Acute Carbon Tetrachloride Research Articles

Vitamin D3-induced hypercalcemia increases carbon tetrachloride-induced hepatotoxicity through elevated oxidative stress in mice.

The aim of this study was to determine whether calcium potentiates acute carbon tetrachloride (CCl4) -induced toxicity. Elevated calcium levels were induced in mice by pre-treatment with cholecalciferol (vitamin D3; V.D3), a compound that has previously been shown to induce hypercalcemia in human and animal models. As seen previously, mice injected with CCl4 exhibited increased plasma levels of alanine aminotransferase, aspartate aminotransferase, and creatinine; transient body weight loss; and increased lipid peroxidation along with decreased total antioxidant power, glutathione, ATP, and NADPH. Pre-treatment of these animals with V.D3 caused further elevation of the values of these liver functional markers without altering kidney functional markers; continued weight loss; a lower lethal threshold dose of CCl4; and enhanced effects on lipid peroxidation and total antioxidant power. In contrast, exposure to V.D3 alone had no effect on plasma markers of liver or kidney damage or on total antioxidant power or lipid peroxidation. The potentiating effect of V.D3 was positively correlated with elevation of hepatic calcium levels. Furthermore, direct injection of CaCl2 also enhanced CCl4-induced hepatic injury. Since CaCl2 induced hypercalcemia transiently (within 3 h of injection), our results suggest that calcium enhances the CCl4-induced hepatotoxicity at an early stage via potentiation of oxidative stress.

C57BL/6 Substrains Exhibit Different Responses to Acute Carbon Tetrachloride Exposure: Implications for Work Involving Transgenic Mice.

Biological differences exist between strains of laboratory mice, and it is becoming increasingly evident that there are differences between substrains. In the C57BL/6 mouse, the primary substrains are called 6J and 6N. Previous studies have demonstrated that 6J and 6N mice differ in response to many experimental models of human disease. The aim of our study was to determine if differences exist between 6J and 6N mice in terms of their response to acute carbon tetrachloride (CCl4) exposure. Mice were given CCl4 once and were euthanized 12 to 96 h later. Relative to 6J mice, we found that 6N mice had increased liver injury but more rapid repair. This was because of the increased speed with which necrotic hepatocytes were removed in 6N mice and was directly related to increased recruitment of macrophages to the liver. In parallel, enhanced liver regeneration was observed in 6N relative to 6J mice. Hepatic stellate cell activation occurred earlier in 6N mice, but there was no difference in matrix metabolism between substrains. Taken together, these data demonstrate specific and significant differences in how the C57BL/6 substrains respond to acute CCl4, which has important implications for all mouse studies utilizing this model.

Protective effect of Curcuma longa L. extract on CCl4-induced acute hepatic stress

BackgroundThe Curcuma longa L. (CLL) rhizome has long been used to treat patients with hepatic dysfunction. CLL is a member of the ginger family of spices that are widely used in China, India, and Japan, and is a common spice, coloring, flavoring, and traditional medicine. This study was performed to evaluate the hepatoprotective activity of CLL extract and its active component curcumin in an acute carbon tetrachloride (CCl4)-induced liver stress model.MethodsAcute hepatic stress was induced by a single intraperitoneal injection of CCl4 (0.1 ml/kg body weight) in rats. CLL extract was administered once a day for 3 days at three dose levels (100, 200, and 300 mg/kg/day) and curcumin was administered once a day at the 200 mg/kg/day. We performed alanine transaminase (ALT) and aspartate transaminase (AST). activity analysis and also measured total lipid, triglyceride, and cholesterol levels, and lipid peroxidation.ResultsAt 100 g CLL, the curcuminoid components curcumin (901.63 ± 5.37 mg/100 g), bis-demethoxycurcumin (108.28 ± 2.89 mg/100 g), and demethoxycurcumin (234.85 ± 1.85 mg/100 g) were quantified through high liquid chromatography analysis. In CCl4-treated rats, serum AST and ALT levels increased 2.1- and 1.2-fold compared with the control. AST but not ALT elevation induced by CCl4 was significantly alleviated in CLL- and curcumin-treated rats. Peroxidation of membrane lipids in the liver was significantly prevented by CLL (100, 200, and 300 mg/kg/day) on tissue lipid peroxidation assay and immunostaining with anti-4HNE antibody. We found that CLL extract and curcumin exhibited significant protection against liver injury by improving hepatic superoxide dismutase (p < 0.05) and glutathione peroxidase activity, and glutathione content in the CCl4-treated group (p < 0.05), leading to a reduced lipid peroxidase level.ConclusionOur data suggested that CLL extract and curcumin protect the liver from acute CCl4-induced injury in a rodent model by suppressing hepatic oxidative stress. Therefore, CLL extract and curcumin are potential therapeutic antioxidant agents against acute hepatotoxicity.

Hepatoprotective Effects of Nonpolar Extracts from Inflorescences of Thistles Cirsium vulgare and Cirsium ehrenbergii on Acute Liver Damage in Rat.

Background:Drugs for the treatment of liver diseases are scarce and not effective enough. Some species of the genus Cirsium possess hepatoprotective activity. There are no studies on the hepatoprotective effects of nonpolar extracts from inflorescences of thistles Cirsium vulgare and Cirsium ehrenbergii, and there are few reports on their chemical composition.Objective:The aim is to obtain the hexane extract from inflorescences of both thistles and to identify preliminarily their main chemical component, and to evaluate the hepatoprotective properties of the extracts.Materials and Methods:Hexane extracts were obtained using a Soxhlet apparatus. The chemical composition was analyzed using infrared spectra and gas chromatography-mass spectrometry. Two doses (250 and 500 mg/kg, p.o.) of both extracts were administered to assess their hepatoprotective effect on acute carbon tetrachloride (TC)-induced liver damage in rats using biochemical markers of necrosis, cholestasis, functionality, oxidative stress, and histological analysis.Results:Extracts were shown to have a very similar chemical profile. Their major constituent seems to be lupeol acetate. The two doses of both extracts demonstrated comparable hepatoprotective properties because they significantly diminished all the liver injury indicators (P < 0.05) and were corroborated using histopathology.Conclusion:This is the first study on the hepatoprotective effects of nonpolar extracts from inflorescences of thistles C. vulgare and C. ehrenbergii. Hexane extracts administration totally prevented the acute TC-induced liver damage. The preliminary chemical analysis strongly suggests the lupeol acetate as their major constituent. Lupeol and its derivatives have been previously reported as antiinflammatory and hepatoprotective agents.SUMMARY Hexane extracts of both thistles kept normal liver functionality and glycogen store in carbon tetrachloride-induced acute liver damageHexane extracts of both thistles showed anti-necrotic and anti-cholestatic effects, also diminished the lipid peroxidation and nitric oxide levels on the carbon tetrachloride-induced acute liver damageThe two doses of hexane extracts administered (250 and 500 mg/kg) prevented the liver injury in a very similar extentBoth nonpolar extracts are chemically very similar and their main compound seems to be lupeol acetate. Abbreviations used: TC: Carbon tetrachloride; FT-IR: Fourier transform Infrared spectroscopy; GC-MS: Gas chromatography – Mass spectrometry; V: Vehicle; E: Extract; Ecv: Extract of Cirsium vulgare; Ece: Extract of Cirsium ehrenbergii; AP: Alkaline phosphatase; GGTP: γ-Glutamyl transpeptidase; ALT: Alanine aminotransferase; DB: Direct bilirubin; TB: Total bilirubin; LP: Lipid peroxidation; MDA: Malondialdehyde; NO: Nitric oxide; TNF-α: Tumor necrosis factor-α.

Gallic Acid and Dodecyl Gallate Prevents Carbon Tetrachloride-Induced Acute and Chronic Hepatotoxicity by Enhancing Hepatic Antioxidant Status and Increasing p53 Expression.

Gallic acid (3,4,5-trihydroxybenzoic acid, GA), a natural phenolic acid has been reported as a strong antioxidant. Therefore the present study was designed to evaluate the effects of GA and dodecyl gallate (DGA) against acute and chronic carbon tetrachloride (CCl4)-induced hepatotoxicity. For acute model, rats were orally treated with GA and DGA for 7 d prior to CCl4 by intraperitoneally (i.p.) injection. For the chronic model, rats were orally treated with GA or DGA and CCl4 i.p. twice a week for four weeks. In both acute and chronic models, the CCl4-treated groups showed significantly increase in serum hepatic enzyme activities and histopathologic alterations, as well as a disruption in antioxidative status. In contrast, the treatment with GA and DGA restored serum hepatic enzymes activities, improved histopathologic alterations, increased glutathione (GSH) and decreased lipid peroxidation levels. The activities of liver antioxidant enzymes were increased by GA and DGA only in acute model. The expression of p53 gene increased about 3.5 times after GA and DGA treatments, which could result in cell death of damaged hepatocytes preventing of a lifelong liver failure. Thus, these results suggest that GA and DGA has the potential to prevent liver damages as the case of fibrosis condition.

Evaluation of antioxidant and hepatoprotective effects of white cabbage essential oil

Context: There have been no reports of the extraction of essential oil (EO) from white cabbage [Brassica oleracea L. var. capitata (L.) Alef. f. alba DC. (Brassicaceae)] (Bocfal) or its chemical composition, antioxidant activity, or hepatoprotective effects. Objective: To extract Bocfal EO, to identify and quantify its chemical components, to assess their antioxidant capacity, and to evaluate the hepatoprotective properties of Bocfal EO. Materials and methods: Bocfal EO was obtained using hydrodistillation (200 mm Hg/58 °C). The chemical composition was analyzed using GC-MS and was quantified using GC-FID. The antioxidant activity of Bocfal EO and its main constituents was evaluated using TBARS in rat brain homogenates. A Bocfal EO hepatoprotective effect (192 mg/kg) on acute carbon tetrachloride (CT)-induced liver damage was determined in rats using biochemical markers and histological analysis. Diallyl disulphide (DADS) (1 mmol/kg) was used as a control for comparison. Results: Bocfal EO contained organic polysulphides (OPSs), such as dimethyl trisulphide (DMTS) 65.43 ± 4.92% and dimethyl disulphide (DMDS) 19.29 ± 2.16% as major constituents. Bocfal EO and DMTS were found to be potent TBARS inhibitors with IC50 values of 0.51 and 3 mg/L, respectively. Bocfal EO demonstrated better hepatoprotective properties than did DADS (p < 0.05), although both slightly affected the hepatic parenchyma per se, as observed using histopathology. Discussion and conclusion: The antioxidant properties of Bocfal EO and DMTS may be the mechanism of hepatoprotective action; the parenchymal disturbances by Bocfal EO or DADS alone may be related to the high doses used.

Cocoa polyphenols exhibit antioxidant, anti-inflammatory, anticancerogenic, and anti-necrotic activity in carbon tetrachloride-intoxicated mice

The therapeutic effects of cocoa polyphenols on acute carbon tetrachloride (CCl4)-intoxicated mice were investigated. After determining polyphenols profile in the cocoa extract (CE), CE at a dose of 34.5 mg/kg and epicatechin (EC) at a dose of 2.24 mg/kg were intraperitoneally (i.p.) administered to BALB/cN mice following CCl4 treatment. CE and EC post-treatments suppressed hepatotoxicity and inflammation, ameliorated serum markers of liver injury, returned blood lactate and glucose levels to normal, stimulated synthesis and storage of liver glycogen, and modulated glucose metabolism imbalance induced by CCl4. Cocoa polyphenols also exhibited early stage antifibrotic and anticarcinogenic effects. They affected beneficially the mitochondrial functionality acting on dysfunction in mitochondrial respiration caused by CCl4 and antioxidants regulation at subcellular levels.

Experimental evidence for the therapeutic potential of tempol in the treatment of acute liver injury.

Oxidative stress is one of the mechanisms involved in the acute carbon tetrachloride (CCl4)-induced hepatotoxicity. Since 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, known as tempol, has powerful antioxidant properties, we investigated its potential hepatoprotective effects and the underlying mechanisms that may add further benefits for its clinical usefulness using an acute model of CCl4-induced hepatotoxicity. One hour after CCl4 induction of acute hepatotoxicity, mice were treated with a daily dose of 20mg/kg/day tempol for 3days. It was found that treatment of animals with tempol significantly negated the pathological changes in liver function parameters as well as histology induced by CCl4. In addition, tempol significantly ameliorated CCl4-induced lipid peroxidation and GSH depletion, and improved catalase activity. Furthermore, tempol alleviated the inflammation induced by CCl4 as indicated by reducing the liver expression level of nuclear factor-kappa B (NF-κB) and tumor necrosis factor-α (TNF-α). Finally, tempol significantly reduced expression level of the B-cell lymphoma-2 protein (Bcl-2) and active caspase-3 which are known markers of apoptosis. In conclusion, the present study provides important evidences for the promising hepatoprotective effects of tempol that can be explained by amelioration of oxidative stress mainly through replenishment of GSH, restoration of antioxidant enzyme activities, and reduction of lipid peroxides alongside its anti-inflammatory properties.

Tissue-type plasminogen activator suppresses activated stellate cells through low-density lipoprotein receptor-related protein 1

Hepatic stellate cell (HSC) activation and trans-differentiation into myofibroblast (MFB)-like cells is key for fibrogenesis after liver injury and a potential therapeutic target. Recent studies demonstrated that low-density lipoprotein receptor-related protein 1 (LRP1)-dependent signaling by tissue-type plasminogen activator (t-PA) is a pro-fibrotic regulator of the MFB phenotype in kidney. This study investigated whether LRP1 signaling by t-PA is also relevant to HSC activation following injury. Primary and immortalized rat HSCs were treated with t-PA and assayed by western blot, MTT, and TUNEL. In vitro results were then verified using an in vivo, acute carbon tetrachloride (CCl4) injury model that examined the phenotype and recovery kinetics of MFBs from wild-type animals vs mice with a global (t-PA) or HSC-targeted (LRP1) deletion. In vitro, in contrast to kidney MFBs, exogenous, proteolytically inactive t-PA suppressed, rather than induced, activation markers in HSCs following phosphorylation of LRP1. This process was mediated by LRP1 as inhibition of t-PA binding to LRP1 blocked the effects of t-PA. In vivo, following acute injury, phosphorylation of LRP1 on activated HSCs occurred immediately prior to their disappearance. Mice lacking t-PA or LRP1 retained higher densities of activated HSCs for a longer time period compared with control mice after injury cessation. Hence, t-PA, an FDA-approved drug, contributes to the suppression of activated HSCs following injury repair via signaling through LRP1. This renders t-PA a potential target for exploitation in treating patients with fibrosis.

Hepatoprotective effect of oral application of a silymarin extract in carbon tetrachloride-induced hepatotoxicity in rats

Abstract Background Silymarin derived from the milk thistle plant “Silybum marianum” is composed of four major flavonolignans. Clinical as well as experimental studies indicate hepatoprotective effects of silymarin. However, the underlying mechanisms are only incompletely understood. The aim of this study was to assess the effect of oral administration of a defined silymarin extract in the model of acute carbon tetrachloride (CCl4) induced liver injury. Methods A single dose of a silymarin extract (SE; 20 or 100 mg/kg body weight) was given to rats by oral gavage. Subsequently, rats were injected with a single dose of CCl4 (2 ml/kg body weight). Results After 24h, analysis of liver to body weight ratio, serum levels of transaminases and histological analysis revealed a marked liver damage which was inhibited by SE in a dose dependent manner. CCl4-induced expressions of pro-inflammatory and pro-fibrogenic genes were significantly reduced in SE treated rats. Molecular analysis revealed that SE reduced the expression of the pro-inflammatory chemokine MCP-1, the pro-fibrogenic cytokine TGF-beta as well as collagen I in isolated human hepatic stellate cells (HSC), which are the key effector cells of hepatic fibrosis. Conclusion Oral administration of the tested silymarin extract inhibited hepatocellular damage in a model of acute liver injury. Moreover, we newly found that the silymarin extract had direct effects on pro-inflammatory and pro-fibrogenic gene expression in HSCs in vitro. This indicates that direct effects on HSC also contribute to the in vivo hepatoprotective effects of silymarin, and further promote its potential as anti-fibrogenic agent also in chronic liver disease.

Hepatocyte-specific Bid depletion reduces tumor development by suppressing inflammation-related compensatory proliferation.

Liver cancer is a major health-care concern and its oncogenic mechanisms are still largely unclear. Persistent hepatocyte cell death is a common feature among various chronic liver diseases, the blocking of which presents as logical treatment. Therefore, we aimed at investigating tumor development in mice with hepatocyte-specific Bid depletion--a BH3-only Bcl-2 family member that amplifies apoptotic death signals. Hepatocyte-specific conditional Bid-knockout mice (Bid(Δhep)) were injected with 25 mg/kg diethylnitrosamine (DEN) at 14 days of age, and liver tumorigenesis was investigated 9 months later. Additionally, different models of acute liver injury were used including: acute high-dose DEN challenge, 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet and carbon tetrachloride (CCL4) injection. Bid(Δhep) mice developed significantly fewer tumors, showed smaller maximal and average tumor size and reduced tumor incidence. In the acute DEN model, 48 h post injection we observed a significant reduction in liver injury in Bid(Δhep) animals, assessed via serum transaminases and liver histopathology. Furthermore, TNF-α, IL-1ß, cJUN and IL-6 mRNA expression was reduced. These findings were accompanied by reduced compensatory hepatocyte proliferation in Bid(Δhep) mice when compared with controls by immunohistochemistry for Ki67 and proliferating cell nuclear antigen 48 h after DEN injection. In the acute CCL4 model, Bid(Δhep) mice displayed reductions in liver injury and inflammation when compared with controls. No differences in liver injury and serum bilirubin levels were detected in Bid(Δhep) and Bid(flo/flo) mice fed with DDC, which induces bile duct injury and a ductular reaction. Our study demonstrates that in DEN-induced hepatocellular carcinoma, the inhibition of hepatocyte death pathways through Bid deletion protects animals from tumorigenesis. These results suggest that reducing hepatocyte cell death, liver inflammation and compensatory proliferation has a stronger beneficial effect than the potential side effect of enhancing tumor cell survival.

Hepatoprotective effect of a polysaccharide from Crassostrea gigas on acute and chronic models of liver injury

A water-soluble polysaccharide was isolated from Crassostrea gigas (CGPS-1) by hot-water extraction, isoelectric precipitation, hydrolysis and ultrafiltration without using ethanol. Based on the calibration with Dextran, CGPS-1 had a molecular weight of approximately 6.5×106Da. CGPS-1 was analyzed using high-performance liquid chromatography, Fourier-transform infrared spectroscopy and 1H and 13C nuclear magnetic resonance spectroscopy. Based on the data, CGPS-1 was found to be a uniform glucose polymer. The protective effect of CGPS-1 on acute carbon tetrachloride- and chronic ethanol-induced liver injury was investigated in mice. Treatment with CGPS-1 decreased serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and malondialdehyde (MDA) levels; increased superoxide dismutase (SOD) activity; and improved hepatic injury in both the acute and chronic models of liver injury in mice. These results suggest that CGPS-1 possesses potent hepatoprotective activity.

Hepatoprotective and Nephroprotective Effects of Methanolic Extract of Different Parts of Tamarindus Indica Linn in Rats Following Acute and Chronic Carbon Tetrachloride Intoxication

Hepatoprotective and Nephroprotective Effects of Methanolic Extract of Different Parts of Tamarindus Indica Linn in Rats Following Acute and Chronic Carbon Tetrachloride Intoxication

Deficiency of BPOZ2 Decreases Liver Fibrosis After Chronic Carbon Tetrachloride Administration in Mice.

Bood POZ containing gene type 2 (BPOZ2), a Broad-Complex, Tramtrack, and Bric a brac domain containing protein, is an adaptor protein for the E3 ubiquitin ligase scaffold protein CUL3. It plays an important role in acute carbon tetrachloride (CCl4)-induced liver injury and regeneration in mice. In this study, we investigated the role of BPOZ2 in the process of liver fibrosis induced by chronic CCl4 treatment. The results indicate that BPOZ2 deficiency decreases sustained activation of hepatic stellate cells, attenuates collagen αI(I) and tissue inhibitor of matrix metalloprotease 1 expression, and decreases liver fibrosis after repeated CCl4 administration. These findings suggest BPOZ2 as a new therapeutic target for the prevention and treatment of hepatic fibrosis in chronic liver disease.

Mitochondrial dysfunction and compensatory mechanisms in liver cells during acute carbon tetrachloride-induced rat intoxication

Electron-transport chain and redox-balance of mitochondria are important targets that are damaged during intoxication. The aim of the present work was to estimate the role of impairments in cellular bioenergetic function in the development of liver damage during acute carbon tetrachloride intoxication in rats and to elucidate possible compensatory mechanisms. Acute CCl4-induced rat intoxication (0.8 g/kg or 4 g/kg) resulted in considerable impairments of respiratory and synthetic mitochondrial functions; their manifestations depended on the dose of the toxic agent and the duration of the intoxication increased and accompanied by complete uncoupling of oxidation and phosphorylation processes in liver mitochondria. The intoxication induced considerable liver damage and accumulation of NO in blood plasma and liver tissue. The changes of some parameters of liver mitochondrial functional activity demonstrate an oscillative pattern, reflecting compensatory mechanisms during intoxication that involved increased reduced glutathione level and enhanced succinate dehydrogenase activity.

Pharmacological inhibition of the chemokine CXCL16 diminishes liver macrophage infiltration and steatohepatitis in chronic hepatic injury.

Non-alcoholic fatty liver disease (NAFLD) is a major cause of morbidity and mortality in developed countries, resulting in steatohepatitis (NASH), fibrosis and eventually cirrhosis. Modulating inflammatory mediators such as chemokines may represent a novel therapeutic strategy for NAFLD. We recently demonstrated that the chemokine receptor CXCR6 promotes hepatic NKT cell accumulation, thereby controlling inflammation in experimental NAFLD. In this study, we first investigated human biopsies (n = 20), confirming that accumulation of inflammatory cells such as macrophages is a hallmark of progressive NAFLD. Moreover, CXCR6 gene expression correlated with the inflammatory activity (ALT levels) in human NAFLD. We then tested the hypothesis that pharmacological inhibition of CXCL16 might hold therapeutic potential in NAFLD, using mouse models of acute carbon tetrachloride (CCl4)- and chronic methionine-choline-deficient (MCD) diet-induced hepatic injury. Neutralizing CXCL16 by i.p. injection of anti-CXCL16 antibody inhibited the early intrahepatic NKT cell accumulation upon acute toxic injury in vivo. Weekly therapeutic anti-CXCL16 administrations during the last 3 weeks of 6 weeks MCD diet significantly decreased the infiltration of inflammatory macrophages into the liver and intrahepatic levels of inflammatory cytokines like TNF or MCP-1. Importantly, anti-CXCL16 treatment significantly reduced fatty liver degeneration upon MCD diet, as assessed by hepatic triglyceride levels, histological steatosis scoring and quantification of lipid droplets. Moreover, injured hepatocytes up-regulated CXCL16 expression, indicating that scavenging functions of CXCL16 might be additionally involved in the pathogenesis of NAFLD. Targeting CXCL16 might therefore represent a promising novel therapeutic approach for liver inflammation and steatohepatitis.

The biliary epithelium gives rise to liver progenitor cells

Severe liver diseases are characterized by expansion of liver progenitor cells (LPC), which correlates with disease severity. However, the origin and role of LPC in liver physiology and in hepatic injury remains a contentious topic. We found that ductular reaction cells in human cirrhotic livers express hepatocyte nuclear factor 1 homeobox B (HNF1β). However, HNF1β expression was not present in newly generated epithelial cell adhesion molecule (EpCAM)-positive hepatocytes. In order to investigate the role of HNF1β-expressing cells we used a tamoxifen-inducible Hnf1βCreER/R26R(Yfp/LacZ) mouse to lineage-trace Hnf1β(+) biliary duct cells and to assess their contribution to LPC expansion and hepatocyte generation. Lineage tracing demonstrated no contribution of HNF1β(+) cells to hepatocytes during liver homeostasis in healthy mice or after loss of liver mass. After acute acetaminophen or carbon tetrachloride injury no contribution of HNF1β(+) cells to hepatocyte was detected. We next assessed the contribution of Hnf1β(+) -derived cells following two liver injury models with LPC expansion, a diethoxycarbonyl-1,4-dihydro-collidin (DDC)-diet and a choline-deficient ethionine-supplemented (CDE)-diet. The contribution of Hnf1β(+) cells to liver regeneration was dependent on the liver injury model. While no contribution was observed after DDC-diet treatment, mice fed with a CDE-diet showed a small population of hepatocytes derived from Hnf1β(+) cells that were expanded to 1.86% of total hepatocytes after injury recovery. Genome-wide expression profile of Hnf1β(+) -derived cells from the DDC and CDE models indicated that no contribution of LPC to hepatocytes was associated with LPC expression of genes related to telomere maintenance, inflammation, and chemokine signaling pathways. HNF1β(+) biliary duct cells are the origin of LPC. HNF1β(+) cells do not contribute to hepatocyte turnover in the healthy liver, but after certain liver injury, they can differentiate to hepatocytes contributing to liver regeneration.

Prolonged administration of secretin to normal rats increases biliary proliferation and secretin-induced ductal secretory activity.

Cholangiocyte proliferation is coordinately regulated by a number of gastrointestinal hormones/peptides, some of which display stimulatory effects and some have inhibitory actions on cholangiocyte proliferation. Enhanced biliary proliferation [for example after bile duct ligation (BDL) and partial hepatectomy] is associated with increased expression of secretin receptor (SR), cystic fibrosis transmembrane conductance regulator (CFTR) and Cl(-)/HCO3 (-) anion exchanger 2 and secretin-stimulated ductal secretion, whereas loss/damage of bile ducts [for example after acute carbon tetrachloride (CCl4) administration] is associated with reduced secretin-stimulated ductal secretory activity. There is growing information regarding the role of gastrointestinal hormones the regulation of biliary growth. For example, while gastrin, somatostatin and serotonin inhibit bile duct hyperplasia of cholestatic rats by downregulation of cAMP signaling, secretin has been shown to stimulate the proliferation of normal mice by activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent signaling. However, no information exists regarding the stimulatory effects of secretin on biliary proliferation of normal rats. Thus, we evaluated the in vivo and in vitro effect of secretin on biliary proliferation, the expression of markers key of ductal secretion and secretin-stimulated ductal secretion. Normal male rats were treated with saline or secretin (2.5 nmoles/kg BW/day by osmotic minipumps for one week). We evaluated: (I) intrahepatic bile duct mass (IBDM) in liver sections and PCNA expression in purified cholangiocytes; (II) SR and CFTR mRNA expression and secretin-stimulated cAMP levels in purified cholangiocytes; and (III) secretin-stimulated bile and bicarbonate secretion in bile fistula rats. In vitro, normal rat intrahepatic cholangiocyte lines (NRIC) were treated with BSA (basal) or secretin (100 nM) for 24 to 72 hours in the absence/presence of a PKA or a MEK inhibitor before evaluating proliferation by MTS assays. Prolonged administration of secretin to normal rats increased IBDM and PCNA expression in purified cholangiocytes compared to saline-treated normal rats. Also, secretin increased the expression of proteins (SR and CFTR) that are key in the regulating ductal secretion and enhanced secretin-stimulated cAMP levels and bile and bicarbonate secretion. In vitro, secretin increased the proliferation of NRIC, increase that was prevented by PKA and MAPK inhibitors. We have demonstrated that secretin stimulates both in vivo and in vitro biliary proliferation and secretin-stimulated ductal secretory activity in normal rats. We suggest that the stimulatory effect of secretin on biliary proliferation and secretion may be important for preventing biliary dysfunction during ductopenic disorders.

&lt;i&gt;In vivo&lt;/i&gt; antioxidant and hepatoprotective effects of methanolic extract of &lt;i&gt;dioclea reflexa&lt;/i&gt; seed in rats following acute or chronic liver injury

Methanolic extract of Dioclea reflexa seed was investigated following acute or chronic carbon tetrachloride intoxication in male albino rats. In the acute experiment, rats were pre-treated with extract at 5 mg/kg for three days before administration of carbon tetrachloride(0.6 mL/kg) while in the chronic model, rats received extract at 2.5 mg/kg for 12 consecutive days with 72 hourly administration of carbon tetrachloride at 0.3 mL/kg. In both models, the levels of transaminases and malondialdehyde were significantly (p&lt;0.05) reduced in D. reflexa extract treated rats compared to the carbon tetrachloride control, with concomitant boosting in the levels of superoxide dismutase and catalase activities. These results indicate that the seed extract of D. reflexa possess strong antioxidant and hepatoprotective properties in both acute and chronic hepatocellular damage and oxidative stress that it could impact positively on the health of the eastern Nigerian populace that consumes it regularly.

Regulation by resveratrol of the cellular factors mediating liver damage and regeneration after acute toxic liver injury

Acute liver injury is manifested by different degree of hepatocyte necrosis and may recover via the process of hepatocyte regeneration once the injury is discontinued. Most of the liver injury is associating with inflammatory cytokines. Resveratrol (RSV) is a natural phytoalexin with powerful anti-inflammatory effects. The effects of RSV on cellular factors mediating liver damage and regeneration in acute carbon tetrachloride (CCl4 ) liver injury were investigated. RSV decreased alanine aminotransferase, aspartate aminotransferase, necrosis, and 4-hydroxynonenal in the CCl4 -injured liver. RSV decreased hepatocyte apoptosis by reducing caspase 8 and caspase 3 but not Bax and Bcl-xL. RSV reduced Kupffer cells recruitment, the expressions of tumor necrosis factor-α and interleukin-6, but not interleukin-10. RSV lowered the numbers of anti-5-bromon-2'-deoxyuridine and anti-Ki67-positive hepatocytes. Hepatic hepatocyte growth factor, c-Met and transforming growth factor-α expressions were reduced by RSV, while transforming growth factor-β1 and hepatic stellate cells activation were not changed. RSV reduced the injury-induced CXCL10 elevations in serum and liver in vivo. Besides, RSV inhibited CXCL10 release from CCl4 -injured hepatocytes in vitro. In contrast, recombinant CXCL10 improved the viability of CCl4 -injured hepatocytes. RSV therapy can be beneficial for acute toxic liver injury. RSV reduced hepatocyte apoptosis but limited hepatocyte regeneration possibly through reducing the hepatomitogenic signaling and the release of CXCL10.