thioacetamide and Liver-Failure

The water-soluble acidic polysaccharide from Thalassodendron ciliatum (Forss.) den Hartog was successfully extracted, fractionated and purified. The phytochemical profile of the two water-soluble fractions (F1 and F2), were detected using different analytic techniques. GC-MS analysis revealed the presence of 22 saccharide. Acidic polysaccharide, galacturonic and glucuronic acid were the most abundant. Moreover, paper chromatography and electrophoresis also performed as a preliminary chemical characterization of the polymer. The hepatoprotective activity of the fractions against thioacetamide (TAA) induced liver failure; antioxidant potential and preliminary immunomodulatory activity were assigned in-vivo. The results revealed a potent competence to improve the liver function profile (ALT, AST, total bilirubin, total glyceride, etc.) and a remarkable improvement in liver architecture in comparison to the challenged intoxicated groups. Moreover, they showed high anti-oxidative properties and a promising immunomodulatory influence via Il6. These findings provide new insight into the possible role of polysaccharide purified two fractions in the treatment of acute liver injury.

Topics: Animals; Chalcones; Chemical and Drug Induced Liver Injury; Dose-Response Relationship, Drug; Gas Chromatography-Mass Spectrometry; Glycosides; Liver Failure; Male; Polysaccharides; Rats; Rats, Wistar; Thioacetamide

Cerebral oxidative stress (OS) contributes to the pathogenesis of hepatic encephalopathy (HE). Existing evidence suggests that systemic administration of L-histidine (His) attenuates OS in brain of HE animal models, but the underlying mechanism is complex and not sufficiently understood. Here we tested the hypothesis that dipeptide carnosine (β-alanyl-L-histidine, Car) may be neuroprotective in thioacetamide (TAA)-induced liver failure in rats and that, being His metabolite, may mediate the well documented anti-OS activity of His. Amino acids [His or Car (100 mg/kg)] were administrated 2 h before TAA (i.p., 300 mg/kg 3× in 24 h intervals) injection into Sprague-Dawley rats. The animals were thus tested for: (i) brain prefrontal cortex and blood contents of Car and His, (ii) amount of reactive oxygen species (ROS), total antioxidant capacity (TAC), GSSG/GSH ratio and thioredoxin reductase (TRx) activity, and (iii) behavioral changes (several models were used, i.e. tests for reflexes, open field, grip test, Rotarod). Brain level of Car was reduced in TAA rats, and His administration significantly elevated Car levels in control and TAA rats. Car partly attenuated TAA-induced ROS production and reduced GSH/GSSG ratio, whereas the increase of TRx activity in TAA brain was not significantly modulated by Car. Further, Car improved TAA-affected behavioral functions in rats, as was shown by the tests of righting and postural reflexes. Collectively, the results support the hypothesis that (i) Car may be added to the list of neuroprotective compounds of therapeutic potential on HE and that (ii) Car mediates at least a portion of the OS-attenuating activity of His in the setting of TAA-induced liver failure.

Topics: Animals; Carnosine; Liver Failure; Male; Oxidative Stress; Posture; Rats; Rats, Sprague-Dawley; Thioacetamide

Protein homeostatic regulators have been shown to ameliorate single, loss-of-function protein diseases but not to treat broader animal disease models that may involve cell death. Diseases often trigger protein homeostatic instability that disrupts the delicate balance of normal cellular viability. Furthermore, protein homeostatic regulators have been delivered invasively and not with simple oral administration. Here, we report the potent homeostatic abilities of celastrol to promote cell survival, decrease inflammation, and maintain cellular homeostasis in three different disease models of apoptosis and inflammation involving hepatocytes and cardiomyocytes. We show that celastrol significantly recovers the left ventricular function and myocardial remodeling following models of acute myocardial infarction and doxorubicin-induced cardiomyopathy by diminishing infarct size, apoptosis, and inflammation. Celastrol prevents acute liver dysfunction and promotes hepatocyte survival after toxic doses of thioacetamide. Finally, we show that heat shock response (HSR) is necessary and sufficient for the recovery abilities of celastrol. Our observations may have dramatic clinical implications to ameliorate entire disease processes even after cellular injury initiation by using an orally delivered HSR activator.

Topics: Animals; Apoptosis; Cardiomyopathies; Cell Line, Tumor; Cell Survival; Disease Models, Animal; DNA-Binding Proteins; Doxorubicin; GATA4 Transcription Factor; Gene Expression; Heat Shock Transcription Factors; Heat-Shock Proteins; Humans; Interleukin-1beta; Interleukin-6; Liver; Liver Failure; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Pentacyclic Triterpenes; Thioacetamide; Transcription Factors; Triterpenes; Tumor Necrosis Factor-alpha

L-citrulline (Cit) is a co-product of NO synthesis and a direct L-arginine (Arg) precursor for de novo NO synthesis. Acute liver failure (ALF) is associated with increased nitric oxide (NO) and cyclic GMP (cGMP) synthesis in the brain, indirectly implicating a role for active transport of Cit. In the present study we characterized [(3)H]Cit uptake to the cortical brain slices obtained from control rats and rats with thioacetamide (TAA)-induced ALF ("TAA slices"). In both control and TAA slices the uptake was partially Na(+)-dependent and markedly inhibited by substrates of systems L and N, including L-glutamine (Gln), which accumulates in excess in brain during ALF. Cit uptake was not affected by Arg, the y(+)/y(+)L transport system substrate, nor by amino acids taken up by systems A, xc (-)or XAG. The Vmax of the uptake in TAA slices was ~60 % higher than in control slices. Chromatographic (HPLC) analysis revealed a ~30 % increase of Cit concentration in the cerebral cortical homogenates of TAA rats. The activity of argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL), the two enzymes of Cit-NO cycle catalyzing synthesis of Arg, showed an increase in TAA rats, consistent with increased ASS and ASL protein expression, by ~30 and ~20 %, respectively. The increased Cit-NO cycle activity was paralleled by increased expression of mRNA coding for inducible nitric oxide synthase (iNOS). Taken together, the results suggest a role for Cit in the activation of cerebral NO synthesis during ALF.

Topics: Animals; Arginine; Argininosuccinate Lyase; Argininosuccinate Synthase; Cerebral Cortex; Citrulline; In Vitro Techniques; Kinetics; Liver Failure; Male; Nerve Tissue Proteins; Nitric Oxide; Rats; Rats, Sprague-Dawley; Thioacetamide

Inflammation plays a pivotal role in liver injury. Gabexate mesilate (GM, a protease inhibitor) inhibits inflammation by blocking various serine proteases. This study examined the effects of GM on hepatic encephalopathy in rats with acute and chronic liver failure.. Acute and chronic liver failure (cirrhosis) were induced by intraperitoneal TAA administration (350 mg/kg/day for 3 days) and common bile duct ligation, respectively, in male Sprague-Dawley rats. Rats were randomized to receive either GM (50 mg/10 mL/kg) or saline intraperitoneally for 5 days. Severity of encephalopathy was assessed by the Opto-Varimex animal activity meter and hemodynamic parameters, mean arterial pressure and portal pressure, were measured (only in chronic liver failure rats). Plasma levels of liver biochemistry, ammonia, nitrate/nitrite, interleukins (IL) and tumor necrosis factor (TNF)-alpha were determined.. In rats with acute liver failure, GM treatment significantly decreased the plasma levels of alanine aminotransferase (P = 0.02), but no significant difference of motor activity, plasma levels of ammonia, IL-1beta, IL-6, IL-10 and TNF-alpha or survival was found. In chronic liver failure rats, GM significantly lowered the plasma TNF-alpha levels (P = 0.04). However, there was no significant difference of motor activity, other biochemical tests or survival found. GM-treated chronic liver failure rats had higher portal pressure (P = 0.04) but similar mean arterial pressure in comparison with saline-treated rats.. Chronic GM treatment does not have a major effect on hepatic encephalopathy in rats with TAA-induced acute liver failure and rats with chronic liver failure induced by common bile duct ligation.

Topics: Animals; Anti-Inflammatory Agents; Biomarkers; Blood Pressure; Chronic Disease; Common Bile Duct; Disease Models, Animal; Enzymes; Gabexate; Hepatic Encephalopathy; Inflammation Mediators; Ligation; Liver; Liver Failure; Liver Failure, Acute; Male; Motor Activity; Portal Pressure; Rats; Rats, Sprague-Dawley; Serine Proteinase Inhibitors; Severity of Illness Index; Thioacetamide; Time Factors

Hyperammonemia is a common complication of acute and chronic liver diseases. Often accompanied with side effects, therapeutic interventions such as antibiotics or lactulose are generally targeted to decrease the intestinal production and absorption of ammonia. In this study, we aimed to modulate hyperammonemia in three rodent models by administration of wild-type Lactobacillus plantarum, a genetically engineered ammonia hyperconsuming strain, and a strain deficient for the ammonia transporter. Wild-type and metabolically engineered L. plantarum strains were administered in ornithine transcarbamoylase-deficient Sparse-fur mice, a model of constitutive hyperammonemia, in a carbon tetrachloride rat model of chronic liver insufficiency and in a thioacetamide-induced acute liver failure mice model. Constitutive hyperammonemia in Sparse-fur mice and hyperammonemia in a rat model of chronic hepatic insufficiency were efficiently decreased by Lactobacillus administration. In a murine thioacetamide-induced model of acute liver failure, administration of probiotics significantly increased survival and decreased blood and fecal ammonia. The ammonia hyperconsuming strain exhibited a beneficial effect at a lower dose than its wild-type counterpart. Improved survival in the acute liver failure mice model was associated with lower blood ammonia levels but also with a decrease of astrocyte swelling in the brain cortex. Modulation of ammonia was abolished after administration of the strain deficient in the ammonium transporter. Intestinal pH was clearly lowered for all strains and no changes in gut flora were observed.. Hyperammonemia in constitutive model or after acute or chronic induced liver failure can be controlled by the administration of L. plantarum with a significant effect on survival. The mechanism involved in this ammonia decrease implicates direct ammonia consumption in the gut.

Topics: Acute Disease; Alanine; Ammonia; Animals; Carbon Tetrachloride; Chronic Disease; Disease Models, Animal; Hyperammonemia; Lactobacillus plantarum; Lactulose; Liver Failure; Male; Mice; Mice, Inbred C57BL; Probiotics; Rats; Rats, Inbred Lew; Thioacetamide

In thioacetamide-induced liver injury a modification of isoprenoid content and an increase of reactive oxygen species has been described. We have examined how reactive oxygen species influence the 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate limiting enzyme of the isoprenoid biosynthetic pathway, to verify if changes of that enzyme activity are involved in the changed lipid composition of the liver.. In chronic and acute thioacetamide-treated rat liver we measured the reactive oxygen species content, the activation state and K(M), the level and degradation rate of the hepatic reductase, its short term regulatory enzymes and the liver lipid profile.. In thioacetamide-treated rat liver, the reactive oxygen species content is high and the reductase is fully activated with no modifications in its K(M) and its short term regulatory enzymes. The reductase level is reduced in chronic thioacetamide treated rats and its degradation rate is altered.. The data show a relationship between reactive oxygen species production and altered 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. It is suggested that reducing the levels of reactive oxygen species may improve the altered lipid profile found in liver injury.

Topics: Animals; Blotting, Western; Disease Models, Animal; Enzyme Activation; Hydroxymethylglutaryl CoA Reductases; Liver Failure; Male; Oxidative Stress; Phosphorylation; Rats; Rats, Wistar; Reactive Oxygen Species; Spectrometry, Fluorescence; Thioacetamide

Hepatic encephalopathy (HE), a consequence of liver damage, is associated with cognitive deficits. In this study, behavioral activity, non-associative learning, associative memory, cognitive coordination and flexibility were investigated in rats with subclinical HE evoked by thioacetamide treatment. Non-associative learning was studied in the open field (OF) set up in 12 HE and 8 saline-injected control rats (C). Memory was examined in spatial place avoidance tasks in 10 HE and 10 C rats. The Room+ Arena- task involved the selection of distal room stimuli from irrelevant arena stimuli (i.e. intramaze cues and/or self-motion information), which engages processes of cognitive coordination. Following the Room+ Arena- training, cognitive flexibility of rats was tested in the Arena+ place avoidance condition, which demands the previously ignored stimuli from arena. In the OF test HE and control rats behaved similar. They displayed high activity in the first block of each session and this pattern was stable. In both groups of rats darkness enhanced locomotor activity in comparison to light only in the first block. The HE and C rats avoided the to-be-avoided place in the Room+ Arena- task, whereas only HE rats were affected in the Arena+ task. In conclusion, these results demonstrate cognitive inflexibility in HE rats. We suggest that (1) the behavioral changes in the TAA model are typical of subclinical HE and (2) test for cognitive flexibility may be modified towards a routine use in patients with subclinical HE.

Topics: Adaptation, Psychological; Animals; Association Learning; Avoidance Learning; Cognition; Discrimination Learning; Disease Models, Animal; Exploratory Behavior; Hepatic Encephalopathy; Liver Failure; Male; Maze Learning; Motor Activity; Rats; Rats, Wistar; Spatial Behavior; Thioacetamide

The hepatic lesion produced as a result of oxidative stress is of wide occurrence. In the present study, the effect of tungsten on liver necrosis and fulminant hepatic failure (FHF) has been studied in rats treated with various compounds known to produce oxidative stress. Supplementation of animals with sodium tungstate for 7 weeks before the induction of liver injury by chemicals including thioacetamide (TAA), carbon tetrachloride (CCl(4)), or chloroform (CHCl(3)) could protect progression of hepatic injury. Various biochemical changes associated with liver damage and oxidative stress were measured. Hepatic malondialdehyde content, endogenous tripeptide, and reduced glutathione were measured as oxidative stress markers. The activity of xanthine oxidase, which generates reactive oxygen species (ROS) as a by-product, was also determined and found to be perturbed. Tungsten supplementation to rats caused a significant decrease in lipid peroxidation and lowered the levels of the biochemical markers of hepatic lesions produced by TAA, CCl(4) (CCl(4)), or CHCl(3). Tungsten could also cause an increase in the survival rate in rats receiving lethal doses of TAA, CCl(4), or CHCl(3). The protective effect of tungsten, however, is suggested to be limited to the conditions where the hepatic lesion is reported to be due to the generation of ROS. The progression of liver injury produced by the compounds causing oxidative stress without initiating the generation of free radicals such as bromobenzene (BB), or acetaminophen (AAP), could not be inhibited by tungsten. The possible mechanism explaining the role of oxyanionic form of tungsten in free radical-induced hepatic lesions is discussed.

Topics: Acetaminophen; Alkaline Phosphatase; Allopurinol; Animals; Bromobenzenes; Carbon Tetrachloride Poisoning; Chloroform; Dimethyl Sulfoxide; Female; Lethal Dose 50; Liver; Liver Failure; Necrosis; Oxidative Stress; Rats; Rats, Wistar; Thioacetamide; Transaminases; Tungsten Compounds

Thioredoxin (Trx) is a small redox-active protein with antioxidant and antiapoptotic effects. Trx transgenic (Tg) mice are more resistant to cerebral infarction and survive longer than wild-type (WT) C57BL/6 mice. The aim of the present study was to investigate the protective role of Trx in acute hepatitis models. The expression of endogenous Trx was decreased in thioacetamide (TAA)-induced acute hepatitis. TAA (100 microg/g) was injected intraperitoneally in WT and Tg mice. Survival rate after TAA injection was higher in Tg mice than in WT mice. The level of oxidative stress was significantly less in Tg mice than in WT mice, as shown by the protein carbonylation assay and lipid peroxidation assay. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive cells were less in Tg mice than in WT mice, which was consistent with DNA laddering assay. Caspase-3 and caspase-9 activities and cytochrome c release were significantly inhibited in Tg mice compared with those in WT mice. In addition, lipopolysaccharide (LPS) plus d-galactosamine (GalN), or anti-Fas antibody (Jo2) were injected. Survival rate after LPS plus GalN injection was much higher in Tg mice than in WT mice. In contrast, there was no difference in survival rate after Jo2 injection between WT and Tg mice. In conclusion, transgene of Trx attenuated TAA- or LPS-induced acute lethal hepatitis. In addition to an antioxidant effect, Trx has the potential to protect acute liver injury via an antiapoptotic effect, which mainly inhibits mitochondria-mediated apoptosis signaling.

Topics: Acute Disease; Animals; Antibodies; Apoptosis; Chemical and Drug Induced Liver Injury; Down-Regulation; fas Receptor; Galactosamine; Humans; Lipopolysaccharides; Liver Failure; Male; Mice; Mice, Inbred C57BL; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Survival Rate; Thioacetamide; Thioredoxins

To assess lethal hepatic injury by combined treatment of radiation (RT) plus chemotherapy in a rat model with thioacetamide (TAA)-induced liver cirrhosis.. Male Wistar rats were treated with 0.3 g/L TAA in drinking water. The development of liver cirrhosis was histologically confirmed, and the degree of liver function impairment was assessed by indocyanine green retention test (ICG R15). The established cirrhotic rats were given one of the following treatments: partial liver radiotherapy (25 Gy on about one-third of the whole liver), 5-fluorouracil (5-FU) chemotherapy (50 mg/kg), and combined treatment of partial RT plus 5-FU. The treated rats were closely followed until either death or 30 weeks after the treatment, and the postmortem liver sampling was examined for lethal hepatic injury by the treatments.. The rats developed overt liver cirrhosis after 30 weeks of TAA treatment. At that time, the mean ICG R15 level in the TAA-treated rats (TAA-rats) was 14.1% +/- 0.7% compared to 4.6% +/- 0.7% in the control (p < 0.05). The 30-week survival rates in the control and TAA-rats were 100% (5/5) and 75% (6/8), respectively, after partial liver RT (p = 0.72). In the 5-FU chemotherapy group, the survival in TAA-rats was only one-half of that in the controls (100% vs. 50%, p = 0.06). Poor survival in TAA-rats was shown also in the combined group of partial RT plus 5-FU (87.5% vs. 16.7%, p = 0.06). The rats that died before the last observation time showed advanced cirrhosis with areas of lobular collapse, in contrast to the moderate cirrhotic features in those that survived.. In a rat cirrhosis model with mildly impaired liver function, combined treatment of partial RT plus 5-FU resulted in significantly high incidence of lethal liver injury. The results in this study show that a combined treatment of RT plus chemotherapy in cirrhotic patients should be applied with extreme caution.

Topics: Animals; Combined Modality Therapy; Fluorouracil; Liver; Liver Cirrhosis, Experimental; Liver Failure; Male; Radiotherapy; Rats; Survival Rate; Thioacetamide; Treatment Outcome

Hepatic stimulator substance (HSS) is a liver-specific growth factor implicated in hepatocellular proliferation and hepatoprotection in models of acute liver injury. In the present study, we examined the effect of exogenous HSS administration on liver proliferating capacity and survival outcome in an experimental animal model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA) in rats.. Fulminant hepatic failure was induced in adult male Wistar rats by three consecutive intraperitoneal injections of TAA (400 mg/kg of body weight), at 24 h time intervals. The animals received intraperitoneally either a saline solution or HSS (50 mg protein/kg of body weight), 2 h after the second and third TAA injections. The animals were killed at 6, 12 and 18 h post the last injection of TAA.. Levels of liver enzymes and urea in serum, blood ammonia values, liver histology, stage of hepatic encephalopathy and survival were statistically significantly improved in TAA-intoxicated and HSS-treated rats compared to TAA-intoxicated and saline-treated ones. Furthermore, HSS ameliorated liver regenerative indices--DNA biosynthesis, thymidine kinase activity and hepatocyte mitotic activity--in a statistically significant manner.. Our data suggest the beneficial effect of HSS administration in this animal model of FHF and encephalopathy, supporting evidence for a possible use of HSS as supportive therapy, by increasing hepatocellular proliferation, in management of FHF.

Topics: Animals; Growth Substances; Hepatic Encephalopathy; Injections, Intraperitoneal; Intercellular Signaling Peptides and Proteins; Liver Failure; Liver Regeneration; Male; Mitogens; Models, Animal; Peptides; Rats; Rats, Wistar; Sulfur Compounds; Survival Analysis; Thioacetamide

Hepatic stimulator substance (HSS) is a known liver-specific but species-nonspecific growth factor. In the present study we examined the activity of the endogenously produced HSS in an established experimental model of fulminant hepatic failure (FHF) and encephalopathy, induced by repeated injections of thioacetamide (TAA). FHF was induced by three consecutive intraperitoneal injections of TAA (400 mg/kg body weight) in rats, at time intervals of 24 hr. The animals were killed at 0, 6, 12, or 18 hr following the last injection of TAA. The rate of tritiated thymidine incorporation into hepatic DNA, the enzymatic activity of liver thymidine kinase (EC 2.7.1.21), and the assessment of mitotic index in hepatocytes were used to estimate liver regeneration. HSS extract obtained from the livers of TAA-treated rats, sacrificed at the above-mentioned time points was tested for its activity. Increased HSS activity was noted in all TAA-treated animals, presenting a peak at 12 hr following the third TAA dose, suggesting active participation of this growth factor in hepatocyte replication in this animal model of FHF and encephalopathy. It may also be suggested that up-regulation of HSS activity could be used in future as a therapeutic approach in FHF.

Topics: Animals; Disease Models, Animal; Growth Substances; Hepatic Encephalopathy; Humans; Injections, Intraperitoneal; Intercellular Signaling Peptides and Proteins; Liver; Liver Failure; Liver Function Tests; Liver Regeneration; Male; Necrosis; Peptides; Rats; Rats, Wistar; Thioacetamide; Up-Regulation

Reactive oxygen species and nuclear factor kappa B (NF-kappaB) activation have been implicated in the pathogenesis of cell injury in experimental models of liver damage. The aim of the present study was to examine whether pyrrolidine dithiocarbamate (PDTC), an anti oxidant and inhibitor of NF-kappaB activation, would prevent hepatic damage induced in a rat model of thioacetamide (TAA)-induced liver failure.. Fulminant hepatic failure was induced in the control and treatment groups by two intraperitoneal injections of TAA (either 300 or 400 mg/kg) at 24-h intervals. In the treatment groups, rats were treated also with PDTC (60 mg/kg/24 h, i.p.), initiated 24 h prior to TAA.. Liver enzymes, blood ammonia, and hepatic levels of thiobarbituric acid reactive substances (P<0.001) and protein carbonyls (P<0.05) were significantly lower in rats treated with PDTC compared to TAA only. Liver histology and the survival rate in the PDTC-treated rats were also improved (P<0.01 compared to TAA only). NF-kappaB activation, 2 and 6 h after TAA administration, was inhibited by PDTC.. In a rat model of fulminant hepatic failure, the administration of PDTC attenuated liver damage and improved survival. This effect may be due to decreased oxidative stress and inhibition of NF-kappaB activation.

Topics: Ammonia; Animals; Antioxidants; Lipid Peroxidation; Liver; Liver Failure; Male; NF-kappa B; Oxidative Stress; Proteins; Pyrrolidines; Rats; Rats, Wistar; Reactive Oxygen Species; Survival Rate; Thioacetamide; Thiobarbituric Acid Reactive Substances; Thiocarbamates; Transaminases

Increased GABA-mediated neurotransmission, reported to occur in hepatic encephalopathy (HE), is associated with a decrease in the release of Met-enkephalin and the expression of its coding gene in the brain. Furthermore, patients with cirrhosis and a history of HE exhibit increased sensitivity to the neuroinhibitory effects of morphine. Thus, there is a rationale to study the status of the endogenous opioid system in HE. The aim of this study was to determine whether mu-opioid receptors in the brain are up-regulated in a well characterized model of HE. Binding parameters of mu-opioid receptors were derived by assaying the binding of the opiate agonist [3H]-tyr-D-Ala-Gly-N-Methyl-Phe-Gly-ol (DAMGO) to brain membranes from rats with precisely defined stages of HE and control animals. The mean density of mu-opioid receptor sites (Bmax) in rats with stage II, III, and IV HE was 15, 29, and 33% higher, respectively, than the corresponding control value (p<0.01). In addition, the affinity of mu opioid receptors for the agonist (1/Kd) also increased with progression of HE (mean for stage IV HE vs. corresponding control mean, p<0.01). In conclusion, in liver failure, increased density and affinity of central mu-opioid receptors in the brain may: (i) be the basis for the documented increased sensitivity to opiate agonists; and (ii) occur as a consequence of increased GABAergic tone reducing neuronal synthesis and release of opioid agonist peptides.

Topics: Animals; Brain; Cell Membrane; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; gamma-Aminobutyric Acid; Hepatic Encephalopathy; Liver Failure; Male; Morphine; Rats; Receptors, Opioid, mu; Thioacetamide; Tritium; Up-Regulation

Serum hyaluronic acid (HA) is widely distributed in connective tissues, and the majority of circulating HA is degraded by hepatic sinusoidal endothelial cells (SECs) via a receptor recycling pathway. Our previous clinical study revealed that monitoring serum HA levels after hepatectomy is useful in predicting the development of liver failure. In the present study, to determine the mechanism of the high HA levels after hepatectomy, especially in patients with liver cirrhosis, expression of the major HA receptor, CD44, and its mRNA was investigated in SECs isolated from rats with thioacetamide-induced liver cirrhosis subjected to 70% hepatectomy (group I) and from rats with a normal liver that were subjected to 70% hepatectomy (group II). The 48-hour postoperative survival rate in group I (13.3%) was significantly lower than in group II (100%). In group II, the expression of CD44 mRNA had increased significantly at 6 hours after hepatectomy, and this was followed by progressive increases in expression of CD44, indicating activation of SEC function. The increased serum HA levels after hepatectomy in group II became normal as CD44 expression increased. By contrast, the expression of CD44 and CD44 mRNA in group I was markedly attenuated after hepatectomy. The very low CD44 expression was followed by a significant and sustained increase in serum HA levels, indicating functional failure of the SECs. These results suggest that the significantly impaired functional reserve of SECs in liver cirrhosis is associated with increased mortality after 70% hepatectomy.

Topics: Alanine Transaminase; Animals; Hepatectomy; Hepatocytes; Hyaluronan Receptors; Hyaluronic Acid; Liver Cirrhosis, Experimental; Liver Failure; Male; Microscopy, Fluorescence; Models, Animal; Predictive Value of Tests; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thioacetamide

Hepatic encephalopathy is a multifactorial neuropsychiatric syndrome accompanying acute or chronic liver failure. Techniques for developing animal models of hepatic encephalopathy associated with acute or chronic liver failure, or vascular shunting are illustrated. In addition, the behavioral and biochemical characteristics of these models are described.

Topics: Animals; Disease Models, Animal; Galactosamine; Hepatic Artery; Hepatic Encephalopathy; Hypertension, Portal; Ligation; Liver Failure; Male; Portacaval Shunt, Surgical; Postoperative Complications; Rats; Rats, Sprague-Dawley; Species Specificity; Suture Techniques; Thioacetamide

Expression and activation of hepatocyte growth factor (HGF) is stimulated by a complex system of interacting proteins, with thrombin playing an initial role in this process. The impact of temporary occlusion of the hepatobiliary tract with fibrin glue (major component thrombin) on the HGF system in acute and chronic liver damage in a rat model was investigated.. Chronic liver damage was induced in 40 rats by daily intraperitoneal application of thioacetamide (100 mg/kg) for 14 days. After 7 days half of them received an injection of 0.2 mL fibrin glue into the hepatobiliary system. Daily intraperitoneal administration of thioacetamide continued for 7 consecutive days. The rats were then sacrificed for blood and tissue analysis. Acute liver failure was induced in 12 rats by intraperitoneal administration of a lethal dose of thioacetamide (500 mg/kg per day for 3 days) after an injection with 0.2 mL fibrin glue into their hepatobiliary tract. Survival rates and histological outcome were investigated and compared with control animals.. Fibrin glue occluded rats showed significantly lower liver enzyme activities and serum levels of bilirubin, creatinine and urea nitrogen. Immunohistochemistry revealed a significant increase in c-met-, HGFalpha- and especially HGFbeta-positive cells. Rats subjected to a lethal dose of thioacetamide survived when fibrin glue was applied 24 hours prior to the toxic challenge. These animals showed normal liver structure and no clinical abnormalities.. Fibrin glue occlusion of the hepatobiliary tract induces therapeutic and prophylactic effects on chronic and acute liver failure by stimulating the HGF system. Therefore, fibrin glue occlusion might be useful in treating toxic liver failure.

Topics: Animals; Fibrin Tissue Adhesive; Hepatocyte Growth Factor; Immunohistochemistry; Injections, Intraperitoneal; Liver; Liver Failure; Liver Failure, Acute; Liver Regeneration; Male; Proto-Oncogene Proteins c-met; Rats; Rats, Sprague-Dawley; Statistics, Nonparametric; Survival Analysis; Thioacetamide; Tissue Adhesives

Hepatic encephalopathy, a complex neuropsychiatric syndrome secondary to acute liver failure, chronic parenchymal liver disease or portal-systemic shunting, may possibly develop through mediators of endotoxin and tumor necrosis factor-alpha (TNF-alpha). However, there are no published data concerning the relationships between the severity of encephalopathy and the plasma levels of endotoxin and TNF-alpha.. Male Sprague-Dawley rats weighing about 300-350 g were used. Fulminant hepatic failure was induced by intraperitoneal injection ofthioacetamide (350 mg/kg/day) for 3 consecutive days. Severity of encephalopathy was assessed by measuring motor counts using an Opto-Varimex animal activity meter. Plasma levels of endotoxin and TNF-alpha were determined by chromogenic Limulus assay and ELISA method, respectively.. Our study revealed that higher plasma levels of endotoxin (> 5.9 pg/ml) and TNF-alpha (> 18.8 pg/ml) were significantly associated with more blunted motor activities in rats with fulminant hepatic failure (p < 0.05). A significant correlation was observed between plasma concentrations of endotoxin and TNF-alpha (r = 0.59, p < 0.001). Plasma levels of endotoxin were weakly correlated with the total movements in an open field (r = -0.34, p = 0.032) and the counts of ambulatory (r = -0.38, p = 0.014) and vertical movements (r = -0.40, p = 0.010). There were no correlations between the motor counts and plasma levels of TNF-alpha (p > 0.05).. In addition to endotoxin and TNF-alpha, other factors may participate in the pathogenesis of hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure.

Topics: Animals; Endotoxins; Hepatic Encephalopathy; Liver Failure; Male; Motor Activity; Rats; Rats, Sprague-Dawley; Thioacetamide; Tumor Necrosis Factor-alpha

The cytokine IL-6 plays a significant role in liver regeneration in conjunction with additional growth factors (HGF, TNF-alpha, and TGF-alpha). Many IL-6 effects depend on a naturally occurring soluble IL-6 receptor (sIL-6R). Here, the chimeric protein hyper-IL-6, constructed from the human IL-6 protein fused to a truncated form of its receptor, was found to have superagonistic IL-6 properties, and as such, enhanced liver cell regeneration. Hyper-IL-6 reversed the state of hepatotoxicity and enhanced the survival rates of rats suffering from fulminant hepatic failure after D-galactosamine administration. The hyper-IL-6 protein has a significant potential for use in the treatment of severe human liver diseases.

Topics: Animals; Apoptosis; Cell Division; Disease Models, Animal; Galactosamine; Humans; Interleukin-6; Liver Failure; Liver Regeneration; Male; Rats; Rats, Inbred F344; Receptors, Interleukin; Receptors, Interleukin-6; Recombinant Fusion Proteins; Thioacetamide

Subclinical hepatic encephalopathy (SHE) was produced in rats by two intraperitoneal injections of TAA at 24 h intervals and the animals were examined 21 days later. Concentrations of the neuroactive amino acids taurine (Tau), glutamate (Glu) and aspartate (Asp), were measured in the cerebral cortical microdialysates of thioacetamide (TAA)-treated and untreated control rats. During microdialysis some animals were awake while others were anesthetized with ketamine plus xylazine. There was no difference in the water content of cerebral cortical slices isolated from control and SHE rats, indicating a recovery from cerebral cortical edema that accompanies the acute, clinical phase of hepatic encephalopathy in this model. When microdialysis was carried out in awake rats, dialysate concentrations of all the three amino acids were 30% to 50% higher in SHE rats than in control rats. Ketamine anesthesia caused a 2.2% increase of water content of cerebral cortical slices and increased Asp, Glu, and Tau concentration in microdialysates of control rats. In SHE rats, ketamine anesthesia produced a similar degree of cerebral edema, however, it did not alter Asp and Glu concentrations in the microdialysates. These data may reflect on one hand a neuropathological process of excitotoxic neuronal damage related to increased Glu and Asp, on the other hand neuroprotection from neuronal swelling indicated by Tau redistribution in the cerebral cortex. The reduction of the effects of SHE on Glu and Asp content in ketamine-anesthesized rats is likely to be due to interference of ketamine with the NMDA receptor-mediated component of the SHE-evoked excitatory neurotransmitter efflux and/or reuptake of the two amino acids. By contrast, the SHE-related increase of Tau content was not affected by ketamine anesthesia, indicating that the mechanism(s) underlying SHE-evoked accumulation of Tau must be different from the mechanism causing release of excitatory amino acids. The results with ketamine advocate caution when using this anesthetic in studies employing the cerebral microdialysis technique for measurement of extracellular amino acids.

Topics: Anesthetics, Dissociative; Animals; Aspartic Acid; Body Water; Cerebral Cortex; Extracellular Space; Glutamic Acid; Ketamine; Liver Failure; Male; Microdialysis; Rats; Rats, Wistar; Taurine; Thioacetamide

Rats treated with oxindole (10-100 mg/kg i.p.), a putative tryptophan metabolite, showed decreased spontaneous locomotor activity, loss of the righting reflex, hypotension, and reversible coma. Brain oxindole levels were 0.05 +/- 0.01 nmol/g in controls and increased to 8.1 +/- 1.7 or 103 +/- 15 nmol/g after its administration at doses of 10 or 100 mg/kg i.p., respectively. To study the role that oxindole plays in the neurological symptoms associated with acute liver failure, we measured the changes of its concentration in the brain after massive liver damage, and we investigated the possible metabolic pathways leading to its synthesis. Rats treated with either thioacetamide (0.2 and 0.4 g/kg i.p., twice) or galactosamine (1 and 2 g/kg i.p.) showed acute liver failure and a large increase in blood or brain oxindole concentrations (from 0.05 +/- 0.01 nmol/g in brains of controls to 1.8 +/- 0.3 nmol/g in brains of thioacetamide-treated animals). Administration of tryptophan (300-1,000 mg/kg p.o.) caused a twofold increase, whereas administration of indole (10-100 mg/kg p.o.) caused a 200-fold increase, of oxindole content in liver, blood, and brain, thus suggesting that indole formation from tryptophan is a limiting step in oxindole synthesis. Oral administration of neomycin, a broad-spectrum, locally acting antibiotic agent able to reduce intestinal flora, significantly decreased brain oxindole content. Taken together, our data show that oxindole is a neurodepressant tryptophan metabolite and suggest that it may play a significant role in the neurological symptoms associated with acute liver impairment.

Topics: Acute Disease; Animals; Anti-Bacterial Agents; Brain; Galactosamine; Hypnotics and Sedatives; Indoles; Liver Failure; Male; Neomycin; Oxindoles; Rats; Rats, Wistar; Thioacetamide; Tryptophan

Acute liver failure was induced in rats by successive administrations of thioacetamide over 3 days. At progressing stages of hepatic encephalopathy (HE), brains were fixed with microwave irradiation for analysis of metabolite levels or with formaldehyde for histopathological analysis. Metabolite levels were determined using 1H-nuclear magnetic resonance spectroscopy of perchloric acid extracts of the frontal cortex, parietal or occipital cortex, hippocampus, striatum, brain stem, and cerebellum. After thioacetamide treatment, thioacetamide and its metabolites were detected in the brains at levels that did not correlate with the stage of HE. No changes were observed in the levels of N-acetylaspartate, alanine, gamma-aminobutyric acid, aspartate, or inositol in any brain region after thioacetamide treatment. HE was accompanied by elevated glutamine, glucose, and lactate throughout the brain. At all stages of HE, taurine was decreased in the neocortex and hippocampus, and glutamate and choline compounds were decreased in the frontal cortex. None of the metabolite changes showed progression with the stage of HE. Progressing HE was accompanied by increasing neuronal injury in layer III of the neocortex, in the Purkinje cells of the cerebellum, and in the hippocampus, particularly in the CA4 sector. The similarity of this distribution of injury to that associated with excitotoxic injury suggests that metabolic abnormalities after acute hepatic failure may give rise to adverse effects at excitatory (glutamatergic) neuronal receptors, leading to neuronal injury and clinical symptoms of progressing encephalopathy in this model. However, neuronal injury and the presence of thioacetamide and its metabolites in the brain raise questions about the validity of thioacetamide-induced liver failure as a model for clinical HE.

Topics: Animals; Brain; Hepatic Encephalopathy; Liver Failure; Magnetic Resonance Spectroscopy; Male; Rats; Rats, Sprague-Dawley; Reference Values; Thioacetamide