Ascorbic acid concentrations in dimethylnitrosamine-induced hepatic fibrosis in rats

Molecular pathogenesis of metabolic dysfunction-associated steatotic liver disease, steatohepatitis, hepatic fibrosis and liver cirrhosis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by intense deposition of fat globules in the hepatic parenchyma that could potentially progress to liver cirrhosis and hepatocellular carcinoma. Here, we evaluated a rat model to study the molecular pathogenesis of the spectrum of MASLD and to screen therapeutic agents. SHRSP5/Dmcr rats were fed a high-fat and cholesterol (HFC) diet for a period of 12 weeks and evaluated for the development of steatosis (MASLD), steatohepatitis, fibrosis and cirrhosis. A group of animals were sacrificed at the end of the 4th, 6th, 8th and 12th weeks from the beginning of the experiment, along with the control rats that received normal diet. Blood and liver samples were collected for biochemical and histopathological evaluations. Immunohistochemical staining was performed for α-SMA and Collagen Type I. Histopathological examinations demonstrated steatosis at the 4th week, steatohepatitis with progressive fibrosis at the 6th week, advanced fibrosis with bridging at the 8th week and cirrhosis at the 12th week. Biochemical markers and staining for α-SMA and Collagen Type I demonstrated the progression of steatosis to steatohepatitis, hepatic fibrosis and liver cirrhosis in a stepwise manner. Control animals fed a normal diet did not show any biochemical or histopathological alterations. The results of the present study clearly demonstrated that the HFC diet-induced model of steatosis, steatohepatitis, hepatic fibrosis and cirrhosis is a feasible, quick and appropriate animal model to study the molecular pathogenesis of the spectrum of MASLD and to screen potent therapeutic agents.

Therapeutic implication of human placental extract to prevent liver cirrhosis in rats with metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is always accompanied with hepatic fibrosis that could potentially progress to liver cirrhosis and hepatocellular carcinoma. Employing a rat model, we evaluated the role of human placental extract (HPE) to arrest the progression of hepatic fibrosis to cirrhosis in patients with MASH. SHRSP5/Dmcr rats were fed with a high-fat and high-cholesterol diet for 4 weeks and evaluated for the development of steatosis. The animals were divided into control and treated groups and received either saline or HPE (3.6 ml/kg body weight) subcutaneously thrice a week. A set of animals were killed at the end of 6th, 8th, and 12th weeks from the beginning of the experiment. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), hepatic malondialdehyde (MDA), and glutathione content were measured. Immunohistochemical staining was performed for α-smooth muscle actin (α-SMA), 4-hydroxy-2-nonenal (4-HNE), collagen type I, and type III. Control rats depicted progression of liver fibrosis at 6 weeks, advanced fibrosis and bridging at 8 weeks, and cirrhosis at 12 weeks, which were significantly decreased in HPE-treated animals. Treatment with HPE maintained normal levels of MDA and glutathione in the liver. There was marked decrease in the staining intensity of α-SMA, 4-HNE, and collagen type I and type III in HPE treated rats compared with control animals. The results of the present study indicated that HPE treatment mediates immunotropic, anti-inflammatory, and antioxidant responses and attenuates hepatic fibrosis and early cirrhosis. HPE depicts therapeutic potential to arrest the progression of MASH towards cirrhosis.

Mitigation of intrahepatic cholestasis induced by 17α-ethinylestradiol via nanoformulation of Silybum marianum L

BACKGROUND

Cholestasis is an important predisposing factor for hepatocyte damage, liver fibrosis, primary biliary cirrhosis, and even liver failure. Silybum marianum L. (SM) plant is used in teas or eaten in some countries due to its antioxidant and hepatoprotective properties. Because of its low and poor oral bioavailability, so we improve the therapeutic activity of Silybum marianum L. extract (SM) by studying the potential effects of nanoformulation of Silybum marianium L. extract (nano-SM) on 17α-ethinylestradiol (EE)-induced intrahepatic cholestasis.

METHODS

Thirty female Sprague-Dawley rats were divided into 5 groups (6 rats/group). Group I: Rats were received the treatment vehicle and served as normal group. Group II:Rats were injected daily with EE (10 mg/kg) for five successive days. Group III-V: Rats were injected daily with EE (10 mg/kg) and treated with either Ursodeoxycholic acid (UDCA) (40 mg/kg), SM (100 mg/kg) and nano-SM (100 mg/kg) orally once/day throughout the trialfor five successive days, respectively.

RESULTS

Nano-SM greatly dampened the increase in serum levels of total and direct bilirubin, alanine aminotransaminase, aspartate aminotransaminase, and alkaline phosphatase caused by EE. Furthermore, nano-SM increased the hepatic contents of reduced glutathione (GSH) and catalase (CAT) and also upregulated the relative hepatic gene expressions of Rho-kinase (ROCK-1), myosin light chain kinase (MLCK), and myosin phosphatase target subunit (MYPT1) compared to the EE-induced group. Administration of nano-SM reduced hepatic lipid peroxidation and downregulated the relative hepatic expressions of the nuclear factor-kappa B (NF-ҡB) and interleukin-1β (IL-1β). In addition, nano-SM improved the histopathological changes induced by EE.

CONCLUSION

Nano-SM possessed a superior effect over SM, which can be considered an effective protective modality against EE-induced cholestatic liver injury through its antioxidant, anti-inflammatory activities, and enhancing bile acid (BA) efflux.

Favorable Aspects of Silymarin in Linezolid Treatment Against Diabetic Methicillin-Resistant Staphylococcus aureus (MRSA) Infected Rats

Background:

Linezolid used for diabetic methicillin-resistant Staphylococcus aureus (MRSA) infections is limited due to hepatotoxicity, lactic acidosis, anemia, and oxidative stress induced by diabetes and linezolid therapy. Silymarin is a hepatoprotective, antioxidant, antibacterial, and antidiabetic.

Objective:

The research investigated the role of silymarin in linezolid treatment against MRSA-infected diabetic rats.

Methods:

Type 2 diabetes mellitus (T2DM) was induced by a high-fat diet (58% calories fat) for 2 weeks, followed by a single intraperitoneal injection of streptozotocin (STZ) 35 mg/kg into Wistar rats. The diabetic rats were rendered neutropenic and subcutaneously injected with 106 CFU/ml of MRSA. Linezolid and silymarin were administered orally at a dose of 50 mg/kg twice daily for 14 days. The bacterial load/abscess, hematological, biochemical, enzymatic parameters, antioxidants, and histopathological studies were performed on the 42nd day.

Results:

The MRSA was confirmed by PCR assay. The minimum inhibitory concentration of linezolid was found to be 0.5-2 μg/ml. The linezolid treated MRSA infected diabetic rats showed 9.69 x 103 CFU / abscess bacterial count, decreased intestinal alkaline phosphatase (IAP), RBC, antioxidants, elevated lactate, and liver markers than diabetic rats. The silymarin treatment showed a decrease in the bacterial count (2.98 x 103 CFU / abscess), serum lactate, liver markers, increased IAP levels, and antioxidants in linezolid treated diabetic infected rats.

Conclusion:

The research concluded that silymarin could be a better herbal therapeutic agent that attenuated diabetic and linezolid induced complications in MRSA-infected diabetic rats.

Epigallocatechin-3-gallate inhibits osteopontin expression and prevents experimentally induced hepatic fibrosis

Osteopontin (OPN) is a matricellular cytokine and a stress-induced profibrogenic molecule that promotes activation of stellate cells during the pathogenesis of hepatic fibrosis. We studied the protective effects of epigallocatechin-3-gallate (EGCG) to suppress oxidative stress, inhibit OPN expression, and prevent experimentally induced hepatic fibrosis. Liver injury was induced with intraperitoneal injections of N-nitrosodimethylamine (NDMA) in a dose of 1 mg/100 g body weight on 3 consecutive days of a week for 28 days. A group of rats received 0.2 mg EGCG/100 g body weight orally everyday during the study. The animals were sacrificed on day 28th from the beginning of exposure. Serum levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid were measured. Immunohistochemistry and/or real-time PCR were performed for α-SMA, 4-HNE, OPN, collagen type I, and type III. Serial administrations of NDMA produced well developed fibrosis and early cirrhosis in rat liver. Treatment with EGCG significantly reduced serum/plasma levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid and prevented deposition of collagen fibers in the hepatic tissue. Protein and/or mRNA levels demonstrated marked decrease in the expression of α-SMA, 4-HNE, OPN, collagen type I, and type III. Treatment with EGCG prevented excessive generation of reactive oxygen species, suppressed oxidative stress, significantly reduced serum and hepatic OPN levels, and markedly attenuated hepatic fibrosis. The results indicated that EGCG could be used as a potent therapeutic agent to prevent hepatic fibrogenesis and related adverse events.

Chemopreventive and Therapeutic Efficacy of Enhalus acoroides against Diethylnitrosamine Induced Hepatocellular Carcinoma in Wistar Albino Rats

Hepatocellular carcinoma is the second most cause of death among the various cancers worldwide. Recent research searching an alternative therapy for cancer treatment without or less side effects. Many studies indicated the beneficial effects of Enhalus acoroides. There has been no scientific validation on antioxidant and chemopreventive potential of ethanolic extract E. acoroides against hepatoma. To assess the hepatoprotective activity of E. acoroides (EEEA) against DEN-induced hepatoma using Wistar albino rats. Animals were distributed into five groups, each containing six rats. To Group I - control rats - normal saline given. Groups II, III, IV and V rats were injection of DEN at a dose of 100 mg/kg body weight i.p. to induce liver cancer. At the commencement of 6th week, Group III rats supplemented with EEEA at a dose of 200 mg/kg body weight/day upto 16 weeks. Group IV rats supplemented with EEEA for 1 week before the administration of DEN and continued till the sixteenth week. Group V supplementation of silymarin at a dose of 100 mg/kg body weight at the beginning of 6th week after the injection of DEN and continued upto 16 weeks and considered as positive control rats. The efficiency of E. acoroides for its antioxidant hepatoprotective and activity evaluated in rats against DEN-induced liver damage. The hepatoprotective ability of EEEA at a dose of 200 mg/kg was examined against DEN at a dose of 100 mg/kg/b.w. induced hepatotoxicity and analysed by evaluating serum liver and kidney marker levels, lipid profile (TG, HDL, LDL and total cholesterol) and serum tumour markers (DNA, RNA, AFP and CEA). Supplementation of EEEA to DEN treated rats was determined by evaluating various antioxidant biomarkers (SOD, CAT, GPx, GSH, Vit E and Vit C). Histopathological studies and morphometric gross analysis were also support the consequences of this study. A significant improvement of antioxidant defence and declined MDA levels within the serum of EEEA treated animals compared to the DEN-induced hepatoma. The supplementation of EEEA declined the serum liver, kidney and serum tumour marker levels and lipid profile as comparatively to Group I rats. The histopathological changes were changed on supplementation of EEEA demonstrating its protecting effects on hepatocytes as comparatively to Group I rats. Our significances recognized that crude extract (ethanol) of E. acoroides revealed a potential impact against DEN-induced hepatoma and assists as a superior choice for chemopreventive treatments.

Metabolism of N-nitrosodimethylamine, methylation of macromolecules, and development of hepatic fibrosis in rodent models

Hepatic fibrosis and cirrhosis are chronic diseases affecting liver and a major health problem throughout the world. The hallmark of fibrosis and cirrhosis is inordinate synthesis and deposition of fibril forming collagens in the extracellular matrix of the liver leading to nodule formation and loss of normal architecture. Hepatic stellate cells play a crucial role in the pathogenesis and progression of liver fibrosis through secretion of several potent fibrogenic factors that trigger hepatocytes, portal fibrocytes, and bone marrow-derived fibroblasts to synthesize and deposit several connective tissue proteins, especially collagens between hepatocytes and space of Disse. Regulation of various events involved in the activation and transformation of hepatic stellate cells seems to be an appropriate strategy for the arrest of hepatic fibrosis and liver cirrhosis. In order to unravel the molecular mechanisms involved in the pathogenesis and progression of hepatic fibrosis, to determine proper and potent targets to arrest fibrosis, and to discover powerful therapeutic agents, a quick and reproducible animal model of hepatic fibrosis and liver cirrhosis that display all decompensating features of human condition is required. This review thoroughly evaluates the biochemical, histological, and pathological features of N-nitrosodimethylamine-induced model of liver injury, hepatic fibrosis, and early cirrhosis in rodents.

Atriplex halimus aqueous extract abrogates carbon tetrachloride-induced hepatotoxicity by modulating biochemical and histological changes in rats

The objective of this study was to evaluate the potential protective effect of Atriplex halimus aqueous leaves extract (AHAE) against acute carbon tetrachloride (CCl₄)-induced oxidative stress in rats. Rats were randomly divided into four groups: group (C) served as a control treated with 1 ml/(kg bw) of olive oil, and group (CCl₄) was treated with 1 ml CCl₄/(kg bw) dissolved in olive oil administered by intraperitoneal way. Rats of group (CCl₄+AHAE) have received CCl₄ and treated with 200 mg AHAE/(kg bw). Animals of group (AHAE) were treated with 200 mg/(kg bw) of AHAE. A significant increase in malondialdehyde levels in liver associated with a decrease in antioxidant enzyme activities and reduced glutathione content was observed in CCl₄ group compared to controls. The administration of AHAE to CCl₄+AHAE group improved all parameters studied. We conclude that CCl₄ induces oxidative stress and modifies biochemical parameters and histological aspects of liver. Administration of AHAE alleviates the toxicity induced by this organic compound.

Alteration of Trace Elements during Pathogenesis of N-Nitrosodimethylamine Induced Hepatic Fibrosis

The biochemical abnormalities and oxidative stress during pathogenesis of hepatic fibrosis could lead to alteration of trace elements. We studied the alteration of major trace elements during the pathogenesis of N-nitrosodimethylamine (NDMA)-induced hepatic fibrosis in rats. The biochemical and pathological indices of liver functions and hepatic fibrosis were evaluated. Serum and liver levels of copper, iron and zinc were determined using atomic absorption spectrophotometry. Cobalt, manganese, and molybdenum in the serum and liver were estimated by inductively coupled plasma mass spectrometry. Serial administrations of NDMA resulted in decreased serum albumin, biochemical abnormalities, increase of total liver collagen, and well-developed fibrosis and early cirrhosis. Serum and liver zinc content significantly decreased on all the days following NDMA administration. When copper and molybdenum markedly increased in the serum, liver molybdenum decreased dramatically. Both iron and manganese content significantly increased in the liver following NDMA-induced fibrosis. The results of the present study indicate that alteration of trace elements during pathogenesis of hepatic fibrosis is due to metabolic imbalance, biochemical abnormalities, decreased serum albumin, and ascites following NDMA-induced liver injury. The modulation of trace elements during hepatic fibrosis could play a prominent role in progression of the disease.

Molecular mechanisms in the pathogenesis of N-nitrosodimethylamine induced hepatic fibrosis

Hepatic fibrosis is marked by excessive synthesis and deposition of connective tissue proteins, especially interstitial collagens in the extracellular matrix of the liver. It is a result of an abnormal wound healing in response to chronic liver injury from various causes such as ethanol, viruses, toxins, drugs, or cholestasis. The chronic stimuli involved in the initiation of fibrosis leads to oxidative stress and generation of reactive oxygen species that serve as mediators of molecular events involved in the pathogenesis of hepatic fibrosis. These processes lead to cellular injury and initiate inflammatory responses releasing a variety of cytokines and growth factors that trigger activation and transformation of resting hepatic stellate cells into myofibroblast like cells, which in turn start excessive synthesis of connective tissue proteins, especially collagens. Uncontrolled and extensive fibrosis results in distortion of lobular architecture of the liver leading to nodular formation and cirrhosis. The perpetual injury and regeneration process could also results in genomic aberrations and mutations that lead to the development of hepatocellular carcinoma. This review covers most aspects of the molecular mechanisms involved in the pathogenesis of hepatic fibrosis with special emphasize on N-Nitrosodimethylamine (NDMA; Dimethylnitorsmaine, DMN) as the inducing agent.

Curcumin attenuates hepatic fibrosis and insulin resistance induced by bile duct ligation in rats

Recent studies have strongly indicated the hepatoprotective effect of curcumin; however, the precise mechanisms are not well understood. This study aimed to determine the protective effect of curcumin on hepatic damage and hepatic insulin resistance in biliary duct ligated (BDL) fibrotic rat model. To accomplish this, male Wistar rats were divided into four groups (eight for each): sham group, BDL group, sham+Cur group and BDL+Cur group. The last two groups received curcumin at a dose of 100 mg/kg daily for 4 weeks. The mRNA/protein expression levels of Ras-related C3 botulinum toxin substrate 1 (Rac1), Rac1-GTP, dinucleotide phosphate oxidase 1 (NOX1), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signalling 3 (SOCS3), insulin receptor substrate 1 (IRS1), extracellular signal-regulated kinase 1 (ERK1), specific protein 1 (Sp1) and hypoxia-inducible factor-1α (HIF-1α) were measured by real-time PCR and Western blotting, respectively. Fasting blood glucose, insulin and Leptin levels were determined and homoeostasis model assessment-estimated insulin resistance, as an index of insulin resistance, was calculated. Curcumin significantly attenuated liver injury and fibrosis, including amelioration of liver histological changes, reduction of hepatic enzymes, as well as decreased expression of liver fibrogenesis-associated variables, including Rac1, Rac1-GTP, NOX1, ERK1, HIF-1α and Sp1. Curcumin also attenuated leptin level and insulin resistance, which had increased in BDL rats (P<0·05). Furthermore, compared with the BDL group, we observed an increase in IRS1 and a decrease in SOCS3 and STAT3 expression in the curcumin-treated BDL group (P<0·05), indicating return of these parameters towards normalcy. In conclusion, Curcumin showed hepatoprotective activity against BDL-induced liver injury and hepatic insulin resistance by influencing the expression of some genes/proteins involved in these processes, and the results suggest that it can be used as a therapeutic option.

Determination of selenium during pathogenesis of hepatic fibrosis employing hydride generation and inductively coupled plasma mass spectrometry

Serum and liver selenium levels were studied during the pathogenesis of N-nitrosodimethylamine (NDMA) induced hepatic fibrosis in rats. The degree of fibrosis was assessed with Masson’s trichrome staining and quantifying collagen content in the liver. Lipid peroxides were measured in blood and liver samples and total glutathione and glutathione peroxidase were assayed in the liver tissue to evaluate oxidative stress. Interleukin-6 (IL-6) and transforming growth factor-β1 (TGF-β1) were measured in the serum. Selenium levels were determined using inductively coupled plasma-mass spectrometry (ICP-MS) after acid digestion and hydride generation of selenium. Serial administrations of NDMA produced well-developed fibrosis and early cirrhosis in the liver with 4-fold increase of total collagen content and deposition of collagen fibers. Blood and hepatic lipid peroxides, serum IL-6 and TGF-β1 were significantly increased. There was significant reduction in hepatic glutathione and glutathione peroxidase levels. Serum and liver selenium were remarkably decreased on all the days studied. The results suggest that decreased selenium and glutathione peroxidase contribute to the impairment of cellular antioxidant defense, which in turn results in oxidative stress and trigger pathogenesis of hepatic fibrosis. The study further demonstrated that ICP-MS with hydride generation technique is a reliable and sensitive method for determination of selenium in biological samples.

Propolis reduces Leishmania amazonensis-induced inflammation in the liver of BALB/c mice

Experimental models of mouse paw infection with L. amazonensis show an induction of a strong inflammatory response in the skin, and parasitic migration may occur to secondary organs with consequent tissue injury. There are few studies focusing on the resolution of damage in secondary organs caused by Leishmania species-related cutaneous leishmaniasis. We investigated the propolis treatment effect on liver inflammation induced by Leishmania amazonensis infection in the mouse paw. BALB/c mice were infected in the hind paw with L. amazonensis (10(7)) promastigote forms. After 15 days, animals were treated daily with propolis (5 mg/kg), Glucantime (10 mg/kg), or with propolis plus Glucantime combined. After 60 days, mice were euthanized and livers were collected for inflammatory process analysis. Liver microscopic analysis showed that propolis reduced the inflammatory process compared to untreated infected control. There was a decrease of liver myeloperoxidase and N-acetyl-β-glucosaminidase activity levels, collagen fiber deposition, pro-inflammatory cytokine production, and plasma aspartate transaminase and alanine transaminase levels. Furthermore, propolis treatment enhanced anti-inflammatory cytokine levels and reversed hepatosplenomegaly. Our data demonstrated that daily low doses of Brazilian propolis reduced the secondary chronic inflammatory process in the liver caused by L. amazonensis subcutaneous infection in a susceptible mice strain.

Protective Effect of Curcumin against the Liver Toxicity Caused by Propanil in Rats

We investigated the protective effects of curcumin on propanil-induced alterations in biochemical indices in blood and liver of male Wistar rats. The study consisted of four treatment groups, with six animals each, designated as control, propanil (20mg/kg), curcumin(50 mg/kg), and curcumin (50 mg/kg) + propanil (20 mg/kg). Rats were administered their respective doses orally, every other day, for 28 days. Propanil administration elicited significant (P < 0.001) increases in plasma aspartate aminotransferase and alkaline phosphatase activities, by 24% and 56%, respectively, compared to the control. Treatment with propanil elevated bilirubin, creatinine, and total cholesterol levels in rats, but these were not significant relative to controls. Administration of propanil to rats significantly (P < 0.001) increased lipid peroxidation levels. However, catalase activity, vitamin C, and reduced glutathione levels were significantly reduced. Exposure to propanil did not produce any significant changes in packed cell volume, neutrophils, and leukocyte counts. The supplementation of curcumin attenuated the adverse effects of propanil intoxication by reducing lipid peroxidation levels and restored the levels of serum enzymes and reduced glutathione. The present study showed that propanil increased oxidative stress and altered some biochemical parameters in the rats but curcumin could afford some protection to attenuate propanil-induced toxicity in the liver.

Resveratrol mitigate structural changes and hepatic stellate cell activation in N'-nitrosodimethylamine-induced liver fibrosis via restraining oxidative damage

Resveratrol, a polyphenol, found in skin of red grapes, peanuts and berries possesses anti-inflammatory, anti-carcinogenic and lipid modulation properties. Here, we demonstrate in vivo antifibrotic activity of resveratrol in a mammalian model, wherein hepatic fibrosis was induced by N'-nitrosodimethylamine (NDMA) administration. Apart from being a potent hepatotoxin, NDMA is a known mutagen and carcinogen, as well. To induce hepatic fibrosis, rats were administered NDMA (i.p.) in 10mg/kgb.wt thrice/week for 21 days. Another group of animals received resveratrol supplement (10mg/kgb.wt) subsequent to NDMA administration and were sacrificed weekly. The changes in selected biomarkers were monitored to compare profibrotic effects of NDMA and antifibrotic activity of resveratrol. The selected biomarkers were: sera transaminases, ALP, bilirubin, liver glycogen, LPO, SOD, protein carbonyl content, ATPases (Ca(2+), Mg(2+), Na(+)/K(+)) and hydroxyproline/collagen content. Alterations in liver architecture were assessed by H&E, Masson's trichrome and reticulin staining of liver biopsies. Immuno-histochemistry and immunoblotting were employed to examine expression of α-SMA. Our results demonstrate that during NDMA-induced liver fibrosis transaminases, ALP, bilirubin, hydroxyproline and liver collagen increases, while liver glycogen is depleted. The decline in SOD (>65%) and ATPases, which were concomitant with the elevation in MDA and protein carbonyls, strongly indicate oxidative damage. Fibrotic transformation of liver in NDMA-treated rats was verified by histopathology, immuno-histochemistry and immunoblotting data, with the higher expressivity of α-SMA-positive HSCs being most established diagnostic immuno-histochemical marker of HSCs. Resveratrol-supplement refurbished liver architecture by significantly restoring levels of biomarkers of oxidative damage (MDA, SOD, protein carbonyls and membrane-bound ATPases). Therefore, we conclude that antifibrotic effect of resveratrol is due to restrained oxidative damage and down-regulation of α-SMA, which inhibits HSC activation to obstruct liver fibrosis.

Two xanthones from Swertia punicea with hepatoprotective activities in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia punicea Hemsl. (Gentianaceae) is more commonly known as "Ganyan-cao" and used mainly as a traditional Chinese folk medicine for the treatment of acute bilious hepatitis, cholecystitis, fever, intoxification and jaundice.

MATERIALS AND METHODS

The active hepatoprotective constituents of Swertia punicea were purified using various column chromatography techniques. The structures of two isolated compounds were determined on the basis of spectroscopic data interpretation such as NMR analysis. The hepatoprotective activities of isolated compounds were evaluated by using hepatotoxicity in vitro and dimethylnitrosamine-induced rat hepatic fibrosis in vivo, respectively.

RESULTS

Two xanthones, 1, 7-dihydroxy-3, 4, 8-trimethoxyxanthone (1) and bellidifolin (2) were isolated from the stems of Swertia punicea. The compounds 1 and 2 exhibited notable hepatoprotective activities against carbon tetrachloride (CCl4) -induced HepG2 cell damage, and effectively alleviated the levels of aspartate transaminase (AST), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malonic dialdehyde (MDA) induced by CCl₄ in a concentration-dependent manner. Co-treatment with compound 2 significantly increased the cell viability compared with N-acetyl-p-aminophenol (APAP) treatment. Compound 2 also alleviated APAP-induced hepatotoxicity by increasing glutathione (GSH) content and decreasing hydroxyl free radical (·OH) levels and reactive oxygen specises (ROS) production. In addition, the protective effect of compound 1 significantly alleviated DMN-induced liver inflammation and fibrosis. Oral administration of compound 1 recovered the reduction of albumin (ALB) and reversed the elevation of serum alanine transaminase (ALT), AST and total bilirubin (TBIL) in dimethylnitrosamine (DMN)-induced fibrotic rats. Severe oxidative stress induced in fibrotic rats was evidenced by a 1.5-fold elevation in MDA and a fall in the SOD activity, and treatment with compound 1 protected against these adverse effects. Recovery of rat liver tissue against DMN-induced hepatocellular necrosis, inflammatory changes and hepatic fibrosis by compound 1 is also confirmed by H&E and Masson stained histopathological evaluation of liver tissue.

CONCLUSION

Two xanthones from Swertia punicea exhibited hepatoprotective activities in vitro (compounds 1 and 2) and in vivo (compound 1), respectively.

Effect of sinapic acid against dimethylnitrosamine-induced hepatic fibrosis in rats

Sinapic acid is a member of the phenylpropanoid family and is abundant in cereals, nuts, oil seeds, and berries. It exhibits a wide range of pharmacological properties. In this study, we investigated the hepatoprotective and antifibrotic effects of sinapic acid on dimethylnitrosamine (DMN)-induced chronic liver injury in rats. Sinapic acid remarkably prevented DMN-induced loss of body weight. This was accompanied by a significant increase in levels of serum alanine transaminase, aspartate transaminase, and liver malondialdehyde content. Furthermore, sinapic acid reduced hepatic hydroxyproline content, which correlated with a reduction in the expression of type I collagen mRNA and histological analysis of collagen in liver tissue. Additionally, the expression of hepatic fibrosis-related factors such as α-smooth muscle actin and transforming growth factor-β1 (TGF-β1), were reduced in rats treated with sinapic acid. Sinapic acid exhibited strong scavenging activity. In conclusion, we find that sinapic acid exhibits hepatoprotective and antifibrotic effects against DMN-induced liver injury, most likely due to its antioxidant activities of scavenging radicals, its capacity to suppress TGF-β1 and its ability to attenuate activation of hepatic stellate cells. This suggests that sinapic acid is a potentially useful agent for the protection against liver fibrosis and cirrhosis.

Ameliorative effect of silibinin against N-nitrosodimethylamine-induced hepatic fibrosis in rats

The protective effect of silibinin (SBN) against hepatic fibrosis induced by repeated intermittent administration of N-nitrosodimethylamine (DMN) was investigated in rats. Oral administration of SBN recovered body and liver weight loss and reversed the elevation of serum AST, ALT and ALP accompanied by their fall in the liver tissue in DMN-induced fibrotic rats. Severe oxidative stress induced in fibrotic rats was evidenced by two to three fold elevation in MDA and protein carbonyl levels associated with a fall in the activities of SOD and CAT in repeated DMN treatment and this adversity was protected by SBN post-treatment. Further, the fall in the activities of ATPases and increase in the levels of hydroxyproline and collagen observed in the liver tissue of DMN treated rats was prevented and reversed back toward normalcy by SBN post-treatment. Recovery of rat liver tissue against DMN-induced hepatocellular necrosis, inflammatory changes and hepatic fibrosis by SBN treatment is also confirmed by both H & E and Masson's trichrome stained histopathological evaluation of liver tissue. In conclusion, SBN exhibit hepatoprotective, antioxidant, free radical scavenging, membrane stabilizing and anti-fibrotic activity against DMN-induced hepatic fibrosis suggesting that it may be useful as a therapeutic agent toward amelioration of hepatic fibrosis.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Molecular pathogenesis of hepatic fibrosis and current therapeutic approaches

The pathogenesis of hepatic fibrosis involves significant deposition of fibrilar collagen and other extracellular matrix proteins. It is a rather dynamic process of wound healing in response to a variety of persistent liver injury caused by factors such as ethanol intake, viral infection, drugs, toxins, cholestasis, and metabolic disorders. Liver fibrosis distorts the hepatic architecture, decreases the number of endothelial cell fenestrations and causes portal hypertension. Key events are the activation and transformation of quiescent hepatic stellate cells into myofibroblast-like cells with the subsequent up-regulation of proteins such as α-smooth muscle actin, interstitial collagens, matrix metalloproteinases, tissue inhibitor of metalloproteinases, and proteoglycans. Oxidative stress is a major contributing factor to the onset of liver fibrosis and it is typically associated with a decrease in the antioxidant defense. Currently, there is no effective therapy for advanced liver fibrosis. In its early stages, liver fibrosis is reversible upon cessation of the causative agent. In this review, we discuss some aspects on the etiology of liver fibrosis, the cells involved, the molecular pathogenesis, and the current therapeutic approaches.

Regulation of synthesis and oxidation of fatty acids by adiponectin receptors (AdipoR1/R2) and insulin receptor substrate isoforms (IRS-1/-2) of the liver in a nonalcoholic steatohepatitis animal model

Nonalcoholic steatohepatitis (NASH) is one of the most frequent causes of abnormal liver dysfunction associated with synthesis and oxidation of fatty acids. Adiponectin receptors (AdipoR1/R2) and insulin receptor substrates (IRS-1/-2) are known as modulators of these fatty acid metabolisms in the liver; however, the regulatory roles of these receptors in the synthesis and oxidation of fatty acids are unclear in the liver of NASH. In this study, we examined the roles of hepatic AdipoR1/R2 and IRS-1/-2 in NASH using an animal model. After feeding a high-fat and high-cholesterol diet to obese fa/fa Zucker rats for 8 weeks, rats showed fatty liver spontaneously with inflammation and fibrosis that are characteristic of NASH. The expression levels of AdipoR1/R2 and IRS-2 were significantly decreased, whereas IRS-1 was significantly increased, in NASH. As a result of the decrease of AdipoR1/R2 expression, the messenger RNA expression levels of genes located downstream of AdipoR1/R2, adenosine monophosphate-activated protein kinase α1/α2, which inhibits fatty acid synthesis, and peroxisome proliferator-activated receptor α, which activates fatty acid oxidation, also decreased. Expression level of sterol regulatory element binding protein-1c was found to be elevated, suggesting the up-regulation of IRS-1, and resulted in increased fatty acid synthesis. Furthermore, increase of forkhead box protein A2 expression was observed, which might be associated with the down-regulation of IRS-2, facilitating fatty acid oxidation. Taken together, increased synthesis and oxidation of fatty acids by up- or down-regulation of AdipoR or IRS may contribute to the progression of NASH. Thus, AdipoR and IRS might be crucially important regulators for the synthesis and oxidation of fatty acids in the liver of NASH.

N-acetylcysteine attenuates dimethylnitrosamine induced oxidative stress in rats

Oxidative stress has been implicated in the pathogenesis and progression of various hepatic disorders and hence screening for a good hepatoprotective and antioxidant agent is the need of the hour. The present study was aimed to investigate the hepatoprotective and antioxidant property of N-acetylcysteine (NAC) against dimethylnitrosamine (DMN) induced oxidative stress and hepatocellular damage in male Wistar albino rats. Administration of single dose of DMN (5mg/kg b.w.; i.p.) resulted in significant elevation in the levels of serum aspartate transaminase and alanine transaminase, indicating hepatocellular damage. Oxidative stress induced by DMN treatment was confirmed by an elevation in the status of lipid peroxidation (LPO) and reduction in the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase and in the levels of non-enzymic antioxidants, reduced glutathione, vitamin-C and vitamin-E in the liver tissue. DMN induced oxidative stress and hepatocellular membrane instability was further substantiated by a decline in the status of the membrane bound ATPases in the liver tissue. Post-treatment with NAC (50mg/kg b.w.; p.o.) for 7days effectively protected against the DMN induced insult to liver by preventing the elevation in the status of the serum marker enzymes and LPO, and restoring the activities of both the enzymic and non-enzymic antioxidants and membrane bound ATPases towards normalcy. These results demonstrate that NAC acts as a good hepatoprotective and antioxidant agent in attenuating DMN induced oxidative stress and hepatocellular damage.

Effect of vitamin C on oxidative liver injury due to isoniazid in rats

BACKGROUND

The aim of the present study was to investigate the effect of different doses of vitamin C on oxidative liver injury due to isoniazid (INH) in rats.

METHODS

Rats were divided into four subgroups, each containing 10 rats. Group 1 was the control group; group 2, INH 50 mg/kg per day; group 3, INH 50 mg/kg per day + low-dose vitamin C (100 mg/kg per day); group 4, INH 50 mg/kg per day + high-dose vitamin C (1000 mg/kg per day). INH and vitamin C were administered into their stomachs through an oral tube. After 21 days, measurements were made in both serum and homogenized liver tissues. The levels of glutathione (GSH), superoxide dismutase (SOD) and other biochemical variables were measured. Malondialdehyde (MDA), glutathione peroxidase (GSH-px) and vitamin C were measured using commercial kits.

RESULTS

Aspartate amino transferase and alanine aminotransferase in group 2 were higher than those in groups 1, 3 and 4 (P < 0.008 for both). Serum and tissue levels of MDA in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). There was no difference in the SOD levels between the four groups (P= 0.095). Erythrocyte and tissue GSH in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). Interestingly, erythrocyte and tissue GSH in group 4 were lower than those in group 1 (P < 0.008 for both). Erythrocyte level of GSH-px in group 2 was higher than that in groups 1 and 3 (P < 0.008 for both).

CONCLUSIONS

INH-induced liver injury is associated with oxidative stress, and co-administration of low-dose vitamin C may reduce this damage effectively in a rat model. The antioxidant effect of high-dose vitamin C does not seem more potent compared to the low dose.

Operculina turpethum attenuates N-nitrosodimethylamine induced toxic liver injury and clastogenicity in rats

The root extract of Operculina turpethum (OTE) has been used as an anti-inflammatory, purgative, and hepato-protective agent. N-Nitrosodimethylamine (NDMA) is a potent hepatotoxin that induces fibrosis of the liver. In the present study, we examined the therapeutic effects of OTE root extract against NDMA-induced hepatotoxicity and clastogenicity in rats. Hepatic fibrosis was induced in adult male albino rats through serial intraperitoneal administrations of NDMA at a concentration of 10mg/kg body weight on three consecutive days of each week over a period of three weeks. A group of rats received OTE orally in doses of 75, 150 and 200mg/kg body weight at 5h after the administration of NDMA. The controls and treated animals were sacrificed on days-7, 14 and 21 after the start of the administration of NDMA. The progression of hepatic fibrosis as well as the amelioration effect of OTE was evaluated through histopathologically as well as by immunohistochemical staining for the activation of hepatic stellate cells. Alterations in serum and liver biochemical parameters and LDH isoenzymes were also studied. Serial administration of NDMA resulted in well formed fibrosis in the liver and induction of micronuclei in the bone marrow cells. Staining of alpha-SMA demonstrated activated stellate cells from day-7 onwards which was dramatically increased on day-21. An elevation of micronuclei count, liver function enzymes, serum hydroxyproline levels and LDH isoenzymes 4 and 5 were also observed. All these changes were remarkably reduced in OTE administered animals and fibrogenesis was completely absent. Our results suggest that OTE has hepatoprotective and anti-clastogenic effects against NDMA-induced hepatic fibrosis. Therefore OTE may be used as a hepatoprotective agent against various liver diseases including toxic liver injury.

Elevated serum β-glucuronidase reflects hepatic lysosomal fragility following toxic liver injury in rats

The level of serum β-glucuronidase increases in various pathological conditions, including liver disorders. The aim of this investigation was to study the changes in liver lysosomal membrane stability during experimentally induced hepatic fibrosis that may result in the elevation of serum β-glucuronidase. Liver injury was induced by intraperitoneal injections of N-nitrosodimethylamine (NDMA) in adult male albino rats over 3 weeks. The progression of fibrosis was evaluated histopathologically as well as by monitoring liver collagen content. Lipid peroxides and β-glucuronidase levels were measured in the liver homogenate and subcellular fractions on days 0, 7, 14, and 21 after the start of NDMA administration. Serum β-glucuronidase levels were also determined. A significant increase was observed in β-glucuronidase levels in the serum, liver homogenate, and subcellular fractions, but not in the nuclear fraction on days 7, 14, and 21 after the start of NDMA administration. Lipid peroxides also increased in the liver homogenate and the lysosomal fraction. The measurement of lysosomal membrane stability revealed a maximum lysosomal fragility on day 21 during NDMA-induced fibrosis. In vitro studies showed that NDMA has no significant effect on liver lysosomal membrane permeability. The results of this investigation demonstrated that lysosomal fragility increases during NDMA-induced hepatic fibrosis, which could be attributed to increased lipid peroxidation of lysosomal membrane. In this study, we also elucidated the mechanism of increased β-glucuronidase and other lysosomal glycohydrolases in the serum during hepatic fibrosis.

Comparison of two sample preconcentration strategies for the sensitivity enhancement of flavonoids found in Chinese herbal medicine in micellar electrokinetic chromatography with UV detection

Two on-column preconcentration techniques named stacking with reverse migrating micelles (SRMM) and anion selective electrokinetic injection and a water plug-sweeping with reverse migrating micelles (ASIW-sweep-RMM) were used and compared for concentration and separation of flavonoids in Chinese herbs using reverse migration micellar electrokinetic chromatography (RM-MEKC). The optimal background electrolyte (BGE) used for separation and preconcentration was a solution composed of 20mM phosphoric acid (H(3)PO(4))-100mM sodium dodecyl sulfate (SDS)-20% (v/v) acetonitrile (ACN) buffer (pH 2.0), the applied voltage was -15kV. To achieve reasonable results of the two techniques, the conditions which affected preconcentration were examined. A comparison of used techniques with normal hydrodynamic injection (5s), concerning enhancement factors and limits of detection (LODs) was presented. Under the optimum stacking conditions, about 27-37- and 45-194-fold improvement in the detection sensitivity was obtained for SRMM and ASIW-sweep-RMM, respectively, compared to usual hydrodynamic sample injection (5s). The LODs (S/N=3) for SRMM and ASIW-sweep-RMM in terms of peak height, can reach down to 1.15 x 10(-2) microg/ml for hesperetin and 2.4 x 10(-3) microg/ml for nobiletin, respectively. Finally, the amounts of the six flavonoids in extract of Fructus aurantii Immaturus were successfully determined using ASIW-sweep-RMM. The six analytes were baseline separated with sample matrix under the optimum ASIW-sweep-RMM conditions and the experimental results showed that preconcentration was well achieved after the dilution of sample solutions.

siRNA-mediated knockdown of connective tissue growth factor prevents N-nitrosodimethylamine-induced hepatic fibrosis in rats

Hepatic fibrosis is a dynamic process that involves the interplay of different cell types in the hepatic tissue. Connective tissue growth factor (CTGF) is a highly profibrogenic molecule and plays a crucial role in the pathogenesis of hepatic fibrosis. The aim of the present investigation was three-fold. First, we studied the expression of CTGF in the cultured hepatic stellate cells using immunohistochemical technique. Second, we induced hepatic fibrosis in rats through serial intraperitoneal injections of N-nitrosodimethylamine (NDMA; dimethylnitrosamine, DMN) and studied the upregulation of CTGF and TGF-beta1 during hepatic fibrogenesis. Third, we downregulated CTGF expression using CTGF siRNA and examined the role of CTGF siRNA to prevent the progression of NDMA-induced hepatic fibrosis. The results depicted strong staining of CTGF in the transformed hepatic stellate cells in culture. Serial administrations of NDMA resulted in activation of hepatic stellate cells, upregulation of CTGF and TGF-beta1 both at mRNA and protein levels and well-developed fibrosis in the liver. Immunostaining, Western blot analysis, semiquantitative and real-time RT-PCR studies showed downregulation of CTGF and TGF-beta1 after treatment with CTGF siRNA. The results of the present study demonstrated that CTGF gene silencing through siRNA reduces activation of hepatic stellate cells, prevents the upregulation of CTGF and TGF-beta1 gene expression and inhibits accumulation of connective tissue proteins in the liver. The data further suggest that knockdown of CTGF upregulation using siRNA has potential therapeutic application to prevent hepatic fibrogenesis.

Silymarin modulates the oxidant-antioxidant imbalance during diethylnitrosamine induced oxidative stress in rats

Oxidative stress is a common mechanism contributing to initiation and progression of hepatic damage in a variety of liver disorders. Hence, there is a great demand for the development of agents with potent antioxidant effect. The aim of the present investigation is to evaluate the efficacy of silymarin as a hepatoprotective and an antioxidant against diethylnitrosamine induced hepatocellular damage. Single intraperitoneal administration of diethylnitrosamine (200 mg/kg) to rats resulted in significantly elevated levels of serum aspartate transaminase (AST) and alanine transaminase (ALT), which is indicative of hepatocellular damage. Diethylnitrosamine induced oxidative stress was confirmed by elevated levels of lipid peroxidation and decreased levels of superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase (GR) and glutathione-S-transferase (GST) in the liver tissue. The status of non-enzymic antioxidants like, vitamin-C, vitamin-E and reduced glutathione (GSH) were also found to be decreased in diethylnitrosamine administered rats. Further, the status of membrane bound ATPases was also altered indicating hepatocellular membrane damage. Posttreatment with the silymarin (50 mg/kg) orally for 30 days significantly reversed the diethylnitrosamine induced alterations in the liver tissue and offered almost complete protection. The results from the present study indicate that silymarin exhibits good hepatoprotective and antioxidant potential against diethylnitrosamine induced hepatocellular damage in rats.

Vitamina C

Vitamin C or ascorbic acid is a hydrosoluble vitamin derived from glucose metabolism. It acts as a reductor agent required for synthesis of collagen fibers through hydroxylation of proline and lysine. It also protects the body against damage caused by the free radicals. Humans cannot synthesize ascorbic acid as they lack an enzyme called gulonolactone oxidase. Concentrations in plasma and leukocytes reflect the levels of the diet and body deposits respectively of this vitamin. Among foods with high vitamin C levels are tomatoes, potatoes, and citrus fruits such as limes, oranges and lemons. The current recommendation of daily intake of vitamin C is 90 mg/d for men and 75 mg/d for women. Patients with chronic diseases such as cancer or diabetes or those who smoke need higher doses in their usual diet. Ascorbic acid deficiency gives rise to the appearance of scurvy. This disease is rarely seen in developed countries. The symptoms develop with plasma levels below 0.15 mg/dL. Scurvy is characterized by the presence of weakness, joint pain or skin lesions in form of petechias, gum bleeding, ease of developing bruises or delay in wound healing. The most characteristic skin manifestations are purpuric perifollicular hyperkeratotic papules and the presence of kinky hair.

Mineral metabolism in dimethylnitrosamine-induced hepatic fibrosis

OBJECTIVES

Complications such as ascites during the pathogenesis of hepatic fibrosis and cirrhosis may lead to several abnormalities in mineral metabolism. In the present investigation, we have monitored serum and liver concentrations of calcium, magnesium, sodium and potassium during experimentally induced hepatic fibrosis in rats.

DESIGN AND METHODS

The liver injury was induced by intraperitoneal injections of dimethylnitrosamine (DMN; N-nitrosodimethylamine, NDMA) in doses 1 mg/100 g body weight on 3 consecutive days of each week over a period of 21 days. Calcium, magnesium, sodium and potassium were measured by atomic absorption spectrophotometry in the serum and liver on days 7, 14 and 21 after the start of DMN administration.

RESULTS

Negative correlations were observed between liver function tests and serum mineral levels, except with albumin. Calcium, magnesium, potassium and sodium concentrations in the serum were decreased after the induction of liver injury. The liver calcium content was increased after DMN treatment. No change occurred in liver sodium content. However, magnesium and potassium content was significantly reduced in the hepatic tissue.

CONCLUSIONS

The results suggest that DMN-induced hepatic fibrosis plays certain role in the alteration of essential elements. The low levels of albumin and the related ascites may be one of the major causes of the imbalance of mineral metabolism in hepatic fibrosis and further aggravation of the disease.