Optimization of the dose and route of injection, and characterisation of the time course of carbon tetrachloride-induced hepatotoxicity in the rat

New insight on the acute CCl4-induced hepatotoxicity model in rats

The CCl4-induced hepatotoxicity model is a traditional preclinical assay applied to evaluate potential hepatoprotective compounds. However, several studies have used it with inappropriate dose and exposure time, generating both weak response or irreversible liver injury, as well as lack of representative liver and plasma biomarkers. Therefore, this study aims to determine the best dose and exposure time of CCl4 in Wistar rats, permitting a proper evaluation of potential hepatoprotective effect. Thus, CCl4-intraperitoneal doses of 0.5, 1.0, and 2.0 mL/kg were first evaluated 24 h post-exposure, and then with the best dose achieved, it was also assessed at 6 and 12 h post-exposure. The determination of the main hepatotoxicity biomarkers, including malondialdehyde (MDA), aspartate transaminase (AST), and alanine transaminase (ALT), and histopathological analyses were performed. The results suggest that 6h CCl4 post-exposure is too short to induce ideal liver injury, and at 24 h, a suggestive rat free-radical scavenger mechanism seems to revert CCl4-initiated damage. According to these data, the ideal acute CCl4-induced hepatotoxicity model was established at a dose of 2.0 mL/kg and 12 h post-exposure in Wistar rats, which demonstrated a significant increase of liver MDA levels without irreversible injury, permitting a proper and reliable evaluation of potential hepatoprotective compounds.

Evaluation of hematoprotective, hepatoprotective, and anti-inflammatory potentials of chia seed (Salvia hispanica L.) extract in rats

This study was conducted to evaluate the effects of chia seed extract on CCl4-induced hepatotoxicity, hematological profile, and carrageenan-induced inflammation in rats. Water-ethanol-acetone extract of chia seeds at the doses of 200 and 400 mg/kg body weight/day were applied to evaluate the comparative protective roles. Hematological profile and serum biochemical parameters were measured to evaluate the hematoprotective, and hepatoprotective effects of chia seed extract. Paw thickness and motility level were assessed at 0, 1, 3, 5, and 7 h after sub-planter injection of carrageenan to evaluate the anti-inflammatory potential. Tissue histopathology was performed in both cases. Chia seed extract reduced the elevated level of serum AST and ALT significantly in a dose-dependent manner following intra-peritoneal injection of CCl4. Histopathological study of the liver tissue exhibited acute impairment of the hepatocytes and liver parenchyma following CCl4 exposure, which was markedly regenerated by the chia seed extract treatment. Protective effects of the extracts were also evidenced by the RBC count, Hb (%), PCV (%), ESR, and neutrophil count. Chia seed extract was found to inhibit the carrageenan-induced paw edema and increase motility level in a dose-oriented fashion. Histological examination of the paw tissue revealed severe inflammation characterized by massive infiltration of inflammatory cells in the carrageenan group, which was significantly reduced by chia seed extract treatment. The higher dose of chia seed extract showed significant increases in bodyweight gain and feed efficiency ratio but decrease in visceral fat deposition. These results suggest that chia seeds possess potentials for hematoprotective, hepatoprotective, and anti-inflammatory activities.

Chemico-Pharmacological Screening of the Methanol Extract of Gynura nepalensis D.C. Deciphered Promising Antioxidant and Hepatoprotective Potentials: Evidenced from in vitro, in vivo, and Computer-Aided Studies

Gynura nepalensis D.C. (family: Asteraceae) has abundant uses in the alternative medicinal practice, and this species is commonly used in the treatment of diabetes, rheumatism, cuts or wounds, asthma, kidney stones, cough, urinary tract bleeding, gall bladder stones, hepatitis, diarrhea, hemorrhoids, constipation, vomiting, fertility problems, blood poisoning, septicemia, skin allergy, indigestion, high cholesterol levels, and so on. This study aims to investigate the hepatoprotective and antioxidant potential of the methanol extract of the Gynura nepalensis D.C. (GNME) along with chemical profiling with phytochemical screening. Moreover, prospective phytocompounds have been screened virtually to present the binding affinity of the bioactive components to the hepatic and oxidative receptors. In the hepatoprotective study, alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total protein (TP), and lipid peroxidation (LP) and total bilirubin (TB) have been assessed, and in the antioxidant study, the DPPH free radical scavenging, total antioxidant flavonoid, and phenolic contents were determined. Moreover, the molecular binding affinity of the bioactive component of the plant has been analyzed using PyRx AutoDock Vina, Chimera, and Discovery Studio software. The plant extract showed dose-dependent hepatoprotective potential (p < 0.05, 0.01, 0.001) as well as strong antioxidant properties. Moreover, hepatoprotective and antioxidant molecular docking studies revealed a result varying from −2.90 kcal/mol to −10.1 kcal/mol. 4,5-dicaffeoylquinic acid and chlorogenic acid revealed the highest binding affinity among the selected molecules. However, the plant showed portent antioxidant and hepatoprotective properties in the in vitro, in vivo, and in silico models, and it is presumed that the hepatoprotective properties of the plant extract have occurred due to the presence of the vast bioactive chemical compounds as well as their antioxidant properties. Therefore, advanced studies are recommended to elucidate the pharmacological properties of the plant extracts.

Interaction of Lipoplex with Albumin Enhances Gene Expression in Hepatitis Mice

Understanding the in vivo fate of lipoplex, which is composed of cationic liposomes and DNA, is an important issue toward gene therapy. In disease conditions, the fate of lipoplex might change compared with the normal condition. Here, we examined the contribution of interaction with serum components to in vivo transfection using lipoplex in hepatitis mice. Prior to administration, lipoplex was incubated with serum or albumin. In the liver, the interaction with albumin enhanced gene expression in hepatitis mice, while in the lung, the interaction with serum or albumin enhanced it. In normal mice, the interaction with albumin did not enhance hepatic and pulmonary gene expression. Furthermore, hepatic and pulmonary gene expression levels of albumin-interacted lipoplex were correlated with serum transaminases in hepatitis mice. The albumin interaction increased the hepatic accumulation of lipoplex and serum tumor necrosis factor-α level. We suggest that the interaction with albumin enhanced the inflammation level after the administration of lipoplex in hepatitis mice. Consequently, the enhancement of the inflammation level might enhance the gene expression level. Information obtained in the current study will be valuable toward future clinical application of the lipoplex.

In-depth hepatoprotective mechanistic study of Phyllanthus niruri: In vitro and in vivo studies and its chemical characterization

Phyllanthus niruri L. is a widespread tropical plant which is used in Ayurvedic system for liver and kidney ailments. The present study aims at specifying the most active hepatoprotective extract of P. niruri and applying a bio-guided protocol to identify the active compounds responsible for this effect. P. niruri aerial parts were extracted separately with water, 50%, 70% and 80% ethanol. The cytoprotective activity of the extracts was evaluated against CCl₄-induced hepatotoxicity in clone-9 and Hepg2 cells. Bioassay-guided fractionation of the aqueous extract (AE) was accomplished for the isolation of the active compounds. Antioxidant activity was assessed using DPPH (1, 1-diphenyl-2-picrylhydrazyl) radical scavenging method and ferric reducing antioxidant power (FRAP). The in vivo hepatoprotective activity of AE was evaluated in CCl₄-induced hepatotoxicity in rats at different doses after determination of its LD₅₀. Pretreatment of clone-9 and Hepg2 with different concentrations of AE (1, 0.1, 0.01 mg/ml) had significantly reduced the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) against CCl₄ injures, and restored the activity of the natural antioxidants; glutathione (GSH) and superoxide dismutase (SOD) towards normalization. Fractionation of AE gave four fractions (I-IV). Fractions I, II, and IV showed a significant in vitro hepatoprotective activity. Purification of I, II and IV yielded seven compounds; corilagin C1, isocorilagin C2, brevifolin C3, quercetin C4, kaempferol rhamnoside C5, gallic acid C6, and brevifolin carboxylic acid C7. Compounds C1, C2, C5, and C7 showed the highest (p< 0.001) hepatoprotective potency, while C3, C4, and C6 exhibited a moderate (p< 0.001) activity. The AE exhibited strong antioxidant DPPH (IC₅₀ 11.6 ± 2 μg/ml) and FRAP (79.352 ± 2.88 mM Ferrous equivalents) activity. In vivo administration of AE in rats (25, 50, 100 and 200 mg/kg) caused normalization of AST, ALT, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), total cholesterol (TC), triglycyrides (TG), total bilirubin (TB), glucose, total proteins (TP), urea and creatinine levels which were elevated by CCl₄. AE also decreased TNF-α, NF-KB, IL-6, IL-8, IL10 and COX-2 expression, and significantly antagonizes the effect of CCl₄ on the antioxidant enzymes SOD, catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GSP). The histopathological study also supported the hepatoprotective effect of AE. P. niruri isolates exhibited a potent hepatoprotective activity against CCl₄-induced hepatotoxicity in clone-9 and Hepg2 cell lines through reduction of lipid peroxidation and maintaining glutathione in its reduced form. This is attributable to their phenolic nature and hence antioxidative potential.

Time-Course Evaluation of Iminodipropionitrile-Induced Liver and Kidney Toxicities in Rats: A Biochemical, Molecular and Histopathological Study

Iminodipropionitrile (IDPN) is known to produce axonopathy and vestibular hair cell degeneration. Recent histopathological studies have shown IDPN-induced liver and kidney toxicities in rodents; however, the associated mechanisms are not clearly understood. We investigated the role of proinflammatory cytokines in IDPN-induced liver and kidney toxicities in rats. Rats were treated with saline (control) and IDPN (100 mg/kg, intraperitoneally) daily for 1, 5, and 10 days, respectively. Animals were killed 24 hours after the last dose and liver and kidneys were collected for histopathology and interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α messenger RNA expression analysis. Serum aspartate aminotransferase and alanine aminotransferase activities were significantly increased after 10 doses of IDPN. The level of serum creatinine was initially increased after the first dose of IDPN but subsided on days 5 and 10. Blood urea nitrogen levels were significantly increased on days 5 and 10 following IDPN exposure. Histopathology showed dose-dependent hepatotoxicity in IDPN-treated rats. Iminodipropionitrile-induced expression of proinflammatory cytokines peaked after day 1 in liver and after day 5 in kidneys. In conclusion, repeated exposure of IDPN for 10 days produced significant structural and functional damages in rat liver whereas kidneys showed gradual recovery with time. These findings point toward the role of inflammatory mediators in IDPN-induced toxicity in rats.

Effects of Lawsonia inermis L. (Henna) leaves' methanolic extract on carbon tetrachloride-induced hepatotoxicity in rats

Background:

Natural products with therapeutic properties such as plants, minerals, and animal products, for many years, were the main sources of drugs for the treatment of numerous diseases; hence selection of Lawsonia inermis L. (Henna) to study its hepatoprotective activity was considered.

Objectives:

This was an attempt to evaluate the hepatoprotective effect of L. inermis leaves’ methanolic extract on carbon tetrachloride (CCl₄)-induced hepatotoxicity in rats.

Materials and Methods:

The L. inermis leaves’ methanolic extract, which obtained by maceration, was orally administered in doses of 100 mg/kg and 200 mg/kg to the tested animals to assess its effects on serum levels of hepatotoxicity parameters, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), bilirubin, and total proteins along with histopathological liver sections examination, while silymarin (25 mg/kg), a potent hepatoprotective drug, was used as standard control.

Results:

The two doses of the plant extract showed dose-dependent hepatoprotective effect, as evident by the significant reduction (P < 0.05) in serum levels of AST, ALT, ALP, and bilirubin along with the improvement in histopathological liver sections compared to CCl₄-only treated animals.

Conclusion:

As experimentally evident, it could be concluded that this plant material could provide a hepatoprotective effect that could be attributed to its antioxidant properties.

The effects of Juglans regia L. (walnut) extract on certain biochemical paramaters and in the prevention of tissue damage in brain, kidney, and liver in CCl4 applied Wistar rats

Objective: The purpose of this study is to demonstrate protective effects of walnut samples on CCl

Methods: Walnut fruits were extracted and then subjected to vitamin and flavonoid analyses. The extracts obtained were injected intraperitoneally every other day to Wistar male rats given carbon tetrachloride (CCl

Results: Given the results achieved, it was found that the levels of fatty acids increased in the brain and kidney tissues after CCl

Conclusion: Our data indicates that walnut extract has protective effects against LPO formation in the brain, kidney and liver tissues.

Histological insights in iminodipropionitrile-induced toxicity in rats

Iminodipropionitrile (IDPN) is a prototype nitrile compound that produces excitation, chorea and circling (ECC) syndrome in rodents. Previous studies have implicated vestibular hair cell degeneration in IDPN-induced behavioral abnormalities. Although the pathological changes in vestibular labyrinth of IDPN-treated rats are well documented, the effects of IDPN on other organ systems are not clearly understood. We therefore examined the histopathological alterations in inner ear, brain, liver and kidneys of rats exposed to IDPN. Adult male Wistar rats were divided into two groups of six animals each. Control rats received normal saline whereas the IDPN group was treated with IDPN (100mg/kg, i.p.) daily for 7 days. All the animals were carefully observed for any behavioral abnormality and the dyskinetic movements including the vertical and horizontal head weaving, circling and backward walking were quantified. The animals were sacrificed on day 9 and the samples of cochlea, brain, liver and kidney were collected for histopathology. The results showed a direct correlation between the severity of behavioral deficits and the cellular damage in crista ampullaris in IDPN-treated rats. Histopathology of liver was severely influenced by IDPN treatment, leading to vacuolization of cytoplasm, distorted sinusoids, infiltration of mononuclear cells and necrotic zones. However, the severity of hepatic damage in IDPN-treated rats was independent of the magnitude of vestibular hair cell degeneration as well as the severity of behavioral deficits. Administration of IDPN in the vestibulotoxic doses did not produce any histological changes in the brain cortex and kidneys of rats.

Hepatoprotective effect of commercial herbal extracts on carbon tetrachloride-induced liver damage in Wistar rats

Background:

Various hepatoprotective herbal products from plants are available in Mexico, where up to 85% of patients with liver disease use some form of complementary and alternative medicine. However, only few studies have reported on the biological evaluation of these products.

Objective:

Using a model of carbon tetrachloride (CCl₄)-induced hepatotoxicity in rats, we evaluated the effects of commercial herbal extracts used most commonly in the metropolitan area of Monterrey, Mexico.

Materials and Methods:

The commercial products were identified through surveys in public areas. The effect of these products given with or without CCl₄ in rats was evaluated by measuring the serum concentrations of aspartate amino transferase (AST) and alanine amino transferase (ALT), and histopathological analysis. Legalon^® was used as the standard drug.

Results:

The most commonly used herbal products were Hepatisan^® capsules, Boldo capsules, Hepavida^® capsules, Boldo infusion, and milk thistle herbal supplement (80% silymarin). None of the products tested was hepatotoxic according to transaminase and histological analyses. AST and ALT activities were significantly lower in the Hepavida+CCl₄-treated group as compared with the CCl₄-only group. AST and ALT activities in the silymarin, Hepatisan, and Boldo tea groups were similar to those in the CCl₄ group. The CCl₄ group displayed submassive confluent necrosis and mixed inflammatory infiltration. Both the Hepatisan+CCl₄ and Boldo tea+CCl₄ groups exhibited ballooning degeneration, inflammatory infiltration, and lytic necrosis. The silymarin+CCl₄ group exhibited microvesicular steatosis. The Hepavida+CCl₄- and Legalon+CCL₄-treated groups had lower percentages of necrotic cells as compared with the CCl₄-treated group; this treatment was hepatoprotective against necrosis.

Conclusion:

Only Hepavida had a hepatoprotective effect.

Mesenchymal stem cells restore CCl4-induced liver injury by an antioxidative process

We have investigated BM (bone marrow)-derived MSCs (mesenchymal stem cells) for the treatment of liver injury. It was hypothesized that MSC-mediated resolution of liver injury could occur through an antioxidative process. After being injected with CCl4 (carbon tetrachloride), mice were injected with syngenic BM-derived MSCs or normal saline. Oxidative stress activity of the MSCs was determined by the analysis of ROS (reactive oxygen species) and SOD (superoxide dismutase) activity. In addition, cytoprotective genes of the liver tissue were assessed by real-time PCR and ARE (antioxidant-response element) reporter assay. Up-regulated ROS of CCl4-treated liver cells was attenuated by co-culturing with MSCs. Suppression of SOD by adding an SOD inhibitor decreased the effect of MSCs on injured liver cells. MSCs significantly increased SOD activity and inhibited ROS production in the injured liver. The gene expression levels of Hmox-1 (haem oxygenase-1), BI-1 (Bax inhibitor-1), HGF (hepatocyte growth factor), GST (glutathione transferase) and Nrf2 (nuclear factor-erythoid 2 p45 subunit-related factor 20), attenuated by CCl4, were increased up to basal levels after MSC transplantation. In addition, MSCs induced an ARE, shown by luciferase activity, which represented a cytoprotective response in the injured liver. Evidence of a new cytoprotective effect is shown in which MSCs promote an antioxidant response and supports the potential of using MSC transplantation as an effective treatment modality for liver disease.

Evaluation of liver fibrosis by investigation of hepatic parenchymal perfusion using contrast-enhanced ultrasound: an animal study

PURPOSE

To investigate the value of assessing the hepatic parenchymal perfusion in contrast-enhanced ultrasound (CEUS) for evaluating liver fibrosis, using an animal model.

METHODS

Seventy Sprague-Dawley rats were divided into experimental (n = 35) and control (n = 35) groups. In the experimental group, liver fibrosis was induced by intraperitoneal injection of carbon tetrachloride. CEUS of the liver was performed at a 2-week interval for 14 weeks. Signal intensity of liver parenchyma was analyzed with time-intensity curves. Histologic examination of liver specimens of the animals was performed to assess the fibrosis stage.

RESULTS

The peak signal intensity of hepatic parenchymal perfusion in stage 2-3 fibrosis was significantly lower than that in stage 0-1. The time to peak intensity of hepatic parenchymal perfusion was significantly longer in the experimental group than the control group, and in the stage 3 fibrosis than in stages 0-2 fibrosis. Using time to peak intensity of hepatic parenchymal perfusion to distinguish stage 3 fibrosis and stages 0-2 fibrosis, the optimum cutoff was 75,000 milliseconds with the sensitivity and specificity of 67% and 78%, respectively.

CONCLUSIONS

This animal study showed that CEUS has the potential to be a complementary imaging tool in the evaluation of liver fibrosis.

Alterations of serum protein N-glycosylation in two mouse models of chronic liver disease are hepatocyte and not B cell driven

N-glycosylation of immunoglobulin G (IgG) has an important impact on the modification of the total serum N-glycome in chronic liver patients. Our aim was to determine the role and magnitude of the alterations in which hepatocytes and B cells are involved in two mouse models of chronic liver disease. Common bile duct ligation (CBDL) and subcutaneous injections with CCl(4) were induced in B cell-deficient and wild-type (WT) mice. IgG depletion was performed with beads covered with protein A/G and the depletions were evaluated by SDS-PAGE and Western blot analysis. N-glycan analysis was performed by improved DSA-FACE technology. Structural analysis of the mouse serum N-glycans was performed by exoglycosidase digests and MALDI-TOF mass spectrometry of permethylated glycans. The alterations seen in B cell-deficient mice closely resembled the alterations in WT mice, in both the CBDL and the CCl(4) models. N-glycan analysis of the IgG fraction in both mouse models revealed different changes compared with humans. Overall, the impact of IgG glycosylation on total serum glycosylation was marginal. Interestingly, the amount of fibrosis present in CBDL B cell-deficient mice was significantly increased compared with CBDL WT mice, whereas the opposite was true for the CCl(4) model as determined by Sirius red staining. However, this had no major effect on the alteration of N-glycosylation of serum proteins. Alterations of total serum N-glycome in mouse models of chronic liver disease are hepatocyte-driven. Undergalactosylation of IgG is not present in mouse models of chronic liver disease.

Impact of elevation of total bilirubin level and etiology of the liver disease on serum N-glycosylation patterns in mice and humans

The GlycoFibroTest and GlycoCirrhoTest are noninvasive alternatives for liver biopsy that can be used as a follow-up tool for fibrosis patients and to diagnose cirrhotic patients, respectively. These tests are based on the altered N-glycosylation of total serum protein. Our aim was to investigate the impact of etiology on the alteration of N-glycosylation and whether other characteristics of liver patients could have an influence on N-glycosylation. In human liver patients, no specific alteration could be found to make a distinction according to etiological factor, although alcoholic patients had a significant higher mean value for the GlycoCirrhoTest. Undergalactosylation did not show a significantly different quantitative alteration in the cirrhotic and noncirrhotic population of all etiologies. Importantly, patients with an elevation of total bilirubin level (>2 mg/dl) had a strong increase of glycans modified with alpha1-6 fucose. The fucosylation index was therefore significantly higher in fibrosis/cirrhosis and hepatocellular carcinoma patients with elevated total bilirubin levels irrespective of etiology. Furthermore, in a multiple linear regression analysis, only markers for cholestasis significantly correlated with the fucosylation index. In mouse models of chronic liver disease, the fucosylation index was uniquely significantly increased in mice that were induced with a common bile duct ligation. Mice that were chronically injected with CCl(4) did not show this increase. Apart from this difference, common changes characteristic to fibrosis development in mice were observed. Finally, mice induced with a partial portal vein ligation did not show biological relevant changes indicating that portal hypertension does not contribute to the alteration of N-glycosylation.

Mesenchymal stem cell infusion therapy in a carbon tetrachloride-induced liver fibrosis model affects matrix metalloproteinase expression

In order to investigate the effects of bone marrow-derived MSCs (mesenchymal stem cells) in reversing liver fibrosis and to determine their possible mechanism of action, mouse MSCs were infused into the tail vein of a CCl(4) injection mouse chronic model. MSCs caused a decrease in liver fibrosis histopathologically, 4 weeks after transplantation. The reduction in liver collagen was confirmed by quantitative analysis. Moreover, lipid peroxidation in the CCl(4)/MSC group decreased significantly. Quantitative RT (reverse transcription)-PCR analysis showed administration of MSCs has a significant antifibrotic effect as evidenced by the decrease in expression of liver collagen and increase in MMP13 (matrix metalloproteinase 13) in the CCl(4)/MSC group when compared with the CCl(4) group, 4 weeks after transplantation. The expression of alphaSMA (smooth muscle actin) and TIMP1 was also down-regulated in the CCl(4)/MSC group. Additionally, the expression of MMP9 was significantly up-regulated in the CCl(4)-treated group; however, there was no significant change after MSC injection. Few engrafted cells in the recipient liver and were able to differentiate into albumin-positive cells. In conclusion, MSCs can enhance recovery of a CCl(4)-injured mouse liver through their influence in reducing collagen deposition by possibly affecting expression of MMPs.

Comparison of three research models of portal hypertension in mice: macroscopic, histological and portal pressure evaluation

The characterization of mice models of portal hypertension (PHT) is lacking in the literature. Therefore, the aim of the present study was to make a histological approach during development of PHT in two models of cirrhosis with PHT compared with one model of isolated PHT. The model of isolated PHT was developed by partial portal vein ligation (PPVL). Two portal hypertensive cirrhotic mice models were developed either by common bile duct ligation (CBDL) or administration of carbon tetrachloride (CCl(4)) subcutaneously (twice weekly, 1 ml/kg). These models represent, respectively, a secondary biliary cirrhosis and alcoholic cirrhosis. Mice were killed at several time points to evaluate liver changes by histological and ultrastructural methods. A correlation was made with portal pressure measurements. Histology revealed the absence of fibrosis or cirrhosis in PPVL mice. They developed an isolated portal hypertension. After CBDL induction, the mice developed the characteristics of cirrhosis after 6 weeks, with simultaneous increase in portal pressures. Fifty percent of the mice had ascites at that time point. Sixteen weeks after administration of CCl(4), a micronodular cirrhotic aspect of the liver was seen associated with signs of portal hypertension. This is the first descriptive study of three widely used animal models in mice, allowing the study of pathophysiological changes in cirrhosis and portal hypertension. The PPVL in mice leads to a model of isolated portal hypertension. Secondary biliary cirrhosis developed after 6 weeks of common bile duct ligation in 50% of the mice that developed ascites. Subcutaneous injection of CCl(4) for 16 weeks induces cirrhosis and portal hypertension, without ascites. Moreover, the present study is the first description of a cirrhotic model in mice developed by subcutaneous injections of CCl(4). Well-described mice models will facilitate use of knock-out or transgenic mice and lead to a better understanding of the underlying molecular pathways in the field of portal hypertension and cirrhosis.

Effect of gender, dose, and time on 3-(3,5-dichlorophenyl)-2,4-thiazolidinedione (DCPT)-induced hepatotoxicity in Fischer 344 rats

1. The thiazolidinedione ring present in drugs available for type II diabetes can contribute to hepatic injury. Another thiazolidinedione ring-containing compound, 3-(3,5-dichlorophenyl)-2,4-thiazoli-dinedione (DCPT), produces liver damage in rats. Accordingly, the effects of gender, dose, and time on DCPT hepatotoxicity were therefore evaluated. 2. Male rats were more sensitive to DCPT (0.4-1.0 mmol kg(-1) by intraperitoneal administration) as shown by increased serum alanine aminotransferase levels and altered hepatic morphology 24 h post-dosing. Effects in both genders were dose dependent. In males, DCPT (0.6 mmol kg(-1)) produced elevations in alanine aminotransferases and changes in liver sections 3 h after dosing that progressively worsened up to 12 h. DCPT-induced renal effects were mild. 3. It is concluded that male rats are more susceptible to DCPT hepatotoxicity and that damage occurs rapidly. DCPT primarily affects the liver and can be a useful compound to investigate the role of the thiazolidinedione ring in hepatic injury. However, the gender dependency and rapid onset of DCPT hepatotoxicity require further investigation.

Ameliorative effects of pycnogenol on carbon tetrachloride-induced hepatic oxidative damage in rats

This study evaluated the putative antioxidant activity of Pycnogenol (PYC) against CCl4-induced hepatic oxidative damage in Sprague-Dawley rats. A single oral dose of CCl4 (1.25 mL/kg) produced significantly increased levels of serum aminotransferase (AST) and alanine aminotransferase (ALT) activities. In addition, increased malondialdehyde (MDA) concentration, reduced glutathione (GSH) content, and decreased catalase, superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities were observed in the hepatic tissues. However, concomitant administration with PYC (10 or 20 mg/kg) significantly improved CCl4-induced hepatic injury, as evidenced by the decline of serum AST and ALT activities in a dose dependent manner. Moreover, PYC reduced MDA concentration and increased GSH levels and catalase, SOD and GST activities in hepatic tissues, indicating that concomitant administration with PYC efficiently prevent the CCl4-induced oxidative damage in rats. The free radical scavenging assay showed that PYC has a dose-dependent scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. These results indicate that PYC has an antioxidant effect against CCl4-induced hepatic oxidative damage and is useful as a hepatoprotective agent against various liver diseases induced by oxidative stress.

Interleukin-6 production by peritoneal mesothelial cells and its regulation by inflammatory factors in rats administered carbon tetrachloride intraperitoneally

We previously reported that a high level of interleukin-6 (IL-6), which is protective against CCl(4)-induced hepatotoxicity, is produced in the peritoneal cavity in the early period after ip carbon tetrachloride (CCl(4)) administration. The objective of this study was to identify the tissues and cells involved in IL-6 production and clarify the mechanisms underlying its regulation. IL-6 mRNA levels increased significantly in the serous membranes of the mesentery and peritoneum, but not in the parenchymal organs including liver, kidney and spleen, 3 h after ip CCl(4) administration. Peritoneal mesothelial cells (PMCs), a major cell population in serous membranes, were isolated from rat peritoneal walls by trypsin digestion and cultured with peritoneal exudate fluid (PEF) from CCl(4)-administered rats. PMCs produced a high level of IL-6 in the presence of PEF recovered 0.5 h after ip CCl(4) administration. Analyses of PEF revealed that the levels of prostaglandin E(2) (PGE(2)), histamine, IL-1alpha, IL-1beta and tumor necrosis factor-alpha (TNF-alpha) increased immediately after ip CCl(4) administration. These inflammatory factors, except for histamine, stimulated IL-6 production to varying degrees, in the following order: IL-1alpha>IL-1beta>TNF-alpha>>PGE(2). In summary, the present study indicates that the high level of IL-6 observed in the rat peritoneal cavity after ip CCl(4) administration is at least partially produced by PMCs stimulated cooperatively with IL-1alpha, IL-1beta, TNF-alpha and PGE(2). These inflammatory factors may be released from tissues or cells either stimulated or injured directly by CCl(4).

Protective effects of Pycnogenol on carbon tetrachloride-induced hepatotoxicity in Sprague-Dawley rats

Oxidative damage is implicated in the pathogenesis of various liver injuries. In the present study the ability of Pycnogenol (PYC) as an antioxidant to protect against CCl4-induced oxidative stress and hepatotoxicity in rats was investigated. Four experimental groups of six rats each were constructed: a vehicle control group received the respective vehicles (distilled water and corn oil) only; a CCl4 group received a 14-day repeated intraperitoneal (i.p.) dose of distilled water and then a single oral dose of CCl4 at 1.25 ml/kg; and the CCl4&PYC 10 and CCl4&PYC 20 groups received a 14-day repeated i.p. dose of PYC 10 and 20 mg/kg, respectively, and then a single oral dose of CCl4 at 1.25 ml/kg. Hepatotoxicity was assessed 24 h after the CCl4 treatment by measurement of serum aminotransferase (AST) and alanine aminotransferase (ALT) activities, hepatic malondialdehyde (MDA) and glutathione (GSH) concentrations, and catalase, superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities. The results were confirmed histopathologically. The single oral dose of CCl4 produced significantly elevated levels of serum AST and ALT activities. Histopathological examinations showed extensive liver injuries, characterized by extensive hepatocellular degeneration/necrosis, fatty changes, inflammatory cell infiltration, congestion, and sinusoidal dilatation. In addition, an increased MDA concentration and decreased GSH, catalase, SOD, and GST were observed in the hepatic tissues. On the contrary, PYC treatment prior to the administration of CCl4 significantly prevented the CCl4-induced hepatotoxicity, including the elevation of serum AST and ALT activities and histopathological hepatic lesions, in a dose-dependent manner. Moreover, MDA and GSH levels and catalase, SOD, and GST activities in hepatic tissues were not affected by administration of CCl4, indicating that the pretreatment of PYC efficiently protects against CCl4-induced oxidative damage in rats. The results indicate that PYC has a protective effect against acute hepatotoxicity induced by the administration of CCl4 in rats, and that the hepatoprotective effects of PYC may be due to both the inhibition of lipid peroxidation and the increase of antioxidant activity.

Therapeutic potential of bone marrow-derived mesenchymal stem cells on experimental liver fibrosis

OBJECTIVE

To study the effect of mesenchymal stem cells (MSC) on experimental liver fibrosis in rats.

DESIGN AND METHOD

MSC were derived from bone marrow obtained from femoral and tibial bones of male albino rats. MSC were separated, grown, and propagated in culture for 4 weeks and were characterized morphologically and by detection of CD29 by RT-PCR. They were then infused into the tail vein of female rats that received CCl4 injection to induce liver fibrosis. Rats were divided into 4 groups: control, CCl4, CCl4 plus MSC, and MSC. Liver tissue was examined histopathologically and liver functions (ALT and serum albumin) were estimated for all groups. Y-chromosome gene (sry) was assessed by PCR in liver tissue of the female rats to confirm uptake of the male stem cells. Hydroxyproline content in liver tissue was assessed by chemical methods and expression of the collagen gene (type I) was detected as a marker for liver fibrosis. Results of the present study showed that MSC have a significant antifibrotic effect as evidenced by the significant decrease in liver collagen gene expression as well as the decrease in hydroxyproline content in the CCl4/MSC group (p<0.001) compared to the CCl4 group. The Y-chromosome gene (sry) was detected by RT-PCR in the CCl4/MSC group, but was not detected in control group and other groups. The CD29 gene was expressed in MSC culture, and this confirmed the efficiency of isolation and propagation of MSC in culture. With regard to liver function, there was also a significant improvement and elevation of serum albumin in the CCl4/MSC group compared to the CCl4 group (p<0.05). As regard to the liver enzyme ALT, there was a decrease of its level in the CCl4/MSC group compared to the CCl4 group. However, this was statistically nonsignificant (p>0.05). In conclusion, MSC have a potential therapeutic effect against the fibrotic process through their effect in minimizing collagen deposition in addition to their capacity to differentiate into hepatocytes.

Early induced, high-level interleukin-6 expression in the rat peritoneal cavity into which a hepatotoxicant carbon tetrachloride was administered

IL-6 induction depending on the mode of carbon tetrachloride (CCl4) administration was investigated in rats. After the intraperitoneal (i.p.) administration of CCl4 in 50% corn oil at 1.0 ml/kg body weight, IL-6 level markedly increased in plasma and peaked at 4h. TNF-alpha and IL-1beta levels gradually increased, reaching the maximum at 24h. IL-10 level transiently peaked at 4h and then decreased, but later further increased, reaching the second peak at 24h. Plasma alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) activities peaked at 24h. As the vehicle-to-CCl4 ratio increased, the level of IL-6 decreased and the activities of ALT and SDH increased. After oral CCl4 administration, IL-6 was not significantly detected. IL-6 level in peritoneal exudate fluid (PEF) increased simultaneously with plasma IL-6 level after i.p. CCl4 administration, but the total amount of PEF IL-6 was 37-fold as much as that of plasma IL-6, in contrast to the result that the total amount of plasma IL-6 was 19-fold as much as that of PEF IL-6 after i.p. lipopolysaccharide administration. These results suggest that i.p. administration of CCl4 dissolved in a small amount of vehicle selectively induces a high production of IL-6 in the peritoneal cavity early after the administration. Since IL-6 is a protective cytokine against hepatotoxicity, its induction should be taken into consideration during analysis of data obtained using the CCl4-induced liver injury model.

Functional hepatocyte-like cells derived from mouse embryonic stem cells: A novel in vitro hepatotoxicity model for drug screening

The aim of the present study was to differentiate mouse embryonic stem (mES) cells into a high percentage of hepatocyte-like cells, and to demonstrate their utility as an in vitro hepatotoxicity model. We were able to differentiate 80-90% of mES cells using optimized hepatocyte differentiation medium. These differentiated cells showed typical hepatocyte morphology, expressed hepatic specific genes as shown by RT-PCR and displayed antibody detectable expression of markers specific for hepatic maturation. These hepatocyte-like cells also demonstrated evidence of glycogen storage. These cells when exposed to CCl4, a commonly used hepatotoxicant, showed an elevation of liver function enzymes, SGOT, SGPT and LDH, indicating hepatic damage. Further, this increase was prevented by pre-treatment with N-acetylcysteine, a known anti-oxidant. Thus we propose that the hepatocyte-like cells derived by the present method may prove to be useful as an in vitro model of hepatotoxicity, thereby providing a novel and promising alternative for obtaining large numbers of functional hepatocyte-like cells for in vitro drug metabolism and hepatotoxicity screening of potential drug candidates.

Protective Effect of Arthrospira maxima on Fatty Acid Composition in Fatty Liver

BACKGROUND

Arthrospira maxima has been widely used for nutritional purposes. Additionally, A. maxima has shown immunomodulator, antiviral, antioxidant, vasomotor and hypolipidemic effects in laboratory and animal studies. A. maxima prevents fatty liver induced by either carbon tetrachloride (CCl4) or fructose-rich diet; however, the liver lipid composition in these models is not clearly known yet. The aim of this study was to evaluate the effects of A. maxima on the liver lipid profile in CCl4-induced steatohepatitis.

METHODS

A single sublethal, intraperitoneal dose of CCl4 was administered to male Wistar rats fed a diet with or without 5% A. maxima. Liver lipids: total lipids, triacylglycerols, total cholesterol, free fatty acids, and thiobarbituric acid reactive substances were assessed 24 and 48 h after injury with CCl4. Additionally, triacylglycerols, total cholesterol and aspartate aminotransferase were evaluated in blood.

RESULTS

Forty eight hours after CCl4 treatment, rats fed a diet without A. maxima had serum aspartate aminotransferase and liver triacylglycerols values that were, respectively, 2.2 and 1.4 times higher than those of animals receiving 5% A. maxima in their diet. The same pattern was observed for liver free fatty acids and thiobarbituric acid reactive substances. The groups fed a diet with A. maxima and treated with CCl4 showed a higher saturated fatty acid liver content than the groups without A. maxima in their diet. The percentage of unsaturated fatty acids increased 48 h after CCl4 treatment, but its value was 0.5 times lower in the group receiving A. maxima than in the group fed without A. maxima. In the liver, all animals receiving A. maxima showed a trend towards a lower percentage of unsaturated fatty acids, despite the mentioned increase 48 h after CCl4 treatment.

CONCLUSIONS

The results suggest that, in the fatty liver induced by CCl4, the hepatoprotective effect of A. maxima involves (a) an antioxidant mechanism and (b) a lower unsaturation of the liver fatty acids. The preventive effect of A. maxima on the liver lipid changes induced by CCl4 could be partially explained by its antioxidant action and the ability to increase the synthesis/release of nitric oxide, but not by its soluble dietary fiber.

Seminiferous epithelium of rats with food restriction and carbon tetrachloride-induced cirrhosis

OBJECTIVE

Analyze the changes in the seminiferous epithelium in rats with carbon tetrachloride-induced cirrhosis (CCl4).

MATERIALS AND METHODS

Forty-eight male Wistar rats aged 45-50 days, weighing 150-180 grams were used. Twenty-two rats underwent CCl4-induced cirrhosis with CCl4 0.25 mL/Kg weekly intragastrically once a week, during 10 weeks. Additionally, they had a 44% food restriction diet (Group 1). The control group was divided in two subgroups: 13 rats had a 44% food restriction diet and no CCl4 (Group 2) and 10 rats were not submitted to CCl4 or food restriction (Group 3). After 10 weeks, the rats were sacrificed and liver sections were collected for histological analysis. The testicular analysis was carried out to evaluate the frequency of tubules in stages VIII and XIV.

RESULTS

The mean rates of stage VIII in animals with food restriction plus CCl4-induced cirrhosis and food restriction without CCl4 were significantly different from animals without either food restriction or CCl4 (18.1 +/- 5.5%, 20.5 +/- 2.5% and 13.4 +/- 3.5%, respectively, p = 0.002). The mean rate of stage VIII in rats with cirrhosis was not significantly different from rats without cirrhosis (18.1 +/- 5.5% and 17.4 +/- 4.6% respectively). The mean frequency of stage XIV in rats with cirrhosis was significantly greater than rats without cirrhosis (4.7 +/- 2.3% and 6.8 +/- 1.9% respectively, p = 0.027).

CONCLUSION

Animals with CCl4-induced cirrhosis and food restriction have shown alterations in spermatogenic cycle that were not seen in rats without CCl4-induced cirrhosis and food restriction.