Protective effects of glutamine dipeptide and α-tocopherol against ischemia–reperfusion injury in the isolated rat liver

Gut Microbiota-Derived Glutamine Attenuates Liver Ischemia/Reperfusion Injury via Macrophage Metabolic Reprogramming

BACKGROUND & AIMS

Many studies have revealed crucial roles of the gut microbiota and its metabolites in liver disease progression. However, the mechanism underlying their effects on liver ischemia/reperfusion (I/R) injury remain largely unknown. Here, we investigate the function of gut microbiota and its metabolites in liver I/R injury.

METHODS

C57BL/6 mice was pretreated with an antibiotic cocktail. Then, we used multi-omics detection methods including 16s rRNA sequencing, ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) to explore the changes of gut microbiota and metabolites in both feces and portal blood to reveal the mechanism of their protective effect in liver I/R injury.

RESULTS

We found that antibiotic pretreatment (ABX) could significantly reduce the severity of I/R-induced hepatic injury, and this effect could be transferred to germ-free mice by fecal microbiota transplantation (FMT), suggesting a protective role of the gut microbiota depletion. During I/R, the rates of serum α-ketoglutarate (αKG) production and glutamate reduction, downstream products of gut microbiota-derived glutamine, were more significant in the ABX mice. Then, we showed that αKG could promote alternative (M2) macrophage activation through oxidative phosphorylation, and oligomycin A could inhibit M2 macrophage polarization and reversed this protective effect.

CONCLUSIONS

These findings show that the gut microbiota and its metabolites play critical roles in hepatic I/R injury by modulating macrophage metabolic reprogramming. Potential therapies that target macrophage metabolism, including antibiotic therapies and novel immunometabolism modulators, can be exploited for the treatment of liver I/R injury.

Alanyl-Glutamine Protects against Lipopolysaccharide-Induced Liver Injury in Mice via Alleviating Oxidative Stress, Inhibiting Inflammation, and Regulating Autophagy

Acute liver injury is a worldwide problem with a high rate of morbidity and mortality, and effective pharmacological therapies are still urgently needed. Alanyl-glutamine (Ala-Gln), a dipeptide formed from L-alanine and L-glutamine, is known as a protective compound that is involved in various tissue injuries, but there are limited reports regarding the effects of Ala-Gln in acute liver injury. This present study aimed to investigate the protective effects of Ala-Gln in lipopolysaccharide (LPS)-induced acute liver injury in mice, with a focus on inflammatory responses and oxidative stress. The acute liver injury induced using LPS (50 μg/kg) and D-galactosamine (D-Gal) (400 mg/kg) stimulation in mice was significantly attenuated after Ala-Gln treatment (500 and 1500 mg/kg), as evidenced by reduced plasma alanine transaminase (ALT) (p < 0.01, p < 0.001), aspartate transaminase (AST) (p < 0.05, p < 0.001), and lactate dehydrogenase (LDH) (p < 0.01, p < 0.001) levels, and accompanied by improved histopathological changes. In addition, LPS/D-Gal-induced hepatic apoptosis was also alleviated by Ala-Gln administration, as shown by a greatly decreased ratio of TUNEL-positive hepatocytes, from approximately 10% to 2%, and markedly reduced protein levels of cleaved caspase-3 (p < 0.05, p < 0.001) in liver. Moreover, we found that LPS/D-Gal-triggered oxidative stress was suppressed after Ala-Gln treatment, the effect of which might be dependent on the elevation of SOD and GPX activities, and on GSH levels in liver. Interestingly, we observed that Ala-Gln clearly inhibited LPS/D-Gal exposure-induced macrophage accumulation and the production of proinflammatory factors in the liver. Furthermore, Ala-Gln greatly regulated autophagy in the liver in LPS/D-Gal-treated mice. Using RAW264.7 cells, we confirmed the anti-inflammatory role of Ala-Gln-targeting macrophages.

Beneficial effects of natural compounds on experimental liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a phenomenon inherent to hepatic surgery that severely compromises the organ functionality, whose underlying mechanisms involve cellular and molecular interrelated processes leading to the development of an excessive inflammatory response. Liver resident cells and those recruited in response to injury generate pro-inflammatory signals such as reactive oxygen species, cytokines, chemokines, proteases and lipid mediators that contribute to hepatocellular necrosis and apoptosis. Besides, dying hepatocytes release damage-associated molecular patterns that actívate inflammasomes to further stimulate inflammatory responses leading to massive cell death. Since liver IRI is a complication of hepatic surgery in man, extensive preclinical studies have assessed potential protective strategies, including the supplementation with natural compounds, with the objective to downregulate nuclear factor-κB functioning, the main effector of inflammatory responses. This can be accomplished by either the activation of peroxisome proliferator-activated receptor-α, G protein-coupled receptor 120 or antioxidant signaling pathways, the synthesis of specific pro-resolving mediators, downregulation of Toll-like receptor 4 activity or additional contributory mechanisms that are beginning to be understood. The latter aspect is a crucial issue to be accomplished in preclinical studies, in order to establish adequate conditions for the supplementation with natural products before major liver surgeries in man involving warm IR, such as hepatic trauma or resection of large intrahepatic tumors.

Renalase Attenuates Mouse Fatty Liver Ischemia/Reperfusion Injury through Mitigating Oxidative Stress and Mitochondrial Damage via Activating SIRT1

Liver ischemia/reperfusion (IR) injury is a severe complication of liver surgery. Moreover, nonalcoholic fatty liver disease (NAFLD) patients are particularly vulnerable to IR injury, with higher rates of postoperative morbidity and mortality after liver surgeries. Our previous study found that renalase (RNLS) was highly sensitive and responsive to oxidative stress, which may be a promising biomarker for the evaluation of the severity of liver IR injury. However, the role of RNLS in liver IR injury remains unclear. In the present study, we intensively explored the role and mechanism of RNLS in fatty liver IR injury in vivo and in vitro. C57BL/6 mice were divided into 2 groups feeding with high-fat diet (HFD) and control diet (CD), respectively. After 20 weeks' feeding, they were suffered from portal triad blockage and reflow to induce liver IR injury. Additionally, oleic acid (OA) and tert-butyl hydroperoxide (t-BHP) were used in vitro to induce steatotic hepatocytes and to simulate ROS burst and mimic cellular oxidative stress following portal triad blockage and reflow, respectively. Our data showed that RNLS was downregulated in fatty livers, and RNLS administration effectively attenuated IR injury by reducing ROS production and improving mitochondrial function through activating SIRT1. Additionally, the downregulation of RNLS in the fatty liver was mediated by a decrease of signal transduction and activator of transcription 3 (STAT3) expression under HFD conditions. These findings make RNLS a promising therapeutic strategy for the attenuation of liver IR injury.

Citrulline decreases hepatic endotoxin-induced injury in fructose-induced non-alcoholic liver disease: anex vivostudy in the isolated perfused rat liver

Steatosis can sensitise the liver to various challenges and favour the development of non-alcoholic fatty liver disease (NAFLD). In this context, fructose feeding promotes endotoxin translocation from the gut, contributing to disease progression via an inflammatory process. Citrulline is protective against fructose-induced NAFLD; we hypothesised that this property might be related to its anti-inflammatory and antioxidative action against endotoxin-induced hepatic injuries. This hypothesis was evaluated in a model of perfused liver isolated from NAFLD rats. Male Sprague–Dawley rats (n30) were fed either a standard rodent chow or a 60 % fructose diet alone, or supplemented with citrulline (1 g/kg per d) for 4 weeks. After an evaluation of their metabolic status, fasted rats received an intraperitoneal injection of lipopolysaccharide (LPS) (2·5 mg/kg). After 1 h, the livers were isolated and perfused for 1 h to study liver function and metabolism, inflammation and oxidative status.In vivo, citrulline significantly decreased dyslipidaemia induced by a high-fructose diet and insulin resistance. In the isolated perfused rat livers, endotoxaemia resulted in higher cytolysis (alanine aminotransferase release) and higher inflammation (Toll-like receptor 4) in livers of fructose-fed rats, and it was prevented by citrulline supplementation. Oxidative stress and antioxidative defences were similar in all three groups. Amino acid exchanges and metabolism (ammonia and urea release) were only slightly different between the three groups. In this context of mild steatosis, our results suggest that fructose-induced NAFLD leads to an increased hepatic sensitivity to LPS-induced inflammation. Citrulline-induced restriction of the inflammatory process may thus contribute to the prevention of NAFLD.

Neuroprotective effects of Aceglutamide on motor function in a rat model of cerebral ischemia and reperfusion

PURPOSE

To investigate the effect and underlying mechanism of Aceglutamide on motor dysfunction in rats after cerebral ischemia-reperfusion.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h transient middle cerebral artery occlusion (MCAO). Aceglutamide or vehicle was intraperitoneally given to rats at 24 h after reperfusion and lasted for 14 days. Subsequently functional recovery was assessed and number of tyrosine hydroxylase (TH)-positive neurons in substantia nigra (SN) was analyzed. Tumor necrosis factor receptor-associated factor 1(TRAF1), P-Akt and Bcl-2/Bax were determined in mesencephalic tissue by Western blot method. PC12 cells and primary cultured mesencephalic neurons were employed to further investigate the mechanism of Aceglutamide.

RESULTS

Aceglutamide treatment improved behavioral functions, reduced the infarction volume, and elevated the number of TH-positive neurons in the SN. Moreover, Aceglutamide significantly attenuated neuronal apoptosis in the SN. Meanwhile Aceglutamide treatment significantly inhibited the expression of TRAF1 and up-regulated the expression of P-Akt and Bcl-2/Bax ratio both in vitro and in vivo.

CONCLUSIONS

Aceglutamide ameliorated motor dysfunction and delayed neuronal death in the SN after ischemia, which involved the inhibition of pro-apoptotic factor TRAF1 and activation of Akt/Bcl-2 signaling pathway. These data provided experimental information for applying Aceglutamide to ischemic stroke treatment.

L-Alanyl-Glutamine Attenuates Oxidative Stress in Liver Transplantation Patients

BACKGROUND

Ischemia/reperfusion injury during liver transplantation can cause severe damage to the graft. The objective of this randomized, double-blind study was to evaluate the possible protective effects of L-alanyl-glutamine on the liver graft.

METHODS

The sample included 33 patients from a liver transplantation service in Northeastern Brazil. Before cold ischemia, the patients received 50 g of L-alanyl-glutamine (treatment group) or saline (control group) through the portal vein. The graft was biopsied at the time of recovery, at the beginning of warm ischemia, and at the end of transplantation to determine malondialdehyde (MDA), heat-shock protein (Hsp)70, nuclear factor kappa-beta (NFkB), superoxide dismutase (SOD), and reduced glutathione (GSH) levels.

RESULTS

The blood parameters were similar in the two groups. In the treatment group, MDA did not increase at the beginning of cold ischemia and decreased at the end of transplantation. This phenomenon was not observed in the control group. GSH, SOD, Hsp70, and NFkB levels were similar in the two groups.

CONCLUSIONS

Our findings suggest that preconditioning with L-alanyl-glutamine attenuates the effects of ischemia/reperfusion-related oxidative stress and reduces lipid peroxidation in the grafts of liver transplantation patients.

Rodent models of hepatic ischemia-reperfusion injury: time and percentage-related pathophysiological mechanisms

Ischemia and reperfusion (IR) injury remains one of the major problems in liver surgery and transplantation, which determines the viability of the hepatic tissue after resection and of the grafted organ. This review aims to elucidate the mechanisms involved in IR injury of the liver in rodent experimental studies and the preventative methods and pharmacologic agents that have been applied. Many time- and percentage-related liver IR injury rodent models have been used to examine the pathophysiological mechanisms and the parameters implicated with different morbidity, mortality, and pathology findings. The most preferred experimental rodent model of liver IR is the induction of 70% IR for 45 min, which is associated with almost 100% survival. In this model, plasma levels of several parameters such as alanine transaminase, aspartate aminotransferase, gamma-glutamyltransferase, endothelin-1, malonodialdehyde, tumor necrosis factor α, interleukin 1b, inducible nitric oxide synthase, and caspases are increased. The increase of caspases is associated with the initiation of hepatic cellular apoptosis. The main injuries observed 24 h after reperfusion are nuclear pyknosis, cytoplasmic hypereosinophilia, severe necrosis, and loss of intercellular borders. Both ischemic pre- and post-conditioning preventative methods and pharmacologic agents are successfully applied to alleviate the IR injuries. The selection of the time- and percentage-related liver IR injury rodent model and the potential preventative method should be related to the clinical question being answered.

Preconditioning with glutamine protects against ischemia/reperfusion-induced hepatic injury in rats with obstructive jaundice

OBJECTIVE

To ascertain whether glutamine (Gln) pretreatment protects rats with obstructive jaundice from hepatic ischemia/reperfusion (I/R) injury and to determine the underlying molecular mechanisms.

METHODS

An obstructive jaundice rat model was developed by bile duct ligation. On the first day after the operation, all rats were randomized into two groups and received oral Gln or normal saline (NS) daily for 7 days. Then both groups underwent a 15-min liver ischemia via the Pringle maneuver. Blood samples as well as liver and intestinal tissues were harvested and measured after 1, 6 and 24 h of reperfusion.

RESULTS

The results showed that the histological morphology of the liver and intestinal tissues significantly improved in the Gln group after I/R injury compared with the NS group. Serum proteins and enzymes associated with hepatic function also significantly improved in the Gln group. The level of glutathione increased and the levels of malondialdehyde and myeloperoxidase decreased in the Gln group. The levels of interleukin-1β and tumor necrosis factor-α decreased in the Gln group. Moreover, bcl-2 protein expression was upregulated and intercellular adhesion molecule 1 and bax protein expression downregulated in the Gln group; the caspase 3 mRNA level significantly increased in the Gln group.

CONCLUSIONS

The study demonstrates that preconditioning with Gln significantly improves hepatic structure and function after I/R injury in rats with obstructive jaundice. The protective effect of Gln was mediated by the inhibition of reactive oxygen species and inflammation as well as a reduction in hepatocyte apoptosis.

Autofluorescence of liver tissue and bile: organ functionality monitoring during ischemia and reoxygenation

BACKGROUND AND OBJECTIVE

Autofluorescence (AF) based optical biopsy of liver tissue is a powerful approach for the real-time diagnosis of its functionality. Since increasing attention is given to the bile production and composition to monitor the liver metabolic engagement in surgery and transplantation, we have investigated the bile AF properties as a potential, additional diagnostic parameter.

STUDY DESIGN/MATERIALS AND METHODS

Spectrofluorometric analysis has been performed in real time on a rat liver model of warm ischemia and reperfusion-60 minutes partial portal vein and hepatic artery clamping and subsequent restoration of blood circulation-in comparison with sham operated rats. The AF spectra have been recorded through a single fiber optic probe (366 nm excitation) from both liver tissue and bile, collected from the cannulated bile duct, and analyzed by means of curve fitting procedures. Bile composition has been also analyzed through biochemical assays of bilirubin, total bile acids (TBA) and proteins.

RESULTS

Both liver and bile AF signal amplitude and spectral shape undergo changes during induction of ischemia and subsequent reperfusion. The liver tissue response is mainly ascribable to changes in NAD(P)H and flavins and their redox state, largely dependent on oxygen supply, and to the decrease of both vitamin A and fatty acid AF contributions. During comparable times, sham operated rat livers undergo smaller alterations in AF spectral shape, indicating a continuous, slight increase in the oxidized state. Bile AF emission shows a region in the 510-600 nm range ascribable to bilirubin, and resulting from the contribution of two bands, centered at about 515-523 and 570 nm, consistently with its bichromophore nature. Variations in the balance between these two bands depend on the influence of microenvironment on bilirubin intramolecular interchromophore energy transfer efficiency and are likely indicating alteration in a bile composition. This event is supported also by changes observed in the 400-500 nm emission region, ascribable to other bile components.

CONCLUSIONS

In parallel with the intratissue AF properties, mainly reflecting redox metabolic activities, the bile AF analysis can provide additional information to assess alterations and recovery in the balance of liver metabolic activities.

Vitamin E modulates apoptosis and c-jun N-terminal kinase activation in ovarian torsion-detorsion injury

The aim of this study was to evaluate the role of vitamin E in follicular degeneration and to assess histopathological and biochemical changes following ischemia-reperfusion (IR) injury in rat ovaries. Twenty-eight Wistar albino rats were randomly divided into four groups: sham, 4h torsion, 24h detorsion, and a vitamin E group. Thirty minutes before detorsion, a single dose of 200mg/kg vitamin E was administered intraperitoneally. The ovarian histology score was determined, serum levels of malondialdehyde (MDA) and myeloperoxidase (MPO) were measured. The apoptosis of granulosa cells and the phospho-c-jun N-terminal kinase (p-JNK) and phospho-p38 (p-p38) immunoreactivities of these cells were determined. MDA and MPO levels were significantly increased in the torsion and detorsion groups. Hemorrhage, edema, and congestion were also apparent in these groups. In addition, the apoptotic index and the immunoreactivity of p-JNK were highest in the detorsion group, which also showed marked follicular degeneration. However, p-p38 activity was not affected by torsion-detorsion (TD) induction. Vitamin E ameliorated TD-induced histological alterations. It also decreased serum levels of MDA and MPO, reduced the activity of p-JNK in the ovaries, and reduced numbers of apoptotic follicular cells. In conclusion, these data indicate that vitamin E attenuated ovarian follicular degeneration by inhibiting the immunoreactivity of p-JNK and reducing the apoptosis of granulosa cells.

The effect of sodium metabisulphite on active avoidance performance in hypercholesterolemic rats

The purpose of this study was to investigate the effects of hypercholesterolemia and sulphite on active avoidance learning. Male Wistar rats were divided into eight groups as follows: Control (C), Sulphite (S), Vitamin E (E), Sulphite + Vitamin E (SE), Hypercholesterolemia (H), Hypercholesterolemia + Sulphite (HS), Hypercholesterolemia + Vitamin E (HE), and Hypercholesterolemia + Sulphite + Vitamin E (HSE). At the end of the experimental period, the serum cholesterol level (mean ± SD) was significantly higher in H group (111.5 ± 11.11 mg dL(-1) ) as compared to C group (63.5 ± 4.9 mg dL(-1) ). Levels of thiobarbituric acid reactive substances (TBARS) were increased in HS group as compared to C, H, and S groups. Vitamin E reduced TBARS levels in HSE group compared with HS group. Active avoidance results indicated that hypercholesterolemia was associated with learning impairment. Our data clearly revealed that the combination of hypercholesterolemia and sulphite results in exaggerated impairment of active avoidance. Vitamin E improved active avoidance in HSE group compared with HS group. Therefore, the synergistic effect of hypercholesterolemia and sulphite may be associated with a considerable health risk.

Effect of glutamine on the total antioxidant system of rats subjected to renal ischemia and reperfusion

PURPOSE: To evaluate the protective effects of glutamine administered before renal ischemia-reperfusion on plasma antioxidant protection, and lung and renal tissue injury. METHODS: 33 rats underwent right nephrectomy. On the eighth postoperative day, animals were randomized into three groups (n=11): glutamine, control and sham. Each group of animals received, by gavage, a particular diet for 7 days. On day 14 following nephrectomy, the animals were subjected to left renal ischemia-reperfusion. After this, blood samples were collected and the animals were killed. At necropsy the kidney and lung were removed for histology. RESULTS: The levels of total antioxidant capacity were higher in the glutamine group and control group compared with the sham group. The levels of glutathione peroxidase in both the sham and glutamine groups were higher when compared with the control group (p<0.05). The level of superoxide dismutase in the sham group was clearly higher than that in the glutamine and control groups. Histological examination showed no differences between the three groups. CONCLUSION: Prior intake of glutamine improves total antioxidant capacity and increases glutathione peroxidase levels in rats subjected to renal ischemia-reperfusion.

Vitamin E derivative ETS-GS reduces liver ischemia-reperfusion injury in rats

BACKGROUND

Ischemic liver injury is often the result of surgical procedures such as liver transplantation and hepatic resection. Liver damage occurs after reperfusion, leading to increased systemic inflammation. Recent studies have reported that vitamin E and glutathione can ameliorate ischemia-reperfusion (I/R) injury. In the present study, we evaluated the ability of a new vitamin E derivative, ETS-GS, to improve liver I/R injury.

MATERIALS AND METHODS

Male Wistar received a subcutaneous injection of ETS-GS (10 mg/kg) or saline before experimentally-induced liver I/R injury or sham treatment. The rats were sacrificed after the 60-min ischemia and 24-h reperfusion. Histology and serum levels of cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-6, and high-mobility group box 1 (HMGB1) protein] and liver enzymes were determined to evaluate the protective effects of ETS-GS.

RESULTS

We found that ETS-GS treatment attenuated I/R-induced histologic alterations, reduced levels of liver enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH). In addition, ETS-GS treatment decreased serum cytokine levels.

CONCLUSIONS

Taken together, our results demonstrate that ETS-GS attenuates I/R injury in a rat model and suggests that ETS-GS may exert anti-inflammatory effects. Accordingly, ETS-GS may have therapeutic potential to treat various clinical conditions involving I/R injury.

Protective effects of glutamine preconditioning on ischemia-reperfusion injury in rats

BACKGROUND

Hepatic ischemia-reperfusion injury is a common phenomenon in hepatic surgical procedures and can result in further severe damage. This study aimed to investigate the protective effects of glutamine preconditioning on hepatic ischemia-reperfusion injury in rats and its dose-dependency.

METHODS

Thirty-two healthy male Wistar rats were randomly divided into four groups (n=8 per group). One group received 0.9% NaCl (control) and the other three received glutamine (Gln groups) 4 hours before ischemia. The Gln groups were named GL, GM, and GH according to the glutamine dose. The liver was subjected to 1 hour of ischemia and 2 hours of reperfusion. Two hours later, the levels of alanine aminotransferase (ALT), intracellular free calcium (Ca2+), and activity of Na+/K+ adenosine triphosphatase (ATPase) and superoxide dismutase (SOD) were assessed, and liver tissue sections were examined under a microscope.

RESULTS

The Gln and control groups differed in the concentration of intracellular free calcium (P<0.05), and the activity of Na+/K+ ATPase and SOD in the Gln groups was higher than in the control group (P<0.05). The ALT level was lower in the GM and GH groups than in the control group (P<0.05). The levels of Na+/K+ ATPase and SOD rose gradually with increasing glutamine dose (P<0.05), and the concentration of Ca2+ declined gradually with increasing glutamine dose (P<0.05). The degree of hepatocyte injury was milder in the Gln groups than in the control group.

CONCLUSIONS

Glutamine preconditioning protected effectively against hepatic ischemia-reperfusion injury. These protective effects were related to the dose of glutamine and due to the reduction of intracellular calcium overload and the improvements in the activity of Na+/K+ ATPase and SOD.

Preconditioning with L-alanyl-glutamine reduces hepatic ischemia-reperfusion injury in rats

PURPOSE: To evaluate the effects of pre-conditioning with L-alanyl- glutamine (L-Ala-Gln) in rats subjected to total hepatic ischemia. METHODS: Thirty Wistar rats, average weight 300g, were randomly assigned to 3 groups (n=10): G-1 - Saline, G-2- L-Ala-Gln, G-3-control (Sham). G-1 and G-3 groups were treated with saline 2.0 ml or L-Ala-Gln (0.75mg/Kg) intraperitoneally (ip) respectively, 2 hours before laparotomy. Anesthetized rats were subjected to laparotomy and total hepatic ischemia (30 minutes) induced by by clamping of portal triad. Control group underwent peritoneal puncture, two hours before the sham operation (laparotomy only). At the end of ischemia (G1 and G2), the liver was reperfused for 60 minutes. Following reperfusion blood samples were collected for evaluation of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels. Liver (medium lobe) was removed for immunohistochemistry study with antibody for Caspase-3. RESULTS: It was found a significant decrease (p<0.05) of ALT levels (270.6 +40.8 vs 83.3 +5.5 - p <0.05), LDH (2079.0 +262.4 vs. 206.6 +16.2 - p <0.05) and Caspase-3 expression (6.72 +1.35 vs. 2.19 +1.14, p <0.05) in rats subjected to I / R, comparing the group treated with L-Ala -Gln with G-2. Also, the ALT level was significantly lower (P<0.05) in G-1 and G-2 groups than in G-3 (control group). CONCLUSION: L-Ala-Gln preconditioning in rats submitted to hepatic I/R significantly reduces ALT, LDH and Caspase-3 expression, suggesting hepatic protection.

Glutamine protects ischemia-reperfusion induced acute lung injury in isolated rat lungs

Glutamine has been used to treat a number of diseases via modulating the inflammatory response. The purpose of this study is to investigate whether glutamine has a beneficial effect in ischemia-reperfusion (IR) induced acute lung injury in an isolated rat lung model. Typical acute lung injury in rats was successfully induced by 60 min of ischemia and 60 min of reperfusion. At the end of experiment, bronchoalveolar lavage fluid (BALF), perfusate and lung tissues were collected to evaluate the degree of lung injury. Glutamine (20 mM) was administrated before ischemia or after ischemia. IR caused a significant increase in the capillary filtration coefficient; lung weight gain; lung weight to body weight ratio; wet to dry weight ratio; pulmonary arterial pressure; and protein concentration and lactate dehydrogenase level in BALF. Tumor necrosis factor-α and cytokine induced neutrophil chemoattractant-1 in perfusate, and malondialdehyde levels, carbonyl content and myeloperoxidase activities in lung tissue were also significantly increased. In addition, the lung tissues showed increased septal thickness and neutrophil infiltration. Furthermore, NF-κB activity and degradation of IκB-α were significantly increased in the lungs. Treatment with glutamine before ischemia or after ischemia significantly decreased the increase in these parameters. Our study showed that glutamine treatment decreased IR-induced acute lung injury. The protective mechanism may be due to the inhibition of NF-κB activation and the attenuation of oxidative stress.