Beneficial effects of N-acetylcysteine on sodium taurocholate-induced pancreatitis in rats

Role of Gasotransmitters in Inflammatory Edema

Significance: Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are, to date, the identified members of the gasotransmitter family, which consists of gaseous signaling molecules that play central roles in the regulation of a wide variety of physiological and pathophysiological processes, including inflammatory edema. Recent Advances: Recent studies show the potential anti-inflammatory and antiedematogenic effects of NO-, CO-, and H2S-donors in vivo. In general, it has been observed that the therapeutical effects of NO-donors are more relevant when administered at low doses at the onset of the inflammatory process. Regarding CO-donors, their antiedematogenic effects are mainly associated with inhibition of proinflammatory mediators (such as inducible NO synthase [iNOS]-derived NO), and the observed protective effects of H2S-donors seem to be mediated by reducing some proinflammatory enzyme activities. Critical Issues: The most recent investigations focus on the interactions among the gasotransmitters under different pathophysiological conditions. However, the biochemical/pharmacological nature of these interactions is neither general nor fully understood, although specifically dependent on the site where the inflammatory edema occurs. Future Directions: Considering the nature of the involved mechanisms, a deeper knowledge of the interactions among the gasotransmitters is mandatory. In addition, the development of new pharmacological tools, either donors or synthesis inhibitors of the three gasotransmitters, will certainly aid the basic investigations and open new strategies for the therapeutic treatment of inflammatory edema. Antioxid. Redox Signal. 40, 272-291.

N-Acetylcysteine Suppresses Microglial Inflammation and Induces Mortality Dose-Dependently via Tumor Necrosis Factor-α Signaling

N-acetylcysteine (NAC) is an antioxidant that prevents tumor necrosis factor (TNF)-α-induced cell death, but it also acts as a pro-oxidant, promoting reactive oxygen species independent apoptosis. Although there is plausible preclinical evidence for the use of NAC in the treatment of psychiatric disorders, deleterious side effects are still of concern. Microglia, key innate immune cells in the brain, play an important role in inflammation in psychiatric disorders. This study aimed to investigate the beneficial and deleterious effects of NAC on microglia and stress-induced behavior abnormalities in mice, and its association with microglial TNF-α and nitric oxide (NO) production. The microglial cell line MG6 was stimulated by Escherichia coli lipopolysaccharide (LPS) using NAC at varying concentrations for 24 h. NAC inhibited LPS-induced TNF-α and NO synthesis, whereas high concentrations (≥30 mM) caused MG6 mortality. Intraperitoneal injections of NAC did not ameliorate stress-induced behavioral abnormalities in mice, but high-doses induced microglial mortality. Furthermore, NAC-induced mortality was alleviated in microglial TNF-α-deficient mice and human primary M2 microglia. Our findings provide ample evidence for the use of NAC as a modulating agent of inflammation in the brain. The risk of side effects from NAC on TNF-α remains unclear and merits further mechanistic investigations.

Pharmacological prevention of post-operative pancreatitis: systematic review and meta-analysis of randomized controlled trials on animal studies

BACKGROUND

Postoperative pancreatic fistula (POPF) remains a significant complication of pancreatic resection with recent evidence showing a strong association between post-operative pancreatitis and subsequent development of POPF. Incidence and severity of pancreatitis following endoscopic therapy has been effectively reduced with indomethacin prophylaxis, however further agents require evaluation. We present a systematic literature review and meta-analysis of the prophylactic treatment with corticosteroids or n-acetyl cysteine (NAC) of induced pancreatitis in rodent models.

METHODS

A systematic literature search was conducted using Pubmed, Medline, Embase and Cochrane library to identify eligible randomized control trials (RCT) involving animal models that examined NAC or corticosteroids. The primary outcome was the subsequent effect on serum amylase and IL-6 and the histopathological markers of severity such as pancreatic oedema and necrosis.

RESULTS

Four RCTs (n = 178) met inclusion criteria examining NAC and eight RCTs (n = 546) examining corticosteroid agents (dexamethasone, hydrocortisone, methylprednisolone). Prophylactic administration of all corticosteroid agents showed a net effect in favour of reducing markers of severity of pancreatitis. NAC showed a significant reduction in severity of amylase and necrosis.

CONCLUSION

The RCTs examined suggest that prophylactic administration of corticosteroid agents and NAC can reduce the severity of pancreatitis as indicated by histopathologic markers, serum amylase and IL-6 levels.

Current trends in pharmacological approaches for treatment and management of acute pancreatitis – a review

Objectives

Acute pancreatitis (AP) is an inimical disorder associated with overall mortality rates between 10-15%. It is a disorder of the exocrine pancreas which is characterized by local and systemic inflammatory responses primarily driven by oxidative stress and death of pancreatic acinar cells. The severity of AP ranges from mild pancreatic edema with complete recuperative possibilities to serious systemic inflammatory response resulting in peripancreatic/pancreatic necrosis, multiple organ failure, and death.

Key findings

We have retrieved the potential alternative approaches that are developed lately for efficacious treatment of AP from the currently available literature and recently reported experimental studies. This review summarizes the need for alternative approaches and combinatorial treatment strategies to deal with AP based on literature search using specific key words in PubMed and ScienceDirect databases.

Summary

Since AP results from perturbations of multiple signaling pathways, the so called “monotargeted smart drugs” of the past decade is highly unlikely to be effective. Also, the conventional treatment approaches were mainly involved in providing palliative care instead of curing the disease. Hence, many researchers are beginning to focus on developing alternate therapies to treat AP effectively. This review also summarizes the recent trends in the combinatorial approaches available for AP treatment.

N-Acetylcysteine enhances the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation in rats with severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) is a high mortality disease, for which there is a lack of effective therapies. Previous research has demonstrated that bone marrow-derived mesenchymal stem cells (BMSCs), which have immunomodulatory and antioxidant properties, have potential for the treatment of SAP. It remains unclear, however, whether the free radical scavenger N-acetylcysteine (NAC) can enhance the therapeutic efficacy of BMSC transplantation in SAP. In this study, we investigated the effect of combining treatment with NAC and BMSCs in a rat model of SAP.

METHODS

SAP was induced by injection of sodium taurocholate into the pancreatic duct and, after successful induction of SAP, the rats were treated with BMSCs and NAC, either singly or in combination.

RESULTS

After 3 days, serum levels of amylase, proinflammatory factors, malondialdehyde, and reactive oxygen species were significantly decreased in animals treated with BMSCs or NAC, compared with vehicle-treated animals. In contrast, total glutathione, superoxide dismutase and catalase were markedly increased after treatment with BMSCs or NAC. However, oxidative stress markers and inflammatory factors were significantly improved in the SAP + BMSCs + NAC group compared with those in the SAP + NAC group and the SAP + BMSCs group.

CONCLUSIONS

Combined NAC and BMSC therapy was found to alleviate oxidative stress damage to the pancreas and to inhibit the inflammatory response to a significantly greater extent than single therapy with either BMSCs or NAC. Because NAC enhances the therapeutic efficacy of BMSC transplantation in a rat model of SAP, combined therapy may provide a promising new approach for the treatment of SAP.

Recombinant human hepatocyte growth factor provides protective effects in cerulein-induced acute pancreatitis in mice

Acute pancreatitis is a multifactorial disease associated with profound changes of the pancreas induced by release of digestive enzymes that lead to increase in proinflammatory cytokine production, excessive tissue necrosis, edema, and bleeding. Elevated levels of hepatocyte growth factor (HGF) and its receptor c-Met have been observed in different chronic and acute pancreatic diseases including experimental models of acute pancreatitis. In the present study, we investigated the protective effects induced by the recombinant human HGF in a mouse model of cerulein-induced acute pancreatitis. Pancreatitis was induced by 8 hourly administrations of supramaximal cerulein injections (50 µg/kg, ip). HGF treatment (20 µg/kg, iv), significantly attenuated lipase content and amylase activity in serum as well as the degree inflammation and edema overall leading to less severe histologic changes such as necrosis, induced by cerulein. Protective effects of HGF were associated with activation of pro-survival pathways such as Akt, Erk1/2, and Nrf2 and increase in executor survival-related proteins and decrease in pro-apoptotic proteins. In addition, ROS content and lipid peroxidation were diminished, and glutathione synthesis increased in pancreas. Systemic protection was observed by lung histology. In conclusion, our data indicate that HGF exerts an Nrf2 and glutathione-mediated protective effect on acute pancreatitis reflected by a reduction in inflammation, edema, and oxidative stress.

Protective effects of phloridzin against methotrexate-induced liver toxicity in rats

BACKGROUND

Liver is the largest internal organ concerning with metabolism, hormonal balance and clarifying of the toxins. One of the main complications of methotrexate (MTX) therapy was the hepatic injury.

OBJECTIVE

This study was conducted to elucidate the possible protective effects of phloridzin (PHL) against MTX-induced hepatotoxicity as compared to standard agent N-acetylcysteine (NAC).

MATERIALS AND METHODS

Rats were randomly divided into a normal control group, a respective group (PHL 40mg/kg/day orally (p.o.) for 10 consecutive days), a hepatotoxicity control group (MTX 20mg/kg, i.p., once), and three treated groups received NAC (150mg/kg/day; a reference standard), PHL (40mg/kg/day) and PHL (80mg/kg/day) p.o. for 10 consecutive days, at the end of the day 3 of the experiment rats were administered MTX. Assessed biomarkers included serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) as liver function parameters, serum tumor necrosis factor-α (TNF-α) and cyclooxygenase-II (COX-II), as inflammatory biomarkers, hepatic total antioxidant capacity (TAC), thiobarbituric acid reactive substances (TBARS), glutathione reduced (GSH), nitrite (NO₂^-), catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) as oxidative stress biomarkers. Furthermore, hepatic caspase-3 expression was assessed. Biochemical and molecular estimations reinforced by histopathological findings.

RESULTS

Rats pre-treated with PHL significantly reduced hepatic injury, evidenced by significant reductions in ALT, AST and LDH, TNF-α and COX-II levels, significant reductions in hepatic NO₂^- and TBARS levels, and significant elevations in hepatic TAC, GSH, GST, CAT and SOD levels. Additionally, downregulation of hepatic caspase-3 expression. Finally, histopathological results consistent with our previous findings.

CONCLUSION

PHL protects against hepatic injury in rats mainly through mitigation of oxidative stress, inflammation and apoptosis in hepatic tissues and may be promising to alleviate and early treatment of MTX-induced hepatoxicity in man.

The "Scope" of Post-ERCP Pancreatitis

Pancreatitis is the most common adverse event of endoscopic retrograde cholangiopancreatography, with the potential for clinically significant morbidity and mortality. Several patient and procedural risk factors have been identified that increase the risk of post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP). Considerable research efforts have identified several pharmacologic and procedural interventions that can drastically affect the incidence of PEP. This review article addresses the underlying mechanisms at play for the development of PEP, identifying patient and procedural risk factors and meaningful use of risk-stratification information, and details current interventions aimed at reducing the risk of this complication.

Antioxidant Effect of Ukrain Versus N-Acetylcysteine Against Acute Biliary Pancreatitis in An Experimental Rat Model

Purpose/Aim: Oxidative stress plays an important role in the pathogenesis of acute pancreatitis (AP). We compared the therapeutic effects of Ukrain (NSC 631570) and N-acetylcysteine (NAC) in rats with AP.

MATERIALS AND METHODS

Forty male Sprague Dawley rats were divided into four groups: controls; AP; AP with NAC; and AP with Ukrain. AP was induced via the ligation of the bile-pancreatic duct; drugs were administered intraperitoneally (i.p.) 30 min and 12 h after AP induction. Twenty-four hours after AP induction, animals were sacrificed and the pancreas was excised. Levels of malondialdehyde (MDA) and nitric oxide (NO), and activity levels of tumor necrosis factor (TNF)-α, and myeloperoxidase (MPO) were measured in tissue samples. Total oxidant status (TOS), total antioxidant status (TAS), and total bilirubin, as well as activity levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), amylase and lipase were measured in serum samples. Pancreatic tissue histopathology was also evaluated.

RESULTS

Test drugs reduced levels of MDA, NO, TNF-α, total bilirubin, AST, ALT, TOS and MPO, amylase and lipase activities (P < 0.001), and increased TAS (P < 0.001). Rats treated with test drugs attenuated AP-induced morphologic changes and decreased pancreatic damage scores compared with the AP group (P < 0.05). Both test drugs attenuated pancreatic damage, but the therapeutic effect was more pronounced in rats that received Ukrain than in those receiving NAC.

CONCLUSIONS

These results suggest that treatment with Ukrain or NAC can reduce pancreatic damage via anti-inflammatory and antioxidant effects.

Artesunate ameliorates severe acute pancreatitis (SAP) in rats by inhibiting expression of pro-inflammatory cytokines and Toll-like receptor 4

Severe acute pancreatitis (SAP) is a severe clinical condition with significant morbidity and mortality. Multiple organs dysfunction (MOD) is the leading cause of SAP-related death. The over-release of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α is the underlying mechanism of MOD; however, there is no effective agent against the inflammation. Herein, artesunate (AS) was found to increase the survival of SAP rats significantly when injected with 3.5% sodium taurocholate into the biliopancreatic duct in a retrograde direction, improving their pancreatic pathology and decreasing serum amylase and pancreatic lipase activities along with substantially reduced pancreatic IL-1β and IL-6 release. In vitro, AS-pretreatment strongly inhibited IL-1β and IL-6 release and their mRNA expressions in the pancreatic acinar cells treated with lipopolysaccharide (LPS) but exerted little effect on TNF-α release. Additionally, AS reduced the mRNA expressions of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) p65 as well as their protein expressions in the pancreatic acinar cells. In conclusion, our results demonstrated that AS could significantly protect SAP rats, and this protection was related to the reduction of digestive enzyme activities and pro-inflammatory cytokine expressions via inhibition of TLR4/NF-κB signaling pathway. Therefore, AS may be considered as a potential therapeutic agent against SAP.

Reactive oxygen species, Ca(2+) stores and acute pancreatitis; a step closer to therapy?

Disruption of Ca(2+) homeostasis can lead to severe damage of the pancreas, resulting in premature activation of digestive enzymes, vacuolisation and necrotic cell death, features typical of acute pancreatitis (AP). Therefore a fine balance between Ca(2+) release from internal stores, Ca(2+) entry and extrusion mechanisms is necessary to avoid injury. Precipitants of AP induce Ca(2+) overload of the pancreatic acinar cell that causes mitochondrial dysfunction, via formation of the mitochondrial permeability transition pore (MPTP), loss of ATP production and consequent necrosis. Oxidative stress has been shown to occur in the development of AP and may modify Ca(2+) signalling events in the acinar cell. However, the precise pathophysiological involvement is currently unclear and antioxidant therapy in the clinic has largely proved ineffective. Possible reasons for this are discussed, including evidence that ROS generation may determine cell death patterns. In contrast, recent evidence has indicated the potential for AP therapy via the prevention of Ca(2+)-dependent mitochondrial damage. Multiple approaches are indicated from preclinical findings; 1) inhibition of Ca(2+) release by IP3R blockade, 2) inhibition of Ca(2+) entry through Orai1 blockade and 3) prevention of MPTP formation. Clinical trials of drugs which prevent mitochondrial dysfunction induced by Ca(2+) overload of pancreatic acinar cells are imminent and may provide patient benefit for a disease that currently lacks specific therapy.

Effects of the mitochondria-targeted antioxidant mitoquinone in murine acute pancreatitis

Although oxidative stress has been strongly implicated in the development of acute pancreatitis (AP), antioxidant therapy in patients has so far been discouraging. The aim of this study was to assess potential protective effects of a mitochondria-targeted antioxidant, MitoQ, in experimental AP using in vitro and in vivo approaches. MitoQ blocked H2O2-induced intracellular ROS responses in murine pancreatic acinar cells, an action not shared by the control analogue dTPP. MitoQ did not reduce mitochondrial depolarisation induced by either cholecystokinin (CCK) or bile acid TLCS, and at 10 µM caused depolarisation per se. Both MitoQ and dTPP increased basal and CCK-induced cell death in a plate-reader assay. In a TLCS-induced AP model MitoQ treatment was not protective. In AP induced by caerulein hyperstimulation (CER-AP), MitoQ exerted mixed effects. Thus, partial amelioration of histopathology scores was observed, actions shared by dTPP, but without reduction of the biochemical markers pancreatic trypsin or serum amylase. Interestingly, lung myeloperoxidase and interleukin-6 were concurrently increased by MitoQ in CER-AP. MitoQ caused biphasic effects on ROS production in isolated polymorphonuclear leukocytes, inhibiting an acute increase but elevating later levels. Our results suggest that MitoQ would be inappropriate for AP therapy, consistent with prior antioxidant evaluations in this disease.

Trimetazidine significantly reduces cerulein-induced pancreatic apoptosis

OBJECTIVE

Acute pancreatitis continues to be associated with significant rates of mortality and morbidity, and therapeutic options are still very limited. We aimed to investigate the efficacy of trimetazidine on cerulein-induced pancreatic apoptosis and histopathological and biochemistrical consequences of acute pancreatitis.

METHODS

Thirty-two Wistar albino rats were randomized into four groups (group 1: control group; group 2: acute pancreatitis group; group 3: acute pancreatitis and trimetazidine treatment group; group 4: placebo group). Acute edematous pancreatitis was induced by subcutaneous cerulein injection (20 μg/kg) four times at one-hour intervals. Trimetazidine was prepared in suspension form. In group 3, after gas anesthesia, trimetazidine was administrated to rats via a catheter. Serum interleukin (IL)-1β, tumor necrosis factor (TNF)-α, amylase, lipase and leukocyte levels, pancreatic apoptotic status and pancreatic Schoenberg scores were determined for all groups. Results are given as the mean ± SD. A value of P<0.05 was accepted as statistically significant. SPSS for Windows v15.0 was used for statistical analyses.

RESULTS

In the acute pancreatitis group IL-1β, amylase, lipase and leukocyte levels were elevated and pancreatic histopathological evaluation revealed a diagnosis of acute pancreatitis IL-1β amylase and lipase levels and pancreatic inflammation were decreased significantly in the trimetazidine group (P<0.01). White blood cell counts and TNF-α concentrations for the trimetazidine group and the acute pancreatitis group were not significantly different. Trimetazidine significantly reduced apoptosis in pancreatic tissues and Schoenberg scores were also significantly reduced (P<0.05).

CONCLUSION

In this study, we showed that trimetazidine treatment significantly decreases the levels of IL-1β, amylase and lipase reduces pancreatic apoptosis and ameliorates the histopathological findings of cerulein-induced acute pancreatitis. Trimetazidine could be a new therapeutic option in the early treatment of acute pancreatitis.

Oxidative stress and inflammatory signaling in cerulein pancreatitis

Oxidative stress is considered to be an important regulator of the pathogenesis of acute pancreatitis. Reactive oxygen species (ROS) regulate the activation of inflammatory cascades, the recruitment of inflammatory cells and tissue damage in acute pancreatitis. A hallmark of the inflammatory response in pancreatitis is the induction of cytokine expression, which is regulated by a number of signaling molecules including oxidant-sensitive transcription factors such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinases (MAPKs). Cross-talk between ROS and pro-inflammatory cytokines is mediated by NF-κB, AP-1, STAT3, and MAPKs; this crosstalk amplifies the inflammatory cascade in acute pancreatitis. Therapeutic studies have shown that antioxidants and natural compounds can have beneficial effects for patients with pancreatitis and can also influence the expression of proinflammatory cytokines in cerulein-induced pancreatitis. Since oxidative stress may activate inflammatory signaling pathways and contribute to the development of pancreatitis, antioxidant therapy may alleviate the symptoms or prevent the development of pancreatitis. Since chronic administration of high doses of antioxidants may have deleterious effects, dosage levels and duration of antioxidant treatment should be carefully determined.

Effectiveness of interleukin-1 receptor antagonist (Anakinra) on cerulein-induced experimental acute pancreatitis in rats

AIM

Acute pancreatitis (AP) is defined as an inflammatory disease of the pancreas. The purpose of this study was to examine the effectiveness of Anakinra on cerulein-induced experimental pancreatitis rat model by using the results of biochemical and histopathological findings.

MATERIALS AND METHODS

Cerulein was administered to induce AP in rats. Group 1 was the sham group. Subcutancerulein was injected to the rats in group 2 for experimental pancreatitis group. In groups 3 and 4, 100 and 50 mg/kg intraperitoneal Anakinra were injected after the induction of experimental pancreatitis by subcutaneous cerulein in rats, respectively. Lastly, in group 5, rats were injected with intraperitoneal saline and subcutan cerulean for placebo group. The following parameters were evaluated: histopathological score of pancreatitis, apoptotic index, amylase, lipase, TNF-α levels, IL-1β and the leukocyte count.

RESULTS

When the results of serum amylase, lipase, TNF-α and IL-1β levels, the leukocyte count, histopathologic scores and apoptotic indices of control group compared to the results of other groups, the differences exhibited statistical significance (all p < 0.05). On the other hand, when the results of fourth group compared with the results of third group, the data demonstrated statistical insignificance (p > 0.05). However, no any significant differences were found between the results of fourth and fifth groups (p > 0.05).

CONCLUSION

In the light of these results, cerulein is an appropriate agent for experimental AP rat model and Anakinra has a favorable therapeutic effect on acute experimental pancreatitis model. Moreover, Anakinra significantly decreases cerulein-related pancreatic tissue injury and pancreatic apoptosis.

Free radicals and acute pancreatitis: much ado about … something

There is a convincing body of evidence that oxidative stress is involved in the pathogenesis of acute pancreatitis. The effects of different radical scavengers suggested that reactive oxygen metabolites are generated at very early stage of disease and contribute to amplify the pancreatic damage. Oxidative stress is also involved in the progression of the disease from a local damage to a systemic organ failure. However, therapeutic use of antioxidants failed to clearly show a clinical benefit in different trials. Therefore, although antioxidants alone seem to be not enough for the treatment of severe acute pancreatitis, future combined therapeutic strategies should include antioxidants in its composition.

Oxidative stress in acute pancreatitis: lost in translation?

Oxidative stress has been implicated in the pathogenesis of acute pancreatitis, a severe and debilitating inflammation of the pancreas that carries a significant mortality, and which imposes a considerable financial burden on the health system due to patient care. Although extensive efforts have been directed towards the elucidation of critical underlying mechanisms and the identification of novel therapeutic targets, the disease remains without a specific therapy. In experimental animal models of acute pancreatitis, increased oxidative stress and decreased antioxidant defences have been observed, changes also detected in patients clinically. However, despite the promise of studies evaluating the effects of antioxidants in these model systems, translation to the clinic has thus far been disappointing. This may reflect many factors involved in the design of both preclinical and clinical evaluations of antioxidant therapy, not least the fact that most experimental studies have focussed on pre-treatment rather than post-injury assessment. This review has examined evidence relating to the involvement of oxidative stress in the pathophysiology of acute pancreatitis, focussing on experimental models and the clinical experience, including the experimental techniques employed and potential of antioxidant therapy.

N-acetylcysteine improves pancreatic microcirculation and alleviates the severity of acute necrotizing pancreatitis

Background/Aims

To investigate the beneficial effect of N-Acetylcysteine (NAC) on pancreatic microvascular perfusion in acute necrotizing pancreatitis (ANP).

Methods

Fifty-four rats were divided into a control group, an ANP group and an NAC-treated group. The ANP model was established by a retrograde injection of 3% sodium taurocholate into the pancreatic duct. The NAC-treated group received an intravenous infusion of NAC just 2 hours before and 30 minutes after the induction of ANP. The pancreatic microvascular perfusion was measured with laser Doppler flowmetry and pancreatic samples were collected for histological examination.

Results

The microvascular perfusion in the NAC-treated group decreased slightly and exhibited a significant increase compared to the ANP group (p<0.01). A pathological examination revealed that edema and inflammatory infiltration decreased, and the hemorrhaging and necrosis of the pancreas were significantly reduced.

Conclusions

NAC could improve pancreatic microvascular perfusion and alleviate the severity of sodium taurocholate-induced ANP, possibly representing a new therapeutic approach to prevent the progression of ANP.

Beneficial effects of trypsin inhibitors derived from a spider venom peptide in L-arginine-induced severe acute pancreatitis in mice

HWTI is a 55-residue protein isolated from the venom of the spider Ornithoctonus huwena. It is a potent trypsin inhibitor and a moderate voltage-gated potassium channel blocker. Here, we designed and expressed two HWTI mutants, HWTI-mut1 and HWTI-mut2, in which the potassium channel inhibitory activity was reduced while the trypsin inhibitory activity of the wild type form (approximately 5 EPU/mg) was retained. Animal studies showed that these mutants were less toxic than HWTI. The effects of HWTI and HWTI-mut1 were examined in a mouse model of acute pancreatitis induced by intraperitoneal injection of a large dose of L-arginine (4 mg/kg, twice). Serum amylase and serum lipase activities were assessed, and pathological sections of the pancreas were examined. Treatment with HWTI and HWTI-mut1 significantly reduced serum amylase and lipase levels in a dose dependent manner. Compared with the control group, at 4 mg/kg, HWTI significantly reduced serum amylase level by 47% and serum lipase level by 73%, while HWTI-mut1 significantly reduced serum amylase level by 59% and serum lipase level by 72%. Moreover, HWTI and HWTI-mut1 effectively protected the pancreas from acinar cell damage and inflammatory cell infiltration. The trypsin inhibitory potency and lower neurotoxicity of HWTI-mut1 suggest that it could potentially be developed as a drug for the treatment of acute pancreatitis with few side effects.

The protective effects of taurine on experimental acute pancreatitis in a rat model

The aim of this study was to investigate the protective effects of taurine (Tau) on experimental acute pancreatitis (AP) in a rat model by measuring cytokines and oxidant stress markers.

Forty rats were randomly divided into four groups: sham, AP, Tau and AP + Tau. AP was induced with sodium taurocholate. No treatment was given to the AP. All rats were killed 5 days later. Pancreatic tissues of rats and blood samples were obtained.

Tau treatment significantly decreased serum amylase activity ( p < 0.001), total injury score ( p < 0.001), malondialdehyde levels ( p < 0.001) and myeloperoxidase (MPO) activity ( p < 0.001). There was no significant difference between the Tau and AP + Tau groups in serum and pancreatic tumor necrosis factor-α, interleukin (IL)-1β and IL-6 levels ( p = 1.000). Histopathologic scores in the AP + Tau and Tau groups were significantly lower compared with the AP group (both p < 0.001).

These results showed that Tau reduces lipid peroxidation, amylase and MPO activities and the concentrations of proinflammatory cytokines secondary to AP and also increases superoxide dismutase and glutathione peroxidase activities in rats with sodium taurocholate-induced AP. It also has a marked ameliorative effect at histopathologic lesions. With these effects, Tau protects the cells from oxidative damage, reduces inflammation and promotes regression of pancreatic damage.

Effects of Chai-Qin-Cheng-Qi decoction () on acute pancreatitis-associated lung injury in mice with acute necrotizing pancreatitis

OBJECTIVE: To investigate the effects of Chai-Qin-Cheng-Qi Decoction (, CQCQD) on acute pancreatitis-associated lung injury in mice with acute necrotizing pancreatitis (ANP). METHODS: Thirty healthy mice were randomly divided into three groups: an ANP group (ANP+placebo, n=10); a treatment group (ANP+CQCQD, n=10); and a control group (normal mice+placebo, n=10). ANP was induced by intraperitoneal injection with 8% L-arginine (4 μg/kg), and the control group was injected with normal saline. The treatment group received CQCQD (20 mL/kg), and the ANP and control groups received placebo (sucrose and starch) intragastrically at 2 h intervals. After the third intragastric administration, blood, pancreatic tissues and right lung tissues were collected for measurement of serum interleukin-6 (IL-6) and interleukin-10 (IL-10) by enzyme-linked immunosorbent assay, and the expression of heat shock protein 70 (HSP70) in lung tissue was determined by Western blot analysis. Pathological changes of pancreatic tissue and lung tissue were examined. RESULTS: Serum IL-6 was significantly higher in the ANP group compared with the control and the treatment groups (1589.63±377.28 vs. 927.46±210.42 pg/mL, P<0.05, and 1589.63±377.28 vs. 1107.73±351.62 pg/mL, P<0.05, respectively). The IL-10 concentration was significantly lower in the ANP group compared with the treatment group (920.64±101.68 vs. 1177.84±201.72 pg/mL, P<0.05), but no signififi cant difference was found between the ANP and control groups and between the treatment and control groups. The expression level of HSP70 in the ANP and control groups was signififi cantly lower than in the treatment group (0.93±0.03 vs. 1.42±0.21, P<0.01, and 0.81±0.09 vs. 1.42±0.21, P<0.01, respectively). There was no signififi cant difference in HSP70 levels between the ANP and control groups. Histological scores of pancreatic and lung tissue were significantly decreased in the treatment group compared with the ANP groups (4.50±0.54 vs. 6.20±1.65, P<0.05, and 3.00±0.63 vs. 3.87±0.83, P<0.05, respectively). CONCLUSIONS: The incidence of acute pancreatitisassociated lung injury in ANP mice correlates positively with serum IL-6 concentration. CQCQD may inhibit IL-6 induction and increase IL-10 concentration and HSP70 expression, effectively reducing lung injury.

N-acetyl cysteine suppresses the foam cell formation that is induced by oxidized low density lipoprotein via regulation of gene expression

Foam cells derived from macrophages have been implicated as markers of early stage atherosclerosis development. In this study, we found that N-acetyl cysteine (NAC), a well-known inhibitor of reactive oxygen species (ROS), decreased the generation of ROS and suppressed foam cell formation in the presence of oxidized low density lipoprotein through down-regulation of cluster of differentiation 36 expression. We investigated gene expression profiles in order to determine the effects of NAC on foam cell formation using a microarray analysis. The level of apolipoprotein E, which is involved in lipid efflux, was increased and the levels of the antioxidant genes glutathione peroxidase 1 and 3 were also increased. The expression levels of the oxidative stress response and the DNA repair genes were decreased. These results were confirmed using quantitative real-time PCR. Our results indicate that oxidative stress plays an important role in foam cell formation, and that regulation of oxidation using antioxidants is a potential therapeutic method for blocking atherosclerosis development.

Antifibrotic and antioxidant effects of N-acetylcysteine in an experimental cholestatic model

OBJECTIVES

Several studies have suggested that oxidative stress may play an important role in the pathogenesis of hepatic injury during cholestasis in rats and humans. The aim of this study was to evaluate the ability of N-acetylcysteine (NAC) to prevent the damage induced by bile duct ligation (BDL) for 28 days in male Wistar rats.

METHODS

NAC was administered daily (300 mg/kg, orally) for 28 days. Alanine aminotransferase was quantified in the serum; lipid peroxidation, glutathione, and catalase activity were measured in the liver. Fibrosis was assessed by measuring the liver hydroxyproline content; transforming growth factor-β (TGF-β), interleukin (IL)-6, and IL-10 were determined in the liver by a western blot and quantified densitometrically.

RESULTS

The induction of cholestatic damage by BDL was associated with an increase in alanine aminotransferase. Oxidative stress was also evaluated; lipid peroxidation increased, whereas the liver glutathione content and catalase activity decreased by BDL. NAC treatment prevented these alterations. Hydroxyproline was increased by chronic BDL, but NAC preserved the normal hydroxyproline levels. Cytokines TGF-β, IL-6, and IL-10 increased after 28 days of BDL. NAC was effectively significant in preventing TGF-β and IL-6 expression and further augmented the IL-10 expression.

CONCLUSION

Our data indicate that in the development to cholestatic liver damage, oxidative stress plays an important role and this in turn leads to fibrosis. This study shows that the beneficial effects of NAC are because of its antioxidant and immunomodulatory properties.

Hyperbaric oxygen and N-acetylcysteine treatment in L-arginine-induced acute pancreatitis in rats

BACKGROUND

This study was designed to evaluate the combined effects of hyperbaric oxygen (HBO) and N-acetylcysteine (NAC) on acute necrotizing pancreatitis in rats.

METHODS

Experiments were performed in 50 male Wistar rats, which were divided into five groups (N = 10 for each group). The first group received normal saline (0.9% NaCl) intraperitoneal and served as the control group. In the second group, acute pancreatitis was induced by 3.2-g/kg body weight L-arginine intraperitoneal twice at an interval of 1 hr, which has been shown previously to produce severe necrotizing acute pancreatitis. In the third group, NAC treatment (1000 mg/kg) was given after 1 hr of the induction of acute pancreatitis twice 24 hr apart. In the fourth group, animals received HBO, 6 hr after the induction of pancreatitis twice 12 hr apart. In the fifth group, animals received together NAC as in Group 3 and HBO treatment as in Group 4. Groups 1, 2, and 3 were left under normal atmospheric pressures. Twelve hours after last treatment, the animals were killed by exsanguinations. Blood samples were studied for amylase, calcium, and lactate dehydrogenase (LDH), pancreatic histology, pancreatic tissue malondialdehyde, superoxide dismutase, and glutathione levels.

RESULTS

Acute pancreatitis is reduced by the treatment of NAC, HBO, NAC + HBO. HBO + NAC groups performed statistically the best in preventing L-arginine-induced acute necrotising pancreatitis.

CONCLUSIONS

NAC especially combined with HBO, decreases oxidative stress parameters, serum amylase, calcium, and LDH levels, as well as histopathologic score.

Multidrug strategies are effective in the treatment of severe experimental pancreatitis

BACKGROUND

Trypsinogen activation, oxygen radicals, cytokines, leukocyte infiltration, and pancreatic ischemia are important steps in the pathogenesis of necrotizing pancreatitis and associated systemic complications. Several drugs that inhibit those pathogenetic steps attenuated biochemical and histologic changes, while survival remained low. The aim of the present study was to evaluate the benefit of multidrug approaches compared to monotherapies on organ injury and survival in acute experimental pancreatitis in the rat model of retrograde bile injection combined with intravenous cerulein.

METHODS

Necrotizing pancreatitis was induced in rats. After a therapy-free interval of 6 hours, 10 treatment regimens were evaluated: multidrug regimen 1, which contained the protease inhibitor gabexate mesilate, oxygen-free radical scavengers, nitric oxide donor L-arginine, a platelet-activating factor antagonist, and antibodies against intracellular adhesion molecule-1 (ICAM-1) dissolved in dextran, was compared to multidrug regimen 2 (dextran, acetylcysteine, L-arginine, and anti-ICAM-1), monotherapies of each of the drugs, and standard intravascular volume replacement.

RESULTS

Both multidrug regimens significantly reduced pancreatic and systemic injury and microcirculatory disturbances compared to any of the monotherapies. Treatment with regimen 1 decreased 24-hour mortality to 0% and increased long-term survival to 85% (standard therapy, 70% and 15%, respectively). Multidrug regimen 2 was as effective as regimen 1.

CONCLUSION

Treatment of acute necrotizing pancreatitis with multidrug regimens significantly decreases short-term mortality compared to monotherapies. Moreover, multidrug strategies are still effective after a wide therapeutic window. Key to this effective therapy is the inhibition of microcirculatory disturbances and of the systemic inflammatory response. The experimental superiority of the multidrug approach should be confirmed in a clinical trial.

Prevention of Post-ERCP Pancreatitis

Pancreatitis is the most common complication of ERCP. It can be associated with substantial morbidity. Hence, the minimization of both the incidence and severity of post-ERCP pancreatitis is paramount. Considerable efforts have been made to identify factors that may be associated with an increased risk of this complication. In addition, both procedure- and pharmacological-related interventions have been proposed that may prevent this complication. This paper outlines these interventions and presents the evidence to support their use in the prevention of post-ERCP pancreatitis.

Curcumin protects intestinal mucosal barrier function of rat enteritis via activation of MKP-1 and attenuation of p38 and NF-κB activation

Background

Intestinal mucosa barrier (IMB) dysfunction results in many notorious diseases for which there are currently few effective treatments. We studied curcumin's protective effect on IMB and examined its mechanism by using methotrexate (MTX) induced rat enteritis model and lipopolysaccharide (LPS) treated cell death model.

Methodology/Principal Findings

Curcumin was intragastrically administrated from the first day, models were made for 7 days. Cells were treated with curcumin for 30 min before exposure to LPS. Rat intestinal mucosa was collected for evaluation of pathological changes. We detected the activities of D-lactate and diamine oxidase (DAO) according to previous research and measured the levels of myeloperoxidase (MPO) and superoxide dismutase (SOD) by colorimetric method. Intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were determined by RT-PCR and IL-10 production was determined by ELISA. We found Curcumin decreased the levels of D-lactate, DAO, MPO, ICAM-1, IL-1β and TNF-α, but increased the levels of IL-10 and SOD in rat models. We further confirmed mitogen-activated protein kinase phosphatase-1 (MKP-1) was activated but phospho-p38 was inhibited by curcumin by western blot assay. Finally, NF-κB translocation was monitored by immunofluorescent staining. We showed that curcumin repressed I-κB and interfered with the translocation of NF-κB into nucleus.

Conclusions/Significance

The effect of curcumin is mediated by the MKP-1-dependent inactivation of p38 and inhibition of NF-κB-mediated transcription. Curcumin, with anti-inflammatory and anti-oxidant activities may be used as an effective reagent for protecting intestinal mucosa barrier and other related intestinal diseases.

Therapeutic effect of caffeic acid phenethyl ester on cerulein-induced acute pancreatitis

AIM: To evaluate the therapeutic role of caffeic acid phenethyl ester (CAPE) in a rat model of cerulean-induced acute pancreatitis (AP).

METHODS: Seventy male Wistar albino rats were divided into seven groups. Acute edematous pancreatitis was induced by subcutaneous cerulein injection (20 μg/kg) four times at 1-h intervals. CAPE (30 mg/kg) was given by subcutaneous injection at the beginning (CAPE 1 group) and 12 h after the last cerulein injection (CAPE 2 group). Serum amylase, lipase, white blood cell count, and tumor necrosis factor (TNF)-α levels were measured, and pancreatic histopathology was assessed.

RESULTS: In the AP group, amylase and lipase levels were found to be elevated and the histopathological evaluation showed massive edema and inflammation of the pancreas, with less fatty necrosis when compared with sham and control groups. Amylase and lipase levels and edema formation decreased significantly in the CAPE therapy groups (P < 0001); especially in the CAPE 2 group, edema was improved nearly completely (P = 0001). Inflammation and fatty necrosis were partially recovered by CAPE treatment. The pathological results and amylase level in the placebo groups were similar to those in the AP group. White blood cell count and TNF-α concentration was nearly the same in the CAPE and placebo groups.

CONCLUSION: CAPE may be useful agent in treatment of AP but more experimental and clinical studies are needed to support our observation of beneficial effects of CAPE before clinical usage of this agent.

N-acetylcysteine prevents carbon tetrachloride-induced liver cirrhosis: role of liver transforming growth factor-beta and oxidative stress

OBJECTIVES

N-acetylcysteine (NAC) is an antioxidant, a precursor of reduced glutathione, and an inhibitor of the profibrotic cytokine liver transforming growth factor-beta (TGF-beta). Carbon tetrachloride (CCl4) cirrhosis is characterized by oxidative stress and fibrosis. Therefore, the aim of this work was to study the effect of NAC on experimental cirrhosis.

METHODS

CCl4 was chronically administered for 8 weeks along with 300 mg/kg of NAC orally once a day. Alkaline phosphatase, alanine aminotransferase, and gamma-glutamyltranspeptidase were measured in plasma. Hydroxyproline, glycogen, lipid peroxidation, glutathione were determined in liver samples by colorimetric methods. TGF-beta was evaluated by western blotting, and a histopathological analysis was performed.

RESULTS

Serum markers of liver damage increased by CCl4 intoxication (P<0.05), whereas cotreatment with NAC prevented these increases (P<0.05); glycogen was depleted in the cirrhotic group (P<0.05), but preserved by NAC (P<0.05). Lipid peroxidation increased and glutathione decreased by the administration of CCl4 (P<0.05), again NAC prevented both effects (P<0.05). Importantly, collagen increased by about seven-fold in the CCl4 group (P<0.05); administration of NAC preserved the normal levels of collagen (P<0.05). Biochemical determinations were corroborated by hematoxylin and eosin, and trichromic stains. Western blots revealed a four-fold increase in TGF-beta in the group receiving CCl4, NAC cotreatment abolished TGF-beta signal (P<0.05).

CONCLUSION

Our results strongly suggest that NAC prevents experimental cirrhosis by two mechanisms: by preventing oxidative stress and by downregulating the profibrogenic cytokine TGF-beta. As NAC is currently used in humans intoxicated with paracetamol, it can be tested in fibrotic or cirrhotic patients under controlled trials.

Role of oxidative stress in pancreatic inflammation

Reactive oxygen and reactive nitrogen species (ROS/RNS) have been implicated in the pathogenesis of acute and chronic pancreatitis. Clinical and basic science studies have indicated that ROS/RNS formation processes are intimately linked to the development of the inflammatory disorders. The detrimental effects of highly reactive ROS/RNS are mediated by their direct actions on biomolecules (lipids, proteins, and nucleic acids) and activation of proinflammatory signal cascades, which subsequently lead to activation of immune responses. The present article summarizes the possible sources of ROS/RNS formation and the detailed signaling cascades implicated in the pathogenesis of pancreatic inflammation, as observed in acute and chronic pancreatitis. A therapeutic ROS/RNS-scavenging strategy has been advocated for decades; however, clinical studies examining such approaches have been inconsistent in their results. Emerging evidence indicates that pancreatitis-inducing ROS/RNS generation may be attenuated by targeting ROS/RNS-generating enzymes and upstream mediators.

Redox status of acute pancreatitis as measured by cyclic voltammetry: initial rodent studies to assess disease severity

OBJECTIVE

To determine whether serum antioxidant capacity as measured by the electrochemical technique cyclic voltammetry could be used to resolve differences in the severity of an inflammatory disease such as acute pancreatitis.

DESIGN

Experimental animal study.

SETTING

Animal laboratory, Department of Surgery, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

A total of 48 inbred male Wistar rats were studied in five experimental groups. Group 1 (baseline reference, immediate euthanasia, n = 14) had no surgical intervention. Group 2 (sham, n = 9) had identical surgical procedures to the pancreatitis groups except for the intraductal infusion. Groups 3-5 (n = 9, n = 10, and n = 6, respectively) had acute pancreatitis induced by the pancreatic intraductal infusion of 3%, 4%, or 5% sodium taurocholate, respectively. Groups 2-5 were killed after 12 hrs.

MEASUREMENTS AND MAIN RESULTS

Cyclic voltammetry involves scanning the voltage of a working electrode while recording the anodic current produced as the low molecular weight antioxidants in the solution are oxidized on the surface of the working electrode. The current produced is proportional to the combined concentration of the antioxidants. There was a significant positive correlation of the first cyclic voltammetric peak maximum with pancreatic histologic severity (Spearman's r = .51, p = .007) and with a number of other markers of systemic severity, notably bicarbonate (r = -.57, p = .002), base excess (r = -.65, p < .001), urea (r = .68, p < .001), and calcium (r = -.60, p = .008). The first cyclic voltammetric peak maximum was superior at indicating the severity of the disease state compared with a standard method of total antioxidant capacity measurement.

CONCLUSIONS

In experimental pancreatitis, the first cyclic voltammetric peak maximum showed significant correlations with histologic and systemic indices of severity. Further clinical studies are now needed to define the role of cyclic voltammetry in monitoring the progression of this and other severe illness in the critical care setting.

From acute pancreatitis to end-organ injury: mechanisms of acute lung injury

BACKGROUND

Multi-organ dysfunction, and in particular lung injury, is often responsible for the unfavorable outcome of patients with severe acute pancreatitis. Understanding of the mechanisms by which local inflammation in the pancreas leads to end-organ injury is crucial for the development of new therapeutic strategies.

METHODS

A MEDLINE search was performed with the terms "acute pancreatitis," "lung injury," "inflammatory response," "SIRS," and "multi-organ dysfunction." Pertinent articles were selected for analysis.

RESULTS

Modulation of the inflammatory response using a combination of immunomodulatory agents may decrease the incidence of severe pancreatitis-related acute lung injury and acute respiratory distress syndrome.

CONCLUSION

Clinical trials are of utmost importance to establish the validity of such strategies.

Zerumbone exerts a beneficial effect on inflammatory parameters of cholecystokinin octapeptide-induced experimental pancreatitis but fails to improve histology

OBJECTIVE

Our experiments were designed to investigate the effects of zerumbone pretreatment on cholecystokinin octapeptide (CCK-8)-induced acute pancreatitis in rats.

METHODS

Male Wistar rats weighing 240 to 280 g were divided into a control group, a group treated with CCK-8, a group receiving 20 mg/kg zerumbone before CCK-8 administration, and a group treated with zerumbone only.

RESULTS

The serum amylase and lipase activities and the pancreatic weight-body weight ratio were significantly reduced by zerumbone pretreatment, but the drug failed to influence the histological parameters of pancreatitis. The anti-inflammatory effects of the drug were manifested in decreases in the cytosolic interleukin 6 and tumor necrosis factor alpha concentrations and an elevation in the I-kappaB concentration, whereas the antioxidant ability of zerumbone was demonstrated by reductions in inducible nitric oxide synthase, Mn- and Cu/Zn-superoxide dismutase activities in the zerumbone-treated rats.

CONCLUSION

Zerumbone ameliorated the changes of several parameters of acute pancreatitis probably by interfering with I-kappaB degradation, but in the applied dose, it failed to influence the histology of the disease.

Acute pancreatitis: animal models and recent advances in basic research

Acute pancreatitis (AP) is characterized by edema, acinar cell necrosis, hemorrhage, and severe inflammation of the pancreas. Patients with AP present with elevated blood and urine levels of pancreatic digestive enzymes, such as amylase and lipase. Severe AP may lead to systemic inflammatory response syndrome and multiorgan dysfunction syndrome, which account for the high mortality rate of AP. Although most (>80%) cases of AP are associated with gallstones and alcoholism, some are idiopathic. Although the pathogenesis of AP has not yet been elucidated, a common feature is the premature activation of trypsinogen within pancreatic tissues, which triggers autodigestion of the gland. Recent advances in basic research suggest that etiologic factors including cyclooxygenase-2, substance P, and angiotensin II may have novel roles in this disease. Basic research data obtained thus far have been based on animal models of AP ranging from mild edematous pancreatitis to severe necrotizing pancreatitis. In view of this, an adequate selection of experimental animal models is of paramount importance. Notwithstanding these animal models, it should be emphasized that none of these models mimic the clinical situation where varying degrees of severity usually occur. In this review, commonly used animal models of AP will be critically evaluated. A discussion of recent advances in our knowledge about AP risk factors is also included.

N-acetylcysteine does not prevent post-endoscopic retrograde cholangiopancreatography hyperamylasemia and acute pancreatitis

AIM: Acute pancreatitis (AP) is the most common and often severe complication of endoscopic retrograde cholangiopancreatography (ERCP). The early step in the pathogenesis of acute pancreatitis is probably the capillary endothelial injury mediated by oxygen-derived free radicals. N-acetylcysteine - a free radical scavenger may be potentially effective in preventing post-ERCP acute pancreatitis and it is also known that N-acetylcysteine (ACC) can reduce the severity of disease in experimental model of AP.

METHODS: One hundred and six patients were randomly allocated to two groups. Fifty-five patients were given N-acetylcysteine (two 600 mg doses orally 24 and 12 h before ERCP and 600 mg was given iv, twice a day for two days after the ERCP). The control group consisted of 51 patients who were given iv. isotonic saline twice a day for two days after the ERCP. Serum and urine amylase activities were measured before ERCP and 8 and 24 h after the procedure. The primary outcome parameter was post-ERCP acute pancreatitis and the secondary outcome parameters were differences between groups in serum and urine amylase activity.

RESULTS: There were no significant differences in the rate of post-ERCP pancreatitis between two groups (10 patients overall, 4 in the ACC group and 6 in the control group). There were also no significant differences in baseline and post-ERCP serum and urine amylase activity between ACC group and control group.

CONCLUSION: N-acetylcysteine fails to demonstrate any significant preventive effect on post-ERCP pancreatitis, as well as on serum and urine amylase activity.

Effect of melatonin on the severity of L-arginine-induced experimental acute pancreatitis in rats

AIM: To determine the effect of melatonin pre- and post-treatment on the severity of L-arginine (L-Arg) -induced experimental pancreatitis in rats.

METHODS: Male Wistar rats (25) were divided into five groups. Those in group A received two injections of 3.2 g/kg body weight L-Arg i.p. at an interval of 1 h. In group MA, the rats were treated with 50 mg/kg body weight melatonin i.p. 30 min prior to L-Arg administration. In group AM, the rats received the same dose of melatonin 1 h after L-Arg was given. In group M, a single dose of melatonin was administered as described previously. In group C the control animals received physiological saline injections i.p. All rats were exsanguinated 24 h after the second L-Arg injection.

RESULTS: L-Arg administration caused severe necrotizing pancreatitis confirmed by the significant elevations in the serum amylase level, the pancreatic weight/body weight ratio (pw/bw), the pancreatic IL-6 content and the myeloperoxidase activity, relative to the control values. Elevation of the serum amylase level was significantly reduced in rats given melatonin following L-Arg compared to rats injected with L-Arg only. The activities of the pancreatic antioxidant enzymes (Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase (CAT)) were significantly increased 24 h after pancreatitis induction. Melatonin given in advance of L-Arg significantly reduced the pancreatic CAT activity relative to that in the rats treated with L-Arg alone. In the liver, L-Arg significantly increased the lipid peroxidation level, and the glutathione peroxidase and Cu/Zn-SOD activities, whereas the Mn-SOD activity was reduced as compared to the control rats. Melatonin pre-treatment prevented these changes.

CONCLUSION: Melatonin is an antioxidant that is able to counteract some of the L-Arg-induced changes during acute pancreatitis, and may therefore be helpful in the supportive therapy of patients with acute necrotizing pancreatitis.

Clinical implications of oxidative stress and antioxidant therapy

Oxidative stress occurs when there is an imbalance between generation of reactive oxygen species and inadequate antioxidant defense systems. Oxidative stress can cause cell damage either directly or through altering signaling pathways. Oxidative stress is a unifying mechanism of injury in many types of disease processes, including gastrointestinal diseases. For example, in alcoholic liver disease, reactive oxygen species have been detected through direct spin-trapping techniques and through indirect markers, such as products of lipid peroxidation. A host of antioxidants have protected against liver injury in animal models of alcoholic liver disease. Similarly, in inflammatory bowel disease, oxidative stress has been postulated to play a role in disease initiation and progression, and antioxidant therapy, such as green tea polyphenols and gene therapy with superoxide dismutase, has a markedly attenuated disease. Downregulation of specific detoxification genes may play a role in the pathogenesis of inflammatory bowel disease, especially in ulcerative colitis. Oxidative stress is postulated to play a sustaining role in acute and chronic pancreatitis. Antioxidant supplementation has been used with some success in the treatment of chronic pancreatitis. This review covers recent findings related to oxidative stress in liver disease, inflammatory bowel disease, and pancreatitis.

Identifying and defusing weapons of mass inflammation in carcinogenesis

The continued cancer risks associated with chronic inflammation necessitate the identification of inflammatory molecules and the cancer pathways they affect. Evidence indicates that there are multiple mechanisms linking inflammation to cancer and that there are multiple targets for chemoprevention. Here, we review some of the key factors and the cancer pathways they disturb as a necessary prerequisite to the identification of targets for chemoprevention.

Intravenous N-acetylcysteine does not prevent post-ERCP pancreatitis

BACKGROUND

Acute pancreatitis remains the most common complication of ERCP. Prophylactic administration of N-acetylcysteine (NAC) probably decreases the incidence and the severity of experimental pancreatitis. The aim of the present study was to assess the efficacy of intravenous NAC for prevention of post-ERCP pancreatitis in humans, who represent an appropriate model to study the potential role of NAC in this setting.

METHODS

A prospective, double-blind, placebo-controlled trial was conducted in 256 patients who underwent ERCP. Patients were randomized to receive intravenous NAC at a loading dose of 70 mg/kg 2 hours before and 35 mg/kg at 4-hour intervals for a total of 24 hours after the procedure, or to receive normal saline solution as placebo. Patients were clinically evaluated, and serum amylase levels were measured before and 6 hours and 24 hours after the procedure. Standardized criteria were used to diagnose and to grade the severity of post-ERCP pancreatitis.

RESULTS

A total of 249 patients were included in the analysis. The two groups were matched for age, gender, underlying disease and indication for treatment, ERCP findings, and type of treatment. The overall incidence of post-ERCP acute pancreatitis was 10.8%, with 12.1% in the NAC group and 9.6% in the placebo group. There were no statistical differences in the incidence or severity grades between the groups. The mean duration of hospitalization for pancreatitis also was similar in the NAC group and the placebo group (3.6 +/- 0.9 and 3 +/- 1.5 days, respectively).

CONCLUSIONS

The results of this trial show the absence of any beneficial effect of NAC on the incidence and the severity of ERCP-induced pancreatitis.