reperfusion 90 min); (4). OzoneOP+I/R; (5). OzoneOP+l-NAME+I/R; and (6). l-NAME+I/R. The following parameters were measured: plasma transaminases (aspartate aminotransferase, alanine aminotransferase) as an index of hepatocellular injury; in homogenates of hepatic tissue: nitrate/nitrite as an index of NO production; superoxide dismutase (SOD), catalase (CAT) and glutathione levels as markers of endogenous antioxidant system; and finally malondialdehyde+4-hydroxyalkenals (MDA+4-HDA) and total hydroperoxides (TH) as indicators of oxidative stress. Results: A correspondence between liver damage and the increase of NO, CAT, TH, glutathione and MDA+4-HDA concentrations were observed just as a decrease of SOD activity. OzoneOP prevented and attenuated hepatic damage in I/R and OzoneOP+l-NAME+I/R, respectively, in close relation with the above-mentioned parameters. CONCLUSIONS: These results show that OzoneOP protected against liver I/R injury through mechanisms that promote a regulation of endogenous NO concentrations and maintenance of cellular redox balance. Ozone treatment may have important clinical implications, particularly in view of the increasing hepatic transplantation programs.     

Moderate endurance exercise in patients with sickle cell anaemia: effects on oxidative stress and endothelial activation

Very few studies have investigated the effects of exercise on the biological parameters involved in vaso‐occlusive events in sickle cell anaemia (SCA). The aim of this study was to test how a mild‐moderate endurance exercise modulates oxidative stress, nitric oxide bioavailability and endothelial activation in SCA patients and healthy individuals. Eleven patients with SCA and 15 healthy subjects completed a 20‐min duration submaximal cycling exercise at ≈45 Watts. Plasma markers of oxidative stress, antioxidant activity, endothelial activation and nitric oxide bioavailability were investigated before and after the exercise. Nitric oxide levels, anti‐oxidant capacity, soluble (s)E‐selectin and sP‐selectin did not change in response to this exercise. Except for the malondialdehyde levels, which increased in the two groups, the other markers of oxidative stress remained unchanged in both groups in response to exercise. Soluble vascular cell adhesion molecule 1 levels were increased at the end of exercise in both groups. sL‐selectin decreased and soluble intercellular adhesion molecule 1 increased with exercise in SCA patients only. The present data suggest that patients with SCA may undertake mild‐moderate physical activities without any acute clinical complications, but care should be taken because oxidative stress and endothelial activation significantly increased in some patients.     

Vasoactive mediators and the progression from oedematous to necrotising experimental acute pancreatitis.

Little is known about the pathophysiological factors that determine the clinical severity of acute pancreatitis. Because impairment of pancreatic circulation and oxygenation is associated with greater disease severity and morphological damage in experimental pancreatitis it has been suggested that various vasoactive mediators might participate in the progression from the oedematous to the necrotising variety of the disease. This study used an animal model of acute pancreatitis induced by intravenous caeruleint (10 micrograms/kg/h for up to six hours), which does not entail either haemorrhage or significant necrosis of the pancreas. This study considered whether the administration or the inhibition of either nitric oxide, bradykinin, or adrenergic mediators can convert this mild variety into haemorrhagic and necrotising pancreatitis. Neither nitric oxide nor catecholamines were involved in the progression from oedematous to haemorrhagic pancreatitis. Their substitution, activation, and inhibition all failed to change the severity of the disease process. Bradykinin alone seemed to be critically involved in the pathogenesis of pancreatic haemorrhage and necrosis. However, the inhibition of bradykinin and not its activation or substitution increased the severity of the disease.