Inhibition of sepsis-induced pancreatic injury by leukotriene receptor antagonism via modulation of oxidative injury, and downregulation of in�ammatory markers in experimental rats

Purpose The purpose of this study is to investigate the effect of montelukast on lipopolysaccharide (LPS)-induced pancreatitis. Methods Acute pancreatitis was induced by a single dose of LPS (6 mg/kg, i.p.) while montelukast was given in two different doses (10 and 20 mg/kg/day) for three consecutive days prior to injection of LPS. Results Acute pancreatitis was demonstrated by signi�cant increases in serum levels of pancreatic enzymes lipase and amylase and lactate dehydrogenase (LDH). Proin�ammatory response activation was evident by elevated serum levels of nitric oxide (NO) and increased pancreatic concentrations of tumor necrosis factor-α (TNF-α ), interleukin-1 (IL-1 β ) and intercellular adhesion molecule-1 (ICAM-1). The activity of myeloperoxidase (MPO), a neutrophil in�ltration marker, has also been increased. Oxidative stress was con�rmed by signi�cant increases in the concentrations of lipid peroxides measured as thiobarbituric acid reactive substances (TBARS) and decreases in the concentrations of reduced glutathione (GSH) in the pancreatic tissues of animals treated with LPS. Histological examination con�rmed the biochemical alterations. Montelukast treatment reversed all these biochemical indices and histopathological changes that were induced by LPS. Montelukast reduced the increase in serum levels of lipase, amylase, LDH, total nitrite/nitrate, TNF-α , IL-1 β and ICAM-1. MPO activities and TBARS concentrations were also suppressed while GSH content was increased in pancreatic tissues.


Introduction
Sepsis is a clinical complication associated with substantial morbidity and mortality (Dickson and Lehmann, 2019).It is a common condition of life-threatening multi-organ dysfunction which arises as a dysregulated host immune response to an infection (Chaari et al., 2016;Dickson and Lehmann, 2019;Korneev, 2019).According to the World Health Organization records, sepsis affects thirty million people per year globally and six million of them die.However, due to the lack of data from many developing countries, these numbers are probably underestimated (Dickson and Lehmann, 2019;Korneev, 2019).
Sepsis may develop into a septic shock when the immune system fails to control the infection (Meneses et al., 2019).In septic shock, uncontrolled massive in ammatory response that intended to reduce excessive in ammation lead to a local collateral damage in the infected site, systemic damage and failure of organ (Fontaine et al., 2016).Usually, sepsis develops by Gram-negative pathogens when barrier tissues are disrupted (Korneev, 2019).For septic patients, endotoxins of pathogens, that are released during microbial growth, are detectable in the bloodstream.These endotoxins play a role in inducing a pro-in ammatory immune response (Dickson and Lehmann, 2019).
Microbial components also known as pathogen-associated molecular patterns (PAMPs), that include lipopolysaccharide (LPS), lipoproteins, peptidoglycans or lipoteichoic acids, are the key to sepsis induction (Fontaine et al., 2016).The innate immunity identi es bacterial structures as foreign by several major receptor families called pattern recognition receptors (PRRs), such as NOD-like and RIG-like receptors, Toll-like receptors (TLRs) and scavenger receptors (Dickson and Lehmann, 2019;Korneev, 2019).Such receptors activation leads to a systemic production of pro-in ammatory chemokines and cytokines (Korneev, 2019).Induction of experimental in ammatory response associated with sepsis can be achieved in various models.LPS is considered as an important tool for this purpose because of its role as a highly potent proin ammatory agent (Batista et al., 2019).LPS is a molecule found in the outer cell membrane of Gramnegative bacteria, its main target is to act on the TLRs (Zielen, Trischler and Schubert, 2015;Batista et al., 2019;Dickson and Lehmann, 2019).Administration of LPS is mostly a low-invasive nonsurgical model, it does not imply an active infection, but the host immune pathway is activated (Dickson and Lehmann, 2019;Korneev, 2019).
In ammatory response is an essential immune-defensive mechanism for the presence of any infectious or non-infectious stimuli (Fontaine et al., 2016;Meneses et al., 2019).Sustained in ammation, however, may eventually lead to pathological complications ranging from mild to fatal (Meneses et al., 2019;Kapoor and Kumar, 2020).Pancreatic injury is one of those complications that is common among patients with septic shock (Chaari et al., 2016).
A few studies, most of them with a limited number of patients, investigated pancreatic dysfunction among critically-ill patients (Chaari et al., 2016).Experimental studies have shown that the exposure of the pancreas to LPS is associated with increased release of pro-in ammatory cytokines and apoptosis (Chaari et al., 2016).The annual incidence of acute pancreatitis was shown to be ranging from 5 to 30 per 100,000 populations, 1.60 of them die (Moggia et al., 2017;Garg and Singh, 2019).
Lipid mediators of in ammation are bioactive molecules, which include prostaglandins (PGs) and leukotrienes (LTs), and play important roles in immune homeostasis and are responsible for the symptoms of an allergic and in ammatory reaction (Jo-Watanabe et al., 2019; Kapoor and Kumar, 2020).
LTs are an in ammatory mediators found in leukocytes and other in ammatory cells and considered to be important drug targets (Yokomizo et al., 2018;Kapoor and Kumar, 2020).
The formation of LTs occurs through lipoxygenation of arachidonic acid through the 5-lipoxygenase (5-LO) pathway (Yokomizo et  Acute pancreatitis following septic shock is a multifactorial disease with several in ammatory mediators involved in its pathogenesis (Szatmary et al., 2022).Although the etiopathogenesis of the disease is wellunderstood, still no single drug to counteract in ammation and repair the damage has been described.
The current work studies the potential bene cial effects of montelukast, leukotriene receptor antagonist, on sepsis-induced pancreatic injury in rats.

Animals
Adult male Wistar rats, weighing 200-225 g, were used in this study.They were obtained from the Animal Care Center, College of Medicine, King Saud University.All the animals were fed a standard rat chow and water ad libitum and kept in a temperature-controlled environment (20 to 22°C) with an alternating cycle of 12-hour light and dark.They were kept for one-week acclimatization period and were handled and treated in accordance with the strict guiding principles of the National Institution of Health for experimental care and use of animals.The experimental design and procedures were approved by the Institutional Ethical Committee for Animal Care and Use at the King Saud University, Riyadh, Kingdom of Saudi Arabia (IRB No., E-16-1985).

3. Experimental Design
Rats were randomly divided into six groups of 10 rats each.Control group received the same volume of the vehicle for montelukast.Montelukast group received the drug at a dose of 20 mg/kg /day orally for three days.Lipopolysaccharide group (LPS) received the same vehicle for montelukast for three days followed by a single intraperitoneal injection of LPS (6.0 mg /kg) (Collin et al., 2004).LPS and montelukast groups were pre-treated orally with different doses of montelukast (10 and 20 mg /kg/day, orally via gavage); 3 days later, animals received a single intraperitoneal injection of LPS.LPS was dissolved in saline while montelukast was suspended in 0.5% carboxymethyl cellulose in saline.The doses of montelukast chosen were based upon our preliminary experiments and on previous literature (Ozkan et al., 2010).

4. Collection of Samples
At the end of the experiments, animals were lightly anesthetized with ether, and blood samples were collected, centrifuged immediately and the isolated sera were stored at − 80°C and used within 48 h for the determination of biochemical indices for pancreatic dysfunction.Pancreatic tissues were removed from animals immediately after decapitation and rapidly rinsed with ice-cold saline, blotted dry, and snapfrozen in liquid nitrogen before being stored at -80°C for further analysis.

Pancreatic enzymes
Pancreatic enzymes (lipase and amylase) were assessed using the commercially available kits according to the manufacturer's directions.

LDA assay
Serum LDH as a marker of cytotoxicity was evaluated using commercially available kit according to the manufacturer's direction.

6. Oxidative stress markers
Thiobarbituric Acid Reactive Substances Lipid peroxidation as an indicator of oxidative pancreatic injury was measured as thiobarbituric acid reactive substance (TBARS) as previously described by Buege and Aust. (1978).TBARS concentrations were calculated using 1,3,3,3,3 tetra-ethoxy propane as a standard.The results were expressed as nmol/g wet tissue weight.

Reduced glutathione
Pancreatic reduced glutathione (GSH) content was determined as previously described by Ellman, (1959) depending on the reaction of Ellman's reagent (5, 5-dithio-bis (2-nitrobenzoic acid), (DTNB), with the thiol group of GSH at pH 8.0 to give yellow color of 5-thiol-2-nitrobenzoate anion.This was measured spectrophotometrically at 412 nm and the results were expressed as µmol/g wet tissue.

7. Myeloperoxidase Activity
Pancreatic myeloperoxidase (MPO) activity was assessed as an indicator to neutrophil in ltration according to the methods of Hillegas et al. (1990).Frozen pancreatic tissues were weighed and homogenized in 10 vol of 50 mM phosphate buffer, pH 6 containing 0.5% hexadecyl-trimethylammonium bromide (HETAB) and 10 mM EDTA.After homogenization, and ultrasonication, the homogenates were centrifuged at 20,000×g for 20 min at 4°C.The activity of MPO was detected by measuring O-dianisidine hydrochloride oxidation by H 2 O 2 at 460 nm.Aliquots of supernatant (0.3 ml) were added to 2.3 ml of the reaction mixture containing 50 mM PBS, O-dianisidine, and 20 mM H 2 O 2 solution.The changes in absorbance at 460 nm were measured with a spectrophotometer for 3 min.MPO activity was expressed as U/g wet tissue.

8. Nitrite/Nitrate Concentration
Serum nitrite/ nitrate concentration was measured using a speci c enzyme-linked immunosorbent assay kit according to the manufacturer's directions.

9. Proin ammatory cytokines
The tissues of the pancreas were homogenized directly on ice in ve volumes of normal saline.The homogenates were centrifuged at 1200×g for 10 min.Tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) were measured in the supernatant using enzyme-linked immunosorbent assay (ELISA) as stated in the manufacturer's protocol.

ICAM-1 Level
Serum level of ICAM-1, an adhesion molecule, was determined by a commercially available enzymelinked immunosorbent assay (ELISA) kits according to the instructions of the manufacturer.

Histopathological studies
Morphological examination of pancreatic tissues was performed in hematoxylin and eosin-stained slides as described previously in detail (Schmidt et al., 1992).Slides were examined by an experienced pathologist without knowledge of the treatment given.The histological grading of edema, leukocytic in ammatory in ltration, vacuolization of acinar cells, hemorrhages and necrosis was made using a scale ranging from 0 (absent) to 3 for maximal alteration (Tani et al., 1987;Schmidt et al., 1992).Results of histological examination have been expressed as a predominant histological grading in each experimental group of animals.

11. Statistical Analysis
Results were expressed as means ± SEM.The statistical signi cance of any difference in each parameter among the groups was evaluated by one-way ANOVA, using Tukey-Kramer multiple comparisons test as post hoc test.P values of < 0.05 was considered statistically signi cant.

1. LDH and Pancreatic Injury Markers
A single LPS injection (6 mg/kg) resulted in severe signi cant elevation in serum LDH re ecting cellular injury (Fig. 1A).This cellular damage was supported by the increases in serum amylase and lipase levels compared to control rats, demonstrating the development of pancreatic injury (Fig. 1B&C) respectively.Montelukast administration (10, and 20 mg/kg/d) for 3 days prior to sepsis induction corrected the elevation in LDH leakage as well as pancreatic enzymes as compared to LPS group.Montelukast at the higher dose (20 mg) was signi cantly better than the lower dose (10 mg).

2. TNF-α and IL-1 β
LPS injection at a dose of (6 mg/kg, i.p.) resulted in signi cant increase in serum TNF-α level (Fig. 2A) and IL-1 β (Fig. 2B) as compared to control rats (P < 0.05).Montelukast administration to LPS group accentuated the elevation in serum TNF-α and IL-1 β levels when compared with LPS group alone and the higher dose of montelukast was signi cant than the lower dose of montelukast (10 mg).

2. Effect of montelukast on pancreatic injury markers
LPS administration resulted in signi cant (P < 0.05) increases in serum amylase and lipase levels as compared to control rats, demonstrating the development of pancreatic injury (Fig. 1A &B) respectively.Montelukast administration (10, and 20 mg/kg/d) for 3 days prior to sepsis induction corrected the elevation in pancreatic enzymes as compared to LPS group.Montelukast at the higher dose (20 mg) was signi cantly better than 10 mg.

Nitrite/nitrate level
Induction of sepsis by LPS resulted in a signi cant elevation in serum nitrite/nitrate level reaching about four-fold the value observed in vehicle-treated control group (Fig. 3A).Pretreatment with montelukast (10, and 20 mg/kg/d) for three days prior to induction of sepsis signi cantly reduced the serum nitrite/nitrate level in comparison with LPS-treated rats.The higher dose of montelukast (20 mg/kg/d) was signi cantly (P < 0.05) different from the lower dose (10 mg/kg/d).

4. ICAM-1
LPS injection resulted in a signi cant (P < 0.05) increment in serum ICAM-1 level as compared to vehicletreated control group (Fig. 3A).Prior administration with montelukast suppressed the increase in serum ICAM-1 level induced by LPS as compared with LPS group.The largest dose of za rlukast (20 mg/kg) was superior (P < 0.05) than the lower dose in reducing LPS-induced serum ICAM-1 elevation.

TBARS concentration
As illustrated in (Fig. 4A), rats injected with a single dose of LPS (6 mg /kg, i.p) caused an increase in TBARS by 445% pancreas as compared to vehicle-treated control group re ecting lipid peroxidation and oxidative pancreatic injury.TBARS Pre-treatments with montelukast signi cantly (P < 0.05) attenuated LPS-evoked increase in TBARS concentration compared to LPS group alone.

GSH concentration
The effect of montelukast on GSH content in LPS-treated animals is presented in (Fig. 4B).Results showed that LPS decreased pancreatic GSH content by 50% compared to saline-treated control rats.
Prior-treatment with montelukast was able to signi cantly (P < 0.05) increase pancreatic GSH concentration up to 145% and 180% compared to the value in LPS-treated group at 10 mg and 20 mg respectively.

7. MPO activity
LPS injection produced a signi cant increase (P < 0.05) in MPO activity compared to the corresponding control group re ecting pancreatic neutrophil in ltration (Fig. 4C).The MPO activity was increased by about two-fold in the pancreas as compared to the corresponding control values of the vehicle-treated control groups.Montelukast treatment signi cantly reduced pancreatic MPO concentration compared to LPS group alone.

8. Histological results
The control group showed normal architecture (Fig. 5A).Congestion, moderate to severe edema, and hemorrhagic spots were found in the pancreatic tissues after LPS treatment.Numerous in ammatory cells in ltration can also be observed (Fig. 5B).Montelukast alleviated the histopathologic changes and presented features as mild edema, and minimal in ammatory in ltration (Fig. 5C, Table 1).

Discussion
Acute pancreatitis due to septic shock is an in ammatory disease that has not been extensively studied and few, if any, effective treatments have been tested.The correlation between leukotriene antagonists and LPS-induced pancreatitis has not been studied before.Therefore, the present study investigated the prophylactic effects of montelukast against LPS-induced AP in an animal model.The results showed that montelukast treatment, as an antagonist of the leukotriene receptors, reduced the in ammatory response, oxidative stress, and the severity of AP.Accordingly, the deactivation of leukotriene receptors through the 5-lipoxygenase pathway using montelukast may have a bene cial effect on LPS-induced pancreatitis.
Amylase and lipase are enzymes released during pancreatitis, and their serum levels are used as biochemical markers to verify the diagnosis and therapeutic effect of AP (Özkan et  Pranlukast, a cysteinyl receptor antagonist, decreased pancreatic edema, amylase level and provided protection against cerulein-induced pancreatitis (Hirano, 1997).Özkan et al. 2010 showed the ability of montelukast to attenuate the increase in plasma amylase and lipase levels in cerulein-induced pancreatitis (Özkan et al., 2010).Furthermore, Angı et al. studied the effects of montelukast before and after induction of AP by cerulein and showed a decrease in biochemical markers in the group that was given montelukast before cerulein, while no signi cant differences were observed in the other group that was given montelukast after cerulein (Angı et al., 2016).On the contrary, Oruc et al., reported worsening of the histopathological score and no improvement in amylase levels after treatment with, another leukotriene receptor antagonist, za rlukast (Oruce et al., 2004).
In a double-blind placebo-controlled trial of a leukotriene receptor antagonist in chronic pancreatitis in humans, no signi cant effect for montelukast was observed (Cartmell et al., 2004).
Overproduction of oxygen-free radicals and unbalanced natural scavenging mechanisms may cause microvascular dysfunction after organ dysfunction in sepsis ( Coskun et al., 2011;Chaari, et al., 2016).
Peroxidation of lipid membranes during AP due to the oxidative pancreatic tissue damage results in the destruction of cell membranes and the formation of thiobarbituric acid-reactive substances (Khodir et al., 2014).LPS injection caused signi cant oxidative pancreatic injury demonstrated as an increase in TBARS level with a concomitant reduction in reduced GSH level.All these alterations were totally reversed by montelukast suggesting antioxidant effects of montelukast against sepsis-induced acute pancreatic Montelukast protected against LPS-induced oxidative injury to lung, and kidney (Khodir et al., 2014) and heart (Khodir et al., 2016).Sophocarpine, another leukotriene receptor antagonist, signi cantly inhibited the alteration in TBARS in LPS-induced lung injury ( Lu et al., 2019).Parallel to our ndings, other studies suggested that anti-in ammatory agents can inhibit both the in ammatory and the oxidative stress in different organ injuries, such as sophocarpine (Lu et al., 2019), ulinastatin in LPS-induced acute lung injury (Cao et al., 2018), resolvin D1 in experimental acute pancreatitis and associated lung injury (Liu et al., 2016), and quercetin in LPS-induced depressive-like symptoms by inhibiting neuroin ammation via modulation of NFκB/iNOS signaling pathway ( Adeoluwa, et al., 2023).
LPS is known to stimulate the production of a variety of in ammatory and chemotactic cytokines (Tang et al., 2023).Increasing the release of pro-in ammatory cytokines is essential for septic shock pathogenesis, which can be responsible for continuing interactions between different types of cells, and may intensify the in ammation and lead to multi-organ failure, and death ( In summary, the present study provides evidence that montelukast can dampen the in ammatory responses observed after sepsis and exerts protective effects against the deleterious effects of sepsis on pancreas.Leukotriene antagonists may have potential for developing as novel treatment for sepsisinduced acute pancreatic injury.Leukotriene antagonists may be an important target for the clinical prevention and treatment of AP in the future.Further studies are warranted to ascertain this.

Declarations Author Contribution Statement
injury.Previous studies support the implication of oxidative stress and in ammatory pathways in the pathophysiology of various diseases including acute pancreatitis (Pereda et al., 2006; Ma et al., 2018).

Figure 1 Effects
Figure 1

Figure 2 Effects
Figure 2

Figure 3 Effects
Figure 3

Figure 4 Effects
Figure 4

Figure 5 Effect
Figure 5 (Kapoor and Kumar, 2020)t al., 2019; Kapoor and Kumar, 2020).LTs are classi ed into two groups, each of which acts upon different LT receptors: leukotriene B4 (LTB4), which acts upon LT receptors BLT1 and BLT2 and cysteinyl LTs (CysLTs), which act upon CysLT receptor 1 (CysLTR1) and CysLT receptor 2 (CysLTR2) (Jo-Watanabe et al., 2019).CysLTs are produced by leukocytes primarily eosinophils, basophils, mast cells and macrophages (Tamada and Ichinose, 2016; Jo-Watanabe et al., 2019).CysLT 1 receptors are expressed in in ammatory cells, as neutrophils, mast cells, and monocytes/macrophages and are activated by CysLTs (Jo-Watanabe et al., 2019).CysLTs are implicated in various diseases, including allergic rhinitis, asthma, cardiovascular disease, and atopic dermatitis (Kapoor and Kumar, 2020).Allergic reactions and in ammation can be treated by either preventing in ammatory mediators release or by inhibiting the effects of released mediators on their target cells(Kapoor and Kumar, 2020).A
(Hirano, 1997;Özkan et al.6).In the current study, LPS induced severe elevation in serum amylase and lipase levels indicating pancreatic injury.The administration of montelukast before LPS reduced serum amylase and lipase levels indicating protective action of, leukotriene antagonist, montelukast.Nothing is available in the literature about the effect of leukotriene antagonists in LPS-induced pancreatitis and there are contradictions about their effects in other different models of pancreatitis.While some studies showed bene t from the use of leukotriene antagonists in cerulein-induced pancreatitis(Hirano, 1997;Özkan et al. (Cartmell et al., 2004;and in taurocholate-induced necrotizing pancreatitis(Liao et al., 2018) others debate agianst their bene ciary(Cartmell et al., 2004; Oruce et al., 2004).
(Tang et al., 2018)2018 )n et al., 2011;Kandikattu et al., 2023)in ammatory cytokines, especially TNF-α, have been shown to be early regulators of the immune response and may cause the release of secondary cytokines such as IL-1β, reactive oxygen species (ROS), and other in ammatory mediators (e.g., inducible nitric oxide synthase, iNOS)(Amiot et al., 1997;Cen et al., 2016).These cytokines play an important role in the induction of leukocyte in ltration and induce many local and systemic indicators of in ammation(Özkan et al., 2010;Cen et al., 2016).Previous studies have reported that the overproduction of TNF-α is involved in the tissue injury induced by LPS( Lu et al., 2019).In our study, LPS caused a signi cant increase in TNF-α and IL-1β levels, indicating a systemic in ammatory response, while montelukast treatment showed a prophylactic effect of these elevations.These data suggest that the anti-in ammatory effect of montelukast may account for a decrease in cytokine-related pancreatic injury due to the suppression of the pro-in ammatory mediators.Other studies supported the ability of montelukast to suppress the release of in ammatory markers in LPS-induced injuries to other organs as lung and kidney(Khodir et al., 2014); heart(Khodir et al., 2016); liver(Mohamadin et al., 2011)and LPS-induced bone destruction(Wei et al., 2018).Coskun et al. reported that the reduction in pro-in ammatory cytokines (TNF-α and IL-6) when montelukast was administered following the application of cecal ligation and puncture (CLP, a model of polymicrobial sepsis)(Coskun et al., 2011).Montelukast showed protective effects on proin ammatory response in different tissue injuries including rheumatoid arthritis(Dong et al. 2018).In hippocampal injury,Saad et al. (2014)reported that neuroprotective effects by montelukast occurred by the reduction of antioxidant stress, in ammatory and apoptotic indicators.Neutrophils play key roles in the occurrence and development of in ammatory responses in many diseases including pancreatitis(Mócsai et al., 2013;Yang et al., 2015).Neutrophil in ltration was evident in the present study by increased pancreatic ICAM-1 level, an effect that was attenuated by montelukast.These results support the involvement of neutrophils in ltration and leukotriene generations in acute pancreatitis.Neutrophils initiate endothelial cells detachment and release granules as lipocalin 2 and myeloperoxidase (MPO) that have peroxidase activity and may catalyze oxidative stress(Bedouhène et al., 2020).Neutrophils can enhance expression of ROS and NADPH oxidase which in turn further stimulate neutrophils to produce more pro-in ammatory cells(Yang et al., 2015).The stimulation of neutrophils during in ammation triggers the release of myeloperoxidase (MPO) which is an active enzyme found in neutrophils and other tissue-damaging substances(Özkan et al., 2010;Coskun et al., 2011).In the present study, the increase in MPO activity during pancreatic injury was signi cantly reduced by montelukast, re ecting blockade of neutrophil in ltration as a possible mechanism for the protective effect of montelukast on the pancreas.These results coincide with other studies in different models of injury(Özkan et al., 2010;Coskun et al., 2011;Kandikattu et al., 2023).High level of MPO was observed after LPS administration in the current study further ascertain neutrophil in ltration in LPS-induced pancreatitis.Increased MPO levels were associated with lung injury (LV et al., 2020) and observed in pancreatitis(Han et al., 2023).Montelukast reduced LPS-induced pancreatic injury by inhibiting the formation of reactive oxygen species and myeloperoxidase.NO is a key signaling molecule in the pathogenesis of in ammation in AP.The results of animal models and clinical trials indicate complex interactions between local and systemic in ammatory mediators, including NO(Glaucer et al., 1991).LPS challenge bursts massive production of NO that can cause cellular injury, either directly or indirectly by forming reactive nitrogen intermediates.NO can react with Pyelonephritis induced by Escherichia coli(Tuğtepe et al., 2007) and Parkinson's disease induced by rotenone(Nagarajan et al., 2018 )and in prostate cancer cells(Tang et al., 2018)and lung cancer cells(Tsai et al., 2018).
(Zhang et al., 2000, Cuzzocrea et al., 2006)ata, 2002)or with superoxide (O2.-) anion to form peroxynitrite(Zhang et al., 2000, Cuzzocrea et al., 2006)eventually resulting in further pancreatic glutathione depletion and oxidative damage.NO can also stimulate the production of a variety of other in ammatory mediators including TNF-α and IL-1β (Marcinkiewicz et al., 1995).Montelukast might exert its actions by its antioxidant activity or by down-regulation of the iNOS expression.The ability of antioxidants to attenuate LPS-induced pancreatitis has been demonstrated in other studies.Montelukast is a very promising drug that shows bene cial effects in various disorders including acute kidney injury following ischemia/reperfusion (Hagar and Abd El Tawab, 2012), neuronal ischemia/ reperfusion (Saad et al., 2015), Cisplatin-induced renal dysfunction (Suddek et al., 2013), Rhabdomyolysis-induced acute renal failure (Helmy et al., 2012),