Thymoquinone supplementation reverses acetaminophen-induced oxidative stress,nitric oxide production and energy decline in mice liver

This study was undertaken to evaluate the protective effect of thymoquinone (TQ) against acetaminophen-induced hepatotoxicity. Mice were given TQ orally at three different doses (0.5, 1 and 2 mg/kg/day) for 5 days before a single hepatotoxic dose of acetaminophen (500 mg/kg i.p.). TQ supplementation dramatically reduced acetaminophen-induced hepatotoxicity, in a dose-dependent manner, as evidenced by decreased serum alanine aminotransferase (ALT) activities.Acetaminophen (500 mg/kg i.p.) resulted in a significant increase in serum ALT and total nitrate/nitrite, hepatic lipid peroxides and a significant decrease in hepatic reduced glutathione (GSH) and ATP in a time-dependent manner. Interestingly, supplementation of TQ (2 mg/kg/day) for 5 days before acetaminophen administration resulted in reversal of acetaminophen-induced increase in ALT, total nitrate/nitrite, lipid peroxide and a decrease in GSH and ATP. Moreover, TQ did not affect acetaminophen-induced early decrease in hepatic GSH indicating lack of the effect on the metabolic activation of acetaminophen.In conclusion, TQ is effective in protecting mice against acetaminophen-induced hepatotoxicity possibly via increased resistance to oxidative and nitrosative stress as well as its ability to improve the mitochondrial energy production.     

ACE inhibition and protection from doxorubicin-induced cardiotoxicity in the rat

The angiotensin converting enzyme inhibitor zofenopril has been shown to possess cardioprotective effects toward myocardial damage induced by chronic doxorubicin treatment in the rat. In the present study we have investigated the relationship between cardioprotection exerted by 2 angiotensin converting enzyme inhibitors (zofenopril and lisinopril) and degree of inhibition of cardiac versus serum angiotensin converting enzyme. Both zofenopril and lisinopril produced a dose-dependent inhibition of serum and cardiac angiotensin converting enzyme in rats (0.1, 1 or 10 mg/kg/day in the diet for 1 week). However, zofenopril at 0.1 mg/kg/day showed a significantly (P < 0.05) greater inhibition of angiotensin converting enzyme in the myocardium than in the serum (Δ about 20%). Using dose levels (0.1 mg/kg/day and 10 mg/kg/day) which inhibits partially (about 50%) or almost totally (about 80%) serum angiotensin converting enzyme, we evaluated the effects of zofenopril and lisinopril in preventing cardiac alterations (QαT prolongation) induced by chronic treatment with doxorubicin (1.5 mg/kg q7dx5 i.v.). Zofenopril, at a dose level (0.1 mg/kg/day) that did not affect haemodynamics and only partially inhibits serum angiotensin converting enzyme activity, almost totally prevent the QαT lengthening induced by doxorubicin, whereas lisinopril was ineffective at this dose level. At the higher dose level (10 mg/kg/day), both angiotensin converting enzyme inhibitors totally prevented the electrocardiographic alteration induced by chronic doxorubicin administration. Cardioprotection exerted by zofenopril at a dose level that partially inhibits serum angiotensin converting enzyme without affecting haemodynamics, suggests that inhibition of cardiac angiotensin converting enzyme and additional cardioprotective mechanism(s) may have a role in its ability to prevent myocardial damages in the rat subjected to chronic anthracycline treatment.     

Alleviation of hepatic injury by chrysin in cisplatin administered rats: Probable role of oxidative and inflammatory markers

BackgroundCisplatin is an effective and extensively used chemotherapeutic agent to treat range of malignancies, but its therapeutic use is limited because of dose-dependent nephrotoxicity and hepatotoxicity. Several published reports advocate that supplementation with antioxidant can influence cisplatin induced hepatic damage.MethodIn the present study the Wistar rats were subjected to concurrent prophylactic oral treatment of chrysin (25 and 50 mg/kg b.wt.) against the hepatotoxicity induced by intraperitoneal administration of cisplatin (7.5 mg/kg b.wt.). Efficacy of chrysin against the hepatotoxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, histopathological changes and expression levels of molecular markers of inflammation.ResultsChrysin ameliorated cisplatin-induced lipid peroxidation, xanthine oxidase activity, glutathione depletion, decrease in antioxidant (catalase, glutathione reductase, superoxide dismutase, glutathione peroxidase and glucose-6 phosphate dehydrogenase) and phase-II detoxifying (glutathione-S-transferase and quinone reductase) enzyme activities. Chrysin also attenuated expression of COX-2, iNOS and levels of NFκB and TNF-α, and hepatic tissue damage which were induced by cisplatin. Histological findings further supported the protective effects of chrysin against cisplatin-induced hepatic damage.ConclusionThe results of the present study demonstrate that oxidative stress and inflammation are closely associated with cisplatin-induced toxicity and chrysin shows the protective efficacy against cisplatin-induced hepatotoxicity possibly via attenuating the oxidative stress and inflammatory response.     

Multi-targeted protection of acetaminophen-induced hepatotoxicity in mice by tannic acid

Tannic acid (TA) is the polyphenol that has beneficial health effects against oxidative stress. However, the hepatoprotective effects of TA are still relatively unknown. In the present study, we evaluated the effects of TA on an acetaminophen (APAP)-induced hepatotoxicity model, which was established by administration of 400 mg/kg of APAP. The levels of alanine transferase (ALT), aspartate transferase (AST), dendothelin-1 (ET-1), nitric oxide (NO) and malondialdehyde (MDA) in the APAP-induced hepatotoxicity mice were significantly increased (up to ~ 200%), while their levels were reduced by pretreatment with TA (25 and 50 mg/kg) (P < 0.05). The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the APAP-induced hepatotoxicity mice were significantly reduced (lower to ~ 65%), while their activities were increased by pretreatment with TA (25 and 50 mg/kg) (P < 0.05). In addition, pretreatment with oral TA (25 and 50 mg/kg) for 3 days before the APAP administration dose-dependently ameliorated changes in hepatic histopathology, suppressed overexpression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), c-fos, c-jun, NF-κB (p65) and caspase-3 (all P < 0.05), downregulated bax and upregulated bcl-2, nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) (all P < 0.05) in the liver. These results indicate that TA exhibits significant hepatoprotective effects against APAP-induced hepatotoxicity and suggest that the hepatoprotective mechanisms of TA may be related to anti-oxidation, anti-inflammation and anti-apoptosis.     

Effect of astaxanthin on hepatocellular injury following ischemia/reperfusion

This study investigated the effect of astaxanthin (ASX; 3,3-dihydroxybeta, beta-carotene-4,4-dione), a water-dispersible synthetic carotenoid, on liver ischemia–reperfusion (IR) injury. Astaxanthin (5 mg/kg/day) or olive oil was administered to rats via intragastric intubation for 14 consecutive days before the induction of hepatic IR. On the 15th day, blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60 min, followed by 60 min reperfusion. At the end of the experimental period, blood samples were obtained from the right ventricule to determine plasma alanine aminotransferase (ALT) and xanthine oxidase (XO) activities and animals were sacrificed to obtain samples of nonischemic and postischemic liver tissue. The effects of ASX on IR injury were evaluated by assessing hepatic ultrastructure via transmission electron microscopy and by histopathological scoring. Hepatic conversion of xanthine dehygrogenase (XDH) to XO, total GSH and protein carbonyl levels were also measured as markers of oxidative stress. Expression of NOS2 was determined by immunohistochemistry and Western blot analysis while nitrate/nitrite levels were measured via spectral analysis. Total histopathological scoring of cellular damage was significantly decreased in hepatic IR injury following ASX treatment. Electron microscopy of postischemic tissue demonstrated parenchymal cell damage, swelling of mitochondria, disarrangement of rough endoplasmatic reticulum which was also partially reduced by ASX treatment. Astaxanthine treatment significantly decreased hepatic conversion of XDH to XO and tissue protein carbonyl levels following IR injury. The current results suggest that the mechanisms of action by which ASX reduces IR damage may include antioxidant protection against oxidative injury.     

Glutathione S-transferase A1 (GSTA1) release,an early indicator of acute hepatic injury in mice

Three acute hepatic injury models (a CCl₄-induced model, APAP-induced model and ethanol-induced model) in mice were used to study the importance of GSTA1 in acute hepatic injury by comparison with a standard enzyme marker, alanine aminotransferase (ALT). GSTA1 release was demonstrated to be an earlier and more sensitive indicator of hepatotoxicity than was ALT. Significant increases in GSTA1 were detected at 2 h after CCl₄ exposure, while ALT was undetected at this time. GSTA1 was also a more sensitive indicator of hepatotoxicity than ALT after 6 h. In the APAP and ethanol models, GSTA1 was markedly increased earlier than ALT, at 2 h post exposure. The release of GSTA1 was significantly increased at a dose of 12.5 mg/kg (CCl₄ model), 100 mg/kg (APAP model) and 10 ml/kg (ethanol model), the lowest exposure concentration for each model. In contrast, AST release was not statistically significant. These results suggest that GSTA1 can be detected at low concentrations during the early stages of acute hepatic injury and that GSTA1 is a more sensitive and more accurate indicator than ALT.     

Protective effect of nimesulide against hepatic ischemia/reperfusion injury in rats: Effects on oxidant/antioxidants,DNA mutation and COX-1/COX-2 levels

BackgroundNimesulide is a pharmacological agent and selective COX-2 inhibitor. It has anti-inflammatory, analgesic and antipyretic properties. The purpose of this study was to investigate the effect of nimesulide on oxidant/antioxidant, DNA mutation and COX-1/COX-2 activities in rat liver tissue with induced ischemia/reperfusion (I/R).MethodsBefore the experiment, rats were divided into four groups; liver ischemia/reperfusion (LIR), 50 mg/kg nimesulide + liver ischemia/reperfusion (NLIR50), 100 mg/kg nimesulide + liver ischemia/reperfusion (NLIR100) and a control group to be given a sham operation (SG). Malondialdehyde (MDA), total glutathione (GSH) levels and myeloperoxidase (MPO), COX-1/COX-2 enzyme activities and DNA damage product level results from liver tissues and serum AST and ALT levels were determined. The data obtained were compared with the results from the liver ischemia/reperfusion and sham operation groups.ResultsMDA levels, MPO and COX-2 activities and products of DNA injury were significantly lower in the groups given nimesulide, and particularly the NLIR100 group, compared to the LIR group (p < 0.05), while tGSH levels were significantly higher (p < 0.05). There was no significant difference between the NLIR50 and NLIR100 groups and the LIR group in terms of COX-1 levels (p > 0.05). AST and ALT levels were significantly lower in the other groups compared to the LIR group (p < 0.05).ConclusionsNimesulide at 100 mg/kg prevented oxidative liver damage induced with I/R significantly better than at a dose of 50 mg/kg. These experimental findings indicate that nimesulide may be useful in the treatment of hepatic I/R damage.     

Berberine inhibits dyslipidemia in C57BL/6 mice with lipopolysaccharide induced inflammation

BackgroundInhibiting the action of proprotein convertase subtilisin/kexin type 9 (PCSK9) on the low-density lipoprotein receptor (LDLR) has emerged as a novel therapeutic target for hypercholesterolemia. Here we investigated the effect of berberine, natural plant extracts, on PCSK9-LDLR pathway in C57BL/6 mice with lipopolysaccharide (LPS) induced inflammation.MethodsForty female mice were divided into four groups (n = 10): control, LPS (5 mg/kg), LPS + berberine 10 (5 mg/kg LPS plus 10 mg/kg berberine), and LPS + berberine 30 (5 mg/kg LPS plus 30 mg/kg berberine). Changes in the levels of blood lipids [total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C)]; pro-inflammatory cytokines [interferon-γ (IFNγ), tumor necrosis factor α (TNFα), and interleukin-1α (IL-1α)], 8-isoprostane, hepatic expressions of PCSK9 and LDLR were determined.ResultsBerberine pretreatment reduced the expression of hepatic PCSK9, decreased the plasma TC, TG, LDL-C, IFNγ, TNFα, IL-1α, and 8-isoprostane concentrations; increased HDL-C level and LDLR expression in mice.ConclusionThe present results suggest that berberine inhibits dyslipidemia in C57BL/6 mice with LPS induced inflammation through regulating PCSK9-LDLR pathway.     

Cholecystokinin protects mouse liver against ischemia and reperfusion injury

BackgroundCholecystokinin (CCK), as a gastrointestinal hormone, has an important protective role against sepsis or LPS-induced endotoxic shock. We aim to address the role of CCK in hepatic ischemia followed by reperfusion (I/R) injury.Materials and methodsA murine model of 60 min partial hepatic ischemia followed by 6 h of reperfusion was used in this study. CCK and CCKAR Levels in blood and liver were detected at 3 h, 6 h, 12 h and 24 h after reperfusion. Then the mice were treated with CCK or proglumide, a nonspecific CCK-receptor (CCK-R) antagonist. Mice were randomly divided into four groups as follows: (1) sham group, in which mice underwent sham operation and received saline; (2) I/R group, in which mice were subjected to hepatic I/R and received saline; (3) CCK group, in which mice were subjected to hepatic I/R and treated with CCK (400 μg/kg); (4) proglumide group (Pro), in which mice underwent hepatic I/R and treated with proglumide (3 mg/kg); CCK and proglumide were administrated via tail vein at the moment of reperfusion. Serum AST (sAST) and serum ALT (sALT) were determined with a biochemical assay and histological analysis were performed with hematoxylin-eosin (H&E). Cytokines (IL-1β, IL-6, IL-10, TNF-α) expressions in blood were determined with enzyme-linked immunosorbent assay (ELISA). The MPO (myeloperoxidase) assay were used to measure neutrophils' infiltration into the liver. The apoptotic index (TUNEL-positive cell number / total liver cell number × 100%) was calculated to assess hepatocelluar apoptosis. Finally, activation of NF-κB and phosphor-p38 expression in liver homogenates were analyzed with Western Blot (WB).ResultsOur findings showed that 1) CCK and CCK-AR were upregulated in our experimental model over time; 2) Treatment with CCK decreased sAST/sALT levels, inflammatory hepatic injury, neutrophil influx and hepatocelluar apoptosis, while proglumide aggravated hepatic injury.ConclusionThese findings support our hypothesis and suggest that CCK played a positive role in the ongoing inflammatory process leading to liver I/R injury.     

Antioxidant activity and hepatoprotective property of leaf extracts of Boerhaavia diffusa Linn against acetaminophen-induced liver damage in rats

Extracts of Boerhaavia diffusa leaves were evaluated for antioxidant and hepatoprotective properties in the acetaminophen-induced liver damage model. Antioxidative evaluation of ethanolic extract gave total phenolic content, total flavonoid content, vitamin C content and vitamin E content and the levels of selenium and zinc as 6.6 ± 0.2 mg/g tannic acid equivalent, 0.092 ± 0.003 mg/g quercetin equivalent, 0.21 ± 0.03 mg/g, 0.054 ± 0.002 mg/g, 0.52 ± 0.05 ppm and 9.28 ± 0.16 ppm, respectively. The DPPH scavenging capacity and the reductive potential were 78.32 ± 2.41% and 0.65 ± 0.02 mg/g ascorbic acid, respectively. Pretreatment with aqueous and ethanolic extracts decreased the activities of alkaline phosphatase, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and the level of bilirubin in the serum that were elevated by acetaminophen. The two extracts also ameliorated the elevation in the activities of the enzymes in the liver. Acetaminophen intoxication led to reduction in serum and liver albumin levels which were not significantly increased by pretreatment with the extracts. The extracts also protected against acetaminophen induced lipid peroxidation. These results indicated that leaf extracts from B. diffusa possess hepatoprotective property against acetaminophen-induced liver damage which may be mediated through augmentation of antioxidant defenses.     

Astaxanthin pretreatment attenuates acetaminophen-induced liver injury in mice

BackgroundAcetaminophen (APAP) is a conventional drug widely used in the clinic because of its antipyretic-analgesic effects. However, accidental or intentional APAP overdoses induce liver injury and even acute liver failure (ALF). Astaxanthin (ASX) is the strongest antioxidant in nature that shows preventive and therapeutic properties, such as ocular protection, anti-tumor, anti-diabetes, anti-inflammatory, and immunomodulatory effects. The aim of present study was to determine whether ASX pretreatment provides protection against APAP-induced liver failure.MethodsMale C57BL/6 mice were randomly divided into 7 groups, including control, oil, ASX (30 mg/kg or 60 mg/kg), APAP and APAP + ASX (30 mg/kg or 60 mg/kg) groups. Saline, olive oil and ASX were administered for 14 days. The APAP and APAP + ASX groups were given a peritoneal injection of 700 mg/kg or 300 mg/kg APAP to determine the 5-day survival rate and for further observation, respectively. Blood and liver samples were collected to detect alanine transaminase (ALT), aspartate transaminase (AST), inflammation, oxidative stress and antioxidant systems, and to observe histopathologic changes and key proteins in the mitogen-activated protein kinase (MAPK) family.ResultsASX pretreatment before APAP increased the 5-day survival rate in a dose-dependent manner and reduced the ALT, AST, hepatic necrosis, reactive oxygen species (ROS) generation, lipid peroxidation (LPO), oxidative stress and pro-inflammatory factors. ASX protected against APAP toxicity by inhibiting the depletion of glutathione (GSH) and superoxide dismutase (SOD). Administration of ASX did not change the expression of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and P38. However, phosphorylation of JNK, ERK and P38 was reduced, consistent with the level of tumor necrosis factor alpha (TNF-α) and TNF receptor-associated factor 2 (TRAF2).ConclusionASX provided protection for the liver against APAP hepatotoxicity by alleviating hepatocyte necrosis, blocking ROS generation, inhibiting oxidative stress, and reducing apoptosis by inhibiting the TNF-α-mediated JNK signal pathway and by phosphorylation of ERK and P38, which made sense in preventing and treating liver damage.     

Effect of exposure to fluoride and acetaminophen on oxidative/nitrosative status of liver and kidney in male and female rats

BackgroundThis study was undertaken to investigate, the effect of 6 weeks treatment with acetaminophen (AAP) and fluoride (F), administered either separately or together, on nitric oxide generation, lipid and protein peroxidation, total antioxidant status and level of reduced glutathione in the liver and kidney of male and female Wistar Han rats. Also, the influence of AAP on F excretion in urine was determined.MethodsThirty adult male and female rats were divided into five equal groups of six each: (I) controls drinking tap water; (II) controls drinking tap water and receiving 1 ml of tap water intragastrically; (III) animals receiving 12 mg F/L in drinking water; (IV) animals receiving 150 mg AAP/kg b.w./day; (V) animals receiving 12 mg F/L in drinking water and 150 mg AAP/kg b.w./day.ResultsF and AAP given separately and both together enhanced oxidative and nitrosative stress in investigated tissues. No gender differences were observed in oxidative/nitrosative stress parameters during treatment with F and/or AAP. Interestingly, the combined exposure to F and AAP resulted in an enhancement of oxidative/nitrosative stress in kidney of male and female rats compared to the group treated separately with F and AAP. No additive effect in the measured parameters in the liver during co-exposure to both xenobiotics was noticed.ConclusionsAs expected, the urinary F excretion increased in an exposure time-dependent manner in rats receiving F or a combination of F and AAP. The study also showed that AAP significantly decreased urinary F.     

Royal jelly attenuates azathioprine induced toxicity in rats

In the present study, we investigated the potential protective effects of royal jelly against azathioprine-induced toxicity in rat. Intraperitoneal administration of azathioprine (50 mg/kg B.W.) induced a significant decrease in RBCs count, Hb concentration, PCV%, WBCs count, differential count and platelet count, hepatic antioxidant enzymes (reduced glutathione and glutathione s-transferase) and increase of serum transaminases (alanine aminotransferase and aspartate aminotransferase enzymes) activities, alkaline phosphatase and malondialdehyde formation. Azathioprine induced hepatotoxicity was reflected by marked pathological changes in the liver. Oral administration of royal jelly (200 mg/kg B.W.) was efficient in counteracting azathioprine toxicity whereas it altered the anemic condition, leucopenia and thrombocytopenia induced by azathioprine. Furthermore, royal jelly exerted significant protection against liver damage induced by azathioprine through reduction of the elevated activities of serum hepatic enzymes. Moreover, royal jelly blocked azathioprine-induced lipid peroxidation through decreasing the malondialdehyde formation. In conclusion, royal jelly possesses a capability to attenuate azathioprine-induced toxicity.     

Attenuation of uremia by orally feeding alpha-lipoic acid on acetaminophen induced uremic rats

Uremia means excess nitrogenous waste products in the blood & their toxic effects. An acute acetaminophen (paracetamol, N-acetyl p-aminophenol; APAP) overdose may result into potentially fatal hepatic and renal necrosis in humans and experimental animals. The aims of this present study were to investigate the protective effect of alpha-lipoic acid (ALA) on oxidative stress & uremia on male albino rats induced by acetaminophen. The study was performed by 24 albino male Wister strain rats which were randomly divided into four groups: Group I, control – receives normal food and water, Groups II, III & IV receive acetaminophen interperitoneally at the dose of 500 mg/kg/day for 10 days, from 11th day Groups III & IV were treated with ALA at the dose of 5 mg & 10 mg/100 g/day for 15 days, respectively. After 25 days of treatment, it was observed that there was a significant increase in plasma urea, creatinine, sodium and malondialdehyde (MDA) levels (p < 0.05) but a significant decrease in super oxide dismutase (SOD) & catalase activity & potassium level in uremic group is compared with control group & there was a significant increase in SOD & catalase (p < 0.05) & a significant decrease in serum urea, creatinine & Na and MDA (p < 0.05) in Group III & Group IV is compared with Group II & significant changes were observed in high ALA dose group. In conclusion it was observed that the ALA has nephroprotective activities by biochemical observations against acetaminophen induced uremic rats.     

Acetaminophen-induced hepatic glycogen depletion and hyperglycemia in mice

Two hours following administration of a hepatotoxic dose of acetaminophen (500 mg/kg, i.p.) to mice, liver sections stained with periodic acid Schiff reagent showed centrilobular hepatic glycogen depletion. A chemical assay revealed that following acetaminophen administration (500 mg/kg) hepatic glycogen was depleted by 65% at 1 hr and 80% at 2 hr, whereas glutathione was depleted by 65% at 0.5 hr and 80% at 1.5 hr. Maximal glycogen depletion (85% at 2.5 hr correlated with maximal hyperglycemia (267 mg/100 ml at 2.5hr). At 4.0 hr following acetaminophen administration, blood glucose levels were not significantly different from saline-treated animals; however, glycogen levels were still maximally depleted. A comparison of the dose-response curves for hepatic glycogen depletion and glutathione depletion showed that acetaminophen (50–500 mg/kg at 2.5 hr) depleted both glycogen and glutathione by similar percentages at each dose. Since acetaminophen (100 mg/kg at 2.5 hr) depleted glutathione and glycogen by approximately 30%, evidence for hepatotoxicity was examined at this dose to determine the potential importance of hepatic necrosis in glycogen depletion. Twenty-four hours following administration of acetaminophen (100 mg/kg) to mice, histological evidence of hepatic necrosis was not detected and serum glutamate pyruvate transaminase (SGPT) levels were not significantly different from saline-treated mice. The potential role of glycogen depletion in altering the acetaminophen-induced hepatotoxicity was examined subsequently. When mice were fasted overnight, hepatic glutathione and glycogen were decreased by 40 and 75%, respectively, and fasted animals showed a dramatic increase in susceptibility to acetaminophen-induced hepatotoxicity as measured by increased SGPT levels. Availability of glucose in the drinking water (5%) overnight resulted in glycogen levels similar to those in fed animals, whereas hepatic glutathione levels were not significantly different from those of fasted animals. Fasted animals and animals given glucose water overnight were equally susceptible to acetaminophen-induced hepatotoxicity, as quantitated by increases in SGPT levels 24 hr after drug administration. The potential role of a reactive metabolite in glycogen depletion was investigated by treating mice with N-acetylcysteine to increase detoxification of the reactive metabolite. N-Acetylcysteine treatment of mice prevented acetaminophen-induced glycogen depletion.     

Evaluation of efficacy of natural astaxanthin and vitamin E in prevention of colistin-induced nephrotoxicity in the rat model

ObjectiveWe evaluated the effect of astaxanthin (ASX) and vitamin E (vit E) on colistin methanesulfonate (CMS) induced-nephrotoxicity in rats.MethodsAnimals were treated with sterile saline, 300 000 or 450 000 IU/kg/day of CMS, CMS + ASX (20 mg/kg), CMS + vit E (100 mg/kg), or CMS + 1 ml/kg olive oil (OO) for 7 days. The plasma/urine creatinine (Cr) level, urine γ-glutamyl-transferase (GGT) level, and renal tissue activities in malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reductase (GSH), as well as renal histology were performed.ResultsCMS induced a tubular damage, increased the GGT and MDA levels, and decreased the activities of SOD, CAT, GPx and GSH. Co-treatment with ASX or vit E restored all biochemical parameters cited above and improved the histopathological damage.ConclusionNephrotoxicity induced by CMS might be due to oxidative damage. The improvement by ASX or vit E seems to be related to their antioxidant properties.     

Chlorpromazine-induced hepatotoxicity during inflammation is mediated by TIRAP-dependent signaling pathway in mice

Inflammation is a major component of idiosyncratic adverse drug reactions (IADRs). To understand the molecular mechanism of inflammation-mediated IADRs, we determined the role of the Toll-like receptor (TLR) signaling pathway in idiosyncratic hepatotoxicity of the anti-psychotic drug, chlorpromazine (CPZ). Activation of TLRs recruits the first adaptor protein, Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) to the TIR domain of TLRs leading to the activation of the downstream kinase, c-Jun-N-terminal kinase (JNK). Prolonged activation of JNK leads to cell-death. We hypothesized that activation of TLR2 by lipoteichoic acid (LTA) or TLR4 by lipopolysaccharide (LPS) will augment the hepatotoxicity of CPZ by TIRAP-dependent mechanism involving prolonged activation of JNK. Adult male C57BL/6, TIRAP^+/+ and TIRAP^?/? mice were pretreated with saline, LPS (2 mg/kg) or LTA (6 mg/kg) for 30 min or 16 h followed by CPZ (5 mg/kg) or saline (vehicle) up to 24 h. We found that treatment of mice with CPZ in presence of LPS or LTA leads to ~ 3–4 fold increase in serum ALT levels, a marked reduction in hepatic glycogen content, significant induction of serum tumor necrosis factor (TNF) α and prolonged JNK activation, compared to LPS or LTA alone. Similar results were observed in TIRAP^+/+ mice, whereas the effects of LPS or LTA on CPZ-induced hepatotoxicity were attenuated in TIRAP^?/? mice. For the first time, we show that inflammation-mediated hepatotoxicity of CPZ is dependent on TIRAP, and involves prolonged JNK activation in vivo. Thus, TIRAP-dependent pathways may be targeted to predict and prevent inflammation-mediated IADRs.     

Inhibitory actions of mGlu4 receptor ligands on cocaine-, but not nicotine-, induced sensitizing and conditioning locomotor responses in rats

BackgroundMale Wistar rats were used to verify the hypothesis that metabotropic glutamate 4 (mGlu₄) receptor ligands may modulate the locomotor effects evoked by cocaine or nicotine.MethodsThe preferential mGlu₄ receptor orthosteric agonist (2S)-2-amino-4-[hydroxy[hydroxy(4-hydroxy-3-methoxy-5-nitrophenyl)methyl]phosphoryl]butanoic acid (LSP1-2111) and the mGlu₄ receptor positive allosteric modulator (+)-cis-N¹-(3,4-dichlorophenyl)cyclohexane-1,2-dicarboxamide (Lu AF21934) were used in the study. Rats were given repeated pairings of a test environment with cocaine (10 mg/kg), nicotine (0.4 mg/kg) or the respective vehicles for 5 days. On day 10, animals were challenged with cocaine (10 mg/kg, cocaine sensitization), nicotine (0.4 mg/kg, nicotine sensitization) or vehicle (conditioned hyperlocomotion) in experimental cages.ResultsGiven on day 10, LSP1-2111 (3 mg/kg) as well as Lu AF21934 (2.5–5 mg/kg) decreased the expression of cocaine sensitization. In another set of experiments, LSP1-2111 (3 mg/kg) and Lu AF21934 (5 mg/kg) administered on day 10 attenuated the conditioned hyperlocomotion in rats treated repeatedly with cocaine. Neither LSP1-2111 (1–3 mg/kg) nor Lu AF21934 (2.5–5 mg/kg) changed the expression of nicotine sensitization and conditioned hyperlocomotion in rats treated repeatedly with nicotine. None of the mGlu₄ receptor agonist/modulator altered the basal locomotor activity or acute hyperactivity to cocaine or nicotine.ConclusionsThe present data indicate that pharmacological stimulation of mGlu₄ receptors reduces the cocaine-induced expression of sensitization as well as conditioned hyperactivity. In contrast, mGlu₄ receptor activation seems to be devoid of any effect on the locomotor effects of nicotine.     

Analysis of changes in hepatic gene expression in a murine model of tolerance to acetaminophen hepatotoxicity (autoprotection)

Pretreatment of mice with a low hepatotoxic dose of acetaminophen (APAP) results in resistance to a subsequent, higher dose of APAP. This mouse model, termed APAP autoprotection was used here to identify differentially expressed genes and cellular pathways that could contribute to this development of resistance to hepatotoxicity. Male C57BL/6J mice were pretreated with APAP (400 mg/kg) and then challenged 48 h later with 600 mg APAP/kg. Livers were obtained 4 or 24 h later and total hepatic RNA was isolated and hybridized to Affymetrix Mouse Genome MU430_2 GeneChip. Statistically significant genes were determined and gene expression changes were also interrogated using the Causal Reasoning Engine (CRE). Extensive literature review narrowed our focus to methionine adenosyl transferase-1 alpha (MAT1A), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), flavin-containing monooxygenase 3 (Fmo3) and galectin-3 (Lgals3). Down-regulation of MAT1A could lead to decreases in S-adenosylmethionine (SAMe), which is known to protect against APAP toxicity. Nrf2 activation is expected to play a role in protective adaptation. Up-regulation of Lgals3, one of the genes supporting the Nrf2 hypothesis, can lead to suppression of apoptosis and reduced mitochondrial dysfunction. Fmo3 induction suggests the involvement of an enzyme not known to metabolize APAP in the development of tolerance to APAP toxicity. Subsequent quantitative RT-PCR and immunochemical analysis confirmed the differential expression of some of these genes in the APAP autoprotection model. In conclusion, our genomics strategy identified cellular pathways that might further explain the molecular basis for APAP autoprotection.