Nephroprotective effects of b-carotene on ACE gene expression, oxidative stress and antioxidant status in thioacetamide induced renal toxicity in rats

β -carotene is one of carotenoid natural pigments, which are produced by plants and are accountable for the bright colors of various fruits and vegetables. These pigments have been widely studied for their ability to prevent chronic diseases and toxicities. This study was designed to evaluate the effects of β-carotene on angiotensin converting enzyme (ACE) gene expression, oxidative stress and antioxidant status in thioacetamide induced renal toxicity. Total 24 albino wistar rats of male sex (200-250gm) were divided into 6 groups as Group-1: The control remained untreated; Group-2: Received thioacetamide (200mg/kg b.w; i.p) for 12 weeks; Group-3: Received β-carotene orally (200mg/kg b.w), for 24 weeks; and Group-4: Received thioacetamide (200mg/kg b.w; i.p) for 12 weeks + received β-carotene orally (200mg/kg b.w), for further 12 weeks. The expression of ACE gene in thioacetamide induced renal toxicity in rats as well as supplemented with β-carotene was investigated and compared their level with control groups by using the quantitative RT-PCR method. The ACE gene expression was significantly increase in TAA rats as compare to control rats specifies that TAA induced changes in ACE gene of kidney, elevated renal ACE has been correlated with increase hypertensive end organ renal damage. The quantity of ACE gene were diminish in our rats who received β-Carotene after TAA is administered, for this reason they seemed to be defended against increased ACE levels in kidney bought by TAA. In pre- and post-treatment groups, we studied the role of β-Carotene against thioacetamide in the kidney of Wistar rats. Experimental confirmation from our study illustrates that β-Carotene can certainly work as a successful radical-trapping antioxidant our results proved that TAA injury increased lipid peroxidation and diminish antioxidant GSH, SOD and CAT in renal tissue. Since β-Carotene administration recover renal lipid peroxidation and antioxidants, it give the impression that β-Carotene protects renal tissue against thioacetamide-induced oxidative damage.

Dectin-1 Regulates Hepatic Fibrosis and Hepatocarcinogenesis by Suppressing TLR4 Signaling Pathways

Dectin-1 is a C-type lectin receptor critical in anti-fungal immunity, but Dectin-1 has not been linked to regulation of sterile inflammation or oncogenesis. We found that Dectin-1 expression is upregulated in hepatic fibrosis and liver cancer. However, Dectin-1 deletion exacerbates liver fibro-inflammatory disease and accelerates hepatocarcinogenesis. Mechanistically, we found that Dectin-1 protects against chronic liver disease by suppressing TLR4 signaling in hepatic inflammatory and stellate cells. Accordingly, Dectin-1(-/-) mice exhibited augmented cytokine production and reduced survival in lipopolysaccharide (LPS)-mediated sepsis, whereas Dectin-1 activation was protective. We showed that Dectin-1 inhibits TLR4 signaling by mitigating TLR4 and CD14 expression, which are regulated by Dectin-1-dependent macrophage colony stimulating factor (M-CSF) expression. Our study suggests that Dectin-1 is an attractive target for experimental therapeutics in hepatic fibrosis and neoplastic transformation. More broadly, our work deciphers critical cross-talk between pattern recognition receptors and implicates a role for Dectin-1 in suppression of sterile inflammation, inflammation-induced oncogenesis, and LPS-mediated sepsis.

Investigation of Therapeutic Effects of α-Mangostin on Thioacetamide-Induced Cirrhosis in Rats

OBJECTIVE

To determine the effects of alpha-mangostin on thioacetamide (TAA)-induced liver cirrhosis in rats.

MATERIAL AND METHOD

Male Wistar rats were divided into 3 groups and treated with intraperitoneal injections of TAA (200 mg/kg) 3 times per week for per week for 8, 12 and 16 weeks, respectively. One subgroup was left untreated whereas the other two were treated either with 100 mg/kg α-mangostin or vehicle alone (80% DMSO, 20% water), which were administered intraperitoneally 3 times per weekfor a total of4 weeks. The incidence offibrotic nodules on the liver and the serum levels of the liver enzymes aspartate transaminase (AST) and alanine transaminase (ALT) were measured. Moreover the liver cirrhosis-related genes expression and p53 protein level in liver were analyzed by quantitative reverse transcription PCR and Western blot analysis, respectively.

RESULTS

Fibrotic nodules on the liver were formed upon treatment with TAA for 12 or 16 weeks. The nodules were then reduced by treatment with α-mangostin as compared to treatment with the vehicle DMSO. Moreover, the serum levels of the liver enzymes AST and ALT after treatment with α-mangostin decreased as compared to DMSO alone. The liver cirrhosis-related genes expression showed no significant differences, whereas the p53 protein level in liver showed that α-mangostin reduced risk of liver fibrosis through the decrease in p53 expression as compared to the TAA_DMSO treatment.

CONCLUSION

The results suggest that α-mangostin has a beneficial therapeutic effect in the TAA liver cirrhosis model. Further investigations on mechanisms of α-mangostin as therapeutic agent should be determined.

Alpha-Mangostin Partially Preserves Expression of Ammonia-Metabolizing Enzymes in Thioacetamide-Induced Fibrotic and Cirrhotic Rats

BACKGROUND

Ammonia metabolizing enzymes, carbamyol phosphate synthetase (CPS) and glutamine synthetase (GS), are expressed in the periportal and pericentral hepatocytes, respectively. CPS and GS function complementary to ensure complete ammonia detoxification. Immunohistochemical analysis confirmed the decline of both CPS and GS in cirrhotic rat liver induced by thioacetamide (TAA). Alpha-mangostin (AM), a major derivative of xanthone from mangosteen, has been reported to possess a wide range of pharmacological properties.

OBJECTIVE

To examine the preventive effects of AM on CPS and GS expression in fibrotic and cirrhotic rats induced by TAA over sixteen weeks.

MATERIAL AND METHOD

Twenty-four male Wistar rats were divided into 4 groups of 6 animals each. Group 1 was for control. Group 2 wasfor pure TAA treatment. Group 3 was for pure AM administration. Group 4, prevention group, was concurrently treated with TAA and AM. Immunohistochemical technique was employed in order to elucidate the expression of CPS and GS in each animal group.

RESULTS

Immunohistochemical staining for CPS and GS showed an increasing decline from week eight to sixteen under pure-TAA condition. Fibrous bridgings, nodule formations, and regenerative nodules were detected. Pure-AM condition yielded strongly CPS and GS-stained hepatocytes in afashion similar to the control. Results from the prevention group showed a decreasing decline of CPS and GS immuno-reactivity from week eight to sixteen as compared to pure-TAA condition. Fewer fibrous portal-caval bridgings were observed at week eight and CPS-positive hepatocytes were found in continuous rings.

CONCLUSION

Alpha-mangostin could partially preserve the normal expression of ammonia-metabolizing enzymes under TAA-induced fibrotic and cirrhotic conditions.

Tranilast reduces serum IL-6 and IL-13 and protects against thioacetamide-induced acute liver injury and hepatic encephalopathy

Hepatic encephalopathy is a serious neuropsychiatric disorder usually affecting either acute or chronic hepatic failure patients. Hepatic encephalopathy was replicated in a validated rat model to assess the potential protective efficacy of tranilast against experimentally induced hepatic encephalopathy. Thioacetamide injection significantly impaired hepatic synthetic, metabolic and excretory functions with significant increase in serum NO, IL-6 and IL-13 levels and negative shift in the oxidant/antioxidant balance. Most importantly, there was a significant increase in serum ammonia levels with significant astrocytes' swelling and vacuolization; hallmarks of hepatic encephalopathy. Tranilast administration (300 mg/kg, orally) for 15 days significantly improved hepatic functions, restored oxidant/antioxidant balance, reduced serum NO, IL-6 and IL-13 levels. Meanwhile, serum ammonia significantly declined with significant reduction in astrocytes' swelling and vacuolization. Several mechanisms can be implicated in the observed hepato- and neuroprotective potentials of tranilast, such as its anti-inflammatory potential, its antioxidant potential as well as its immunomodulatory properties.

Effects of a high protein diet on cognition and brain metabolism in cirrhotic rats

Hepatic encephalopathy (HE) is a neurological complication observed in patients with liver disease. Patients who suffer from HE present neuropsychiatric, neuromuscular and behavioral symptoms. Animal models proposed to study HE resulting from cirrhosis mimic the clinical characteristics of cirrhosis and portal hypertension, and require the administration of hepatotoxins such as thioacetamide (TAA). The aim of this study was to assess the effects of a high protein diet on motor function, anxiety and memory processes in a model of cirrhosis induced by TAA administration. In addition, we used cytochrome c-oxidase (COx) histochemistry to assess the metabolic activity of the limbic system regions. Male rats were distributed into groups: control, animals with cirrhosis, Control rats receiving a high protein diet, and animals with cirrhosis receiving a high protein diet. Results showed preserved motor function and normal anxiety levels in all the groups. The animals with cirrhosis showed an impairment in active avoidance behavior and spatial memory, regardless of the diet they received. However, the animals with cirrhosis and a high protein diet showed longer escape latencies on the spatial memory task. The model of cirrhosis presented an under-activation of the dentate gyrus and CA3 hippocampal subfields and the medial part of the medial mammillary nucleus. The results suggest that a high protein intake worsens spatial memory deficits shown by the TAA-induced model of cirrhosis. However, high protein ingestion has no influence on the COx hypoactivity associated with the model.

Pyrroloquinoline-quinone suppresses liver fibrogenesis in mice

Liver fibrosis represents the consequences of a sustained wound healing response to chronic liver injuries, and its progression toward cirrhosis is the major cause of liver-related morbidity and mortality worldwide. However, anti-fibrotic treatment remains an unconquered area for drug development. Accumulating evidence indicate that oxidative stress plays a critical role in liver fibrogenesis. In this study, we found that PQQ, a natural anti-oxidant present in a wide variety of human foods, exerted potent anti-fibrotic and ROS-scavenging activity in Balb/C mouse models of liver fibrosis. The antioxidant activity of PQQ was involved in the modulation of multiple steps during liver fibrogenesis, including chronic liver injury, hepatic inflammation, as well as activation of hepatic stellate cells and production of extracellular matrix. PQQ also suppressed the up-regulation of RACK1 in activated HSCs in vivo and in vitro. Our data suggest that PQQ suppresses oxidative stress and liver fibrogenesis in mice, and provide rationale for the clinical application of PQQ in the prevention and treatment of liver fibrosis.

Liver toxicity of thioacetamide is increased by hepatocellular iron overload

An increase in hepatic iron concentration might exacerbate liver injury. However, it is unknown whether hepatic iron overload may exacerbate acute liver injury from various toxins. Therefore, we evaluated how manipulations to increase hepatic iron concentration affected the extent of acute liver injury from thioacetamide. In this study, we used rats with either "normal" or increased hepatic iron concentration. Iron overload was induced by either providing excess iron in the diet or by injecting iron subcutaneously. Both routes of providing excess iron induced an increase in hepatic iron overload. Meanwhile, the subcutaneous route induced both hepatocellular and sinusoidal cell iron deposition; the oral route induced lesser degree of hepatic iron concentration and only hepatocellular iron overload. Thioacetamide administration to the rats with "normal" hepatic iron concentration induced hepatic cell necrosis and apoptosis associated with a remarkable increase in serum aminotransaminases and depletion of hepatic glutathione and other antioxidative indices. Thioacetamide administration to the iron-overloaded rats exacerbated the extent of liver injury only in the rats orally induced with iron overload. In the rats subcutaneously induced with iron overload, the extent of liver injury from thioacetamide was not different from that observed in the rats with "normal" iron overload. It was concluded that the outcome of thioacetamide-induced acute liver injury may depend on both the level of hepatic iron concentration and on the cellular distribution of iron. While isolated hepatocellular iron overload may exacerbate thioacetamide-induced acute liver injury, a combined hepatocellular and sinusoidal cell iron deposition, even at high hepatic iron concentration, had no such an effect.

Celastrol, an oral heat shock activator, ameliorates multiple animal disease models of cell death

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.

Effect of epigallocatechin gallate on uncoupling protein 2 in acute liver injury

BACKGROUND

The aim of this study was to investigate the effect of epigallocatechin gallate (EGCG) on uncoupling protein 2 regulation in an acute liver injury-animal model.

METHODS

Twenty seven male Wistar rats were divided into three groups: control group (n = 9), TAA group (n = 9): acute liver injury was induced by the intraperitoneal injection of thioacetamide (200 mg/kg) and EGCG/TAA (n = 9 rats): Epigallocatechin gallate was given two weeks prior to the induction of acute liver injury by thioacetamide. The levels of uncoupling protein 2, CRP, TNF-α and interleukins (IL) 6 and 18 were analyzed in the liver using PCR analysis.

RESULTS

Q-PCR analysis showed that the genetic expression of UCP2, TNF-α and CRP in the EGCG/TAA group was the least in comparison to other groups (P ≤ 0.005). The IL-6 and IL-18 were upregulated after induction of acute liver injury, but this upregulation was significantly less in the group that received epigallocatechin gallate (EGCG/TAA) compared to the TAA group. In addition, histological examination showed a reduction in hepatocyte injury in EGCG/TAA compared to the TAA group.

CONCLUSION

Epigallocatechin gallate administration prior to induction of acute liver injury down-regulates uncoupling protein 2 expression and reduces IL-6, IL-18, TNF-α and CRP.

Modulation of thioacetamide-induced hepatic inflammations, angiogenesis and fibrosis by andrographolide in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis is a complex disease in which several pathological processes, such as inflammation and angiogenesis, are closely integrated.

MATERIALS AND METHODS

We hypothesised that treatment with the pharmacological agent, andrographolide (AP), which has multiple mechanisms of action, will provide a greater understanding of the role of AP during the multiple pathological processes that occur in advanced liver disease.

RESULTS

Liver fibrogenesis was induced in mice using thioacetamide (TAA), which was administrated for 6 weeks. Andrographolide (5, 20 or 100mg/kg) was then given once daily following TAA injection. Liver collagen was examined using hydroxyproline and α-SMA, while the inflammatory response was quantified by Western blot and RT-PCR assays. Liver angiogenesis, neutrophil infiltration and hypoxia were assessed using CD11b+, vWF and HIF-1α immunostaining. Mice with liver injuries that were treated with andrographolide showed improved inflammatory response and diminished angiogenesis and hepatic fibrosis. Andrographolide treatment inhibited liver neutrophil infiltration, while a decreased in TNF-α and COX-2 signalling indicated macrophage activation. Andrographolide decreased overall liver hypoxia, as shown by the downregulation of hypoxia-inducible cascade genes, such as VEGF. Andrographolide treatment resulted in a significant decrease in hepatic fibrogenesis, α-SMA abundance, and TGF-βR1 expression.

CONCLUSIONS

The present results suggest that multi-targeted therapies directed against angiogenesis, inflammation, and fibrosis should be considered for the treatment of advanced liver injury. They further suggest that andrographolide treatment may be a novel therapeutic agent for the treatment of liver disease.

Citrulline uptake in rat cerebral cortex slices: modulation by Thioacetamide -Induced hepatic failure

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.

Andrographis paniculata leaf extract prevents thioacetamide-induced liver cirrhosis in rats

This study investigated the hepatoprotective effects of ethanolic Andrographis paniculata leaf extract (ELAP) on thioacetamide-induced hepatotoxicity in rats. An acute toxicity study proved that ELAP is not toxic in rats. To examine the effects of ELAP invivo, male Sprague Dawley rats were given intraperitoneal injections of vehicle 10% Tween-20, 5 mL/kg (normal control) or 200 mg/kg TAA thioacetamide (to induce liver cirrhosis) three times per week. Three additional groups were treated with thioacetamide plus daily oral silymarin (50 mg/kg) or ELAP (250 or 500 mg/kg). Liver injury was assessed using biochemical tests, macroscopic and microscopic tissue analysis, histopathology, and immunohistochemistry. In addition, HepG2 and WRL-68 cells were treated invitro with ELAP fractions to test cytotoxicity. Rats treated with ELAP exhibited significantly lower liver/body weight ratios and smoother, more normal liver surfaces compared with the cirrhosis group. Histopathology using Hematoxylin and Eosin along with Masson’s Trichrome stain showed minimal disruption of hepatic cellular structure, minor fibrotic septa, a low degree of lymphocyte infiltration, and minimal collagen deposition after ELAP treatment. Immunohistochemistry indicated that ELAP induced down regulation of proliferating cell nuclear antigen. Also, hepatic antioxidant enzymes and oxidative stress parameters in ELAP-treated rats were comparable to silymarin-treated rats. ELAP administration reduced levels of altered serum liver biomarkers. ELAP fractions were non-cytotoxic to WRL-68 cells, but possessed anti-proliferative activity on HepG2 cells, which was confirmed by a significant elevation of lactate dehydrogenase, reactive oxygen species, cell membrane permeability, cytochrome c, and caspase-8,-9, and, -3/7 activity in HepG2 cells. A reduction of mitochondrial membrane potential was also detected in ELAP-treated HepG2 cells. The hepatoprotective effect of 500 mg/kg of ELAP is proposed to result from the reduction of thioacetamide-induced toxicity, normalizing reactive oxygen species levels, inhibiting cellular proliferation, and inducing apoptosis in HepG2 cells.

Antrodia cinnamomea profoundly exalted the reversion of activated hepatic stellate cells by the alteration of cellular proteins

The direct modulation of Antrodia cinnamomea (AC) on the prominent role of liver fibrosis-hepatic stellate cells (HSCs) in situ remains unclear. Firstly, the administration of A. cinnamomea mycelial extract (ACME) could improve liver morphology and histological changes including collagen formation and GPT activity in the liver of thioacetamide (TAA)-injured rats. The morphology and fatty acid restore of TAA-induced HSCs (THSCs) returned to the non-chemical induced HSCs (NHSCs) type as measured by immunofluorescence and Oil Red O staining. PPARγ was upregulated associated with the lowering of α-SMA protein in NHSC-ACME. ACME inhibited the MMP-2 activity in NHSCs by gelatin Zymography. After LC-MS/MS, the cytoskeleton (tubulin, lamin A) and heat shock protein 8 in NHSC-ACME, and guanylate kinase, brain-specific kinase, SG-II and p55 proteins were downregulated in THSC-ACME. Whereas MHC class II, SMC6 protein, and phospholipase D were upregulated in NHSC-ACME. Furthermore, PKG-1 was downregulated in NHSC-ACME and upregulated in THSC-ACME. SG-II and p55 proteins were downregulated in NHSC-ACME and THSC-ACME by Western blotting. Taken together, the beneficial effect of A. cinnamomea on the induction of HSC cellular proteins is potentially applied as an alternative and complementary medicine for the prevention and amelioration of a liver injury.

In vivo evaluation of ethanolic extract of Zingiber officinale rhizomes for its protective effect against liver cirrhosis

Zingiber officinale is a traditional medicine against various disorders including liver diseases.The aim of this study was to assess the hepatoprotective activity of the ethanolic extract of rhizomes of Z. officinale (ERZO) against thioacetamide-induced hepatotoxicity in rats. Five groups of male Sprague Dawley have been used. In group 1 rats received intraperitoneal (i.p.) injection of normal saline while groups 2-5 received thioacetamide (TAA, 200 mg/kg; i.p.) for induction of liver cirrhosis, thrice weekly for eight weeks. Group 3 received 50 mg/kg of silymarin. The rats in groups 4 and 5 received 250 and 500 mg/kg of ERZO (dissolved in 10% Tween), respectively. Hepatic damage was assessed grossly and microscopically for all of the groups. Results confirmed the induction of liver cirrhosis in group 2 whilst administration of silymarin or ERZO significantly reduced the impact of thioacetamide toxicity. These groups decreased fibrosis of the liver tissues. Immunohistochemistry assessment against proliferating cell nuclear antigen did not show remarkable proliferation in the ERZO-treated rats when compared with group 2. Moreover, factions of the ERZO extract were tested on Hep-G2 cells and showed antiproliferative activity (IC50 38-60 μ g/mL). This study showed hepatoprotective effect of ERZO.

Effect of oral administration of ethanolic extract of Vitex negundo on thioacetamide-induced nephrotoxicity in rats

BACKGROUND

Oxidative stress due to abnormal induction of reactive oxygen species (ROS) molecules is believed to be involved in the etiology of many diseases. Evidences suggest that ROS is involved in nephrotoxicity through frequent exposure to industrial toxic agents such as thioacetamide (TAA). The current investigation was designed to explore the possible protective effects of the leaves of Vitex negundo(VN) extract against TAA-induced nephrotoxicity in rats.

METHODS

Twenty four Sprague Dawleyrats were divided into four groups: (A) Normal control, (B) TAA (0.03% w/v in drinking water), (C) VN100 (VN 100 mg/kg + TAA) and (D) VN300 (VN 300 mg/kg + TAA). Blood urea and serum creatinine levels were measured,supraoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) levels of renal tissue were assayed. Histopathological analysis together with the oxidative stress nicotinamide adenine dinucleotide phosphate (NADPH) oxidase p22phox in kidney sections were examined in all experimental groups.

RESULTS

Blood urea and serum creatinine levels were increased in TAA group as a result of the nephrotoxicity compared to the VN100 and VN300 groups where, the levels were significantly decreased (p < 0.05). Renal MDA level was significantly decreased (p < 0.05) in the VN-treated groups with increased CAT and SOD activities compared to the TAA group. Light microscopic examination of renal tissues stained by H&E stain and Masson's Trichrome for TAA-treated groups revealed severe histopathological changes, whereas specimens obtained from VN-treated groups showed only mild changes. These findings were supported by immunohistochemical results.

CONCLUSIONS

VN extract acts as a natural potent antioxidant to prevent ongoing TAA-induced nephrotoxicity in rats, both biochemically and morphologically.

Regression of fibrosis and reversal of cirrhosis in rats by galectin inhibitors in thioacetamide-induced liver disease

Galectin-3 protein is critical to the development of liver fibrosis because galectin-3 null mice have attenuated fibrosis after liver injury. Therefore, we examined the ability of novel complex carbohydrate galectin inhibitors to treat toxin-induced fibrosis and cirrhosis. Fibrosis was induced in rats by intraperitoneal injections with thioacetamide (TAA) and groups were treated with vehicle, GR-MD-02 (galactoarabino-rhamnogalaturonan) or GM-CT-01 (galactomannan). In initial experiments, 4 weeks of treatment with GR-MD-02 following completion of 8 weeks of TAA significantly reduced collagen content by almost 50% based on Sirius red staining. Rats were then exposed to more intense and longer TAA treatment, which included either GR-MD-02 or GM-CT-01 during weeks 8 through 11. TAA rats treated with vehicle developed extensive fibrosis and pathological stage 6 Ishak fibrosis, or cirrhosis. Treatment with either GR-MD-02 (90 mg/kg ip) or GM-CT-01 (180 mg/kg ip) given once weekly during weeks 8–11 led to marked reduction in fibrosis with reduction in portal and septal galectin-3 positive macrophages and reduction in portal pressure. Vehicle-treated animals had cirrhosis whereas in the treated animals the fibrosis stage was significantly reduced, with evidence of resolved or resolving cirrhosis and reduced portal inflammation and ballooning. In this model of toxin-induced liver fibrosis, treatment with two galectin protein inhibitors with different chemical compositions significantly reduced fibrosis, reversed cirrhosis, reduced galectin-3 expressing portal and septal macrophages, and reduced portal pressure. These findings suggest a potential role of these drugs in human liver fibrosis and cirrhosis.

Ammonia upregulates kynurenine aminotransferase II mRNA expression in rat brain: a role for astrocytic NMDA receptors?

Kynurenine aminotransferase II (KAT-II) is the astrocytic enzyme catalyzing the synthesis of kynurenic acid (KYNA), an endogenous inhibitor of the α7-nicotinic receptor and the NMDA receptor (NMDAr). A previous study demonstrated an increase of KYNA synthesis in the brain of rats with thioacetamide (TAA)-induced acute liver failure. Here we show that TAA administration increases KAT-II expression in the rat cerebral cortex and the effect is mimicked in cerebral cortical astrocytes in culture treated with high (5 mM) concentration of ammonia. KAT-II expression in control and TAA-treated rats was increased by NMDAr antagonist memantine, and the effects of TAA and memantine appeared additive. In astrocytes, the NMDAr antagonist MK-801 raised KAT-II expression as well, while NMDA added alone had no effect. Glutamate decreased KAT-II mRNA level, which was attenuated by MK-801. The results suggest that stimulation of KAT-II expression during hepatic encephalopathy may be associated with a partial inactivation of astrocytic NMDAr by ammonia.

Protein targets of thioacetamide metabolites in rat hepatocytes

Thioacetamide (TA) has long been known as a hepatotoxicant whose bioactivation requires S-oxidation to thioacetamide S-oxide (TASO) and then to the very reactive S,S-dioxide (TASO2). The latter can tautomerize to form acylating species capable of covalently modifying cellular nucleophiles including phosphatidylethanolamine (PE) lipids and protein lysine side chains. Isolated hepatocytes efficiently oxidize TA to TASO but experience little covalent binding or cytotoxicity because TA is a very potent inhibitor of the oxidation of TASO to TASO2. However, hepatocytes treated with TASO show extensive covalent binding to both lipids and proteins accompanied by extensive cytotoxicity. In this work, we treated rat hepatocytes with [(14)C]-TASO and submitted the mitochondrial, microsomal, and cytosolic fractions to 2DGE, which revealed a total of 321 radioactive protein spots. To facilitate the identification of target proteins and adducted peptides, we also treated cells with a mixture of TASO/[(13)C2D3]-TASO. Using a combination of 1DGE- and 2DGE-based proteomic approaches, we identified 187 modified peptides (174 acetylated, 50 acetimidoylated, and 37 in both forms) from a total of 88 nonredundant target proteins. Among the latter, 57 are also known targets of at least one other hepatotoxin. The formation of both amide- and amidine-type adducts to protein lysine side chains is in contrast to the exclusive formation of amidine-type adducts with PE phospholipids. Thiobenzamide (TB) undergoes the same two-step oxidative bioactivation as TA, and it also gives rise to both amide and amidine adducts on protein lysine side chains but only amidine adducts to PE lipids. Despite their similarity in functional group chemical reactivity, only 38 of 62 known TB target proteins are found among the 88 known targets of TASO. The potential roles of protein modification by TASO in triggering cytotoxicity are discussed in terms of enzyme inhibition, protein folding, and chaperone function, and the emerging role of protein acetylation in intracellular signaling and the regulation of biochemical pathways.

Transforming growth factor β neutralization ameliorates pre-existing hepatic fibrosis and reduces cholangiocarcinoma in thioacetamide-treated rats

Considerable evidence has demonstrated that transforming growth factor β (TGF-β) plays a key role in hepatic fibrosis, the final common pathway for a variety of chronic liver diseases leading to liver insufficiency. Although a few studies have reported that blocking TGF-β with soluble receptors or siRNA can prevent the progression of hepatic fibrosis, as yet no evidence has been provided that TGF-β antagonism can improve pre-existing hepatic fibrosis. The aim of this study was to examine the effects of a murine neutralizing TGF-β monoclonal antibody (1D11), in a rat model of thioacetamide (TAA)-induced hepatic fibrosis. TAA administration for 8 weeks induced extensive hepatic fibrosis, whereupon 1D11 dosing was initiated and maintained for 8 additional weeks. Comparing the extent of fibrosis at two time points, pre- and post-1D11 dosing, we observed a profound regression of tissue injury and fibrosis upon treatment, as reflected by a reduction of collagen deposition to a level significantly less than that observed before 1D11 dosing. Hepatic TGF-β1 mRNA, tissue hydroxyproline, and plasminogen activator inhibitor 1 (PAI-1) levels were significantly elevated at the end of the 8 week TAA treatment. Vehicle and antibody control groups demonstrated progressive injury through 16 weeks, whereas those animals treated for 8 weeks with 1D11 showed striking improvement in histologic and molecular endpoints. During the course of tissue injury, TAA also induced cholangiocarcinomas. At the end of study, the number and area of cholangiocarcinomas were significantly diminished in rats receiving 1D11 as compared to control groups, presumably by the marked reduction of supporting fibrosis/stroma. The present study demonstrates that 1D11 can reverse pre-existing hepatic fibrosis induced by extended dosing of TAA. The regression of fibrosis was accompanied by a marked reduction in concomitantly developed cholangiocarcinomas. These data provide evidence that therapeutic dosing of a TGF-β antagonist can diminish and potentially reverse hepatic fibrosis and also reduce the number and size of attendant cholangiocarcinomas.

Protective effects of different extracts of Eucommia ulmoides Oliv. against thioacetamide-induced hepatotoxicity in mice

A comparison of analysis in evaluating the hepatoprotective action of fractional ethanolic (F0), ethyl acetic (F1), n-butanol (F2) and aqueous (F3) extracts of E. ulmoides Oliv. (EUO) against thioacetamide (TAA) induced hepatic damage was studied in mice. The extract (453 mg/kg-F0, 104 mg/kg-F1, 95 mg/kg-F2 and 237 mg/kg-F3 body weight, po, once daily for 15 days) restored serum marker enzymes levels to normal in TAA treated mice. The biochemical biomarkers viz., total protein, albumin and total bilirubin were also restored forward normal level expression pattern of liver protein profile of mice by using sodium dodecyl sulfate polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis showed 144 spots in TAA administered group which were significantly reduced in EUO extracts treated group. Among the four extracts ethyl acetate (F1) and n-butanol (F2) extracts showed more significant liver protection. TAA induced injury can be correlated with its high phenolic content in these extracts which may have hepatoprotective effects in regulating liver proteins by scavenging free radicals.

Reference genes for real-time PCR quantification of microRNAs and messenger RNAs in rat models of hepatotoxicity

Hepatotoxicity is associated with major changes in liver gene expression induced by xenobiotic exposure. Understanding the underlying mechanisms is critical for its clinical diagnosis and treatment. MicroRNAs are key regulators of gene expression that control mRNA stability and translation, during normal development and pathology. The canonical technique to measure gene transcript levels is Real-Time qPCR, which has been successfully modified to determine the levels of microRNAs as well. However, in order to obtain accurate data in a multi-step method like RT-qPCR, the normalization with endogenous, stably expressed reference genes is mandatory. Since the expression stability of candidate reference genes varies greatly depending on experimental factors, the aim of our study was to identify a combination of genes for optimal normalization of microRNA and mRNA qPCR expression data in experimental models of acute hepatotoxicity. Rats were treated with four traditional hepatotoxins: acetaminophen, carbon tetrachloride, D-galactosamine and thioacetamide, and the liver expression levels of two groups of candidate reference genes, one for microRNA and the other for mRNA normalization, were determined by RT-qPCR in compliance with the MIQE guidelines. In the present study, we report that traditional reference genes such as U6 spliceosomal RNA, Beta Actin and Glyceraldehyde-3P-dehydrogenase altered their expression in response to classic hepatotoxins and therefore cannot be used as reference genes in hepatotoxicity studies. Stability rankings of candidate reference genes, considering only those that did not alter their expression, were determined using geNorm, NormFinder and BestKeeper software packages. The potential candidates whose measurements were stable were further tested in different combinations to find the optimal set of reference genes that accurately determine mRNA and miRNA levels. Finally, the combination of MicroRNA-16/5S Ribosomal RNA and Beta 2 Microglobulin/18S Ribosomal RNA were validated as optimal reference genes for microRNA and mRNA quantification, respectively, in rat models of acute hepatotoxicity.

Phenotypic characteristics and proliferative activity of hyperplastic ductule cells in cholangiofibrosis induced by thioacetamide in rats

The oral administration of thioacetamide to rats induces cholangiofibrosis characterized by hyperplasia of ductules surrounded by fibrous tissue. In the present study, we examined the expression of markers of cholangiocyte and hepatocyte phenotypes in these hyperplastic ductule cells and their proliferative activity immunohistochemically. The oral administration of thioacetamide to 21-day-old male Fisher 344 rats for 12 weeks induced multiple areas of various sizes with hyperplastic ductules. The ductules consisted of two types of ductules; ductules composed of cholangiocyte-like cuboidal cells with transparent nuclei and cytoplasm, and of intestinal epithelium-like (IE-like) cells of basophilic nuclei and cytoplasm, and the transition of these two types of cells in the same ductule was sometimes observed. The cholangiocyte-like cells expressed cytokeratin (CK)-7, CK-19 and OV-6 (cholangiocyte phenotype markers) but not Hep Par-1 antigen or HNF4α (hepatocyte phenotype markers). In contrast, the IE-like cells expressed Hep Par-1 antigen and HNF4α but not CK-7, CK-19 or OV-6. The examination of Ki-67 expression showed a much higher proliferative activity for the IE-like cells compared to the cholangiocyte-like cells. The present results show that the hyperplastic ductules induced by thioacetamide are composed of IE-like cells with a high proliferative activity expressing the hepatocyte phenotype markers and of cholangiocyte-like cells with a low proliferative activity expressing the cholangiocyte phenotype markers.

Role of quercetin in preventing thioacetamide-induced liver injury in rats

In hepatic toxicity induced in rats by two injections of thioacetamide (TAA, 350 mg/kg with an interval of 8 hr), the action of quercetin was investigated. After 96 hr, TAA administration resulted in hepatic necrosis, significant increases in serum transaminase activity, and increases in hepatic lipoperoxidation. Thioacetamide-induced hepatotoxicity also showed changes in antioxidant enzymes in the liver of rats, with alterations in p-ERK 1/2 (phosphorylated extracellular-signal related kinase 1/2) as well as an imbalance between proapototic protein Bax and anti-apoptotic protein Bcl-2 expression. With administration of the flavonoid quercetin (50 mg/Kg i.p.) for four consecutive days following TAA, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity were close to normal values in rats. Histological findings suggested that quercetin had a preventive effect on TAA-induced hepatic necrosis. Quercetin treatment caused significant decreases in lipid peroxide levels in the TAA-treated rats, with some changes in antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Quercetin also inhibited the change of the p-ERK1/2 by TAA and significantly prevented the increase in Bax/Bcl-2 ratio, thus preventing apoptosis. Findings indicate that quercetin may have a preventive effect on TAA-induced hepatotoxicity by modulating the oxidative stress parameters and apoptosis pathway.

Role of Kupffer cells in thioacetamide-induced cell cycle dysfunction

It is well known that gadolinium chloride (GD) attenuates drug-induced hepatotoxicity by selectively inactivating Kupffer cells. In the present study the effect of GD in reference to cell cycle and postnecrotic liver regeneration induced by thioacetamide (TA) in rats was studied. Two months male rats, intraveously pretreated with a single dose of GD (0.1 mmol/Kg), were intraperitoneally injected with TA (6.6 mmol/Kg). Samples of blood and liver were obtained from rats at 0, 12, 24, 48, 72 and 96 h following TA intoxication. Parameters related to liver damage were determined in blood. In order to evaluate the mechanisms involved in the post-necrotic regenerative state, the levels of cyclin D and cyclin E as well as protein p27 and Proliferating Cell Nuclear Antigen (PCNA) were determined in liver extracts because of their roles in the control of cell cycle check-points. The results showed that GD significantly reduced the extent of necrosis. Noticeable changes were detected in the levels of cyclin D1, cyclin E, p27 and PCNA when compared to those induced by thioacetamide. Thus GD pre-treatment reduced TA-induced liver injury and accelerated the postnecrotic liver regeneration. These results demonstrate that Kupffer cells are involved in TA-induced liver and also in the postnecrotic proliferative liver states.