Nicotinic acid attenuates experimental non-alcoholic steatohepatitis by inhibiting the NLRP3 inflammasome/pyroptosis pathway.

Non-alcoholic steatohepatitis (NASH) is a global public health concern that may progress into fibrosis, cirrhosis, and liver cancer, with limited curative treatment options. While the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is closely linked to NASH progression, nicotinic acid (NA), a vitamin used for the treatment of dyslipidemia, is an emerging pharmaceutical treatment for hepatic steatosis and fibrosis. Here, we investigated pharmacological effects of NA on experimental NASH and whether NLRP3 inflammasome/pyroptosis inhibition is an associated mechanism of action. Rats were fed a high-fat sucrose diet supplemented with cholesterol and a low dose of CCl4. NA significantly reduced inflammation by decreasing the protein levels of tumor necrosis factor-alpha and nuclear factor kappa B. Moreover, NA inhibited the formation of NLRP3- apoptosis-associated speck-like protein containing caspase recruitment domain-Caspase-1, decreasing interleukin-1beta, interleukin-18, and gasdermin D protein. In addition, NA reduced tumor growth factor-beta, alpha-smooth muscle actin, and hepatic levels of collagen-1, consequently decreasing extracellular matrix synthesis. Our results indicate that NA can inhibit NASH progression and encourage further basic and clinical studies on the use of NA for the treatment of human NASH.

Herbal medicines for the liver: from bench to bedside.

The liver is one of the most complex organs of the human body and is involved in various metabolic processes. Due to its anatomical proximity to the digestive tract, its blood flow, and its contribution to the detoxification process, the liver is susceptible to a wide variety of disorders. Hepatic diseases can be caused by alcoholism, viral infections, malnutrition and xenobiotics, which result in a high frequency of patients with liver disease and subsequent increase in the number of deaths from these diseases, for which adequate treatments are not yet available. Therefore, the search for new alternatives to treat these liver conditions is mandatory. In recent decades, there has been an increase in interest in medicinal herbs due to their safety and hepatoprotective properties that arise from their anti-inflammatory, antioxidant, antifibrotic, antiviral, immunomodulatory and anticancer properties. Epidemiological and clinical studies have shown that the consumption of these compounds is associated with a decrease in the risk of developing liver diseases; thus, medicinal herbs have emerged as a viable option for the treatment of these hepatic pathologies. However, more basic and clinical studies are needed before reaching a final recommendation to treat human liver diseases. This review provides molecular and clinical information on some natural compounds and medicinal herbs that have hepatoprotective effects and could be useful for the treatment of hepatic disorders.

Free radicals, antioxidants, nuclear factor-E2-related factor-2 and liver damage.

Oxidative/nitrosative stress is proposed to be a critical factor in various diseases, including liver pathologies. Antioxidants derived from medicinal plants have been studied extensively and are relevant to many illnesses, including liver diseases. Several hepatic disorders, such as viral hepatitis and alcoholic or nonalcoholic steatohepatitis, involve free radicals/oxidative stress as agents that cause or at least exacerbate liver injury, which can result in chronic liver diseases, such as liver fibrosis, cirrhosis and end-stage hepatocellular carcinoma. In this scenario, nuclear factor-E2-related factor-2 (Nrf2) appears to be an essential factor to counteract or attenuate oxidative or nitrosative stress in hepatic cells. In fact, a growing body of evidence indicates that Nrf2 plays complex and multicellular roles in hepatic inflammation, fibrosis, hepatocarcinogenesis and regeneration via the induction of its target genes. Inflammation is the most common feature of chronic liver diseases, triggering fibrosis, cirrhosis and hepatocellular carcinoma. Increasing evidence indicates that Nrf2 counteracts the proinflammatory process by modulating the recruitment of inflammatory cells and inducing the endogenous antioxidant response of the cell. In this review, the interactions between antioxidant and inflammatory molecular pathways are analyzed.

An aqueous extract of Stevia rebaudiana variety Morita II prevents liver damage in a rat model of cirrhosis that mimics the human disease.

INTRODUCTION AND AIM: Stevia has exhibited antioxidant, antihyperglycemic, antihypertensive and anti-inflammatory properties in several in vivo and in vitro models. The objective of this study was to investigate the ability of an aqueous extract of stevia (AES) to prevent experimental cirrhosis in rats and to explore its mechanism of action. MATERIALS AND METHODS: Liver cirrhosis was induced by administering carbon tetrachloride (CCl4) (400mg/kg by i.p. injection 3 times a week for 12 weeks); AES was administered (100mg/kg by gavage daily) during the CCl4 treatment. Fibrosis was evaluated with histological, biochemical and molecular approaches, and liver damage was assessed with standardized procedures. The profibrotic pathways were analyzed by western blotting, qRT-PCR and immunohistochemistry. RESULTS AND CONCLUSIONS: Chronic CCl4 administration increased nuclear factor kappa B (NF-κB) and proinflammatory cytokine production as well as oxidative parameters such as lipid peroxidation and 4-hydroxynonenal levels, whereas GSH and nuclear factor-E2-related factor 2 (Nrf2) levels were decreased. CCl4 induced profibrogenic mediator expression, hepatic stellate cell (HSC) activation and, consequently, extracellular matrix production. AES exhibited antioxidant, anti-inflammatory and antifibrotic properties, probably because of its capacity to induce Nrf2 expression, reduce NF-κB expression and block several profibrogenic signaling pathways, subsequently inhibiting HSC activation and preventing fibrosis induced by chronic CCl4 administration.

Rebaudioside A administration prevents experimental liver fibrosis: an in vivo and in vitro study of the mechanisms of action involved.

Rebaudioside A (Reb A) is a diterpenoid isolated from the leaves of Stevia rebaudiana (Bertoni) that has been shown to possess pharmacological activity, including anti-inflammatory and antioxidant properties. However, the ability of Reb A to prevent liver injury has not been evaluated. Therefore, we aimed to study the potential of Reb A (20 mg/kg; two times daily intraperitoneally) to prevent liver injury induced by thioacetamide (TAA) administration (200 mg/kg; three times per week intraperitoneally). In addition, cocultures were incubated with either lipopolysaccharide or ethanol. Antifibrotic, antioxidant and immunological responses were evaluated. Chronic TAA administration produced considerable liver damage and distorted the liver parenchyma with the presence of prominent thick bands of collagen. In addition, TAA upregulated the expression of α-smooth muscle actin, transforming growth factor-ß1, metalloproteinases 9, 2 and 13, and nuclear factor kappaB and downregulated nuclear erythroid factor 2. Reb A administration prevented all of these changes. In cocultured cells, Reb A prevented the upregulation of genes implicated in fibrotic and inflammatory processes when cells were exposed to ethanol and lipopolysaccharide. Altogether, our results suggest that Reb A prevents liver damage by blocking oxidative processes via upregulation of nuclear erythroid factor 2, exerts immunomodulatory effects by downregulating the nuclear factor-κB system and acts as an antifibrotic agent by maintaining collagen content.

Stevia rebaudiana tea prevents experimental cirrhosis via regulation of NF-κB, Nrf2, transforming growth factor beta, Smad7, and hepatic stellate cell activation.

Stevia has been shown to prevent oxidative stress and inflammation in carbon tetrachloride­induced cirrhosis models. This study aimed to investigate the ability of an aqueous extract of stevia (AES) to prevent thioacetamide (TAA)­induced cirrhosis in rats and to explore its mechanism of action. Liver cirrhosis was established by administering TAA (200 mg/kg by i.p. injections three times a week for 10 weeks); AES was administered (100 mg/kg by gavage daily) during the TAA treatment. Liver damage and fibrosis were evaluated, and the profibrotic pathways were analyzed by western blotting and immunohistochemistry. TAA increased nuclear factor kappa B (NF­κB) and pro­inflammatory cytokine production, as well as the malondialdehyde and 4­hydroxynonenal levels, whereas the glutathione/glutathione disulfide and nuclear factor­E2­related factor 2 (Nrf2) levels were decreased. Moreover, TAA increased collagen production, hepatic stellate cell (HSC) activation, and expression of profibrogenic mediators. TAA­treated rats that had been exposed to Mn2+ exhibited altered striatal dopamine turnover, indicating hepatic encephalopathy. AES partially or completely prevented all of these effects. AES showed antioxidant, anti­inflammatory, and antifibrotic properties, probably because of its capacity to induce Nrf2 expression, reduce NF­κB expression, and block several profibrogenic signaling pathways, subsequently inhibiting HSC activation and preventing fibrosis and dopamine turnover.

Coffee consumption prevents fibrosis in a rat model that mimics secondary biliary cirrhosis in humans.

Investigations demonstrated that oxidative stress plays an important role in injury promotion in cholestatic liver disease. We hypothesized that coffee attenuates cholestasis-induced hepatic necrosis and fibrosis via its antioxidant, anti-inflammatory, and antifibrotic properties. The major aim of this study was to evaluate the hepatoprotective properties of coffee and caffeine in a model of chronic bile duct ligation (BDL) in male Wistar rats. Liver injury was induced by 28-day BDL, and conventional coffee, decaffeinated coffee, or caffeine was administered daily. After treatment, the hepatic oxidative status was estimated by measuring lipid peroxidation, the reduced to oxidized glutathione ratio, and glutathione peroxidase. Fibrosis was assessed by measuring the liver hydroxyproline content. The transforming growth factor-ß, connective tissue growth factor, α-smooth muscle actin, collagen 1, and interleukin-10 proteins and mRNAs were measured by Western blot and polymerase chain reaction, respectively. Conventional coffee suppressed most of the changes produced by BDL; however, caffeine showed better antifibrotic effects. Coffee demonstrated antioxidant properties by restoring the redox equilibrium, and it also prevented the elevation of liver enzymes as well as hepatic glycogen depletion. Interestingly, coffee and caffeine administration prevented collagen increases. Western blot assays showed decreased expression levels of transforming growth factor-ß, connective tissue growth factor, α-smooth muscle actin, and collagen 1 in the coffee- and caffeine-treated BDL groups. Similarly, coffee decreased the mRNA levels of these proteins. We conclude that coffee prevents liver cirrhosis induced by BDL by attenuating the oxidant processes, blocking hepatic stellate cell activation, and downregulating the main profibrotic molecules involved in extracellular matrix deposition.

Coffee attenuates fibrosis by decreasing the expression of TGF-ß and CTGF in a murine model of liver damage.

This study was performed to evaluate the antifibrotic properties of coffee in a model of liver damage induced by repeated administration of thioacetamide (TAA) in male Wistar rats. In this study, cirrhosis was induced by chronic TAA administration and the effects of co-administration of conventional caffeinated coffee or decaffeinated coffee (CC, DC, respectively) for 8 weeks were evaluated. TAA administration elevated serum alkaline phosphatase (AP), γ-glutamyl transpeptidase (γ-GTP) and alanine aminotransferase (ALAT), liver lipid peroxidation, collagen content, depleted liver glycogen and glutathione peroxidase (GPx) activity. Additionally increased levels of a number of proteins were detected including transforming growth factor-beta (TGF-ß), connective tissue growth factor (CTGF) and alpha-smooth muscle actin (α-SMA), and matrix metalloproteinase (MMP)-2, 9 and 13. Coffee suppressed most of the changes produced by TAA. Histopathological analysis was in agreement with biochemical and molecular findings. These results indicate that coffee attenuates experimental cirrhosis; the action mechanisms are probably associated with its antioxidant properties and mainly by its ability to block the elevation of the profibrogenic cytokine TGF-ß and its downstream effector CTGF. Various components of coffee that have been related to such a favorable effect include caffeine, coffee oils kahweol, cafestol and antioxidant substances; however, no definite evidence for the role of these components has been established. These results support earlier findings suggesting a beneficial effect of coffee on the liver. However, more basic clinical studies must be performed to confirm this hypothesis.

Antifibrotic and antioxidant effects of N-acetylcysteine in an experimental cholestatic model.

OBJECTIVES: Several studies have suggested that oxidative stress may play an important role in the pathogenesis of hepatic injury during cholestasis in rats and humans. The aim of this study was to evaluate the ability of N-acetylcysteine (NAC) to prevent the damage induced by bile duct ligation (BDL) for 28 days in male Wistar rats. METHODS: NAC was administered daily (300 mg/kg, orally) for 28 days. Alanine aminotransferase was quantified in the serum; lipid peroxidation, glutathione, and catalase activity were measured in the liver. Fibrosis was assessed by measuring the liver hydroxyproline content; transforming growth factor-ß (TGF-ß), interleukin (IL)-6, and IL-10 were determined in the liver by a western blot and quantified densitometrically. RESULTS: The induction of cholestatic damage by BDL was associated with an increase in alanine aminotransferase. Oxidative stress was also evaluated; lipid peroxidation increased, whereas the liver glutathione content and catalase activity decreased by BDL. NAC treatment prevented these alterations. Hydroxyproline was increased by chronic BDL, but NAC preserved the normal hydroxyproline levels. Cytokines TGF-ß, IL-6, and IL-10 increased after 28 days of BDL. NAC was effectively significant in preventing TGF-ß and IL-6 expression and further augmented the IL-10 expression. CONCLUSION: Our data indicate that in the development to cholestatic liver damage, oxidative stress plays an important role and this in turn leads to fibrosis. This study shows that the beneficial effects of NAC are because of its antioxidant and immunomodulatory properties.

A novel fluorinated stilbene exerts hepatoprotective properties in CCl(4)-induced acute liver damage.

There has been a recently increase in the development of novel stilbene-based compounds with in vitro anti-inflamatory properties. For this study, we synthesized and evaluated the anti-inflammatory properties of 2 fluorinated stilbenes on carbon tetrachloride (CCl4)-induced acute liver damage. To achieve this, CCl4 (4 g·kg(-1), per os) was administered to male Wistar rats, followed by either 2-fluoro-4'-methoxystilbene (FME) or 2,3-difluoro-4'-methoxystilbene (DFME) (10 mg·kg(-1), per os). We found that although both of the latter compounds prevented cholestatic damage (γ-glutamyl transpeptidase activity), only DFME showed partial but consistent results in the prevention of necrosis, as assessed by both alanine aminotransferase activity and histological analysis. Since inflammatory responses are mediated by cytokines, mainly tumour necrosis factor α (TNF-α), we used the Western blot technique to determine the action of FME and DFME on the expression level of this cytokine. The observed increase in the level of TNF-α caused by CCl4 administration was only prevented by treatment with DFME, in agreement with our biochemical findings. This result was confirmed by measuring interleukin-6 (IL-6) levels, since the expression of this protein depends on the level of TNF-α. In this case, DFME completely blocked the CCl4-induced increase of IL-6. Our results suggest that DFME possesses greater anti-inflammatory properties in vivo than FME. DFME constitutes a possible therapeutic agent for liver disease and could serve as a template for structure optimization.

Coffee and liver diseases.

Coffee consumption is worldwide spread with few side effects. Interestingly, coffee intake has been inversely related to the serum enzyme activities gamma-glutamyltransferase, and alanine aminotransferase in studies performed in various countries. In addition, epidemiological results, taken together, indicate that coffee consumption is inversely related with hepatic cirrhosis; however, they cannot demonstrate a causative role of coffee with prevention of liver injury. Animal models and cell culture studies indicate that kahweol, diterpenes and cafestol (some coffee compounds) can function as blocking agents by modulating multiple enzymes involved in carcinogenic detoxification; these molecules also alter the xenotoxic metabolism by inducing the enzymes glutathione-S-transferase and inhibiting N-acetyltransferase. Drinking coffee has been associated with reduced risk of hepatic injury and cirrhosis, a major pathogenic step in the process of hepatocarcinogenesis, thus, the benefit that produces coffee consumption on hepatic cancer may be attributed to its inverse relation with cirrhosis, although allowance for clinical history of cirrhosis did not completely account for the inverse association. Therefore, it seems to be a continuum of the beneficial effect of coffee consumption on liver enzymes, cirrhosis and hepatocellular carcinoma. At present, it seems reasonable to propose experiments with animal models of liver damage and to test the effect of coffee, and/or isolated compounds of this beverage, not only to evaluate the possible causative role of coffee but also its action mechanism. Clinical prospective double blind studies are also needed.

Pharmacological actions of curcumin in liver diseases or damage.

Since 1900 bc, several therapeutic activities have been attributed to the rhizomes of the plant Curcuma longa for a variety of diseases, including liver disorders. Curcumin, the main active compound obtained from this plant, was first isolated two centuries ago and its structure as diferuloylmethane was determined in 1910. Curcumin has shown anti-inflammatory, anti-oxidant, antifungal, antibacterial and anticancer activities. The pharmacological properties of curcumin were reviewed recently and focused mainly on its anticancer properties. However, its beneficial activity on liver diseases (known centuries ago, and demonstrated recently utilizing animal models) has not being reviewed in depth until now. The curcumin ability to inhibit several factors like nuclear factor-kappaB, which modulates several pro-inflammatory and profibrotic cytokines as well as its anti-oxidant properties, provide a rational molecular basis to use it in hepatic disorders. Curcumin attenuates liver injury induced by ethanol, thioacetamide, iron overdose, cholestasis and acute, subchronic and chronic carbon tetrachloride (CCl(4)) intoxication; moreover, it reverses CCl(4) cirrhosis to some extent. Unfortunately, the number of studies of curcumin on liver diseases is still very low and investigations in this area must be encouraged because hepatic disorders constitute one of the main causes of worldwide mortality.

NF-kappaB in liver diseases: a target for drug therapy.

There are five nuclear factor-kappaB (NF-kappaB) transcription factors with important roles in innate immunity, liver inflammation, fibrosis and apoptosis prevention. Several inhibitors of NF-kappaB, like caffeic acid, captopril, curcumin, pyrrolidine dithiocarbamate, resveratrol, silymarin and thalidomide, have demonstrated antinecrotic, anticholestatic, antifibrotic and anticancer activities in the liver. A link between inflammation and hepatocellular carcinoma through the NF-kappaB pathway has been observed, providing ample experimental support for the tumor-promoting function of NF-kappaB in various models of cancer. NF-kappaB has been associated with the induction of proinflammatory gene expression and has attracted interest as a target for the treatment of inflammatory disease. However, despite much attention being focused on the deleterious effects of NF-kappaB, activation of this factor during the resolution of inflammation is associated with the production of antiinflammatory molecules like interleukin (IL)-10 and the onset of apoptosis. This suggests that NF-kappaB has an antiinflammatory role in vivo involving the regulation of the resolution of inflammation. Also, NF-kappaB promotes liver regeneration by upregulating IL-6 and other molecules like hepatocyte growth factor. It has been postulated that the beneficial properties of NF-kappaB are due to p50 homodimers, whose activation prevents cholestatic and chronic liver injury. More basic understanding on the function of the diverse NF-kappaB factors is urgently needed in different physiological and pathological conditions, because depending on the subunit composition of the dimmer, the disease and the stage of the illness, inhibition of the factor may result in a beneficial or in a deleterious response.

Beneficial drugs for liver diseases.

Liver diseases are a major problem of worldwide proportions. However, the number of drugs actually used successfully in humans is very small. In this review some of the most promising/studied drugs utilized for liver diseases were chosen and analysed critically from the basic to the clinical point of view. Antiviral agents are not discussed because excellent reviews have appeared on this topic. The compounds/preparations described herein are, alphabetically: colchicine, corticosteroids, curcumin, glycyrrhizin, interferons (for their antifibrotic properties), Liv 52, nitric oxide, resveratrol, silymarin, sulfoadenosylmethionine, and thalidomide. Colchicine and corticosteroids have been studied extensively in animals and humans; most clinical studies suggest that these compounds are not useful in the treatment of liver diseases. Glycyrrhizin is an herbal medicine with several components that has interesting hepatoprotective properties in patients with subacute liver failure but deserves more prospective controlled trials. Interferon has shown interesting antifibrotic properties in animals and humans; prospective studies on their antifibrotic/fibrolytic activity are required. Curcumin, resveratrol and thalidomide are very attractive newly discovered protective and curative compounds on experimental hepatic diseases. Their mechanism of action is associated with the ability to down-regulate NF-kappaB and to decrease pronecrotic and profibrotic cytokines. Unfortunately, clinical studies are lacking. Sulfoadenosylmethionine and silymarin are also promising drugs utilized mainly in cholestasis but the benefits can be expanded if more controlled trials are performed. The future is to carry out controlled prospective double-blind multicenter studies with the newly discovered drugs with proven beneficial effects on animals. Fundamental hepatobiology should also be encouraged.

Resolution of liver fibrosis in chronic CCl4 administration in the rat after discontinuation of treatment: effect of silymarin, silibinin, colchicine and trimethylcolchicinic acid.

The purpose of this work was to obtain a suitable model of fibrosis, in which spontaneous reversion was minimal, to study the ability of silymarin, silibinin, colchicine and trimethylcolchicinic acid (TMCA) to reverse it. Reversal of liver fibrosis was studied in male Wistar rats after one, two or three months of CCl(4) administration (0.4 g/kg intraperitoneally, three times per week), by discontinuation of the toxin for 2 months. Silymarin (50 mg/kg), silibinin (50 mg/kg), colchicine (10 microg/rat) and trimethylcolchicinic acid (100 microg/rat) were administered daily, by gavage, after 3 months of CCl(4) administration. Collagen content was determined by measuring hydroxyproline in liver samples; glycogen, was determined utilizing the anthrone reagent; Mallory's trichromic stains of liver sections were performed. The best scheme of treatment was obtained when CCl(4) was administered during three months (collagen increased 6 times). Discontinuation of the toxin for two months produced a significant but relative small reduction of fibrosis (collagen was still 4.5 times over control). Colchicine, TMCA, silymarin or silibinin treatment showed no significant fibrolitic effect. This scheme of treatment may be an excellent tool to study the ability of drugs to reverse fibrosis. The hepatoprotective properties of silymarin, silibinin, colchicine and trimethylcolchinic acid may be irrelevant to reverse established cirrhosis.

Effects of silymarin and vitamins E and C on liver damage induced by prolonged biliary obstruction in the rat.

Oxidative stress, in particular lipid peroxidation, induces collagen synthesis. Thus, we administered various antioxidants to bile duct-ligated rats for 28 days and lipid peroxidation, glutathione content, fibrosis, necrosis and cholestasis were evaluated. Extrahepatic cholestasis was induced by double ligation and section of the common bile duct. The study included eight groups (n=6), four groups were bile duct-ligated and received either vitamin C (50 mg/kg/day, orally), vitamin E (400 IU/rat/day, orally), silymarin (50 mg/kg/12 hr, orally) or vehicles; four groups were sham-operated controls. Collagen content was determined by measuring hydroxyproline in liver samples; malondialdehyde was used to estimate lipid peroxidation levels; reduced and oxidized glutathione were determined fluorometrically; alanine aminotransferase and bilirubins colorimetrically. Bilirubins increased several times, alanine aminotransferase once, reduced/oxidized glutathione ratio decreased three times, lipid peroxidation and collagen increased about three-times by biliary obstruction (p<0.05). Silymarin, vitamin E or C failed to prevent these effects significantly. It is not possible to clarify the role of oxidative stress in the fibrotic process induced by chronic biliary obstruction with the present results. Therefore, it seems reasonable to propose that a wide mixture of antioxidants, administered by the parenteral route (because cholestasis decreased the absorption of lipophilic compounds), is needed to counteract the oxidant stress produced by cholestasis.

Thalidomide ameliorates carbon tetrachloride induced cirrhosis in the rat.

OBJECTIVE: Thalidomide has anti-inflammatory, anti-tumour necrosis factor-alpha and anti-collagen activities. Cirrhosis is characterized by inflammation and fibrosis. Thus, thalidomide was evaluated in an experimental model of liver cirrhosis. METHODS: Male Wistar rats were used. Group 1 (n = 8) received mineral oil i.p. (control); group 2 (n = 15) received CCl(4) i.p. for 8 weeks to induce cirrhosis; group 3 (n = 15) consisted of rats receiving CCl(4) plus thalidomide (200 mg/kg/12 h); animals in group 4 (n = 8) received thalidomide only. Alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (gamma-GTP) and alkaline phosphatase (ALP) were measured in serum, while collagen (hydroxyproline), glycogen and lipid peroxidation were determined in liver samples. A liver histopathological analysis was performed by using Gomori's trichromic staining. RESULTS: Intoxication with CCl(4) induced 33.3% mortality, while thalidomide co-treatment reduced it to 13.3%. The serum activities of ALT, gamma-GTP and ALP increased 3, 2 and 4-fold by CCl(4) treatment; thalidomide completely prevented elevation of these enzymes. In the liver, lipid peroxidation increased about 20-fold and glycogen was abolished in CCl(4) cirrhotic rats; thalidomide completely prevented the former and partially (P < 0.05) the latter. CCl(4) treated rats revealed a loss of normal architecture and nodules of hepatocytes surrounded by thick bands of collagen. Thalidomide + CCl(4) treated rats showed minor histological alterations and thinner bands of collagen. The anti-fibrotic effect estimated by hydroxyproline was partial but significant (P < 0.05). CONCLUSION: Thalidomide prevented necrosis, cholestasis and fibrosis induced by CCl(4). Its mechanism of action may be related to its anti-inflammatory, anti-tumour necrosis factor-alpha and anti-fibrotic activities reported previously.