Serum cytotoxin and oxidant stress markers in N-acetylcysteine treated thioacetamide hepatotoxicity of rats

In vivo hepatoprotective effect of Morinda elliptica stem extract against liver fibrosis induced by thioacetamide

Morinda elliptica L. (Rubiaceae) is a phytomedicinal herb, used to treat gastrointestinal complications in Peninsular Malaysia. The study evaluates the in vivo hepatoprotective activity of ethanolic extract of M. elliptica stem in thioacetamide (TAA) induced liver fibrosis in male Sprague Drawly rats. Thirty adult rats were divided into five groups of six rats each. Rats of the normal control group received intraperitoneal injections (i. p.) of vehicle 10% Tween-20, 5 ml/kg, and hepatotoxic group 200 mg/kg TAA three times per week respectively. Three supplementary groups were treated with TAA plus daily oral silymarin (50 mg/kg) or M. elliptica (250 or 500 mg/kg). After 8 weeks of treatment, all rats were sacrificed. Liver fibrosis was assessed by gross macroscopic and microscopic tissue analysis, histopathological, and biochemical analysis. The livers of the TAA treated group showed uniform coarse granules, hepatocytic necrosis with lymphocytes infiltration. Contrary, the livers of M. elliptica treated groups (250 and 500 mg/kg) were much smoother and the cell damage was much lesser. The livers of M. elliptica treated groups rats showed elevated activity of SOD and CAT with a significant decrease in MDA level at p < .0001. The level of liver damage parameters, that is, ALP, ALT, and AST, bilirubin, total protein, and albumin were restored to the normal comparable to silymarin. M. elliptica stem extract significantly promoted normal rat liver architecture with significant perfections in biochemical parameters. The molecular contents of M. elliptica with hepatoprotective influence could be discovered, is the future prospective of this study.

Drug-induced-acute liver failure: A critical appraisal of the thioacetamide model for the study of hepatic encephalopathy

Hepatic encephalopathy (HE) following acute and chronic liver failure is defined as a complex of neuropsychiatric abnormalities, such as discrete personal changes, sleep disorder, forgetfulness, confusion, and decreasing the level of consciousness to coma. The use and design of suitable animal models that represent clinical features and pathological changes of HE are valuable to map the molecular mechanisms that result in HE. Among different types of animal models, thioacetamide (TAA) has been used extensively for the induction of acute liver injury and HE. This agent is not directly hepatotoxic but its metabolites induce liver injury through the induction of oxidative stress and produce systemic inflammation similar to that seen in acute HE patients. In this short review article, we shortly review the most important pathological findings in animal models of acute HE following the administration of TAA.

Nanoparticle-delivery system enhanced the improvement and recovery in toxicity-induced acute hepatic failure

BACKGROUND

The major curative remedy for advanced liver failure is hepatic transplantation. However, the conventional medicine still shows the limitations and obstacles for liver regeneration. Importantly, it is unclear whether we can get a rapid and high efficacy platform to facilitate to reprogram hepatic capability. The main work of this study was to develop a platform for a nanomedicine-based gene-delivery platform of novel nanoparticles (NNPs) to efficiently facilitate the liver function recovery.

METHODS

In this study, we studied the feasibility and efficiency of NNP and produced the multiple abilities of NNPs for a potential platform of gene transduction. We showed that NNPs played an important role in hepatic protection. The cytoprotective effects of NNPs in toxic-hepatic cells were investigated and evaluated by cell viability, reactive oxygen species production, in vitro cell abilities, and in vivo animal studies.

RESULTS

We demonstrated that NNPs possess the abilities to protect the cell after toxic-stress both in vitro and in vivo. Under the stress condition, our result showed that cell viabilities can be improved by NNP-carried hepatocyte nuclear factor 3 (HNF3) gene (NNP-HNF3), which is a famous hepatic transcriptional factor and regenerative marker to modulate essential molecular pathways activating various hepatic-specific markers. Importantly, compared to control and NNP-control, NNP-HNF3 exhibited the cytoprotective effects that prevented toxic-induced oxidative stress and cell damage in vitro as well as in vivo. Notably, our data showed that NNP-HNF3 treatment may improve toxic-induced hepatic encephalopathy.

CONCLUSION

Herein, we demonstrated that novel nanoparticle, such as NNP-HNF3, serves as a key regulator for protecting the damaged hepatic cell and the bioproduct-based source for the new therapeutics of hepatic failure.

Selective overexpression of cytoglobin in stellate cells attenuates thioacetamide-induced liver fibrosis in mice

Cytoglobin (CYGB), discovered in hepatic stellate cells (HSCs), is known to possess a radical scavenger function, but its pathophysiological roles remain unclear. Here, for the first time, we generated a new transgenic (TG) mouse line in which both Cygb and mCherry reporter gene expression were under the control of the native Cygb gene promoter. We demonstrated that the expression of Cygb-mCherry was related to endogenous Cygb in adult tissues by tracing mCherry fluorescence together with DNA, mRNA, and protein analyses. Administration of a single dose (50 mg/kg) of thioacetamide (TAA) in Cygb-TG mice resulted in lower levels of alanine transaminase and oxidative stress than those in WT mice. After 10 weeks of TAA administration, Cygb-TG livers exhibited reduced neutrophil accumulation, cytokine expression and fibrosis but high levels of quiescent HSCs. Primary HSCs isolated from Cygb-TG mice (HSCCygb-TG) exhibited significantly decreased mRNA levels of α-smooth muscle actin (αSMA), collagen 1α1, and transforming growth factor β-3 after 4 days in culture relative to WT cells. HSCsCygb-TG were resistant to H2O2-induced αSMA expression. Thus, cell-specific overexpression of Cygb attenuates HSC activation and protects mice against TAA-induced liver fibrosis presumably by maintaining HSC quiescence. Cygb is a potential new target for antifibrotic approaches.

Nitric oxide elevation in polytrauma is driven by oxygen radicals

A common problem in management of polytrauma - a simultaneous injury to more than one organ or organ system, at least one of them lethal without intervention - is a discrepancy between a relatively good initial state and a serious subsequent development. Since nitric oxide (NO) is produced in high quantities during tissue injury, we assumed that serum levels of NO (and its oxidation products, NOx) might serve as a prognostic marker of polytrauma severity. However, we found recently that NOx was increased in polytrauma, but not in the most severe cases. The present study was undertaken to test the hypothesis that serum NOx is reduced in severe polytrauma by concomitant overproduction of reactive oxygen species (ROS). Polytrauma was induced in rats under anesthesia by bilateral fracture of femurs and tibiae plus incision of the right liver lobe through laparotomy. Serum NOx was measured by chemiluminescence after hot acidic reduction. The role of ROS was assessed by treatment with an antioxidant, N-acetyl-L-cysteine (NAC). Experimental polytrauma elevated NOx from 11.0+/-0.7 to 23.8+/-4.5 ppb. This was completely prevented by NAC treatment (9.1+/-2.2 ppb). Serum NOx is elevated in severe polytrauma, and this is not reduced by ROS. On the contrary, ROS are necessary for the NOx elevation, probably because ROS produced by inflammatory cells activated by the polytrauma induce massive NO production.

Inhibition of the JAK/STAT pathway by ruxolitinib ameliorates thioacetamide-induced hepatotoxicity

In an attempt to explore the role of the JAK/STAT pathway in liver inflammation, we investigated the effect of intervening this pathway by ruxolitinib in thioacetamide (TAA)-induced hepatotoxicity. Ruxolitinib treatments were administered to male mice either before or after intoxication with TAA. The hepatic histopathological and serum biochemical assessment revealed that ruxolitinib pre-treatments dose-dependently reduced TAA-induced liver injury, caspase 3 cleavage and increase in number of hepatocytes positive for the pro-apoptotic Bax, as well as inflammatory cells positive for F4/80 and myeloperoxidase activity in the liver. Ruxolitinib pre-treatments also curbed TAA-induced rise in NF-κB nuclear expression and STAT3 phosphorylation. Ruxolitinib pre-treatments also lowered TAA-induced elevation of hepatic oxidative stress parameters (total nitrate/nitrite and 4-hydroxynonenal), but did not restore the hepatic antioxidant reduced glutathione. Interestingly, ruxolitinib, especially at a dose of 200 mg/kg, dampened the overproduction of pro-inflammatory cytokines (TNF-α, IL-1β, IFN-γ, IL-23 and IL-17A), which coincided with boosting the release of the anti-inflammatory cytokine IL-10. Ruxolitinib when used as a post-treatment (1 and 3 h after TAA-insult) could still spare the liver from injury and might be clinically applicable. In conclusion, the multimechanistic-hepatoprotective activity of ruxolitinib can be linked to its ameliorative properties on cellular death, oxidative stress and inflammation machinery.

Comprehensive analysis of DNA methylation and gene expression of rat liver in a 2-stage hepatocarcinogenesis model

Recent studies have shown that epigenetic alterations correlate with carcinogenesis in various tissues. Identification of these alterations might help characterize the early stages of carcinogenesis. We comprehensively analyzed DNA methylation and gene expression in livers obtained from rats exposed to nitrosodiethylamine (DEN) followed by a promoter of hepatic carcinogenesis, phenobarbital (PB). The combination of DEN and PB induced marked increases in number and area of glutathione S-transferase-placental form (GST-P)-positive foci in the liver. In the liver of rats that received 30 mg/kg of DEN, pathway analysis revealed alterations of common genes in terms of gene expression and DNA methylation, and that these alterations were related to immune responses. Hierarchical clustering analysis of the expression of common genes from public data obtained through the Toxicogenomics Project-Genomics Assisted Toxicity Evaluation system (TG-GATEs) showed that carcinogenic compounds clustered together. MBD-seq and GeneChip analysis indicated that major histocompatibility complex class Ib gene RT1-CE5, which has an important role in antigen presentation, was hypomethylated around the promoter region and specifically induced in the livers of DEN-treated rats. Further, immunohistochemical analysis indicated that the co-localization of GST-P and protein homologous to RT1-CE5 was present at the foci of some regions. These results suggest that common genes were altered in terms of both DNA methylation and expression in livers, with preneoplastic foci indicating carcinogenic potential, and that immune responses are involved in early carcinogenesis. In conclusion, the present study identified a specific profile of DNA methylation and gene expression in livers with preneoplastic foci. Early epigenetic perturbations of immune responses might correlate with the early stages of hepatocarcinogenesis.

Nanostructured lipid carriers as a novel oral delivery system for triptolide: induced changes in pharmacokinetics profile associated with reduced toxicity in male rats

After oral administration in rodents, triptolide (TP), a diterpenoid triepoxide compound, active as anti-inflammatory, immunosuppressive, anti-fertility, anti-cystogenesis, and anticancer agent, is rapidly absorbed into the blood circulation (from 5.0 to 19.5 minutes after dosing, depending on the rodent species) followed by a short elimination half-life (from about 20 minutes to less than 1 hour). Such significant and rapid fluctuations of TP in plasma likely contribute to its toxicity, which is characterized by injury to hepatic, renal, digestive, reproductive, and hematological systems. With the aim of prolonging drug release and improving its safety, TP-loaded nanostructured lipid carriers (TP-NLCs), composed of Compritol® 888 ATO (solid lipid) and Capryol™ 90 (liquid lipid), were developed using a microemulsion technique. The formulated TP-NLCs were also characterized and in vitro release was evaluated using the dialysis bag diffusion technique. In addition, the pharmacokinetics and toxicology profiles of TP-NLCs were compared to free TP and TP-loaded solid lipid nanoparticles (TP-SLNs; containing Compritol 888 ATO only). Results demonstrate that TP-NLCs had mean particle size of 231.8 nm, increased drug encapsulation with a 71.6% efficiency, and stable drug incorporation for over 1-month. TP-NLCs manifested a better in vitro sustained-release pattern compared to TP-SLNs. Furthermore, TP-NLCs prolonged mean residence time (MRT)_0–t (P<0.001, P<0.001), delayed T_max (P<0.01, P<0.05) and decreased C_max (P<0.01, P<0.05) compared to free TP and TP-SLNs, respectively, which was associated with reduced subacute toxicity in male rats. In conclusion, our data suggest that TP-NLCs are superior to TP-SLNs and could be a promising oral delivery system for a safer use of TP.

'Omics analysis of low dose acetaminophen intake demonstrates novel response pathways in humans

Acetaminophen is the primary cause of acute liver toxicity in Europe/USA, which led the FDA to reconsider recommendations concerning safe acetaminophen dosage/use. Unfortunately, the current tests for liver toxicity are no ideal predictive markers for liver injury, i.e. they only measure acetaminophen exposure after profound liver toxicity has already occurred. Furthermore, these tests do not provide mechanistic information. Here, 'omics techniques (global analysis of metabolomic/gene-expression responses) may provide additional insight. To better understand acetaminophen-induced responses at low doses, we evaluated the effects of (sub-)therapeutic acetaminophen doses on metabolite formation and global gene-expression changes (including, for the first time, full-genome human miRNA expression changes) in blood/urine samples from healthy human volunteers. Many known and several new acetaminophen-metabolites were detected, in particular in relation to hepatotoxicity-linked, oxidative metabolism of acetaminophen. Transcriptomic changes indicated immune-modulating effects (2g dose) and oxidative stress responses (4g dose). For the first time, effects of acetaminophen on full-genome human miRNA expression have been considered and confirmed the findings on mRNA level. 'Omics techniques outperformed clinical chemistry tests and revealed novel response pathways to acetaminophen in humans. Although no definitive conclusion about potential immunotoxic effects of acetaminophen can be drawn from this study, there are clear indications that the immune system is triggered even after intake of low doses of acetaminophen. Also, oxidative stress-related gene responses, similar to those seen after high dose acetaminophen exposure, suggest the occurrence of possible pre-toxic effects of therapeutic acetaminophen doses. Possibly, these effects are related to dose-dependent increases in levels of hepatotoxicity-related metabolites.

Reprogramming induced pluripotent stem cells in the absence of c-Myc for differentiation into hepatocyte-like cells

Induced pluripotent stem cells (iPSCs) with four reprogramming factors (Oct-4/Sox2/Klf-4/c-Myc) have been shown to differentiate into hepatic lineages. However, it was unclear whether obviation of the c-Myc oncogene in iPSCs affected hepatic differentiation or inhibited in vivo tumor formation. In this study, we demonstrated that iPSCs without c-Myc had the capacity to differentiate into hepatocyte-like cells (iPSC-Heps) with biological functions. As detected using planar-radionuclide imaging and Hoechst labeling assays, these iPSCs and iPSC-Heps tended to mobilize to the injured liver area in thioacetamide (TAA)-treated mice. Intravenous transplantation of both iPSCs and iPSC-Heps but not mouse embryonic fibroblasts (MEFs) reduced the hepatic necrotic area, improved liver functions, and rescued TAA-treated mice from lethal acute hepatic failure (AHF). In addition, microarray-based bioinformatics and quantitative RT-PCR showed high expression of antioxidant genes in iPSCs and iPSC-Heps compared to MEFs. In vivo and in vitro studies of NAC pretreatment confirmed that iPSCs and iPSC-Heps potentially suppressed ROS production and activated antioxidant enzymes in TAA-injured livers. Six months after transplantation in TAA-treated mice, tumor formation was not seen in non-c-Myc iPSC grafts. Therefore, reprogramming adult somatic cells without c-Myc may prevent oxidative stress-induced damage and provide a safer alternative for hepatic regeneration in AHF.

An antibody of TNF-alpha did not prevent thioacetamide-induced hepatotoxicity in rats

Tumor necrosis factor (TNF)-α antibodies have been shown to reduce liver damage in different models. We investigated the effects of infliximab (a TNF-α antibody) on liver damage in thioacetamide (TAA)-induced hepatotoxicity in rats. Group 1 (n = 8) was the control group. In group 2 (n = 8), the TAA group, the rats received 300 mg/kg intraperitoneal (ip) TAA daily for 2 days. In group 3 (n = 8), the TAA + Infliximab (INF) group, infliximab (5 mg/kg ip daily) was administered 48 hours before the first dose of TAA daily for 2 days and was maintained for 4 consecutive days. In group 4 (n = 8), the INF group, the rats received only ip infliximab (5 mg/kg) daily. Livers were excised for histopathological and biochemical tests (thiobarbituric-acid-reactive substances [TBARS], and myeloperoxidase [MPO]). Serum ammonia, aspartate transaminase (AST), alanine transaminase (ALT), TNF-α, liver TBARS and MPO levels, and liver necrosis and inflammation scores in the TAA group were significantly higher than in the control and INF groups (all p < 0.01). All parameters except AST were not significantly different between TAA and TAA + INF. In conclusion, our results suggest that oxidative stress plays an important role in TAA-induced hepatotoxicity, and infliximab does not improve oxidative liver damage.

Effects of cytochrome P4503A inducer dexamethasone on the metabolism and toxicity of triptolide in rat

Triptolide (TP), a major active and toxic component of Tripterygium wilfordii, is reported to be converted into four mono-hydroxylated metabolites (m/z 375) by cytochrome P450 (CYP) in vitro, and CYP3A4 was the primary isoform responsible for its hydroxylation. Dexamethasone (DXM), a CYP3A inducer, is frequently combined with TP in clinical therapy. However, the effects of DXM on the metabolism and toxicity of TP are unknown. In this study, the metabolism of TP was investigated in rat liver microsomes pretreated with DXM. The metabolic profile of TP was significantly altered. The V(max) was about 9.58-fold higher than that of vehicle group and the K(m) was about 3.57-fold higher. With DXM, the amount of metabolite M3 was significantly higher than that with no DXM while M1 and M2 were not found, and a new metabolite (m/z 391) was observed. The liver and the kidney toxicity of TP on rat pretreated with DXM were evaluated. We observed that pretreatment with DXM protected against TP hepatotoxicity. No obvious nephrotoxicity was detected on rats treated with TP, whereas the kidney damage was observed in DXM group and the level of toxicity was much reduced with DXM-TP group. This suggested that TP might decrease nephrotoxicity induced by DXM. These studies indicated that DXM had significant impact on the metabolism and the toxicity of TP as a therapeutic agent.

Hepatocytes are protected by herb Phyllanthus niruri protein isolate against thioacetamide toxicity

The herb, Phyllanthus niruri has been known to possess protective activity against various drugs and toxins induced hepatic disorders. Present study was conducted to evaluate the role of the protein isolate of the herb against thioacetamide (TAA)-induced cytotoxicity in mice hepatocytes. In vitro cell viability, lactate dehydrogenase (LDH) and alanine amino transferase (ALT) leakage were measured as the indicators of cell damage. In addition, measurement of the level of non-protein thiol, glutathione (GSH); activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) as well as the extent of lipid peroxidation were carried out to evaluate the prooxidant-antioxidant status of the cell. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay was performed to determine the radical scavenging activity of the protein isolate. Results showed that the administration of the protein isolate prior to TAA exposure significantly reduced the release of LDH and ALT leakage and enhanced the cell viability in a dose-dependent manner in hepatocytes. Besides, the protein isolate appeared to prevent the alterations in GSH levels and activities of the anti-oxidant enzymes related to prooxidant-antioxidant status of hepatocytes. It also reduced the TAA-induced lipid peroxidation significantly as demonstrated by the reduction of malondialdehyde (MDA) production. DPPH radical scavenging assay showed that the protein isolate possessed radical scavenging activity. Combining, the data suggest that the protein isolate could protect hepatocytes from TAA-induced cellular injury probably by its antioxidative and radical scavenging properties.

Hepatoprotective and antioxidative effects of total phenolics from Laggera pterodonta on chemical-induced injury in primary cultured neonatal rat hepatocytes

Although Laggera pterodonta as a folk medicine has been widely used for several centuries to ameliorate some inflammatory ailments as hepatitis in China, there have been no studies of the hepatoprotective and antioxidative effects of this plant. In this paper, the hepatoprotective effect of total phenolics from L. pterodonta (TPLP) against CCI4-, D-GalN-, TAA-, and t-BHP-induced injury was examined in primary cultured neonatal rat hepatocytes. TPLP inhibited the cellular leakage of two enzymes, hepatocyte ASAT and ALAT, caused by these chemicals and improved cell viability. Moreover, TPLP afforded much stronger protection than the reference drug silibinin. Meanwhile, DPPH and superoxide radicals scavenging activities of TPLP were also determined. The present investigation is the first to report chemical-induced injury model in primary cultured neonatal rat hepatocytes and provide evidence for the hepatoprotective and antioxidative effects of L. pterodonta. Neutralizing reactive oxygen species by nonenzymatic mechanisms may be one of main mechanisms of TPLP against chemical-induced hepatocyte injury. Furthermore, The total phenolic content of L. pterodonta and its main component type were quantified, and its principle components isochlorogenic acids were isolated and authenticated. These data support the folkloric uses of L. pterodonta in the treatment of hepatitis.

Attenuation of cadmium chloride induced cytotoxicity in murine hepatocytes by a protein isolated from the leaves of the herb Cajanus indicus L

Cadmium has been recognized as a strong environmental pollutant. Exposure to this heavy metal occurs through the intake of foodstuffs, drinking water and also via the inhalation of air. Present study was conducted to evaluate the protective effect of a 43 kDa protein, isolated from the leaves of the herb Cajanus indicus, against cadmium-induced cytotoxicity in hepatocytes. For this study, cadmium chloride (CdCl(2)) has been used as the source of cadmium. Treatment of hepatocytes with 800 microM CdCl(2) for 3 h caused significant reduction in cell viability in association with the increased levels of glutamate pyruvate transaminase (GPT) and alkaline phosphatase (ALP) leakage. The activities of the antioxidant enzymes, superoxide dismutase, catalase (CAT), glutathione-S-transferase and glutathione reductase, and the levels of cellular metabolites, reduced glutathione (GSH) as well as total thiols have also been decreased under the same treatment. In addition, the toxin enhanced the levels of the lipid peroxidation end products and oxidized glutathione (GSSG). Incubation of hepatocytes with the protein at a dose of 0.1 mg/ml for 3 h prior to the toxin treatment (at a dose of 800 microM for 3 h) restored the activities of all the antioxidant enzymes, the levels of GSH, total thiols, cell viability and also attenuated the increased levels of GPT, ALP, lipid peroxidation and GSSG. In addition, the protein resisted CdCl(2) induced alterations of all the parameters when applied in combination with CdCl(2). Effects of a known antioxidant, vitamin E, and a non-relevant protein, bovine serum albumin against CdCl(2) induced cytotoxicity have also been included in the study. Combining all, we would like to say that the protein possessed protective activity against CdCl(2) induced cytotoxicity in mouse hepatocytes probably via its antioxidant property.

Purification and Characterization of a 43 kD Hepatoprotective Protein from the Herb Cajanus indicus L

Cajanus indicus L, a herb, is popularly known for its hepatoprotective activity. Aqueous extract of the leaves of this plant contains hepatoprotective and hepatostimulatory molecule(s). Present study was aimed to isolate, purify and characterize the active principle(s) responsible for that activity. A hepatoprotective protein molecule has been purified to homogeneity (approximately 300 fold). Homogeneous preparation of the protein was achieved by homogenization, (NH(4))(2)SO(4) precipitation, ion-exchange chromatography, gel filtration and high performance liquid chromatography. The protein purified is composed of a single polypeptide chain having an apparent molecular mass of 43 kD as determined by SDS-PAGE and gel filtration through sephadex G-75 column. The isoelectric point of the protein determined was 4.8. Loss of biological activity after heat and protease treatment confirmed that the active molecule is a protein. Peptide fragments of the protein generated by trypsin cleavage were subjected to MALDI-TOF as well as LC-MS analyses and among the various fragments, four were very prominent and used for the determination of the amino acid sequence of the hepatoprotective protein. While one of the peptide fragment revealed strong sequence homology with plastocyanin, another fragment showed some similarity with a tomato protein present in the NCBI non-redundant database. The third peptide, on the other hand, is unique as it did not show any sequence homology with any known protein in the database. The protein showed maximum hepatoprotective activity when administered at a dose of 2 mg/kg body weight for five days after CCl(4 )administration. Histopathological studies also supported the hepatoprotective nature of the protein. Along with its curative property, the protein also possesses preventive role against a number of toxin induced hepatic damages.

A 43-kDa protein from the leaves of the herb Cajanus indicus L. modulates chloroform induced hepatotoxicity in vitro

A 43-kDa protein isolated from the leaves of the herb Cajanus indicus L. has been shown to possess a protective role against drug- and toxin- induced hepatotoxicity both in vivo and in vitro. The current study was conducted to evaluate its protective action against chloroform (CHCl3)-induced cytotoxicity in hepatocytes. Cellular viability and biochemical parameters such as glutamate pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) release from the cells were measured. In addition, the antioxidant effect of the protein was investigated from the DPPH radical scavenging assay and by determining the levels of the antioxidant enzyme catalase (CAT), cellular reserves of reduced glutathione (GSH), and lipid peroxidation end products (measured as TBARS). Treatment of the cells with CHCl3 decreased cellular viability and increased GPT and LDH. Cells treated with the protein before and immediately after CHCl3 application showed a marked improvement in their viability and reduced leakage of GPT and LDH. The levels of CAT and GSH, which were diminished in cells treated with CHCl3, were restored by protein treatment. CHCl3 induced enhancement of lipid peroxidation in hepatocytes was significantly reduced by protein treatment. Results of the DPPH assay with the protein showed its radical scavenging activity. This data suggests that the protein possesses protective activity against CHCl3-induced cytotoxicity in hepatocytes and protects against CHCl3-induced hepatic damage.

Involvement of P53 and Bax/Bad triggering apoptosis in thioacetamide-induced hepatic epithelial cells

AIM: Thioacetamide (TAA) has been used in studying liver fibrosis and cirrhosis, however, the mechanisms of TAA-induced apoptosis in liver are still unclear. The hepatic epithelial cell line clone 9 was cultured and treated with TAA to investigate the causes of cell death.

METHODS: The cell viability of TAA-induced clone 9 cells was determined using MTT assay. Total cellular GSH in TAA-induced clone 9 cells was measured using a slight modification of the Tietze assay. The activity of caspase 3 in TAA-induced clone 9 cells was monitored by the cleavage of DEVD-p-nitroanaline. TUNEL assay and flow cytometry were applied for the determination of DNA fragmentation and the proportion of apoptosis in TAA-induced clone 9 cells, respectively. The alterations of caspase 3, Bad, Bax and Phospho-P53 contents in TAA-induced clone 9 cells were measured by Western blot.

RESULTS: The experimental data indicated that TAA caused rat hepatic epithelial cell line clone 9 cell death in a dose-and time-dependent manner; 60% of the cells died (MTT assay) within 24 h after 100 mg/L TAA was applied. Apoptotic cell percentage (TUNEL assay) and caspase 3 activities were highest after 100 mg/L TAA was added for 8 h. The release of GSH and the elevation in caspase content after TAA treatment resulted in clone 9 cell apoptosis via oxidative stress and a caspase-dependent mechanism. The phospho-p53, Bax and Bad protein expressions in clone 9 cells were increased after TAA treatment.

CONCLUSION: These results reveal that TAA activates p53, increases caspase 3, Bax and Bad protein contents, perhaps causing the release of cytochrome c from mitochondria and the disintegration of membranes, leading to apoptosis of cells.

Synergistic protection by S-adenosylmethionine with vitamins C and E on liver injury induced by thioacetamide in rats

Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). We investigated the effects of S-adenosylmethionine (SAMe) combined with/without vitamins C and E on TAA-induced acute liver injury in rats. TAA was given intraperitoneally (200 mg kg-1). Antioxidant treatments (SAMe, 25 mg kg-1; vitamin C, 100 mg kg-1; vitamin E, 200 mg kg-1, intraperitoneal) were given 1 h later. Liver histology, enzymology, and ability to release hepatic insulin-sensitizing substance (HISS) were assessed. TAA caused liver tissue injury, increased liver enzymes, and decreased insulin sensitivity (p<0.01). Blockade of HISS release by atropine did not further decrease insulin sensitivity in rats with TAA insult, indicating that the decrease in insulin sensitivity was HISS dependent. Treatment with SAMe alone or vitamins C+E slightly improved liver histology but not the changes in liver enzymes and insulin sensitivity. Combined treatment with SAMe plus vitamins C+E greatly protected the liver from tissue injury, the increase in liver enzymes, and the decrease in insulin sensitivity. In conclusion, acute liver injury causes HISS-dependent insulin resistance (HDIR). There are synergistic antioxidative effects among the antioxidants, SAMe and vitamins C and E, that protect the liver from TAA-induced HDIR, suggesting that antioxidant treatment may best be done using a balanced "cocktail."

A 43 kDa protein from the herb Cajanus indicus L. protects thioacetamide induced cytotoxicity in hepatocytes

The aim of this study was to investigate the role of a hepatoprotective protein isolated from the herb Cajanus indicus L. on thioacetamide (TAA) induced toxicity in isolated mouse hepatocytes. In vitro cell viability, lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and total protein leakage were measured as the indicator of cell damage. The amount of glutathione (GSH) and lipid peroxidation were also measured to determine the oxidative status of the cells. The reduced cell viability in TAA treated hepatocytes was almost completely recovered upon protein treatment. LDH, ALT and total protein secretion outside the cells after TAA treatment confirmed the cell membrane damage. Incubation of hepatocytes with the protein prior to TAA administration significantly prevented the cell membrane damage as revealed from less LDH, ALT and total protein leakage. TAA depleted endogenous antioxidant GSH and increased membrane lipid peroxidation in hepatocytes. The protein had very prominent effect in altering the GSH level and lipid peroxidation. The protein exhibited all these cytoprotective effects in a dose-dependent manner. Besides, measurement of DPPH radical scavenging activity showed that the protein could scavenge free radicals. In addition, the protein resisted TAA induced alterations of various effects when applied in combination with TAA. The cytoprotective activity of the protein was found to be comparable with alpha-tocopherol, a well-known antioxidant. Results suggest that the protein from C. indicus can act as a hepatoprotector and primary antioxidant against TAA-induced cytotoxicity in mouse hepatocytes.

Co-administration of cyclosporine A alleviates thioacetamide-induced liver injury

AIM: To investigate the effects of cyclosporine A (CsA) on thioacetamide (TAA)-induced liver injury.

METHODS: CsA was co-administrated (7.5 μg/kg body weight per day, i.p.) into rat to investigate the role of CsA on TAA-(200 mg/kg body weight per 3 d for 30 d, i.p.)induced liver injury.

RESULTS: The data show that TAA caused liver fibrosis in rat after 30 d of treatment. CsA alleviates the morphological changes of TAA-induced fibrosis in rat liver. The blood glutamyl oxaloacetic transaminase (GOT)/glutamyl pyruvic transaminase (GPT) in the TAA-injury group is elevated compared to that of the normal rat. Compared with the TAA-injury group, the blood GOT/GPT and TGFβ1 (by RT-PCR analysis) are reduced in the CsA plus TAA-treated rat. The level of the transforming growth factor receptor I (TGFβ-R1) in the CsA plus TAA-treated group shows higher than that in the TAA only group, but shows a lower level of the fibroblast growth factor receptor 4 (FGFR4) in the CsA plus TAA-treated group, when using the Western blot analysis. After immunostaining of the frozen section, TGFβ-R1 and FGFR4 are more concentrated in rat liver after CsA plus TAA injury.

CONCLUSION: This result suggests that CsA has an alleviated effect on TAA-induced liver injury by increasing the multidrug resistance P-glycoprotein and could be through the regulation of TGFβ-R1 and FGFR4.

Specific type IV phosphodiesterase inhibitor ameliorates thioacetamide-induced liver injury in rats

BACKGROUND AND AIMS

Rolipram is a specific type IV phosphodiesterase inhibitor that suppresses the activity of immune cells and the production of pro-inflammatory cytokines. In this study, we assessed the effect of rolipram on acute liver injury using thioacetamide (TAA)-induced liver injury in rats as a model.

METHODS

Rats were treated with rolipram (0.5-5 mg/kg, intraperitoneally) or vehicle and injected 30 min later with TAA (100 mg/kg, subcutaneously). Serum transaminase concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) levels were measured and livers were examined for microscopic changes. Dose-dependent protection against TAA liver injury was based on transaminase levels and inflammatory cytokine production, and was measured 9 h after TAA when the peak release of cytokines occurred.

RESULT

Rolipram suppressed liver injury based on serum aspartate transaminase (AST), alanine transaminase (ALT) and histology and reduced TNF-alpha, IL-1beta and GRO/CINC-1 levels. Rolipram, at doses of 0.5-5 mg/kg, suppressed serum transaminase and TNF-alpha production in a dose-dependent manner, and these effects were significant at doses of 2.5 and 5 mg/kg.

CONCLUSION

In our rodent model of acute liver injury, rolipram clearly reduced liver damage and inhibited pro-inflammatory cytokine production. These results suggest that specific type IV phosphodiesterase inhibitors, such as rolipram, have potent hepatoprotective effects that are associated with suppressing inflammatory cytokine production.

Tetramethylpyrazine protects mice against thioacetamide-induced acute hepatotoxicity

In this study, the intraperitoneal administration of 1 mg/kg thioacetamide (TAA) produced hepatotoxicity in mice. The increase in serum SGOT and SGPT produced at 24 h by this regimen was decreased in a dose-dependent manner by coadministration of tetramethylpyrazine (TMP; 10, 25 and 50 mg/kg). A rise in serum interleukin-2 was similarly prevented. Increased concentrations of malondialdehyde (MDA) generated in vitro in liver homogenates prepared from TAA-treated mice were decreased by TMP treatments. The increase in MDA produced by TAA was also prevented by in vitro addition of TMP to liver homogenates. These results suggest that part of the hepatocellular injury induced by TAA is mediated by oxidative stress caused by the action of cytokines through lipid peroxidation. TMP appears to act by preventing lipid peroxidation.

Pyrrolidine dithiocarbamate protects against thioacetamide-induced fulminant hepatic failure in rats

BACKGROUND/AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Xanthine oxidase-derived reactive oxygen metabolites contribute to liver necrosis: protection by 4-hydroxypyrazolo[3,4-d]pyrimidine

Xanthine oxidase (XO) generates reactive oxygen metabolites (ROM) as a by-product while catalyzing their reaction. The present study implicates these ROM in the pathogenesis of liver necrosis produced in rats by the intraperitoneal administration of thioacetamide (TAA; 400 mg/kg b.wt.). After 16 h of TAA administration, the activity of rat liver XO increased significantly compared to that of the control group. At the same time, the level of serum marker enzymes of liver necrosis (aminotransferases and alkaline phosphatase) and tissue malondialdehyde content also increased in TAA treated rats. Tissue malondialdehyde concentration is an indicator of lipid peroxidation and acts as a useful marker of oxidative damage. Pretreatment of rats with XO inhibitor (4-hydroxypyrazolo[3,4-d]pyrimidine; allopurinol (AP)) followed by TAA could lower the hepatotoxin-mediated rise in malondialdehyde level as well as the level of marker enzymes associated with liver necrosis. The survival rate also increased in rats given AP followed by the lethal dose of TAA. In either case, the effect of AP was dose-dependent. Results presented in the paper indicate that increased production of XO-derived ROM contributes to liver necrosis, which can be protected by AP.