Protective potential of montelukast against hepatic ischemia/reperfusion injury in rats

Zafirlukast protects against hepatic ischemia-reperfusion injury in rats via modulating Bcl-2/Bax and NF-κB/SMAD-4 pathways

Hepatic ischemia/reperfusion injury (IRI) is a clinical problem commonly during liver transplantation and other liver surgery. This study aimed to evaluate the protective effect of zafirlukast (ZFK) on IR-induced hepatic injury and investigate its relevant protective mechanism. Thirty-two male Wistar albino rats were randomly allocated to four groups: sham, IRI, ZFK, and ZFK + IR groups. ZFK was administered orally in a dose of 80 mg/kg/day for 10 consecutive days. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBL) levels, and gamma glutamyl transferase (GGT) activity were estimated. Liver tissues were used to assess oxidative stress biomarkers including malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NOx), and reduced glutathione (GSH) contents. Inflammatory cytokines, tumor necrosis factor alpha (TNF-α) and interleukin-33 (IL-33), in addition to apoptosis biomarkers, BCL2 associated X protein (Bax), B-cell lymphoma 2 (Bcl2) and galactine-9 (GAL9) proteins were also assessed. Western blot analysis was performed for vascular endothelial growth factor (VEGF) and fibrinogen expressions. Immunohistochemical analysis for hepatic nuclear factor-kappa B (NF-κB) and SMAD-4 was done in addition to histopathological examination. Our study revealed that ZFK pre-treatment resulted in liver function restoration and oxidative stress correction. Moreover, inflammatory cytokines were significantly reduced and a remarkable reduction of apoptosis, angiogenesis, and clotting formation has been indicated. Additionally, a significant reduction in SMAD-4 and NF-kB protein expressions was observed. These results were supported by hepatic architecture improvement. Our findings revealed that ZFK possesses a potential protective effect against liver IR possibly through its antioxidant, anti-inflammatory and anti-apoptotic properties.

The Effect of Oral Montelukast Administration in Cholesteatoma Development and Inflammation: An Experimental Animal Model

HYPOTHESIS

We hypothesized that oral montelukast treatment could inhibit cholesteatoma formation in an experimental animal model.

BACKGROUND

Inflammation and excessive proliferation have been described in the histopathology of cholesteatoma. The aim of this study was to determine the effect of oral montelukast on cholesteatoma development.

METHODS

Eighteen healthy female Wistar albino rats weighing 250 g were chosen for the study. The animals were divided into two groups: group 1 received montelukast and group 2 was the control group. Intratympanic propylene glycol injection was administered into the left ears and physiologic serum was instilled into the right ears of the animals on the first, eighth, and fifteenth days. The effects of montelukast administration were evaluated by histological examination of the tympanic membrane and middle ear.

RESULTS

Group 1 (montelukast group) showed significant differences in terms of cholesteatoma formation, granulation, epithelial invagination, and inflammation. Cholesteatoma formation in the left ear was observed in 2 (22%) and 8 (89%) rats in groups 1 and 2, respectively (p = 0.015).

CONCLUSION

Development of cholesteatoma and inflammation was significantly lower in the montelukast-administered group. Thus, oral montelukast was found effective in preventing cholesteatoma formation.

Mechanistic insight on the role of leukotriene receptors in ischemic-reperfusion injury

Leukotrienes (LT) are a class of inflammatory mediators produced by the 5-lipoxygenase (5-LO) enzyme from arachidonic acid (AA). We discussed the various LT inhibitors and downstream pathway modulators, such as Mitogen-Activated Protein Kinases (MAPK), Phosphatidylinositol 3-Kinase/Protein Kinase B (PI3K/Akt), 5'-Adenosine Monophosphate-Activated Protein Kinase (AMPK), Protein Kinase C (PKC), Nitric Oxide (NO), Bradykinin, Early Growth Response-1 (Egr-1), Nuclear Factor-κB (NF-κB), and Tumor Necrosis Factor-Alpha (TNF-α), which in turn regulate various metabolic and physiological processes involving I/R injury. A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to understand the nature and mechanistic interventions of the leukotriene receptor modulations in ischemic injury. In the pathophysiology of I/R injuries, LT has been found to play an important role. I/R injury affects most of the vital organs and is characterized by inflammation, oxidative stress, cell death, and apoptosis leading to morbidity and mortality. sThis present review focuses on the various LT receptors, i.e., CysLT, LTC4, LTD4, and LTE4, involved in developing I/R injury in organs, such as the brain, spinal cord, heart, kidney, liver, and intestine.

Montelukast for Medical Delay in Flap Surgery

BACKGROUND

Delay phenomenon can be used for better blood supply of the flap in plastic surgery. Effects of Montelukast have been observed to reduce ischemia/reperfusion injury in various organs due to angiogenic and anti-oxidant effects. The present study aimed to determine the role of Montelukast as medical delay of the flaps.

METHODS

In this experimental study, 42 Wistar rats were divided into 3 equal groups. These groups were Surgical Delay Group (SDG), Medical Delay Group (MDG) and Control Group (CG). In SDG, 8×3 cm rectangular randomized random skin flap was first surgically delayed at rats' back. The MDG received 10 mg/kg oral Montelukast via orogastric tube for 5 days as medical delay. In MDG and SDG flap, harvesting was undertaken after a delayed period, but there was not any delayed period in CG. After delayed period, a segment of the skin flap was biopsied for assessing angiogenesis. After 14th days, the photos were taken and the size of the necrotic area of the flap was measured.

RESULTS

A significant difference was observed between the mean survival and angiogenesis (p=0.002). The same performance was reported between MDG and SDG, which were alike regarding survival and angiogenesis (p>0.05); while there was a significant difference between the control and surgical groups, as well as control and medical groups (p<0.05). Finally, the inflammation showed no significant difference (p>0.05).

CONCLUSION

Regarding positive effects of Montelukast on survival and angiogenesis, it is recommended to be used as a medication for larger studies.

Telluric acid ameliorates hepatic ischemia reperfusion-induced injury in rats: Involvement of TLR4, Nrf2, and PI3K/Akt signaling pathways

In past tellurium-based compounds had limited use, however, their therapeutic potential have been target of interest recently due to antioxidant and anti-inflammatory capabilities in experimental endotoxemia. Nevertheless, their potential hepatoprotective effect against ischemia reperfusion (IR) injury is still obscure. This study examined the possible hepatoprotective effect of telluric acid (TELL), one of tellurium-based compound, against the deteriorating effect hepatic IR injury in rats through directing toll like receptor-4 (TLR4) cascade, phosphoinositide 3-kinase(PI3K)/Akt axis, and nuclear erythroid-related factor-2 (Nrf-2) pathway as possible mechanisms contributed to TELL's effect. Indeed, male Wistar rats were randomized into 3 groups: sham-operated, control IR and TELL (50 µg/kg). TELL was administrated once daily for seven consecutive days prior to the IR induction. Pretreatment with TELL attenuated hepatic IR injury as manifested by hampered plasma aminotransaminases and lactate dehydrogenase activities. Also, TELL opposed IR induced elevation in tissue expression/activity of high-mobility group box protein-1 (HMGB1), TLR4, myeloid differentiation primary-response protein 88 (MyD88), phospho-nuclear factor-kappa B p65 (p-NF-κB p65), phospho-mitogen activated protein kinasep38 (p-MAPKp38) and tumor necrosis factor-alpha (TNF-α). Moreover, TELL reduced the elevated thiobarbituric acid reactive substances along with increased both Nrf-2 and endothelial nitric oxide synthase (eNOS) protein expression, beside replenishment of hepatic reduced glutathione. In addition, TELL induced obvious upregulation of p-PI3K and p-Akt protein expressions together with restoration of histopathological changes in IR injury. In conclusion, TELL purveyed conceivable novel hepatoprotective mechanisms and attenuated events associated with acute hepatic injury via inhibition of TLR4 downstream axis and activation of Nrf-2 and PI3K/Akt signaling cascades. Thus, TELL may provide a novel therapeutic potential for complications of hepatic IR injury.

Is there any effect of montelukast on prevention of myringosclerosis after myringotomy in a rat model?

OBJECTIVES

In this study, our aim was to identify the possible effects of montelukast sodium (ML) on the prevention of experimentally induced myringosclerosis.

MATERIALS AND METHODS

Twenty-eight female Wistar albino rats were used and they were divided into four groups randomly. Tympanic membranes (TM) of all animals were perforated and then group 1 received no treatment (control group), group 2 was treated with a topical saline solution, group 3 received topically ML and group 4 received orally ML. On the 15th day, all animals were euthanized. Tympanic membranes were evaluated otomicroscopically and histopathologically.

RESULTS

The histopathological findings, compared against a control and saline groups, showed the topically and orally ML groups had statistically significant differences of degree of myringosclerosis (p < 0.002) and median thickness of the TMs (p < 0.001). Suppression of inflammation was statistically significant only in the oral ML treatment group (p < 0.002).

CONCLUSION

Oral and topically administration of ML reduced myringosclerosis formation in myringotomies rats.

Protective effects of St. John's wort in the hepatic ischemia/reperfusion injury in rats

OBJECTIVES

The purpose of this study was to investigate possible protective effects of St. John's wort in the hepatic ischemia/reperfusion injury.

MATERIAL AND METHODS

The hepatic artery, portal vein, and bile duct were all clamped for 45 minutes to induce ischemia in rats, and after that reperfusion for 1 hour. SJW was administrated orally, once a day for 3 days before ischemia/reperfusion. The aspartate aminotransferase, alanine aminotransferase, tumor necrosis factor, and interleukin levels were measured in the serum samples. Luminol chemiluminescence, lucigenin luminol chemiluminescence levels; myeloperoxidase. The sodium-potassium ATPase (Na+/K+ ATPase) activity was determined in the liver tissue, and caspase-3 and caspase-9 activity with the bcl-2/bax ratio were measured by the western blot analysis.

RESULTS

The St. John's wort administration recovered the aspartate aminotransferase, alanine aminotransferase, tumor necrosis factor, and IL-1β levels serum parameters meaningfully, while ischemia/reperfusion caused an increase in luminol chemiluminescence, lucigenin luminol chemiluminescence, myeloperoxidase, caspase-3, and caspase-9 activity and led to a decrease in the B-cell lymphoma-2/bcl-2-associated X protein (bcl-2/bax) ratio and the Na+/K+ ATPase activity.

CONCLUSION

The obtained results indicate protective effects of St. John's wort on the ischemia/reperfusion injury through various mechanisms, and we are able to suggest that St. John's wort can clinically create a new therapeutic principle.

Zileuton alleviates acute cisplatin nephrotoxicity: Inhibition of lipoxygenase pathway favorably modulates the renal oxidative/inflammatory/caspase-3 axis

OBJECTIVE

The current study investigated for the first time the possible beneficial effect of zileuton, a selective 5-lipoxygenase inhibitor (5-LOX), against cisplatin-induced acute renal failure.

METHODOLOGY

Male Sprague-Dawley rats (180-200 g) were administered cisplatin once (5 mg/kg, i.p.) alone or combined with oral zileuton (10 mg/kg, given twice; 1 h before and 12 h after cisplatin).

RESULTS

Compared with control rats, acute cisplatin administration caused significant increases of BUN (33.76 ± 7.74 vs 61.88 ± 11.35 mg/dl), serum creatinine (0.61 ± 0.21 vs 1.56 ± 0.28 mg/dl), renal levels of MDA (6.40 ± 1.04 vs 20.52 ± 2.18 nmol/g tissue), NOx (3.45 ± 1.20 vs 17.70 ± 2.27 nmol/g tissue), TNF-α (6.71 ± 0.66 vs 23.71 ± 3.41 pg/g tissue), MPO (0.87 ± 0.09 vs 3.12 ± 0.41 U/mg tissue protein) and renal caspase-3 activity (2.81 ± 0.37 vs 12.70 ± 2.94 U/mg tissue protein). Whereas, total SOD activity (1.99 ± 0.53 vs 0.79 ± 0.06 U/mg tissue protein) and IL-10 (110.98 ± 19.70 vs 62.34 ± 14.42 pg/g tissue) were significantly decreased. Cisplatin-induced nephrotoxicity was further confirmed histopathologically (tubular necrosis, cystic dilatation of renal tubules, vacuolar degeneration of renal tubular epithelium with perivascular oedema, and interstitial fibrosis). These changes were accompanied by alteration in 5-LOX pathway manifested as elevated renal levels of 5-LOX, LTD4 and LTB4. Simultaneous administration of zileuton to the cisplatin-treated rats reversed the deleterious renal insults and restored the measured parameters near to control values.

CONCLUSIONS

These data establish the first experimental evidence that zileuton abrogates cisplatin nephrotoxicity in rats probably via the inhibition of detrimental actions of 5-LOX products, thus favorably affecting renal oxidative/inflammatory/caspase-3 axis. Based on current findings, the therapeutic prospect of zileuton for this purpose is recommended.

Resveratrol and Montelukast Alleviate Paraquat-Induced Hepatic Injury in Mice: Modulation of Oxidative Stress, Inflammation, and Apoptosis

Paraquat (PQ) is one of the most used herbicide worldwide. Its cytotoxicity is attributed to reactive radical generation. Resveratrol (Res) and montelukast (MK) have anti-inflammatory and antioxidant properties. The protective effects of Res, MK, or their combination against PQ-induced acute liver injury have not been investigated before. Therefore, we explored the protective potential of Res and/or MK against PQ hepatic toxicity in a mouse model. Mice were randomly assigned to five groups: group I served as the normal control and group II received a single dose of PQ (50 mg/kg, i.p.). Groups III, IV, and V received PQ plus oral Res (5 mg/kg/day), MK (10 mg/kg/day), and Res/MK combination, respectively. Res and/or MK reduced PQ-induced liver injury, evidenced by normalization of serum total protein, ALT, and AST. Res and/or MK significantly reversed PQ-induced oxidative stress markers glutathione and malondialdehyde. Res and/or MK significantly reduced PQ-induced inflammation reflected in TNF-α levels. Furthermore, Res and/or MK reversed PQ-induced apoptosis assessed by differential expression of p53, Bax, and Bcl-2. Histopathologic examination supported the biochemical findings. Although Res and MK displayed antioxidative, anti-inflammatory, and antiapoptotic activities, their combination was not always synergistic.

The leukotriene receptor antagonist montelukast and its possible role in the cardiovascular field

BACKGROUND

Cysteinyl leukotrienes (LTC4, LTD4, and LTE4) are pro-inflammatory mediators of the 5-lipooxygenase (5-LO) pathway, that play an important role in bronchoconstriction, but can also enhance endothelial cell permeability and myocardial contractility, and are involved in many other inflammatory conditions. In the late 1990s, leukotriene receptor antagonists (LTRAs) were introduced in therapy for asthma and later on, approved for the relief of the symptoms of allergic rhinitis, chronic obstructive pulmonary disease, and urticaria. In addition, it has been shown that LTRAs may have a potential role in preventing atherosclerosis progression.

PURPOSE

The aims of this short review are to delineate the potential cardiovascular protective role of a LTRA, montelukast, beyond its traditional use, and to foster the design of appropriate clinical trials to test this hypothesis.

RESULTS AND CONCLUSIONS

What it is known about leukotriene receptor antagonists? •Leukotriene receptor antagonist, such as montelukast and zafirlukast, is used in asthma, COPD, and allergic rhinitis. • Montelukast is the most prescribed CysLT₁ antagonist used in asthmatic patients. • Different in vivo animal studies have shown that leukotriene receptor antagonists can prevent the atherosclerosis progression, and have a protective role after cerebral ischemia. What we still need to know? • Today, there is a need for conducting clinical trials to assess the role of montelukast in reducing cardiovascular risk and to further understand the mechanism of action behind this effect.

The protective role of montelukast against intestinal ischemia-reperfusion injury in rats

Several drugs are effective in attenuating intestinal ischemia-reperfusion injury (IRI); however little is known about the effect of montelukast. Fifty rats were randomly assigned to 3 groups: model group (operation with clamping), sham group (operation without clamping), and study group (operation with clamping and 0.2, 2 and 20 mg/kg montelukast pretreatment). Intestinal ischemia-reperfusion was performed by occlusion (clamping) of the arteria mesenterica anterior for 45 min, followed by 24 h reperfusion. Intestinal IRI in the model group led to severe damage of the intestinal mucosa, liver and kidney. The Chiu scores of the intestines from the study group (2 and 20 mg/kg) were lower than that of the model group. Intestinal IRI induced a marked increase in CysLTR1, Caspase-8 and -9 expression in intestine, liver and kidney, which were markedly reduced by preconditioning with 2 mg/kg montelukast. Preconditioning with 2 g/kg montelukast significantly attenuated hepatic tissue injury and kidney damage, and decreased plasma interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels in plasma after intestinal IRI. In conclusion, preconditioning with montelukast could attenuate intestinal IRI and the subsequent systemic inflammatory response in rats.

Interleukin 18--binding protein ameliorates liver ischemia--reperfusion injury

BACKGROUND

The aim of this study was to investigate the possible protective effect of interleukin 18-binding protein (IL-18BP) on ischemia-reperfusion (I/R)-induced liver injury in experimental rat models. Liver is one of the most affected organs from I/R process. IL-18 is an important proinflammatory cytokine, which may induce some events such as production of reactive oxygen substances and release of various cytokines. IL-18BP acts as an inhibitor of IL-18. The relationship between IL-18 and IL-18BP has an important place in inflammatory process.

MATERIALS AND METHODS

Rats were equally divided into three groups as follows: sham: Hepatic pedicle dissection was done, but hepatic pedicle clamping was not used. I/R: Sixty minutes of ischemia and 2 h of reperfusion were applied. IR + IL-18BP: Recombinant human IL-18BP (100 μg/kg) was administered 30 min before the surgery. Hepatic pedicle was clamped during 60 min of ischemia and 2 h of reperfusion was achieved.

RESULTS

Liver enzyme levels were significantly lower in the IR + IL-18BP group, when compared with the I/R group. Serum and tissue levels of tumor necrosis factor-α, IL-6, and IL-18 were considerably lower in the IR + IL-18BP group, when compared with the I/R group, but hepatic interferon-γ and IL1β levels were not significant. Serum oxidative stress index level was significantly higher in the I/R group, when compared with the IR + IL-18BP group. In immunostaining, it was observed that pathologic changes were lower in IR + IL-18BP group than the I/R group.

CONCLUSIONS

IL-18BP exhibited anti-inflammatory, antioxidant, and protective effects in I/R-mediated hepatic injury via regulating some liver enzyme activities and cytokine levels. Additionally, these effects have been verified by histomorphologic examination and oxidative stress markers.

Cromoglycate, not ketotifen, ameliorated the injured effect of warm ischemia/reperfusion in rat liver: role of mast cell degranulation, oxidative stress, proinflammatory cytokine, and inducible nitric oxide synthase

Hepatic ischemia/reperfusion (ISCH/REP) is a major clinical problem that is considered to be the most common cause of postoperative liver failure. Recently, mast cells have been proposed to play an important role in the pathophysiology of ISCH/REP in many organs. In contrast, the role played by mast cells during ISCH/REP-induced liver damage has remained an issue of debate. This study aimed to investigate the protective role of mast cells in order to search for an effective therapeutic agent that could protect against fatal ISCH/REP-induced liver damage. A model of warm ISCH/REP was induced in the liver of rats. Four groups of rats were used in this study: Group I: SHAM (normal saline, intravenously [iv]); Group II: ISCH/REP; Group III: sodium cromoglycate + ISCH/REP (CROM + ISCH/REP), and Group IV: ketotifen (KET) + ISCH/REP (KET + ISCH/REP). Liver damage was assessed both histopathologically and biochemically. Mast cell degranulation was assessed histochemically. Lipid peroxidation (malondialdehyde [MDA]) as well as the levels of glutathione (GSH), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), the formation of nitric oxide (NO), and the expression of inducible NO synthase (iNOS) were determined. The results of this study revealed increased mast cell degranulation in the liver during the acute phase of ISCH/REP. Moreover, CROM, but not KET, decreased the activity of alanine aminotransferase, aspartate aminotransferase, and lactic dehydrogenase and maintained normal liver tissue histology. Both CROM and KET protected against mast cell degranulation in the liver. In addition, both CROM and KET decreased IL-6 and TNF-α. However, CROM, but not KET, decreased MDA formation and increased GSH. Furthermore, KET, but not CROM, increased both NO formation and iNOS expression. In conclusion, this study clearly demonstrated mast cell degranulation in warm ISCH/REP in the liver of rats. More importantly, CROM, but not KET, ameliorated the effect of ISCH/REP-induced injury in rat liver. CROM may protect the liver through mast cell stabilization, inhibition of TNF-α, IL-6, MDA, and iNOS and increased GSH. KET may maintain ISCH/REP-induced liver injury through the NO/iNOS pathway.

Montelukast attenuates lipopolysaccharide-induced cardiac injury in rats

This study investigates the possible protective effects of montelukast (MNT) against lipopolysaccharide (LPS)-induced cardiac injury, in comparison to dexamethasone (DEX), a standard anti-inflammatory. Male Sprague Dawley rats (160–180 g) were assigned to five groups ( n = 8/group): (1) control; (2) LPS (10 mg/kg, intraperitoneal (i.p.)); (3) LPS + MNT (10 mg/kg, per os (p.o.)); (4) LPS + MNT (20 mg/kg, p.o.); and (5) LPS + DEX (1 mg/kg, i.p.). Twenty-four hours after LPS injection, heart/body weight (BW) ratio and percent survival of rats were determined. Serum total protein, creatine kinase muscle/brain (CK-MB), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) activities were measured. Heart samples were taken for histological assessment and for determination of malondialdehyde (MDA) and glutathione (GSH) contents. Cardiac tumor necrosis factor α (TNF-α) expression was evaluated immunohistochemically. LPS significantly increased heart/BW ratio, serum CK-MB, ALP, and LDH activities and decreased percent survival and serum total protein levels. MDA content increased in heart tissues with a concomitant reduction in GSH content. Immunohistochemical staining of heart specimens from LPS-treated rats revealed high expression of TNF-α. MNT significantly reduced percent mortality and suppressed the release of inflammatory and oxidative stress markers when compared with LPS group. Additionally, MNT effectively preserved tissue morphology as evidenced by histological evaluation. MNT (20 mg/kg) was more effective in alleviating LPS-induced heart injury when compared with both MNT (10 mg/kg) and DEX (1 mg/kg), as evidenced by decrease in positive staining by TNF-α immunohistochemically, decrease MDA, and increase GSH content in heart tissue. This study demonstrates that MNT might have cardioprotective effects against the inflammatory process during endotoxemia. This effect can be attributed to its antioxidant and/or anti-inflammatory properties.

Silibinin attenuates methotrexate-induced pulmonary injury by targeting oxidative stress

The aim of the present study was to assess the protective effect of silibinin against methotrexate (MTX)-induced pulmonary toxicity. Rats were divided into four groups (MTX, MTX + silibinin, silibinin and control. MTX was injected intraperitoneally (i.p) into female Wistar rats (10 mg/kg/day for 3 days), which resulted in significant increases in the serum levels of alanine aminotransferase, aspartate aminotransferase and oxidant enzymes, including nitric oxide and myeloperoxidase. Furthermore, significant reductions were detected in the serum activity levels of the antioxidative enzymes, glutathione peroxidase and superoxide dismutase, when compared with the control group. However, administration of silibinin (100 mg/kg/day for 10 days, i.p.) was shown to ameliorate the MTX-induced pulmonary toxicity, as indicated by the normalization of the oxidative stress parameters. Furthermore, silibinin treatment was demonstrated to reduce the histopathological changes associated with MTX. In conclusion, silibinin exhibited protective effects against MTX-induced pulmonary toxicity, which may be attributed to its antioxidant activity.

The Effect of Montelukast on Liver Damage in an Experimental Obstructive Jaundice Model

Background

Montelukast is a cysteinyl-leukotriene type 1 (CysLT₁) selective receptor antagonist. In recent years, investigations have shown that montelukast possesses secondary anti-inflammatory activities and also antioxidant effects. For this reason, we aimed to determine the possible effects of montelukast on liver damage in experimental obstructive jaundice.

Methods

30 Wistar-Albino male rats were randomized and divided into three groups of 10 animals each: group I, sham-operated; group II, ligation and division of the common bile duct (BDL) followed by daily intraperitoneal injection of 1 ml of saline; group III, BDL followed by daily intraperitoneal injection of 10 mg/kg montelukast dissolved in saline. The animals were killed on postoperative day 7 by high-dose diethyl ether inhalation. Blood and liver samples were taken for examination.

Results

In this study, liver malondialdehyde (MDA) (p = 0.001), myeloperoxidase (p = 0.003), and total sulfhydryl (SH) (p = 0.009) were found to be significantly different between the BDL + montelukast and the BDL groups. Plasma total SH (p = 0.002) and MDA (p = 0.027) values were also statistically different between these groups. Statistical analyses of histological activity index scores showed that the histopathological damage in the BDL + montelukast group was significantly less than the damage in the control group (p < 0.05 for all pathological parameters).

Conclusion

According to the results of this study, montelukast showed a significant hepatoprotective effect in this experimental obstructive jaundice model, which might be due to its antioxidant and anti-inflammatory activities.

TNF-α suppression by glutathione preconditioning attenuates hepatic ischemia reperfusion injury in young and aged rats

BACKGROUND AND AIM

Hepatic ischemia reperfusion (I/R) stimulates Kupffer cells and initiates injury through tumor necrosis factor-α (TNF-α) upregulation. Aim of this study was to compare the variable effects of reduced glutathione (GSH) pre-treatment on I/R liver injury in young and aged rats.

METHODS

Wistar male rats were sorted into young (groups I-III) and aged (groups IV-VI). All groups except sham (groups I and IV) were subjected to 90-min ischemia and 2-h reperfusion. The treatment groups received 200 mg/kg bwt (groups III and VI) of GSH, 30 min prior to I/R. Variable effects of GSH were studied by transaminase activities, thiobarbituric acid-reactive substances (TBARS), GSH level, GSH/oxidized GSH (GSSG) ratio, TNF-α level, apoptotic markers and confirmed by histopathological observations.

RESULTS

Our findings revealed that I/R inflicted more liver damage in aged rats than young rats. The GSH treatment prior to surgery significantly lowered the serum transaminase activities, hepatic TBARS level and effectively restored the GSH/GSSG ratio in both young and aged rats more remarkably in the mitochondria. Western analysis depicted that the GSH treatment effectively suppressed TNF-α expression and apoptotic markers in both young and aged rats. These findings were further confirmed by terminal deoxynucleotide transferase dUTP nick end labeling assay and histopathological observations of liver sections of young and aged rats.

CONCLUSION

Restoration of GSH/GSSG ratio through GSH pre-conditioning inhibits TNF-α and apoptosis in hepatic I/R injury. Hence, GSH pre-conditioning may be utilized in both young and aged individuals during liver transplantation/surgery for better post-operative outcomes.

Montelukast reduces sepsis-induced lung and renal injury in rats

This study was undertaken to examine the effects of montelukast (MNT) on lung and kidney injury in lipopolysaccharide (LPS) induced systemic inflammatory response. Rats were randomized into 5 groups (n = 8 rats/group): (i) Control; (ii) LPS treated (10 mg/kg body mass, by intraperitoneal (i.p.) injection); (iii) LPS + MNT (10 mg/kg, per oral (p.o.)); (iv) LPS + MNT (20 mg/kg, p.o); (v) LPS + dexamethasone (DEX; 1 mg/kg, i.p.). Twenty-four hours after sepsis was induced, the lung or kidney:body mass ratio and percent survival of rats were determined. Creatinine, blood urea nitrogen (BUN), albumin, total protein, and LDH activity were measured. Lung and kidney samples were taken for histological assessment and for determination of their malondialdehyde (MDA) and glutathione (GSH) contents. The expression of tumour necrosis factor α (TNF-α) in tissue was evaluated immunohistochemically. LPS significantly increased the organ:body mass ratio, serum creatinine, BUN, and LDH, and decreased serum albumin and total protein levels. MDA levels increased in lung and kidney tissues after treatment with LPS, and there was a concomitant reduction in GSH levels. Immunohistochemical staining of lung and kidney specimens from LPS-treated rats revealed high expression levels of TNF-α. MNT suppresses the release of inflammatory and oxidative stress markers. Additionally, MNT effectively preserved tissue morphology as evidenced by histological evaluation. These results demonstrate that MNT could have lung and renoprotective effects against the inflammatory process during endotoxemia. This effect can be attributed to its antioxidant and (or) anti-inflammatory properties.

Induced pluripotent stem cells without c-Myc ameliorate retinal oxidative damage via paracrine effects and reduced oxidative stress in rats

PURPOSE

To investigate the efficacy and mechanisms of non-c-Myc induced pluripotent stem cell (iPSC) transplantation in a rat model of retinal oxidative damage.

METHODS

Paraquat was intravitreously injected into Sprague-Dawley rats. After non-c-Myc iPSC transplantation, retinal function was evaluated by electroretinograms (ERGs). The generation of reactive oxygen species (ROS) was determined by lucigenin- and luminol-enhanced chemiluminescence. The expression of brain-derived neurotrophic factor, ciliary neurotrophic factor, basic fibroblast growth factor (bFGF), stromal cell-derived factor (SDF)-1α, and CXCR4 was measured by immunohistochemistry and ELISA. An in vitro study using SH-SY5Y cells was performed to verify the protective effects of SDF-1α.

RESULTS

Transplantation of non-c-Myc iPSCs effectively promoted the recovery of the b-wave ratio in ERGs and significantly ameliorated retinal damage. Non-c-Myc iPSC transplantation decreased ROS production and increased the activities of superoxide dismutase and catalase, thereby reducing retinal oxidative damage and apoptotic cells. Moreover, non-c-Myc iPSC transplantation resulted in significant upregulation of SDF-1α, followed by bFGF, accompanied by a significant improvement in the ERG. In vitro studies confirmed that treatment with SDF-1α significantly reduced apoptosis in a dose-dependent manner in SH-SY5Y cells. Most transplanted cells remained in the subretinal space, with spare cells expressing neurofilament M markers at day 28. Six months after transplantation, no tumor formation was seen in animals with non-c-Myc iPSC grafts.

CONCLUSIONS

We demonstrated the potential benefits of non-c-Myc iPSC transplantation for treating oxidative-damage-induced retinal diseases. SDF-1α and bFGF play important roles in facilitating the amelioration of retinal oxidative damage after non-c-Myc iPSC transplantation.

Role of cysteinyl leukotriene receptor 1 in intestinal ischemia-reperfusion injury

AIM: To explore the role of cysteinyl leukotriene receptor 1 (CysLTsR1) in intestinal ischemia-reperfusion (I/R) injury.

METHODS: Forty rats were divided into 5 groups: a control group, a model group and low-, medium- and high-dose montelukast groups. After treatment, the water content of the small bowel was determined, and the histological changes in the intestinal tissues were assessed by HE staining. Immunohistochemical assessment of the expression of CysLTR1 and 5-lipoxygenase (5-LOX) was also performed.

RESULTS: Intestinal I/R, small bowel water content (model group 78.13 g ± 1.35 g vs normal group 78.13 g ± 1.35 g, P < 0.05), and CysLTR1 protein and mRNA expression significantly increased in the model group compared with the control group. Application of montelukast decreased intestinal water content (low-, medium-, and high-dose groups 76.47 g ± 1.48 g, 72.67 g ± 5.35 g and 75.39 g ± 3.66 g vs model group 78.13 g ± 1.35 g, P < 0.05), relieved the intestinal tissue injury, and reduced CysLTR1 protein and mRNA expression in intestinal tissues (P < 0.05).

CONCLUSION: CysLTR1 participates in the pathogenesis of intestinal ischemia-reperfusion injury, and may be a target for treatment of I/R injury.

The effects of zileuton and montelukast in reperfusion-induced arrhythmias in anesthetized rats

Background

5-Lipoxygenase is an enzyme involved in the synthesis of leukotriene eicosanoids from arachidonic acid. The therapeutic potential of zileuton, an inhibitor of 5-lipoxygenase, and montelukast, a cysteinyl leukotriene receptor antagonist, for the treatment of ischemia/reperfusion (I/R) injury of the heart has been proposed in a few studies. However, the effects of zileuton and montelukast on I/R-induced arrhythmias have not been determined.

Objective

We assessed the possible protective effects of zileuton and montelukast against I/R-induced arrhythmias.

Methods

Forty-five male Wistar albino rats were divided into 5 groups, each containing 9 rats. Group 1: control, Groups 2 and 3: rats treated with montelukast (10 and 30 mg/kg IP); and Groups 4 and 5: rats treated with zileuton (1 and 3 mg/kg IV) 15 minutes before the induction of ischemia. Ischemia and reperfusion were induced by occluding the left main coronary artery of anesthetized rats for 6 minutes followed by reopening the artery for 6 minutes.

Results

Both doses of zileuton decreased the mean [SE] arrhythmia score (zileuton 1 mg/kg: 1.4 [0.8]; zileuton 3 mg/kg: 1.3 [0.5] vs control: 2.9 [0.3]; P < 0.05), the duration of ventricular tachycardia, and the total length of arrhythmias, but montelukast was not effective to decrease the ventricular arrhythmias during the 6 minutes of reperfusion.

Conclusions

The results indicate for the first time that zileuton exerts an antiarrhythmic effect at different doses and that montelukast is not effective against I/R-induced arrhythmias. These results indicate that zileuton may be a candidate for drug treatment of I/R-induced arrhythmias.

Montelukast prevents ischaemia/reperfusion-induced ovarian damage in rats

OBJECTIVE

To investigate the efficacy of montelukast for prevention of ischaemia/reperfusion (I/R) injury in rat ovary.

STUDY DESIGN

Twenty-four female adult rats were included in the study. I/R injury was induced by CO2 pneumoperitoneum in a laparoscopic rat model. The rats were divided at random into three groups: the sham group was subjected to catheter insertion but was not subjected to pneumoperitoneum; the saline group was subjected to 60 min of pneumoperitoneum and 30 min of reperfusion, with 1 mg/kg physiological saline administered 10 min before pneumoperitoneum; and the montelukast group was subjected to 60 min of pneumoperitoneum and 30 min of reperfusion, with 20mg/kg montelukast administered 10 min before pneumoperitoneum. Damage to ovarian tissue was scored by histopathological evaluation. Caspase-3 expression was determined immunohistochemically. Ovarian tissue levels of malondialdehyde and glutathione, and plasma total antioxidant capacity were measured biochemically.

RESULTS

In comparison with the sham group, ovarian sections in the montelukast group had higher scores for follicular degeneration and oedema (p<0.001). Montelukast treatment prevented tissue damage in ovaries, and this result was significant. Caspase-3 expression was only observed in ovarian surface epithelium in the saline and montelukast groups. However, the mean caspase-3 expression score was higher in the saline group than the montelukast group (p<0.001). Tissue levels of malondialdehyde were higher in the montelukast group than the sham group, but plasma total antioxidant capacity and tissue levels of glutathione were significantly lower. Pretreatment with montelukast reduced lipid peroxidation (p<0.005) and improved antioxidant status in rats (p<0.001).

CONCLUSION

Montelukast is effective for the prevention of I/R-induced damage in rat ovary.

Anti-inflammatory Montelukast prevents toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin: Oxidative stress, histological alterations in liver, and serum cytokine levels

This study aimed to investigate the potential beneficial effects of the montelukast (ML) on oxidative stress and histological alterations in liver tissues and cytokine levels in rats intoxicated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Rats were divided randomly into four equal groups (control, TCDD, ML, TCDD + ML). TCDD were administered by gavages dissolved in corn oil at the doses of 2 µg/kg/week, and ML was given intraperitoneally at the dose of 10 mg/kg/day. Oxidative status, histological alterations, and cytokine levels were analyzed on day 60. The results showed that although TCDD induced oxidative stress via significant increase in formation of thiobarbituric acid reactive substance, it caused a significant decline in glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) levels in liver. Besides, TCDD led to significant histopathological damage in liver and serum cytokine levels alterations (increase in tumor necrosis factor α and interleukin 1β levels). In contrast, ML treatment reversed oxidative effects of TCDD by increasing the levels of GSH, CAT, and SOD and decreasing the formation of TBARS. Also, it can normalize the levels of histological and cytokine alterations induced by TCDD. In conclusion, it was determined that TCDD exposure caused adverse effects on cytokine levels, histological alterations, and oxidative stress in rats. However, ML treatment partially eliminated toxic effects of TCDD. Thus, it was judged that coadministration of ML with TCDD may be useful to attenuate the negative effects of TCDD.

Chitosan oligosaccharides attenuates oxidative-stress related retinal degeneration in rats

This study investigated the therapeutic potential and mechanisms of chitosan oligosaccharides (COS) for oxidative stress-induced retinal diseases. Retinal oxidative damage was induced in Sprague-Dawley rats by intravitreal injection of paraquat (PQ). Low-dose (5 mg/kg) or high-dose (10 mg/kg) COS or PBS was intragastrically given for 14 days after PQ injection. Electroretinograms were performed to determine the functionality of the retinas. The surviving neurons in the retinal ganglion cell layer and retinal apoptosis were determined by counting Neu N-positive cells in whole-mounted retinas and TUNEL staining, respectively. The generation of reactive oxygen species (ROS) was determined by lucigenin- and luminol-enhanced chemiluminescence. Retinal oxidative damages were assessed by staining with nitrotyrosine, acrolein, and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Immunohistochemical studies were used to demonstrate the expression of nuclear factor-kappa B (NF-κB) p65 in retinas. An in vitro study using RGC-5 cells was performed to verify the results. We demonstrated COS significantly enhanced the recovery of retinal function, preserved inner retinal thickness, and decreased retinal neurons loss in a dose-dependent manner. COS administration demonstrated anti-oxidative effects by reducing luminol- and lucigenin-dependent chemiluminenscense levels and activating superoxide dismutase and catalase, leading to decreased retinal apoptosis. COS markedly reduced retinal NF-κB p65. An in vitro study demonstrated COS increased IκB expression, attenuated the increase of p65 and thus decreased NF-κB/DNA binding activity in PQ-stimulated RGC-5 cells. In conclusion, COS attenuates oxidative stress-induced retinal damages, probably by decreasing free radicals, maintaining the activities of anti-oxidative enzymes, and inhibiting the activation of NF-κB.

Effects of montelukast on the healing of ischemic colon anastomoses

BACKGROUND

The aim of this study was to examine whether treatment with montelukast, a selective leukotriene antagonist, would affect anastomotic healing in a reperfused colon rat model with remote ischemia/reperfusion injury.

METHODS

Rats (n = 12 per group) were intraperitoneally administered normal saline or 10 mg/kg montelukast sodium 60 minutes before and for 5 days after surgery. Ischemia was induced for 45 minutes through superior mesenteric artery occlusion. A left colon anastomosis was made. Blood and perianastomotic tissue samples were obtained on postoperative day 5.

RESULTS

Mean anastomotic bursting pressures of the control and montelukast groups were 159.17 ± 29.99 and 216.67 ± 26.40, respectively (P < .001). Compared with saline, montelukast treatment increased the mean tissue hydroxyproline level (2.46 ± .30 vs 3.61 ± .33 μmol/L) and decreased tissue caspase-3 activity (36.06 ± 5.72 vs 21.78 ± 3.87) and malondialdehyde levels (3.43 ± .34 vs 2.29 ± .34 nmol/g) (P < .001 for all). Other plasma markers of injury also showed differences.

CONCLUSIONS

Montelukast prevented ischemia/reperfusion-induced damage in a rat model of colonic anastomotic wound healing.

Beneficial effects of montelukast against methotrexate-induced liver toxicity: a biochemical and histological study

The effects of montelukast against methotrexate-induced liver damage were investigated. 35 Wistar albino female rats were divided into 5 groups as follows: group I: control; group II: montelukast (ML); group III: methotrexate (Mtx); group IV: montelukast treatment after methotrexate application (Mtx + ML); group V: montelukast treatment before methotrexate application (ML + Mtx). At the end of the experiment, the liver tissues of rats were removed. Malondialdehyde (MDA), myeloperoxidase (MPO), and reduced glutathione levels were determined from liver tissues. In addition, the liver tissues were examined histologically. MDA and MPO levels of Mtx group were significantly increased when compared to control group. In Mtx + ML group, these parameters were decreased as compared to Mtx group. Mtx injection exhibited major histological alterations such as eosinophilic staining and swelling of hepatocytes. The glycogen storage in hepatocytes was observed as decreased by periodic acid schiff staining in Mtx group as compared to controls. ML treatment did not completely ameliorate the lesions and milder degenerative alterations as loss of the glycogen content was still present. It was showed that montelukast treatment after methotrexate application could reduce methotrexate-induced experimental liver damage.

Beneficial effects of montelukast against cisplatin-induced acute renal damage in rats

OBJECTIVE

In this study, the therapeutic and protective effects of montelukast against cisplatin (CP)-induced acute renal damage were investigated.

MATERIALS AND METHODS

Thirty-five female rats were divided into five groups as follows: (1) control, (2) montelukast (10 mg/kg daily for 10 days per-oral (p.o.), (3) CP (single dose 7 mg/kg intraperitoneally (i.p.)), (4) CP + montelukast (10 mg/kg daily for 10 days p.o., after 3 days of the injection of CP), (5) montelukast (10 mg/kg daily for 10 days p.o.) + CP (single dose 7 mg/kg i.p., after the last dose of montelukast). At the end of the experiment, malondialdehyde (MDA), a lipid peroxidation product, myeloperoxidase (MPO), and reduced glutathione (GSH) levels were determined in the renal tissue. Also, blood urea nitrogen (BUN) and creatinine (Cr) levels were assayed from the trunk blood samples.

RESULTS

CP treatment caused a significant elevation of MDA, MPO, BUN, and Cr levels when compared with the control group. Also, GSH levels were found to be reduced due to the CP treatment. Montelukast administration after CP injection ameliorated all of these parameters. Our histopathological findings (marked swelling of epithelial cells, tubular dilatation, tubular desquamation, and loss of brush border in the kidney) were consistent with the biochemical results.

CONCLUSION

Montelukast treatment after CP injection exerted therapeutic effects against CP-induced acute kidney damage.

Montelukast ameliorates kidney function and urinary bladder sensitivity in experimentally induced renal dysfunction in rats

Effect of montelukast on the renal dysfunction induced by cisplatin was investigated. A single dose of cisplatin (7 mg/kg, i.p.) induced nephrotoxicity, which was manifested by increasing the sensitivity of isolated urinary bladder rings to acetylcholine (ACh) together with a significant elevation of serum creatinine, blood urea nitrogen, and lactate dehydrogenase. On the other hand, serum albumin was significantly decreased. Moreover, renal dysfunction was further confirmed by a significant increase in lipid peroxides that were measured as malondialdehyde (MDA) in kidney tissue homogenate. Kidney reduced glutathione (GSH) content and superoxide dismutase (SOD) activity were measured, which were decreased and increased, respectively. Administration of montelukast (10 mg/kg/day, p.o.) 5 days before and 5 days after cisplatin injection significantly ameliorated the renotoxic effects of cisplatin, as judged by a significant reduction in the responses of isolated bladder rings to ACh. The deleterious changes induced by cisplatin treatment in kidney function parameters and oxidative stress markers were significantly mitigated by montelukast treatment.

CONCLUSION

Montelukast may be a beneficial remedy for cisplatin-induced renal dysfunction.

Association between leukotriene-modifying agents and suicide: what is the evidence?

The US FDA has issued safety alerts and required manufacturers of leukotriene-modifying agents (LTMAs), including montelukast, zafirlukast and zileuton, to include suicide and neuropsychiatric events as a precaution in the drug label. This paper reviews the existing evidence on the potential association between the LTMAs and suicidal behaviour. We conducted a literature search of MEDLINE, EMBASE and International Pharmaceutical Abstracts from 1995 to 2010 (inclusive) to identify pertinent studies and reports. We also examined data obtained from the FDA adverse event reporting system. To date, there are no well conducted, comparative, observational studies of this association, and the safety alerts are based primarily on case reports. While the FDA safety alerts apply to all three LTMAs, montelukast (known by its trade name Singulair®) is by far the most widely used of these drugs and most of the reports to date regarding suicide pertain to montelukast. From 1998 to 2009 there were 838 suicide-related adverse events associated with leukotrienes reported to the FDA, of which all but five involved montelukast. Nearly all cases were reported in 2008 and 2009 (96.1%) after the FDA warnings. LTMAs are approved for use in asthma and allergic rhinitis, and are effective drugs. Both of these diseases are also associated with suicide, making confirmation of the association more difficult. Given the lack of good evidence, we recommend that a large observational cohort or case-control study be conducted to quantify the association between LTMAs and suicide. Until then, when prescribing LTMAs, clinicians should consider the potential for suicide and monitor patients who may be at elevated risk carefully for suicidal ideation or psychiatric symptoms associated with suicidal behaviour.

Protective effects of montelukast on ischemia-reperfusion injury in rat ovaries subjected to torsion and detorsion: biochemical and histopathologic evaluation

OBJECTIVE

To reveal the effects of montelukast as an antioxidant and tissue protective agent and study the biochemical and histopathologic changes in experimental ischemia and ischemia-reperfusion (I/R) injury in rat ovaries.

DESIGN

Experimental study.

SETTING

Experimental surgery laboratory in a university department.

ANIMAL(S)

Forty-eight rats with experimentally induced ovarian torsion.

INTERVENTION(S)

Group 1: sham; Group 2: ovarian ischemia; Group 3: a 30-hour period of ischemia followed by a 3-hour reperfusion. Groups 4 and 5: rats administered 10 and 20 mg/kg doses of montelukast before a half-hour of ischemia, then ovarian ischemia applied; after a 3-hour period of ischemia, the bilateral ovaries removed. Groups 6 and 7: 3-hour period of ovarian ischemia applied, then 2.5 hours after the ischemia induction, rats given montelukast. Group 8: sham operation and 20 mg/kg of montelukast; at the end of a 3-hour period of ischemia, 3-hours of reperfusion continued.

MAIN OUTCOME MEASURE(S)

Measurement of ovarian tissue concentrations of superoxide dismutase (SOD), glutathione (GSH), lipid peroxidation (LPO) and myeloperoxidase (MPO) activity; and histopathologic examination of all ovarian rat tissue.

RESULT(S)

Montelukast treatment normalized changes of LPO and MPO and stimulated an overproduction of endogenous SOD and GSH. The results of the histologic parameters showed that treatment with montelukast in the I/R group of rats ameliorated the development of ischemia and reperfusion tissue injury.

CONCLUSION(S)

Montelukast at different doses attenuates ovarian I/R-induced ovary tissue injury in rats.