Journal of Hepatology
Volume 42, Issue 1 , Pages 94-101, January 2005

Free radical scavenger (edaravone) prevents endotoxin-induced liver injury after partial hepatectomy in rats

  • Katsushige Tsuji

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • ,
  • A-Hon Kwon

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • Corresponding Author InformationCorresponding author. Tel.: +81 6 6992 1001x3262; fax: +81 6 6992 7343.
    • ,
  • Hideyuki Yoshida

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • ,
  • Zeyu Qiu

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • ,
  • Masaki Kaibori

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • ,
  • Tadayoshi Okumura

      Affiliations

    • Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan
    • ,
  • Yasuo Kamiyama

      Affiliations

    • Department of Surgery, Kansai Medical University, 10-15 Fumizono, Moriguchi, Osaka 570-8507, Japan

Received 29 June 2004; received in revised form 15 September 2004; accepted 21 September 2004. published online 14 October 2004.

Article Outline

Background/Aims

Infection after major surgery, such as massive hepatectomy, induces liver dysfunction, occasionally leading to multiple organ failure and death. We demonstrated the anti-inflammatory effects and functional mechanisms of 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone), a newly synthesized free radical scavenger, on an experimental model of endotoxemia after partial hepatectomy in rats.

Methods

Rats were treated with lipopolysaccharide (LPS) 48h after 70% hepatectomy. Edaravone was administered intravenously before LPS-treatment.

Results

Edaravone markedly improved the survival rate of LPS-treated rats after hepatectomy and inhibited increases in serum levels of AST and LDH. Histopathological analysis demonstrated that edaravone prevented inflammatory changes in the liver, kidney and spleen. Edaravone inhibited the formation of one of the markers of oxidative damage, malondialdehyde. Increases in inflammatory cytokines and cytokine-induced neutrophil chemoattractant (CINC) in serum and liver tissue were inhibited in the edaravone-treated group. An electrophoretic mobility shift assay revealed that edaravone inhibited the activation of the transcription factor, nuclear factor-kappa B (NF-κB). Edaravone also reduced the induction of inducible nitric oxide synthase (iNOS).

Conclusions

Edaravone prevents endotoxin-induced liver injury after partial hepatectomy not only by attenuating oxidative damage, but also by reducing the production of inflammatory cytokines, CINC and iNOS, in part through the inhibition of NF-κB activation.

Keywords: Reactive oxygen intermediates, Oxidative damage, Kupffer cell, Nuclear factor-kappa B, Inflammatory cytokine, Inducible nitric oxide synthase

 

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1. Introduction 

In hepatobiliary surgery, extended hepatectomy is performed for radical resection of malignancies. Despite advances in surgical techniques and perioperative management, liver failure occasionally occurs after such an extended hepatectomy. Clinically, liver failure associated with post-operative infections sometimes leads to multiple organ failure (MOF) and death of the patient [1], [2], [3]. During endotoxemia after hepatectomy, reactive oxygen species (ROS) are involved directly and indirectly in the pathophysiology [4], [5]. Many forms of liver injury are caused by oxidative stress and subsequent free radical formation [6]. In addition, during endotoxemia, Kupffer cells, resident macrophages of the liver, play an important role in the inflammatory immune response [7], [8]. Kupffer cells activated by endotoxin release various inflammatory mediators including eicosanoids, inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interferon (IFN)-γ, cytokine-induced neutrophil chemoattractant (CINC), and free radicals [9], [10], [11], [12]. These inflammatory mediators participate in the process of endotoxemia and liver injury, leading to MOF, individually or by forming a network [7], [13], [14]. These inflammatory cytokines are induced through the activation of the transcription factor, nuclear factor-kappa B (NF-κB). Therefore, the activation of NF-κB in Kupffer cells is a key event during endotoxemia [15], [16].

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a potent and novel synthetic scavenger of free radicals inhibiting not only hydroxyl radicals but also iron-induced peroxidative injuries [17]. It has been suggested that edaravone has protective effects against cerebral and myocardial ischemia-reperfusion injuries in various experimental animal models [18], [19]. Edaravone has been prescribed clinically in Japan, since 2001 to treat patients with cerebral ischemia. Pharmacological studies have suggested that the anti-cerebral ischemic action of edaravone is related to its anti-oxidant action [20]. Recently, the efficacy of edaravone has been investigated for the treatment of liver injury. It has been reported that edaravone inhibited the release of inflammatory cytokines [21], [22], [23]. However, there is still no detailed understanding of the mechanisms involved in this inhibition. Therefore, we designed this study to investigate the protective effects of edaravone against liver injury during endotoxemia after massive hepatectomy and the mechanisms of the anti-inflammatory effects of edaravone.

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2. Materials and methods 

2.1. Experimental design 

Male Sprague–Dawley rats (250g), obtained from Simizu Co., Ltd, Kyoto, Japan, were kept at 22°C under a 12h light-dark cycle and received food and water ad libitum. Rats were anesthetized with ether prior to undergoing 70% hepatectomy [24]. Forty-eight hours after surgery, 1.5mg/kg body weight of LPS (Escherichia coli O55: B6, Sigma, Chemical Co., St Louis, MO) was injected via the penile vein (bolus injection). Edaravone (Mitsubishi Wellpharma Incorporation, Osaka, Japan) dissolved in saline or the same volume of saline was administered by a single intravenous injection, 0.5h before LPS injection (Fig. 1). In a preliminary experiment to determine the optimal time point for the single injection, edaravone (10mg/kg) was injected at 0.5h before, immediately after, and 0.5h after LPS treatment. Survival was assessed for the next 4 days (n=5–10 in each group). Blood samples and livers were obtained from individual rats at the times indicated. All experimental animals used in this study were treated according to the guidelines set by the Animal Care and Use Committee of Kansai Medical University Animal Center.

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  • Fig. 1. 

    Experimental protocol. Rats were treated with lipopolysaccharide (LPS) (1.5mg/kg) 48h after 70% hepatectomy. Edaravone (10mg/kg) was administered by a single intravenous injection 0.5h before LPS treatment.

2.2. Biochemical analysis 

Blood and liver samples were collected as indicated in the legend to Fig. 1. Liver samples stored at −80°C were homogenized in four volumes of cell homogenizing buffer (50mM Tris–HCl, pH 7.4, containing CPI (1X) and 1mM phenylmethylsulfonylfluoride (PMSF)) and centrifuged (16,500×g, 20min). Serum levels of aspartate transaminase (AST), lactate dehydrogenase (LDH), and total bilirubin (TB) were determined using commercial kits. Serum levels of malondialdehyde (MDA) were measured by spectrophotometric assay using a commercially available kit (MDA-586; Oxis Research, Portland, OR, USA). TNF-α, IL-1β, IFN-γ, IL-12 (Biosource International, Camarillo, CA, USA), and CINC-1 (Amersham Biosciences Corp., Piscataway, USA) were measured in serum and liver using commercial kits.

2.3. Histopathological analysis 

Liver, kidney and spleen specimens taken 9h after LPS treatment were fixed in 4% phosphate buffered paraformaldehyde and embedded in paraffin, cut into 3–5μm sections and stained with hematoxylin and eosin.

2.4. Electrophoretic mobility shift assay 

Nuclear extracts were prepared from frozen liver at −80°C [25]. Liver sections (0.1g) were homogenized with a Dounce homogenizer in 2ml of buffer A (10mM Hepes-KOH, pH 7.9, containing 10mM KCl, 1.5mM MgCl2, 1mM dithiothreitol (DTT), 1mM PMSF and 500U/ml Trasylol), allowed to swell for 15min and centrifuged (1100×g, 5min). The pellet was suspended in 1ml of lysis buffer (buffer A supplemented with 0.1% Triton X-100), allowed to stand for 10min and centrifuged (1100×g, 10min). The nuclear pellet was suspended in 80μl of nuclear extraction buffer (20mM Hepes-KOH, pH 7.9, containing 0.42M NaCl, 1.5mM MgCl2, 1mM DTT, 1mM PMSF, 500U/ml Trasylol, 0.2mM EDTA and 25% (v/v) glycerol), incubated for 30min and centrifuged (16,500×g, 20min).

Binding reactions were performed by incubating the nuclear extract in reaction buffer (20mM Hepes-KOH, pH 7.9, 1mM EDTA, 60mM KCl, 10% glycerol, 1μg of poly(dI-dC)) with the probe (40,000dpm) for 20min at room temperature. Products were electrophoresed on a 4.8% polyacrylamide gel in high ionic strength buffer, and dried gels were analyzed by autoradiography. An NF-κB consensus oligonucleotide (5′-AGTTGAGGGGA-CTTTCCCAGGC) from the mouse immunoglobulin light chain was purchased (Promega, Madison, WI, USA) and labeled with [γ-32P]-ATP and T4 polynucleotide kinase. Protein was measured using the method of Bradford [26].

2.5. Serum nitrite/nitrate analysis 

The sum of serum nitrite and nitrate (NO2− and NO3−, metabolites of nitric oxide) was measured using the Griess reagent method [27] using a commercial kit (Roche, Mannheim, Germany).

2.6. Western blot analysis 

Frozen liver samples were homogenized in five volumes of cell solubilizing buffer (10mM Tris–HCl, pH 7.4, containing 1% Triton X-100, 0.5% NP-40, 1mM EGTA, 1mM EDTA, 150mM NaCl and 1mM PMSF) and centrifuged (16,500×g, 15min). The supernatant was subjected to SDS–PAGE (7.5% gel) and electroblotted onto a polyvinylidene-difluoride membrane (Bio-Rad, Hercules, CA, USA). Immunostaining was performed using an ECL blotting detection agent (Amersham, Bucks, UK) and rabbit polyclonal antibody against mouse inducible nitric oxide synthase (iNOS; Affinity-Bio Reagent, Neshanic Station, NJ, USA) as the primary antibody.

2.7. Northern blot analysis 

Total RNA was isolated from liver tissue frozen at −80°C [28]. Liver sections (0.1g) were homogenized in 1.5ml of TRIzol reagent (Invitrogen, Carlsbad CA, USA) according to the manufacturer's instructions, allowed to stand for 30min and centrifuged (16,500×g, 15min). RNA was precipitated with isopropanol. RNA pellets were washed twice with ice-cold 75% (v/v) ethanol, vacuum-dried, and then dissolved in 500μl of sterile H2O. RNAs (10μg) were fractionated by agarose–formaldehyde gel electrophoresis, transferred to membranes (Nytran, Schleicher and Schuell, Dassel, Germany), and immobilized by baking for hybridization with DNA probes. A cDNA probe of rat iNOS (830bp) was provided [29]. cDNAs were radiolabeled with [α-32P]-dCTP using the random-primed method.

2.8. Statistics 

All data were expressed as means±SD. Differences between groups and in survival were identified by Mann–Whitney U-test and the log-rank test, respectively, and P<0.05 was taken to indicate statistical significance.

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3. Results 

3.1. Effect of edaravone on animal survival 

All control animals with 70% hepatectomy died within 24h of LPS treatment. In contrast, the single administration of edaravone at 0.5h before LPS treatment improved this mortality in a dose-dependent manner (Fig. 2(A)), where edaravone (10mg/kg) improved the survival rate to 100%. However, a single administration (10mg/kg) immediately after or 0.5h after LPS treatment increased the survival rate to 40% only (Fig. 2(B)). These data demonstrated that edaravone administered before LPS had a maximal effect on the rate of survival from endotoxemia after hepatectomy.

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  • Fig. 2. 

    Effect of edaravone on survival of rats. (A) Dose dependency: rats were treated with LPS (1.5mg/kg) 48h after partial hepatectomy. Edaravone (1–10mg/kg) was administered 0.5h before LPS injection. (10 rats/group) (B) Optimal point of edaravone injection for maximum effect on survival: rats were treated with LPS as described above. Edaravone (10mg/kg) was administered at 0.5h before, immediately after, or 0.5h after LPS injection. Data represent percentage of animals surviving (5 rats/group). *P<0.05, **P<0.01 vs. vehicle-treated rats with LPS.

3.2. Effect of edaravone on serum AST, LDH, and total bilirubin 

The serum values of AST, LDH and total bilirubin were analyzed to evaluate liver injury. LPS increased serum values of AST and LDH in partially hepatectomized rats (Fig. 3(A) and (B)). The increases in AST and LDH values were reduced significantly by administration of edaravone. Concerning the serum value of total bilirubin, there were no differences between edaravone-treated and untreated rats (data not shown). It suggested that edaravone can attenuate the cellular damage that occurs as a result of hepatic injury by LPS after hepatectomy.

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  • Fig. 3. 

    Effect of edaravone on serum AST and LDH. Partially hepatectomized rats with LPS were treated with, or without, edaravone. Blood samples were collected at the indicated times after LPS treatment. (A) AST and (B) LDH. Data represent mean±SD (n=5–10 rats). *P<0.05 vs. vehicle-treated rats with LPS.

3.3. Effect of edaravone on pathological changes 

The remnant livers from partially hepatectomized rats without LPS showed no significant pathological findings, irrespective of the administration of edaravone (Fig. 4(A) and (B)). Inflammatory cell infiltration, hemorrhagic change, and focal necrosis were prominent in the midzone and periportal regions of the livers 9h after LPS treatment (Fig. 4(C)). In contrast, edaravone prevented these pathological changes markedly (Fig. 4(D)). Moreover, LPS-induced injuries of the kidneys and spleens were observed, suggesting progress toward MOF, but edaravone also prevented these injuries (Fig. 4(E)–(H)).

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  • Fig. 4. 

    Effect of edaravone on pathological change of the liver, spleen and kidney. Liver sections were obtained from LPS-untreated rats 48h after partial hepatectomy for the untreated (A) and the edaravone-treated (B) groups. Liver, spleen, and kidney sections from partially hepatectomized rats with LPS; in the edaravone-untreated (C, E, G) and the treated (D, F, H) (hematoxylin–eosin staining, original magnification×100).

3.4. Effect of edaravone on serum MDA 

The serum levels of MDA changed negligibly after 70% hepatectomy without LPS and edaravone. The serum levels of MDA reached a maximum 6h after LPS treatment and decreased almost to the basal level by 9h. Edaravone inhibited these increases significantly (Fig. 5).

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  • Fig. 5. 

    Effect of edaravone on serum levels of MDA. Partially hepatectomized rats with LPS were treated with, or without, edaravone. Blood samples were collected at the indicated times after LPS treatment. Data represent mean±SD (n=5–10). *P<0.05 vs. vehicle-treated rats with LPS.

3.5. Effect of edaravone on inflammatory cytokines and nitric oxide in serum 

The serum levels of TNF-α, IL-1β, IL-12, IFN-γ and CINC-1 changed negligibly after 70% hepatectomy without LPS and edaravone. Edaravone itself did not increase these values in hepatectomized rats (Fig. 6). The serum levels of TNF-α reached a peak 1h after LPS treatment and decreased gradually to the basal level by 9h. Edaravone inhibited these increases significantly (Fig. 6(A)). IL-1β, IL-12, IFN-γ and CINC-1 reached maximum levels 3h after LPS treatment, and edaravone also inhibited the increases of these cytokines (Fig. 6(B)–(E)). In addition, during endotoxemia, nitric oxide (NO) is derived from the hepatocytes and plays a crucial role in hepatic dysfunction. We measured serum levels of NO2− and NO3− as levels of NO. These serum levels increased after LPS treatment. Edaravone significantly inhibited these increases (Fig. 7).

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  • Fig. 6. 

    Effect of edaravone on serum levels of TNF-a, IL-1β, IL-12, IFN-γ, and CINC-1. Partially hepatectomized rats with LPS were treated with, or without, edaravone. Partially hepatectomized rats without LPS were treated with, or without, edaravone. Blood samples were collected at the indicated times after LPS treatment. (A) TNF-α, (B) IL-1β, (C) IL-12, (D) IFN-γ, and (E) CINC-1. Data represent mean±SD (n=5–10). *P<0.05 vs. vehicle-treated rats with LPS.

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  • Fig. 7. 

    Effect of edaravone on production of nitric oxide. Rats were treated with LPS (1.5mg/kg) 48h after partial hepatectomy. Edaravone (10mg/kg) was administered by a single intravenous injection 0.5h before LPS treatment. Determination of nitric oxide production (nitrite and nitrate). Blood samples were obtained at the indicated times after LPS treatment with, or without, edaravone. Data represent mean±SD (n=5). *P<0.05 vs. vehicle-treated rats with LPS.

3.6. Effect of edaravone on inflammatory cytokines in liver 

During endotoxemia after hepatectomy, liver failure is regarded as a trigger of progression towards MOF. Therefore, inflammatory cytokines derived from Kupffer cells contribute to the injury of other organs, as well as the liver. To determine whether the levels of cytokines derived from the Kupffer cells were increased, we analyzed the levels of TNF-α, IL-1β, IL-12, IFN-γ and CINC-1 in the remnant liver tissue. These cytokines were increased after LPS injection in the edaravone-untreated group. They were considered to be derived from Kupffer cells. Edaravone also prevented the increases of TNF-α, IL-12, and CINC-1 in the liver significantly compared with the edaravone-untreated group (Fig. 8).

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  • Fig. 8. 

    Effect of edaravone on levels of TNF-α, IL-1β, IL-12, IFN-γ, and CINC-1 in the liver. Partially hepatectomized rats with LPS were treated with, or without, edaravone. Liver samples were collected at the indicated times after LPS treatment. (A) TNF-α, (B) IL-1β, (C) IL-12, (D) IFN-γ, and (E) CINC-1. Data represent mean±SD (n=5–10). *P<0.05 vs. vehicle-treated rats with LPS.

3.7. Effect of edaravone on activation of transcription factor, nuclear factor-κB 

Recent evidence indicates that NF-κB is involved in transcriptional activation of a variety of inflammatory genes including TNF-α, IL-1β, CINC and iNOS. To investigate the mechanism of the anti-inflammatory effect of edaravone on liver injury, we examined the effect of edaravone on NF-κB activation (its nuclear translocation and DNA binding) in the liver. Experiments using an electrophoretic mobility shift assay revealed that edaravone inhibited the activation of NF-κB induced by LPS treatment at the level of the entire liver level, showing a significant effect at 3h (Fig. 9).

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  • Fig. 9. 

    Effect of edaravone on NF-κB activation. Rats were treated with LPS (1.5mg/kg) 48h after partial hepatectomy. Edaravone (10mg/kg) was administered by a single intravenous injection 0.5h before LPS treatment. (A) Nuclear extracts (4μg of protein) were prepared from liver at the indicated times, and NF-κB was analyzed by electrophoretic mobility shift assay was performed. (B) The bands corresponding to NF-κB were quantitated by densitometry. Data represent mean±SD (n=5). *P<0.05 vs. vehicle-treated rats with LPS.

3.8. Effect of edaravone on induction of iNOS in the liver 

Finally, we determined whether edaravone influences the induction of iNOS. LPS stimulated the induction of iNOS mRNA and iNOS protein (130kDa) in the remnant liver. Edaravone decreased these inductions at 6 and 9h, respectively, (Fig. 10).

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  • Fig. 10. 

    Effect of edaravone on induction of iNOS. Liver samples were obtained at the indicated times. (A) Northern blot analysis of mRNA levels for iNOS and GAPDH in entire livers. Total RNA (10μg) was loaded onto each lane. (B) Western blot analysis of iNOS protein in entire livers. The cell lysate (260μg protein) was subjected to SDS–PAGE. Samples shown are representative of five samples from each group and time point.

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4. Discussion 

The protective effects of edaravone may be attributable to the free-radical-scavenging ability of edaravone and the fact that it possesses good pharmacological features, such as being lipophilic, readily transferable to tissue, and has effective tissue levels that are maintained after injection [19]. It also has been reported that the distribution of edaravone to the tissues after a single intravenous administration was rapid and that its concentration in the liver 5min after the administration was 5–7 times as high as the concentration in the brain, one of the target organs of edaravone [30]. Recently, the usefulness of edaravone for treating liver injury, including LPS-induced, ischemia/reperfusion-induced, and CCl4-induced injury, has been investigated [21], [22], [23].

Seventy percent hepatectomy is not fatal in rodents, but sensitivity to endotoxin is increased during the early phase after hepatectomy. This increased sensitivity is partly associated with the reduced phagocytic function of the reticuloendothelial system after massive hepatectomy [31]. Therefore, intravenous injection of an even sublethal dose of LPS after hepatectomy induces liver failure [32]. During endotoxemia after hepatectomy, liver failure is regarded as a trigger for progression towards MOF. In fact, the serum levels of AST and LDH increased in a time dependent manner, and necrosis appeared in the kidney and spleen, as well as the remnant liver, after LPS treatment in our study (Fig. 3, Fig. 4). The survival rate of rats without edaravone was 0%, 24h after injection of LPS (Fig. 2). Edaravone inhibited the increases of AST and LDH, and the appearance of pathological changes, resulting in an improvement in the survival rate of the animals to 100%. These results demonstrate that edaravone prevents endotoxin-induced liver injury and the subsequent injury to multiple organs.

It has been demonstrated in many animal models, in vivo and in vitro, that LPS induces the overproduction of ROS, including free radicals such as superoxide anion and hydroxyl radicals. Consequently, oxidative damage occurs in many tissues [33], [34], [35]. Lipid peroxidation, which plays a significant role in oxidative damage [36], was measured indirectly by assessing the increases in the levels of a lipid peroxidation product, MDA [37]. In the present study, serum levels of MDA increased gradually after LPS treatment and reached a maximum after 6h. Edaravone inhibited this increase significantly.

During endotoxemia, inflammatory cytokines, including TNF-α, IL-1β, and IFN-γ, are also considered to play an important role in the injury to the multiple organs, as well as the liver [13]. TNF-α is a key mediator of the cytokine cascade in sepsis [7], [38]. Moreover, in rats, CINC, which is a member of the IL-8 family, is the most potent chemokine for neutrophils [39] and is produced by inflammatory cells such as Kupffer cells in septic conditions [10]. Therefore, inhibiting the release of these mediators is important in anti-inflammatory therapy. In our study, serum TNF-α levels reached a maximum 1h after LPS treatment, followed by increases of other cytokines, including IL-1β, IFN-γ and CINC-1 (Fig. 6). These cytokines also increased in the remnant liver and are considered to be derived from Kupffer cells (Fig. 8). It suggested that the aforesaid increased cytokines in serum were derived in part from Kupffer cells. Edaravone inhibited significantly the increases of inflammatory cytokines in both serum and liver.

The trigger of LPS-induced liver injury is receptor-coupled signaling. One of the earliest events after the interaction of LPS with its receptor, CD14, is the activation of the transcription factor, NF-κB [40]. NF-κB is a heterodimer consisting of two subunits, p65 and p50. In its latent form, NF-κB is located in the cytoplasm and is bound to its inhibitor, I-κB [41]. Once activated, NF-κB is dissociated from IκB and is translocated into the nucleus, where it induces transcriptional up-regulation of various proinflammatory mediators, such as TNF-α, IL-1β, IFN-γ, and CINC-1 [16], [41], [42]. Thus, NF-κB plays a key role during inflammation and proliferation.

In the pathway of activation of NF-κB, reactive oxygen intermediates (ROI) are regarded as second messengers [43], [44]. It has been reported that several anti-oxidants block the activation of NF-κB through the inhibition of ROI in vitro [45], [46], [47]. We hypothesized that edaravone, a free radical scavenger, would also inhibit the activation of NF-κB. Therefore, to elucidate the mechanisms of the inhibition of inflammatory cytokines, we examined the effect of edaravone on the activation of NF-κB in the liver. In this study, we found that edaravone inhibited the activation of NF-κB induced by LPS in the entire liver (Fig. 9). These data suggest that edaravone has an anti-inflammatory effect through the inhibition of NF-κB activation in Kupffer cells. Probably, NF-κB activation was inhibited in other cells. For example, it was inhibited in the hepatocytes, as indicated by the inhibition of iNOS expression (Fig. 10).

Moreover, in this study, the inhibition of iNOS expression led to inhibition of the increased production of nitric oxide (NO) (Fig. 7). NO is a highly reactive free-radical gas. Whereas some studies have suggested that NO plays a hepatoprotective role, recent evidence indicates a crucial role for NO in hepatic dysfunction during endotoxemia [48], [49], [50], [51]. NO is also one of the candidates suspected of causing liver failure during endotoxemia after hepatectomy. Therefore, in this model, the inhibition of NO presumably also is associated with the hepatoprotective effect of edaravone.

In conclusion, we have demonstrated in the present study that edaravone prevents endotoxin-induced liver injury and progression to MOF after partial hepatectomy, not only by the attenuation of oxidative damage but also by decreasing the production of the inflammatory cytokines, CINC and iNOS, in part through the inhibition of NF-κB activation.

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PII: S0168-8278(04)00434-9

doi:10.1016/j.jhep.2004.09.018

Journal of Hepatology
Volume 42, Issue 1 , Pages 94-101, January 2005

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