The selective inhibition of inducible nitric oxide synthase prevents intestinal ischemia-reperfusion injury in mice

Spirulina platensis as a growth booster for broiler; Insights into their nutritional, molecular, immunohistopathological, and microbiota modulating effects

BACKGROUND

The present study is designed to assess the effect of adding various doses of Spirulina platensis (SP) on broiler chicken growth performance, gut health, antioxidant biomarkers, cecal microbiota, histopathology, and immunohistochemistry of inducible nitric oxide synthase (iNOS). 240 male Cobb 500 broiler chicks (1 day old) were placed into four groups (sixty birds/group), then each group was further divided into three replicates of 20 chickens each for 35 days. Birds were allocated as follows; the 1st group (G1), the control group, fed on basal diet, the 2nd group (G2): basal diet plus SP (0.1%), the 3rd group (G3): basal diet plus SP (0.3%), and the 4th group (G4): basal diet plus SP (0.5%).

RESULTS

Throughout the trial (d 1 to 35), SP fortification significantly increased body weight growth (BWG) and feed conversion rate (FCR) (P < 0.05). Bursa considerably increased among the immunological organs in the Spirulina-supplemented groups. Within SP-supplemented groups, there was a substantial increase in catalase activity, blood total antioxidant capacity, jejunal superoxide dismutase (SOD), and glutathione peroxidase (GPX) activity (P < 0.05). Fatty acid binding protein 2 (FABP2), one of the gut barrier health biomarkers, significantly increased in the SP-supplemented groups but the IL-1β gene did not significantly differ across the groups (P < 0.05). Different organs in the control group showed histopathological changes, while the SP-supplemented chicken showed fewer or no signs of these lesions. The control group had higher levels of iNOS expression in the gut than the SP-supplemented groups (p < 0.05). Cecal Lactobacillus count significantly elevated with increasing the rate of SP inclusion rate (p < 0.05).

CONCLUSION

Supplementing broiler diets with SP, particularly at 0.5%, can improve productivity and profitability by promoting weight increase, feed utilization, antioxidant status, immunity, and gastrointestinal health.

Effects of endothelin receptor blockade and COX inhibition on intestinal I/R injury in a rat model: Experimental research

BACKGROUND

Intestinal ischemia is a highly morbid and mortal condition with no specific treatment. The present study aimed to investigate the effects of cyclooxygenase (COX) inhibition synchronized with nitric oxide (NO) release and endothelin (ET) receptor blockade on oxidative stress, inflammation, vasoconstriction, and bacterial translocation which occur during ischemia-reperfusion (I/R) injury in in-vivo rat intestinal I/R model.

MATERIALS AND METHODS

36 male Wistar rats were randomly divided into six groups (n = 6). Superior mesenteric artery blood flow (SMABF) was recorded; SMA was occluded for 30 min; SMABF was re-recorded at the beginning of the reperfusion phase. Rats were sacrificed after the reperfusion period of 60 min. Blood and tissue samples were obtained. Acetylsalicylic acid (ASA), NO-ASA, flurbiprofen (FLUR), and Tezosentan (TS) were administered 15 min after ischemia. Histopathological examination, bacterial translocation, and biochemical analysis were performed in plasma and tissue samples.

RESULTS

SMABF difference, mean Chiu's score and bacterial translocation were increased in the I/R group and decreased in the treatment groups. Plasma LDH, transaminases, intestinal fatty acid-binding protein (I-FABP), TNF-α, ICAM-1, interferon-gamma (IFN-Ɣ) and proinflammatory cytokine panel; tissue lipid peroxidation, MPO, xanthine oxidase (XO), NO, NF-kB levels and the expression of TNF-α were significantly elevated in the I/R group and markedly decreased in the treatment groups. The tissue antioxidant status was decreased in the I/R group and increased in the treatment groups.

CONCLUSION

It is suggested that NO-ASA, TS, and FLUR can be introduced as promising therapeutics to improve intestinal I/R injury.

INSTITUTIONAL PROTOCOL NO

2018-29-05 (Animal Experimentations Ethics Committee, Hacettepe University).

Proper cold stimulation starting at an earlier age can enhance immunity and improve adaptability to cold stress in broilers

The effects of long-term cold stimulation on the immune function of ileum and adaptability to cold stress in broilers were examined. A total of 360 Arbor Acres broilers was divided into 3 groups and four replicates per group. C (control) was reared in normal thermal environment. C-3 and C-12 (treatments) were kept in cold condition of 3 or 12°C lower than the temperature of C from days 8 to 42. At day 42, all the groups were exposed to an acute cold stress challenge, designated as S, S-3, and S-12. The mRNA levels of immune molecules and heat shock proteins as well as oxidative stress-related indicators in ileum tissues, and immunoglobulins contents in serum were examined at 14, 42, and 43 d of age. The C-3 regimen had no adverse effect on production performance, whereas the C-12 regimen reduced the production performance relative to C (P < 0.05). At day 42, C-3 had higher levels of immune indexes (P < 0.05), whereas C-12 had lower levels than C (P < 0.05). No differences in levels of oxidative stress-related indicators were found between C and C-3 at day 42 (P > 0.05). S-3 had higher levels of immune indexes and lower levels of oxidative stress-related indicators (P < 0.05), as compared to S and S-12. The results suggest that 34 d of cold stimulation at 3°C lower than the normal temperature had no adverse impacts on production performance but enhanced the immunity of ileum and adaptability to acute cold challenge in broilers.

The olfactomedin-4 positive neutrophil has a role in murine intestinal ischemia/reperfusion injury

Olfactomedin-4 (OLFM4) identifies a subset of neutrophils conserved in both mouse and man, associated with worse outcomes in several inflammatory conditions. We investigated the role of OLFM4-positive neutrophils in murine intestinal ischemia/reperfusion (IR) injury. Wild-type (WT) C57Bl/6 and OLFM4 null mice were subjected to intestinal IR injury and then monitored for survival or tissues harvested for further analyses. In vivo intestinal barrier function was determined via functional assay of permeability to FITC-dextran. OLFM4 null mice had a significant 7-d survival benefit and less intestinal barrier dysfunction compared with WT. Early after IR, WT mice had worse mucosal damage on histologic examination. Experiments involving adoptive transfer of bone marrow demonstrated that the mortality phenotype associated with OLFM4-positive neutrophils was transferrable to OLFM4 null mice. After IR injury, WT mice also had increased intestinal tissue activation of NFκB and expression of iNOS, 2 signaling pathways previously demonstrated to be involved in intestinal IR injury. In combination, these experiments show that OLFM4-positive neutrophils are centrally involved in the pathologic pathway leading to intestinal damage and mortality after IR injury. This may provide a therapeutic target for mitigation of intestinal IR injury in a variety of common clinical situations.-Levinsky, N. C., Mallela, J., Opoka, A., Harmon, K., Lewis, H. V., Zingarelli, B., Wong, H. R., Alder, M. N. The olfactomedin-4 positive neutrophil has a role in murine intestinal ischemia/reperfusion injury.

Nitric oxide regulates homeoprotein OTX1 and OTX2 expression in the rat myenteric plexus after intestinal ischemia-reperfusion injury

Neuronal and inducible nitric oxide synthase (nNOS and iNOS) play a protective and damaging role, respectively, on the intestinal neuromuscular function after ischemia-reperfusion (I/R) injury. To uncover the molecular pathways underlying this dichotomy we investigated their possible correlation with the orthodenticle homeobox proteins OTX1 and OTX2 in the rat small intestine myenteric plexus after in vivo I/R. Homeobox genes are fundamental for the regulation of the gut wall homeostasis both during development and in pathological conditions (inflammation, cancer). I/R injury was induced by temporary clamping the superior mesenteric artery under anesthesia, followed by 24 and 48 h of reperfusion. At 48 h after I/R intestinal transit decreased and was further reduced by N^ω-propyl-l-arginine hydrochloride (NPLA), a nNOS-selective inhibitor. By contrast this parameter was restored to control values by 1400W, an iNOS-selective inhibitor. In longitudinal muscle myenteric plexus (LMMP) preparations, iNOS, OTX1, and OTX2 mRNA and protein levels increased at 24 and 48 h after I/R. At both time periods, the number of iNOS- and OTX-immunopositive myenteric neurons increased. nNOS mRNA, protein levels, and neurons were unchanged. In LMMPs, OTX1 and OTX2 mRNA and protein upregulation was reduced by 1400W and NPLA, respectively. In myenteric ganglia, OTX1 and OTX2 staining was superimposed with that of iNOS and nNOS, respectively. Thus in myenteric ganglia iNOS- and nNOS-derived NO may promote OTX1 and OTX2 upregulation, respectively. We hypothesize that the neurodamaging and neuroprotective roles of iNOS and nNOS during I/R injury in the gut may involve corresponding activation of molecular pathways downstream of OTX1 and OTX2.NEW & NOTEWORTHY Intestinal ischemia-reperfusion (I/R) injury induces relevant alterations in myenteric neurons leading to dismotility. Nitrergic neurons seem to be selectively involved. In the present study the inference that both neuronal and inducible nitric oxide synthase (nNOS and iNOS) expressing myenteric neurons may undergo important changes sustaining derangements of motor function is reinforced. In addition, we provide data to suggest that NO produced by iNOS and nNOS regulates the expression of the vital transcription factors orthodenticle homeobox protein 1 and 2 during an I/R damage.

Effect of Selenium Deficiency on Nitric Oxide and Heat Shock Proteins in Chicken Erythrocytes

Selenium (Se) deficiency induces various types of diseases, including hemolytic anemia, which is one of the basic pathologies of erythrocyte damage. To investigate the effect of Se deficiency on chicken erythrocytes, we detected the effects of Se deficiency on the nitric oxide (NO) content and the levels of heat shock proteins (Hsps) in chicken erythrocytes, including Hsp27, Hsp40, Hsp60, Hsp70, and Hsp90. One-day-old chickens (180) were randomly divided into two groups, a low-Se group (L group, fed with a 0.008 mg/kg Se diet) and a control group (C group, fed with a 0.2 mg/kg Se diet). Next, erythrocytes were collected at 35 days old, and the NO content, activity of inducible nitric oxide synthase (iNOS), and levels of Hsps (27, 40, 60, 70, and 90) were examined. Compared with the C group, the NO and iNOS levels were significantly higher (P < 0.05), and the Hsps in the mRNA and protein levels were generally higher (P < 0.05) in the L group. Meanwhile, the correlation analysis showed that there were positive correlations between Hsps and NO. Thus, as typical damage biomarkers, NO and Hsps may play special roles in chicken erythrocyte injury by Se deficiency.

Anticoccidial activities of Chitosan on Eimeria papillata-infected mice

Eimeria spp. multiply within the intestinal tract causing severe inflammatory responses. Chitosan (CS), meanwhile, has been shown to exhibit anti-inflammatory activities in different experimental models. Here, we investigated the effect of CS on the outcome of inflammation caused by Eimeria papillata in the mouse intestine. Investigations were undertaken into the oocyst output in feces and developmental stages and goblet cells in intestinal tissue. Assays for lipid peroxidation, nitric oxide (NO), and myeloperoxidase (MPO) were also performed. T cells in intestinal tissue were counted using immunohistochemistry while total IgA in serum or intestinal wash was assayed using ELISA. In addition, mRNA expression of tumor necrosis factor alpha (TNF-α), transforming growth factor β (TGF-β), interleukin (IL)-10, and IL-4 were detected using real-time PCR. The data indicated a reduction in both oocyst output and in the number of parasite developmental stages following CS treatment, while the goblet cell hypoplasia in infected mice was also inhibited. CS decreased lipid peroxidation, NO, and MPO but did not alter the T cell count or IgA levels in comparison to the infected group. The expression of TNF-α and TGF-β decreased but IL-10 and IL-4 increased after CS treatment in comparison to the non-treated infected group. In conclusion, CS showed anti-inflammatory and protective effects against E. papillata infection.

Protective effect of exogenous nitrite in postoperative ileus

BACKGROUND AND PURPOSE

As the pathogenesis of postoperative ileus (POI) involves inflammation and oxidative stress, comparable to ischaemia/reperfusion injury which can be ameliorated with nitrite, we investigated whether nitrite can protect against POI and explored the mechanisms involved.

EXPERIMENTAL APPROACH

We used intestinal manipulation (IM) of the small intestine to induce POI in C57BL/6J mice. Sodium nitrite (48 nmol) was administered intravenously just before IM. Intestinal transit was assessed using fluorescent imaging. Bethanechol-stimulated jejunal circular muscle contractions were measured in organ baths. Inflammatory parameters, neutrophil infiltration, inducible NOS (iNOS) activity, reactive oxygen species (ROS) levels, mitochondrial complex I activity and cGMP were measured in the intestinal muscularis.

KEY RESULTS

Pre-treatment with nitrite markedly improved the delay in intestinal transit and restored the reduced intestinal contractility observed 24 h following IM. This was accompanied by reduced protein levels of TNF-α, IL-6 and the chemokine CCL2, along with reduced iNOS activity and ROS levels. The associated neutrophil influx at 24 h was not influenced by nitrite. IM reduced mitochondrial complex I activity and cGMP levels; treatment with nitrite increased cGMP levels. Pre-treatment with the NO scavenger carboxy-PTIO or the soluble guanylyl cyclase inhibitor ODQ abolished nitrite-induced protective effects.

CONCLUSIONS AND IMPLICATIONS

Exogenous nitrite deserves further investigation as a possible treatment for POI. Nitrite-induced protection of POI in mice was dependent on NO and this effect was not related to inhibition of mitochondrial complex I, but did involve activation of soluble guanylyl cyclase.

Gut region-dependent alterations of nitrergic myenteric neurons after chronic alcohol consumption

Chronic alcohol abuse damages nearly every organ in the body. The harmful effects of ethanol on the brain, the liver and the pancreas are well documented. Although chronic alcohol consumption causes serious impairments also in the gastrointestinal tract like altered motility, mucosal damage, impaired absorption of nutrients and inflammation, the effects of chronically consumed ethanol on the enteric nervous system are less detailed. While the nitrergic myenteric neurons play an essential role in the regulation of gastrointestinal peristalsis, it was hypothesised, that these neurons are the first targets of consumed ethanol or its metabolites generated in the different gastrointestinal segments. To reinforce this hypothesis the effects of ethanol on the gastrointestinal tract was investigated in different rodent models with quantitative immunohistochemistry, in vivo and in vitro motility measurements, western blot analysis, evaluation of nitric oxide synthase enzyme activity and bio-imaging of nitric oxide synthesis. These results suggest that chronic alcohol consumption did not result significant neural loss, but primarily impaired the nitrergic pathways in gut region-dependent way leading to disturbed gastrointestinal motility. The gut segment-specific differences in the effects of chronic alcohol consumption highlight the significance the ethanol-induced neuronal microenvironment involving oxidative stress and intestinal microbiota.

Organ-Protective Effects of Red Wine Extract, Resveratrol, in Oxidative Stress-Mediated Reperfusion Injury

Resveratrol, a polyphenol extracted from red wine, possesses potential antioxidative and anti-inflammatory effects, including the reduction of free radicals and proinflammatory mediators overproduction, the alteration of the expression of adhesion molecules, and the inhibition of neutrophil function. A growing body of evidence indicates that resveratrol plays an important role in reducing organ damage following ischemia- and hemorrhage-induced reperfusion injury. Such protective phenomenon is reported to be implicated in decreasing the formation and reaction of reactive oxygen species and pro-nflammatory cytokines, as well as the mediation of a variety of intracellular signaling pathways, including the nitric oxide synthase, nicotinamide adenine dinucleotide phosphate oxidase, deacetylase sirtuin 1, mitogen-activated protein kinase, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, hemeoxygenase-1, and estrogen receptor-related pathways. Reperfusion injury is a complex pathophysiological process that involves multiple factors and pathways. The resveratrol is an effective reactive oxygen species scavenger that exhibits an antioxidative property. In this review, the organ-protective effects of resveratrol in oxidative stress-related reperfusion injury will be discussed.

Treatment with Recombinant Trichinella spiralis Cathepsin B-like Protein Ameliorates Intestinal Ischemia/Reperfusion Injury in Mice by Promoting a Switch from M1 to M2 Macrophages

Intestinal ischemia/reperfusion (I/R) injury, in which macrophages play a key role, can cause high morbidity and mortality. The switch from classically (M1) to alternatively (M2) activated macrophages, which is dependent on the activation of STAT6 signaling, has been shown to protect organs from I/R injuries. In the current study, the effects of recombinant Trichinella spiralis cathepsin B-like protein (rTsCPB) on intestinal I/R injury and the potential mechanism related to macrophage phenotypes switch were investigated. In a mouse I/R model undergoing 60-min intestinal ischemia followed by 2-h or 7-d reperfusion, we demonstrated that intestinal I/R caused significant intestinal injury and induced a switch from M2 to M1 macrophages, evidenced by a decrease in levels of M2 markers (arginase-1 and found in inflammatory zone protein), an increase in levels of M1 markers (inducible NO synthase and CCR7), and a decrease in the ratio of M2/M1 macrophages. RTsCPB reversed intestinal I/R-induced M2-M1 transition and promoted M1-M2 phenotype switch evidenced by a significant decrease in M1 markers, an increase in M2 markers, and the ratio of M2/M1 macrophages. Meanwhile, rTsCPB significantly ameliorated intestinal injury and improved intestinal function and survival rate of animals, accompanied by a decrease in neutrophil infiltration and an increase in cell proliferation in the intestine. However, a selective STAT6 inhibitor, AS1517499, reversed the protective effects of rTsCPB by inhibiting M1 to M2 transition. These findings suggest that intestinal I/R injury causes a switch from M2 to M1 macrophages and that rTsCPB ameliorates intestinal injury by promoting STAT6-dependent M1 to M2 transition.

The role of nitric oxide and oxidative stress in intestinal damage induced by selenium deficiency in chickens

Nitric oxide (NO) is an essential messenger molecule and is associated with inflammation and oxidative stress. Although NO has important biological functions in mammals, its role in the mechanism that occurs after intestinal injuries in chickens remains unknown. The objective of the present study was to investigate the real role of NO and oxidative stress in the intestinal injuries of chickens induced by selenium (Se) deficiency. A total 150 chickens were randomly divided into the following two groups: a low-Se group (L group, fed a Se-deficient diet containing 0.020 mg/kg Se) and a control group (C group, fed a commercial diet containing 0.2 mg/kg Se). The activities and mRNA levels of glutathione peroxidase (GSH-Px), the production of glutathione (GSH) and NO, and the protein and mRNA levels of inducible nitric oxide synthase (iNOS) were examined in the intestinal tissues (duodenum, jejunum, and rectum) at 15, 25, 35, 45, and 55 days. Methane dicarboxylic aldehyde (MDA) levels were also detected by assay kits. Then, the morphologies of the tissues were observed under the microscope after hematoxylin and eosin staining (H&E staining). The results showed that Se deficiency induced higher inflammatory damage and MDA levels (P < 0.05), which were accompanied by higher levels of iNOS and NO but lower levels of GSH and GSH-Px (P < 0.05). Our results indicated that Se deficiency induced oxidative damage in the intestinal tracts of chickens and that low levels of GSH-Px and high contents of NO may exert a major role in the injury of the intestinal tract induced by Se deficiency.

Ischemic preconditioning and tacrolimus pretreatment as strategies to attenuate intestinal ischemia-reperfusion injury in mice

The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in different intestinal diseases. Several strategies to mitigate IRI are in experimental stages; unfortunately, no consensus has been reached about the most appropriate one. We report a protocol to study ischemic preconditioning (IPC) evaluation in mice and to combine IPC and tacrolimus (TAC) pretreatment in a warm ischemia model. Mice were divided into treated (IPC, TAC, and IPC + TAC) and untreated groups before intestinal ischemia. IPC, TAC, and IPC + TAC groups were able to decrease postreperfusion nitrites levels (P < .05). IPC-containing groups had a major beneficial effect by preserving the integrity of the intestinal histology (P < .05) and improving animal survival (P < .002) compared with TAC alone or the untreated group. The IPC + TAC group was the only one that showed significant improvement in lung histological analysis (P < .05). The TAC and IPC + TAC groups down-regulated intestinal expression of interleukin (II)-6 and IL1b more than 10-fold compared with the control group. Although IPC and TAC alone reduced intestinal IRI, the used of a combined therapy produced the most significant results in all the local and distant evaluated parameters.

Effects of aminoguanidine and melatonin on intestinal ischemia/reperfusion injury in rats: An assessor-blinded, controlled experimental study

BACKGROUND

The reactive oxygen and nitrogen species generated during reperfusion of tissue are characteristic of intestinal ischemia and reperfusion (IIR) injury.

OBJECTIVE

This study was designed to assess whether the administration of aminoguanidine (AG), a selective nitric oxide synthase inhibitor, and/or melatonin has protective potential in IIR injury.

METHODS

Male Wistar albino rats (age, 3-4 weeks; weight, 100-150 g) were divided in a nonrandom fashion into 5 groups of equal size: group 1, IIR injury + AG 100 mg/kg; group 2, IIR injury + melatonin 10 mg/kg; group 3, IIR injury + AG 100 mg/kg + melatonin 10 mg/kg; group 4, sham operation; and group 5, IIR injury alone. Sixty minutes of intestinal ischemia and 4 hours of reperfusion were carried out in all but the sham-operation group. Ileal specimens were obtained from all rats to determine the extent of histologic changes, measure tissue concentrations of malondialdehyde (MDA) and protein carbonyl (PC), and assess the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Specimens were also assessed and scored by a pathologist blinded to the experiment and the data.

RESULTS

Forty rats were divided into 5 groups of 8 each; all 40 survived until study end. In the IIR injury-alone group, mean (SD) MDA concentration and PC content were significantly higher than that of the sham-operation group, and SOD and GPx activity were significantly lower: MDA concentration, 0.86 (0.03) versus 0.54 (0.01) mmol/g protein, respectively; PC content, 0.60 (0.02) versus 0.34 (0.01) mmol/g protein; SOD activity, 104.33 (43.14) versus 2954.72 (109.55) U/g protein; and GPx activity, 10.44 (0.63) versus 24.34 (1.77) U/g protein (all, P < 0.001). Administration of AG, melatonin, and the AG/melatonin combination was associated with significantly higher SOD (1802.31 [102.35], 1776.50 [58.41], and 1924.28 [98.10] U/g protein, respectively) and GPx (17.36 [1.23], 15.96 [1.08], and 18.06 [1.72] U/g protein) activity and significantly lower MDA concentration (0.62 [0.02], 0.64 [0.02], and 0.56 [0.01] mmol/g protein) and PC content (0.53 [0.03], 0.51 [0.01], and 0.49 [0.02] mmol/g protein) compared with the IIR injury-alone group (P < 0.001). Mean intestinal mucosal injury scores were significantly lower in the 3 treatment groups (2.12 [0.35], 1.75 [0.46], and 1.12 [0.35]) compared with the IIR injury-alone group (3.87 [0.35]; all, P < 0.001).

CONCLUSION

In this study, AG, melatonin, or both administered in combination were associated with improvements in oxidative markers in this rat model of IIR injury.

Severe acute pancreatitis complicated with gastrointestinal dysfunction: Pathogenesis, diagnosis and treatment

Severe acute pancreatitis (SAP) is often associated with gastrointestinal dysfunction, leading to gastrointestinal motility disorders and even gastrointestinal failure, which has an important effect on SAP progression and prognosis, directly influences the outcome of treatment, is an important cause of death in patients with SAP, and moreover, has been one of the important prognostic factors for SAP. This review aims to discuss the pathophysiology, pathogenesis, diagnosis and treatment of SAP with gastrointestinal dysfunction.

Effects of nitric oxide synthase inhibition on glutamine action in a bacterial translocation model

Glutamine may be a precursor for NO synthesis, which may play a crucial role in bacterial translocation (BT). The goal of the present study was to investigate the potential effects of glutamine on BT and the immunological response in an experimental model of NO synthase inhibition by NG-nitro-L-arginine methyl ester (l-NAME). Mice were randomly assigned to four groups: sham; intestinal obstruction (IO); IO+500 mg/kg per d glutamine (GLN); IO+GLN plus 10 mg/kg per d l-NAME (GLN/LN). The groups were pretreated for 7 d. BT was induced by ileal ligation and was assessed 18 h later by measuring the radioactivity of 99mTc-Escherichiacoli in the blood and organs. Mucosal damage was determined using a histological analysis. Intestinal permeability (IP) was assessed by measuring the levels of 99mTc-diethylenetriaminepentaacetic acid in the blood at 4, 8 and 18 h after surgery. IgA and cytokine concentrations were determined by ELISA in the intestinal fluid and plasma, respectively. BT was increased in the GLN/LN and IO groups than in the GLN and sham groups. IP and intestinal mucosa structure of the sham, GLN and GLN/LN groups were similar. The GLN group had the highest levels of interferon-γ, while IL-10 and secretory IgA levels were higher than those of the IO group but similar to those of the GLN/LN group. The present results suggest that effects of the glutamine pathway on BT were mediated by NO. The latter also interferes with the pro-inflammatory systemic immunological response. On the other hand, IP integrity preserved by the use of glutamine is independent of NO.

A preclinical study on the protective effect of melatonin against methotrexate-induced small intestinal damage: effect mediated by attenuation of nitrosative stress, protein tyrosine nitration, and PARP activation

PURPOSE

One of the major toxic side effects of methotrexate (MTX) is enterocolitis. To date, there is no efficient standard treatment for this side effect. Nitrosative stress is reported to play a critical role in MTX-induced mucositis. The purpose of this study is to investigate whether pretreatment with melatonin, an inhibitor of nitro-oxidative stress, prevents MTX-induced mucositis in rats.

METHODS

Rats were pretreated with melatonin (20 and 40 mg/kg body weight) i.p. daily 1 h before MTX (7 mg/kg body weight) administration for three consecutive days. After the final dose of MTX, the rats were killed and the small intestines were used for analysis.

RESULTS

The small intestines of MTX-treated rats showed moderate to severe injury. The villi were distorted, blunted, and atrophied and focally absent in various segments of the small intestines. Crypt abscesses were also found, suggesting an inflammatory response. Pretreatment with melatonin had a dose-dependent protective effect on MTX-induced mucositis. Morphology was saved to a moderate extent with 20 mg melatonin pretreatment, and near-normal morphology was achieved with 40 mg melatonin pretreatment. Damage to the villi and crypt abscess was reduced. The villi/crypt ratio was almost restored. Melatonin pretreatment protected the small intestines from MTX-induced damage by attenuating nitrosative stress, protein tyrosine nitration and PARP expression.

CONCLUSION

Because of its versatility in protecting against nitro-oxidative stress and reducing inflammation, we suggest that melatonin could be beneficial in ameliorating MTX-induced enteritis in humans.

Protective role of μ opioid receptor activation in intestinal inflammation induced by mesenteric ischemia/reperfusion in mice

Intestinal ischemia is a clinical emergency with high morbidity and mortality. We investigated whether activation of μ opioid receptor (μOR) protects from the inflammation induced by intestinal ischemia and reperfusion (I/R) in mice. Ischemia was induced by occlusion of the superior mesenteric artery (45 min), followed by reperfusion (5 hr). Sham-operated (SO) and normal (N) mice served as controls. Each group received subcutaneously 1) saline solution, 2) the μOR selective agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO; 0.01 mg kg(-1) ), 3) DAMGO and the selective μOR antagonist [H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2] (CTAP; 0.1 mg kg(-1) ), or 4) CTAP alone. I/R induced intestinal inflammation as indicated by histological damage and the significant increase in myeloperoxidase (MPO) activity, an index of tissue neutrophil accumulation. Tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) mRNA levels were also increased in I/R mice compared with SO. DAMGO significantly reduced tissue damage, MPO activity, and TNF-α mRNA levels in I/R, and these effects were reversed by CTAP. By contrast, DAMGO did not modify IL-10 mRNA levels or gastrointestinal transit. DAMGO's effects are receptor mediated and likely are due to activation of peripheral μORs, because it does not readily cross the blood-brain barrier. These findings suggest that activation of peripheral μOR protects from the inflammatory response induced by I/R through a pathway involving the proinflammatory cytokine TNF-α. Reduction of acute inflammation might prevent I/R complications, including motility impairment, which develop at a later stage of reperfusion and likely are due to inflammatory cell infiltrates.

Anti-inflammatory and antioxidant effects of infliximab on acute lung injury in a rat model of intestinal ischemia/reperfusion

The purpose of this study was to investigate the role of infliximab on acute lung injury induced by intestinal ischemia/reperfusion (I/R). A total of 30 male Wistar albino rats were divided into three groups: sham, I/R and I/R+ infliximab; each group contain 10 animals. Sham group animals underwent laparotomy without I/R injury. After I/R groups animals underwent laparotomy, 1 h of superior mesenteric artery ligation were followed by 1 h of reperfusion. In the infliximab group, 3 days before I/R, infliximab (3 mg/kg) was administered by intravenously. All animals were sacrificed at the end of reperfusion and lung tissues samples were obtained for biochemical and histopathological investigation in all groups. To date, no more biochemical and histopathological changes on intestinal I/R injury in rats by infliximab treatment have been reported. Infliximab treatment significantly decreased the elevated tissue malondialdehyde levels and increased of reduced superoxide dismutase, and glutathione peroxidase enzyme activities in lung tissues samples. Intestinal I/R caused severe histopathological injury including edema, hemorrhage, increased thickness of the alveolar wall and a great number of inflammatory cells that infiltrated the interstitium and alveoli. Infliximab treatment significantly attenuated the severity of intestinal I/R injury. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase and arise in the expression of surfactant protein D in lung tissue of acute lung injury induced by intestinal I/R with infliximab therapy. It was concluded that infliximab treatment might be beneficial in acute lung injury, therefore, shows potential for clinical use. Because of its anti-inflammatory and antioxidant effects, infliximab pretreatment may have protective effects in acute lung injury induced by intestinal I/R.

Protective effect of curcumin on acute lung injury induced by intestinal ischaemia/reperfusion

The aim of this study is to evaluate the role of curcumin on acute lung injury induced by intestinal ischaemia/reperfusion (I/R). A total of 30 male Wistar albino rats were divided into 3 groups: sham, I/R, and I/R + curcumin; each group contains 10 animals. Sham group animals underwent laparotomy without I/R injury. After I/R groups animals underwent laparotomy, 1 h of superior mesenteric artery ligation were followed by 1 h of reperfusion. In the curcumin group, 3 days before I/R, curcumin (100 mg/kg) was administered by gastric gavage. All animals were killed at the end of reperfusion and lung tissue samples were obtained for biochemical and histopathological investigation in all groups. To date, no more biochemical and histopathological changes on intestinal I/R injury in rats by curcumin treatment have been reported. Curcumin treatment significantly decreased the elevated tissue malondialdehyde levels and increased reduced superoxide dismutase, and glutathione peroxidase enzyme activities in lung tissue samples. Intestinal I/R caused severe histopathological injury including oedema, haemorrhage, increased thickness of the alveolar wall, and infiltration of inflammatory cells into alveolar spaces. Curcumin treatment significantly attenuated the severity of intestinal I/R injury. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase and increase in the expression of surfactant protein D in lung tissue of acute lung injury induced by intestinal I/R with curcumin therapy. It was concluded that curcumin treatment may have beneficial effects in acute lung injury, and therefore has potential for clinical use.

Estrogen augments the protection of hypertonic saline treatment from mesenteric ischemia-reperfusion injury

Either estrogen or hypertonic saline (HTS) administration can decrease lung inflammation after ischemia-reperfusion. The present study investigated whether combined treatment with estrogen and HTS could provide further protection from mesenteric ischemia-reperfusion (MSIR) injury. Male C3H/HeOuJ mice were randomly segregated into the following groups: sham-operated (sham), vehicle treatment followed by MSIR (vehicle treated), estrogen treatment followed by MSIR (estrogen treated), HTS treatment and MSIR (HTS treated), and combined treatment of estrogen plus HTS and MSIR (combined treated). In MSIR, mice were subjected to mesenteric ischemia for 60 min followed by reperfusion for 30 min. The histology of the lung and the gut was obtained. Lung injury was evaluated by lung edema and myeloperoxidase (MPO) activity; lung protein expression of macrophage migration inhibitory factor (MIF), toll-like receptor-4 (TLR4), phosphorylated inhibitory κBα (p-IκBα), and inducible nitric oxide synthetase (iNOS) were assayed. Survival analysis was monitored after MSIR for 120 min. Compared with those in the sham-treated group, the lung water ratio, MPO activity, and expressions of MIF, TLR4, p-IκBα, and iNOS were significantly increased in the vehicle-treated group. Diminished MIF, TLR4, p-IκBα, and iNOS expressions were found in the estrogen-treated group, whereas suppression of p-IκBα and iNOS was found in the HTS-treated group. Treatment with estrogen or HTS decreased the lung water and MPO activity. The combined treatment of estrogen and HTS further significantly diminished p-IκBα and iNOS expression, lung edema, and MPO activity and improved the inflammation of the lung and the morphology of the gut in histology compared with the results of a single treatment of estrogen or HTS. Survival analysis showed significantly increased survival in the combination-treated group compared with survival in the HTS-treated group. In conclusion, compared with single-agent use, treatment combining estrogen and HTS further decreases lung p-IκBα and iNOS expressions, as well as the degree of lung injury. These effects may result in better rates of survival from MSIR injury.

Chronic alcohol consumption induces an overproduction of NO by nNOS- and iNOS-expressing myenteric neurons in the murine small intestine

BACKGROUND

There are indications that alterations in the nitric oxide (NO) system of relaxation mediate gastrointestinal motor disturbances induced by chronic alcohol consumption (CAC). As CAC is known to inhibit the motility of the mouse small intestine, we investigated in this model if CAC affects basal NO synthesis by myenteric neurons and which NOS isoforms are involved.

METHODS

The instantaneous NO synthesis of individual neurons was optically measured in whole-mount preparations loaded with the NO synthesis indicator DAF-FM, and the expression of nNOS, iNOS and eNOS was determined by immunohistochemistry.

KEY RESULTS

The DAF-FM recordings showed that CAC induced an increase in neuronal NO synthesis (absolute fluorescence: control 34±12; CAC 140±56; mean±SD; P<0.0004). Neurons of control mice expressed the nNOS (29±3% of total) and iNOS (28±1%) isoforms. eNOS expression was observed in <0.5% of the neurons. Chronic alcohol consumption caused an increase in the proportion of iNOS-expressing neurons (to 33±5%; P<0.01) and a decrease in nNOS-expressing neurons (to 22±3%; P<0.0001), without altering the proportion of NO-producing neurons (control 55±13%; CAC 56± 11%; P=0.82).

CONCLUSIONS & INFERENCES

Chronic alcohol consumption induces a marked increase in NO synthesis by jejunal myenteric neurons, accompanied by an up-regulation of iNOS-expressing neurons and a downregulation of nNOS neurons. We conclude that the overproduction of NO may be a direct cause of gastrointestinal motility disturbances.

Magnolol attenuates the lung injury in hypertonic saline treatment from mesenteric ischemia reperfusion through diminishing iNOS

BACKGROUND

Hypertonic saline (HTS) administration can decrease the inflammation following ischemia reperfusion. Magnolol is a potent antioxidant. The present study investigated whether combined treatment of magnolol and HTS could provide further protection in mesenteric ischemia reperfusion injury.

METHODS

Male C3H/HeOuJ mice were randomly segregated into the following groups: sham-operated (sham), vehicle treatment and mesenteric ischemia reperfusion (MSIR) (vehicle-treated), magnolol treatment and MSIR (magnolol-treated), HTS treatment and MSIR (HTS-treated), as well as co-administration of magnolol plus HTS and MSIR (combined-treated). In MSIR, mice were subjected to mesenteric ischemia for 60 min followed by reperfusion for 30 min. Lung injury was evaluated by lung edema (water ratio) and myeloperoxide (MPO) activity; RNA expression of inducible nitric oxide synthetase (iNOS), TNF-α, and IL-6 were assayed by real time RT-PCR. The formation of peroxynitrite in plasma was assayed by the peroxynitrite-dependent oxidation of dihydrorhodamine 123 (DHR 123) to rhodamine.

RESULTS

Compared with those in the sham-treated group, lung edema and MPO activity, expressions of iNOS, TNF-α and IL-6, and plasma peroxynitrite were significantly increased in the vehicle-treated group. Significant attenuations of these parameters were found in the magnolol-treated or HTS-treated animals. Combined treatment of magnolol and HTS further suppressed the lung edema, iNOS, and TNF-α expressions, and plasma peroxynitrite, compared with the results of a single treatment of magnolol or HTS.

CONCLUSIONS

Compared with single-agent use, co-administration of magnolol and HTS further decreases iNOS expression and plasma peroxynitrite as well as the degree of lung injury from MISR. These results may provide another treatment measure for post-injury immunomodulation.

Effects of oral administration of (L)-arginine, (L)-NAME and allopurinol on intestinal ischemia/reperfusion injury in rats

AIMS

Intestinal ischemia/reperfusion (I/R) injury is implicated in many clinical conditions, and it performs a fundamental role in their pathophysiologies. Oral administration of antioxidants and nitric oxide (NO) donors ameliorate intestinal injury. Here, the effects of l-arginine, allopurinol and N(G)-nitro-l-arginine methyl ester (l-NAME) were investigated.

MAIN METHODS

One hundred twenty-eight male Wistar rats were separated into 4 groups and subjected to occlusion of the superior mesenteric artery for 60 min. The Control group did not receive any substance before the surgical operation. However, the 3 other groups received the following: l-arginine (800 mg/kg body weight; l-Arg group), l-NAME (50mg/kg; l-NAME group) or allopurinol (100mg/kg; Allo group). Each substance was given by mouth in 3 equal doses 24, 12 and 1h before the surgical operation. Each group was then divided into 4 subgroups, which underwent different durations of reperfusion (0, 1, 8 or 24h). At the end of each time point, blood and tissue samples were collected, and histological examinations were performed. Serum nitrite and catalase, intestinal tissue myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT) levels were determined.

KEY FINDINGS

At each reperfusion time point, the Allo group exhibited the mildest histological lesions in contrast to the l-NAME group, which showed the most severe lesions. MPO was decreased significantly in the Allo and l-Arg groups during reperfusion, and allopurinol administration caused earlier and stronger effect. iNOS and NT levels were higher in the l-Arg group and lower in the Allo group. Serum nitrite and catalase were increased in the l-NAME group after 24h.

SIGNIFICANCE

Oral administration of allopurinol exerted a strong and protective effect on the intestinal tissue that was subjected to I/R earlier than l-arginine. This finding was also supported with the MPO, iNOS and NT data.

Panax notoginseng saponins attenuate acute lung injury induced by intestinal ischaemia/reperfusion in rats

BACKGROUND AND OBJECTIVE

Acute lung injury remains a challenge for both clinicians and scientists. The effects of Panax notoginseng saponins (PNS) on acute lung injury induced by intestinal ischaemia/reperfusion (II/R) were studied in rats.

METHODS

Forty-eight Wistar rats were randomly assigned to four groups: (1) a sham-operated group that received laparotomy without II/R (n= 12); (2) a sham + PNS group, which was identical to group 1 except for PNS treatment (n= 12); (3) an II/R group that had 1 h of intestinal ischaemia followed by 3 h of reperfusion (n= 12); and (4) an II/R + PNS group that received 100 mg/kg of PNS, i.v., 15 min before reperfusion (n= 12). The effects of PNS administration on lung tissue histology, activities of oxidant and antioxidant enzymes, levels of malondialdehyde, nitric oxide and inducible nitric oxide synthase activity were examined. Levels of surfactant protein B, cell numbers in BAL fluid and plasma levels of pro-inflammatory cytokines were also examined.

RESULTS

Compared with the II/R group, pulmonary parenchymal damage, activities of oxidant enzymes, levels of malondialdehyde and nitric oxide, inducible nitric oxide synthase activity in lung tissue, and plasma levels of pro-inflammatory cytokines were significantly reduced by PNS treatment. In addition, the decreases in antioxidant enzyme activities were prevented in the II/R + PNS group. Total leukocyte and neutrophil counts were significantly decreased by PNS treatment. The decline in surfactant protein B levels in BAL fluid was reduced in the II/R + PNS group compared with the II/R group.

CONCLUSIONS

Administration of PNS before reperfusion injury alleviates acute lung injury induced by II/R, and this is attributable to the antioxidant and anti-inflammatory effects of PNS.

Alterations in the glutathione metabolism could be implicated in the ischemia-induced small intestinal cell damage in horses

Background

Colic could be accompanied by changes in the morphology and physiology of organs and tissues, such as the intestine. This process might be, at least in part, due to the accumulation of oxidative damage induced by reactive oxygen (ROS) and reactive nitrogen species (RNS), secondary to intestinal ischemia. Glutathione (GSH), being the major intracellular thiol, provides protection against oxidative injury. The aim of this study was to investigate whether ischemia-induced intestinal injury could be related with alterations in GSH metabolism.

Results

Ischemia induced a significant increase in lipid hydroperoxides, nitric oxide and carbon monoxide, and a reduction in reduced glutathione, and adenosine triphosphate (ATP) content, as well as in methionine-adenosyl-transferase and methyl-transferase activities.

Conclusion

Our results suggest that ischemia induces harmful effects on equine small intestine, probably due to an increase in oxidative damage and proinflammatory molecules. This effect could be mediated, at least in part, by impairment in glutathione metabolism.

In vivo visualization of nitric oxide and interactions among platelets, leukocytes, and endothelium following hemorrhagic shock and reperfusion

OBJECTIVES

We examined changes in nitric oxide (NO) distribution in the mesenteric microcirculation after hemorrhagic shock and reperfusion (H/R), and correlated NO production to leukocyte and platelet behavior.

MATERIALS AND METHODS

The behavior of leukocytes and platelets in mesenteric venules was observed by intravital microscopy at 0.5 and 24 h after H/R in male Wistar rats. Transvascular leakage of fluorescein isothiocyanate-labeled albumin was assessed by epi-illumination. The NO-sensitive dye, 4,5-diaminofluorescein diacetate, was used for imaging NO release.

RESULTS

H/R significantly increased vascular albumin leakage and adhesion of leukocytes and platelets (P < 0.05). In H/R 0.5 h rats, NO production in the venular endothelium declined. However, NO production was elevated in H/R 24 h rats in mast cells (P < 0.05). Leukocyte adherence, platelet adherence, and venular permeability were attenuated by iNOS inhibition.

CONCLUSION

Mesenteric endothelial cell dysfunction after H/R 0.5 h is associated with reduced NO, whereas after H/R 24 h is related to increase NO in mast cells.

Chronic L-arginine administration increases oxidative and nitrosative stress in rat hyperoxaluric kidneys and excessive crystal deposition

Hyperoxaluric kidneys show an impaired diuretic response to acute infusion of L-arginine. In this study, we examined the chronic effect of l-arginine supplementation on CaOx crystal formation in hyperoxaluric rat kidneys. Eight groups were tested: control (received drinking water), L group (received L-arginine, 0.6%), LN group [received NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg)], L + LN group (received L-arginine + l-NAME), HP group [received hydroxyl-L-proline (HP, 5%) mixed with chow to induce hyperoxaluria], L + HP group (received HP + L-arginine), HP + LN group, and L + HP + LN group. The duration was 42 days, and each group had eight animals. Urinary biochemistry and renal CaOx amounts were measured, as well as renal expressions of nitric oxide synthase (NOS) isoforms and NAD(P)H oxidase. The distribution of inducible NOS (iNOS), NAD(P)H oxidase, ED1-positive cells, and nitrotyrosine was examined by immunohistochemical and immunofluorescence studies, whereas superoxide production from the kidneys was examined by fluorescence spectrometric assay. Compared with the HP group, the L + HP group had excessive CaOx crystal accumulation and enhanced endothelial NOS (eNOS), iNOS, and NAD(P)H oxidase protein expression in the kidney. Urinary excretion of nitrotyrosine was markedly increased. Increased superoxide formation in the L + HP kidney was derived from NAD(P)H oxidase and uncoupled eNOS, and increased nitrotyrosine formation might derive from iNOS and ED1-positive cells that gathered around the CaOx crystals. L-NAME cotreatment (L + HP + LN group) reduced renal oxidative nitrosative stress and tubular damage, which were induced by L + HP. The results showed that chronic l-arginine treatment to the hyperoxaluric kidney with massive CaOx crystal deposition may have a toxic effect by enhancing intrarenal oxidative and nitrosative stress.

Orchiectomy or testosterone receptor blockade reduces intestinal mucosal damage caused by ischemia-reperfusion insult

The aim of the present study was to investigate whether orchiectomy or administration of flutamide an antagonist of the testosterone receptor can reduce oxidative stress and histologic damage in the rat small bowel subjected to mesenteric ischemia/reperfusion (I/R) injury. A total of 32 Sprague-Dawley rats were divided into four groups. Group 1 was control (sham), group 2 was I/R, group 3 was I/R plus orchiectomy (orchiectomy was performed 14 days before I/R), group 4 was I/R plus flutamide (flutamide was given throughout 14 days before mesenteric IR). Rats were subjected to 45 min of mesenteric ischemia followed by 3 h of reperfusion. The levels of ileal malondialdehyde (MDA) and nitric oxide (NO) were found to be significantly lower in orchiectomy and flutamide treatment groups compared with I/R group (P < 0.05). The histopathological injury scores were consistent with the MDA and NO levels. These results suggest that castration or testosterone receptor blockade decreases the level of intestinal I/R injury in male rats and it is an another example for disease variations based on gender differences.

Acute salivary gland hypofunction in the duct ligation model in the absence of inflammation

Objective

The commonly associated aetiology of salivary gland inflammation and salivary hypofunction has led to the widely held belief that inflammation causes salivary gland hypofunction. Indeed, our own recent study seemed to support this contention. Here, we tested the hypothesis that, in an acute duct ligation model, eliminating inflammation the submandibular gland would recover normal function.

Materials and methods

Ligation of the rat submandibular gland excretory duct for 24 h was used to induce inflammation and salivary gland hypofunction. A group of duct ligated rats was compared with a second group given dexamethasone, on the day of duct ligation. Twenty-four hours later salivary gland function was assessed and salivary glands were collected.

Results

Histology and myeloperoxidase activity assay revealed a profound decrease in inflammatory cell infiltration of ligated glands from rats given dexamethasone, compared with ligated glands in the absence of dexamethasone. Salivary flow rate evoked by methacholine was decreased (P < 0.01) by approximately 56% (ligated vs control, 79 ± 9 μl min⁻¹ g⁻¹vs 177 ± 11 μl min⁻¹ g⁻¹) and salivary flow from ligated dexamethasone-treated and ligated glands was similar.

Conclusion

Despite eliminating the inflammatory reaction in the ligated gland, salivary hypofunction was not reversed, suggesting that other mechanisms must be at work in the ligation-induced salivary hypofunction.

Inducible nitric oxide synthase mediates hypoxia-induced hypoxia-inducible factor-1 alpha activation and vascular endothelial growth factor expression in oxygen-induced retinopathy

OBJECTIVE

Previous studies provided evidence that many factors contribute to retinal angiogenesis, including inducible nitric oxide synthase (iNOS), hypoxia-inducible factor-1 alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF). But the role of nitric oxide generated by iNOS in the regulation of expression of hypoxia-inducible genes in retinopathy of prematurity remains unclear. So we sought to better define the molecular basis of this iNOS-dependent regulation.

METHODS

In this study, using immunohistochemistry, real-time PCR and Western blotting technologies, we investigated the changes of iNOS, HIF-1 alpha, VEGF and phosphatidylinositol 3-kinase/Akt (PI3K/Akt) expressions.

RESULTS

Hypoxia- induced overexpression of iNOS, HIF-1 alpha, VEGF, PI3K/Akt and phosphorylated PI3K/Akt was observed in the untreated retinopathy of the prematurity group. Administration of the selective iNOS inhibitor aminoguanidine hemisulfate markedly decreased the expression of these genes.

CONCLUSIONS

These results indicate that iNOS mediates HIF-1 alpha activation and VEGF expression in retinal angiogenesis and that the PI3K/Akt signaling pathway may play a role in this process.

Nitric oxide synthase isoform inhibition before whole body ischemia reperfusion in pigs: Vital or protective?

BACKGROUND

Nitric oxide (NO) is a critical regulator of vascular tone, and signal transduction. NO is produced via three unique synthases (NOS); endothelial (eNOS), and neuronal (nNOS) are both constitutively expressed and inducible (iNOS) produced primarily after stimulation. NO has been implicated during and after ischemia reperfusion injury as both a detrimental and cardioprotective mediator. Since cardiopulmonary resuscitation (CPR) in ventricular fibrillation (VF) is a model of whole body ischemia reperfusion injury, it provides an opportunity to assess the effects of NO from the three NOS isoforms.

OBJECTIVE

To determine the differential role of nitric oxide synthase isoforms inhibition in ventricular fibrillation CPR and investigate whether inhibition of the NOS isoforms afford any cardioprotection in this model.

METHODS

Thirty-two pigs, weight range 25-35 kg, were assigned to four groups of eight animals each. The animals were randomized to receive (1) N(G)-nitro-L-arginine methyl ester (LNAME), a non-selective endothelial nitric oxide synthase inhibitor, (2) 1-(2-trifluoromethylphenyl) imidazole (TRIM), a selective neuronal NOS inhibitor, (3) aminoguanidine (AMINOG), a selective inducible NOS inhibitor or (4) saline control (Control) in equal volumes, 30 min before induction of ventricular fibrillation (VF). After 3 min VF with no intervention, the animals received standard chest compressions using an automated chest compression device (Thumper) for 15 min. After 18 min of VF, single doses of vasopressin and bicarbonate were given and defibrillation attempted. Hemodynamics, regional blood flows, and echocardiography and were performed, before and after drug infusion, during CPR, and after return of spontaneous circulation (ROSC).

RESULTS

ROSC for 3 h occurred in 5/8 (63%), 1/8 (13%), 0/8 (0%), and 6/8 (75%) in Control, LNAME, TRIM, and AMINOG treated animals, respectively. After infusion of LNAME, there was a significant increase from baseline in blood pressure [127+/-6 mmHg versus 169+/-3 mmHg, p<0.002] and coronary perfusion pressure [119+/-6 mmHg versus 149+/-6 mmHg, p<0.003]. During CPR, there were no differences among groups in hemodynamics or regional blood flow. In surviving animals, AMINOG had significantly better myocardial function (left ventricular ejection fraction, fractional shortening, and wall motion score index) than control or LNAME treated animals, and attenuated the post-resuscitation hyperemic response in heart and brain.

CONCLUSIONS

Intact basal nNOS activity is vital for survival from whole body ischemia reperfusion injury. iNOS inhibition prior to ischemia reperfusion, protects myocardial function after ROSC and decreases myocardial and brain hyperemic response after ROSC.

The effect of L-arginine and aprotinin on intestinal ischemia-reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) results in local mucosal injury, systemic injuries, and organ dysfunction. These injuries are characterized by altered microvascular and epithelial permeability and villous damage. Activation of neutrophils, platelets, and endothelial factors are known to be involved in this process. Cytokines such as TNF-alpha, IL-1, IL-6, and oxygen-derived free radicals are believed to be important pathogenic mediators. Capillary no-reflow is also known to play a role in I/R. The aim of our study was to examine the role of L-arginine, a known nitric oxide (NO) donor, and aprotinin, a protease inhibitor with multiple effects, on intestinal I/R.

METHODS

Pigs weighing 20-25 kg were used. Ischemia was established by clamping the superior mesenteric artery (SMA) at its origin and was sustained for 2 hours. Duration of reperfusion was 2 hours. The animals were divided into four groups: group A, the control group, which was submitted to I/R injury only; group B, in which L-arginine was administered at a rate of 5 mg/kg/min during ischemia and continuing throughout reperfusion; group C, in which aprotinin was administered with an initial bolus dose of 20,000 U/kg during ischemia followed by a continuous dose at 50 U/hour throughout reperfusion; and group D in which both substances were administered. In all groups TNF-alpha, IL-1, and IL-6 levels were measured using ELISA at baseline, 2 hours of ischemia, and 1 hour and 2 hours of reperfusion. SMA blood flow was measured with a Doppler probe at baseline, 10 min, 1 hour, and 2 hours of reperfusion. Histological changes of the intestinal mucosa were examined and graded on a five-point scale in all groups.

RESULTS

In the control group, levels of TNF-alpha, IL-1, and IL-6 were significantly increased during reperfusion (p < 0.05) compared to baseline. Administration of L-arginine and aprotinin led to suppression of the release of TNF-alpha, IL-1, and IL-6 during reperfusion in a statistically significant manner (all p < 0.05). A synergistic or additive effect of L-arginine and aprotinin was not observed. SMA blood flow in the control group was decreased (p > 0.05) during reperfusion compared to baseline. In animals treated with L-arginine and aprotinin, SMA blood flow during reperfusion was significantly increased (p < 0.05) compared to the control group. Histologic examination of the intestinal mucosa was characterized by flattening of the villi and necrosis in the control group. In the treated animals, less severe histological changes were noted.

CONCLUSIONS

Administration of L: -arginine and aprotinin may lead to amelioration of intestinal I/R injury. We did not note a synergistic or additive effect of these two substances. These findings warrant further studies in clinical settings for future treatment efforts.