Evaluation of oxidative stress based on lipid hydroperoxide, vitamin C and vitamin E during apoptosis and necrosis caused by thioacetamide in rat liver

The role of fat-soluble vitamins in efferocytosis

Cell death and the efficient removal of dead cells are two basic mechanisms that maintain homeostasis in multicellular organisms. efferocytosis, which includes four steps recruitment, recognition, binding and signaling, and engulfment. Effectively and quickly removes apoptotic cells from the body. Any alteration in efferocytosis can lead to several diseases, including autoimmune and inflammatory conditions, atherosclerosis, and cancer. A wide range of dietary components affects apoptosis and, subsequently, efferocytosis. Some vitamins, including fat-soluble vitamins, affect different stages of efferocytosis. Among other things, by affecting macrophages, they are effective in the apoptotic cleansing of cells. Also, polyphenols indirectly intervene in efferocytosis through their effect on apoptosis. Considering that there are limited articles on the effect of nutrition on efferocytosis, in this article we will examine the effect of some dietary components on efferocytosis.

Difference in the Mechanism of Iron Overload-Enhanced Acute Hepatotoxicity Induced by Thioacetamide and Carbon Tetrachloride in Rats

Iron overload has been recognized as a risk factor for liver disease; however, little is known about its pathological role in the modification of liver injury. The purpose of this study is to investigate the influence of iron overload on liver injury induced by two hepatotoxicants with different pathogenesis in rats. Rats were fed a control (Cont), 0.8% high-iron (0.8% Fe), or 1% high-iron diet (1% Fe) for 4 weeks and were then administered with saline, thioacetamide (TAA), or carbon tetrachloride (CCl4). Hepatic and systemic iron overload were seen in the 0.8% and 1% Fe groups. Twenty-four hours after administration, hepatocellular necrosis induced by TAA and hepatocellular necrosis, degeneration, and vacuolation induced by CCl4, as well as serum transaminase values, were exacerbated in the 0.8% and 1% Fe groups compared to the Cont group. On the other hand, microvesicular vacuolation induced by CCl4 was decreased in 0.8% and 1% Fe groups. Hepatocellular DNA damage was increased by iron overload in both models, whereas a synergistic effect of oxidative stress by excess iron and hepatotoxicant was only present in the CCl4 model. The data showed that dietary iron overload exacerbates TAA- and CCl4-induced acute liver injury with different mechanisms.

Impact of Antioxidant Feed and Growth Manipulation on the Redox Regulation of Atlantic Salmon Smolts

Accumulating evidence indicates a close relationship between oxidative stress and growth rate in fish. However, the underlying mechanisms of this relationship remain unclear. This study evaluated the combined effect of dietary antioxidants and growth hormone (GH) on the liver and the muscle redox status of Atlantic salmon. There were two sequential experimental phases (EP) termed EP1 and EP2, each lasting for 6 weeks. In EP1, Atlantic salmon were fed either low-(L, 230 mg/kg ascorbic acid (Asc), 120 mg/kg α-tocopherol (α-TOH)), or high-(H, 380 mg/kg Asc, 210 mg/kg α-TOH)vitamin diets. The vitamins were supplemented as stable forms and the feeding was continued in EP2. In EP2, half of the fish were implanted with 3 μL per g body weight of recombinant bovine GH (Posilac^®, 1 mg rbGH g BW⁻¹) suspended in sesame oil, while the other half were held in different tanks and sham-implanted with similar volumes of the sesame oil vehicle. Here, we show that increasing high levels of vitamin C and E (diet H) increased their content in muscle and liver during EP1. GH implantation decreased vitamin C and E levels in both liver and muscle but increased malondialdehyde (MDA) levels only in the liver. GH also affected many genes and pathways of antioxidant enzymes and the redox balance. Among the most consistent were the upregulation of genes coding for the NADPH oxidase family (NOXs) and downregulation of the oxidative stress response transcription factor, nuclear factor-erythroid 2-related factor 2 (nrf2), and its downstream target genes in the liver. We verified that GH increases the growth rate until the end of the trail and induces an oxidative effect in the liver and muscle of Atlantic salmon. Dietary antioxidants do lower oxidative stress but have no effect on the growth rate. The present study is intended as a starting point to understand the potential interactions between growth and redox signaling in fish.

Phytochemical profiling and anti-fibrotic activities of Plumbago indica L. and Plumbago auriculata Lam. in thioacetamide-induced liver fibrosis in rats

This study aimed at investigating the chemical composition and the hepatoprotective activities of Plumbago indica L. and P. auriculata Lam. LC-MS/MS analyses for the hydroalcoholic extracts of the aerial parts of the two Plumbago species allowed the tentative identification of thirty and twenty-five compounds from P. indica and P. auriculata, respectively. The biochemical and histopathological alterations associated with thioacetamide (TAA)-induced liver fibrosis in rats were evaluated in vivo where rats received the two extracts at three different dose levels (100, 200 and 400 mg/kg p.o, daily) for 15 consecutive days with induction of hepatotoxicity by TAA (200 mg/kg/day, i.p.) at 14th and 15th days. Results of the present study showed a significant restoration in liver function biomarkers viz. alanine transaminase (ALT), aspartate transaminase (AST), gamma glutamyl transferase and total bilirubin. The liver homogenates exhibited increased levels of antioxidant biomarkers: reduced glutathione (GSH) and catalase (CAT), accompanied with decline in malondialdehyde (MDA). Furthermore, treated groups exhibited a significant suppression in liver inflammatory cytokines: tumor necrosis factor-α (TNF-α) and interlukin-6 (IL-6), and fibrotic biomarker: alpha smooth muscle relaxant. Histopathological examination of the liver showed normality of hepatocytes. Noteworthy, P. indica extract showed better hepatoprotective activity than P. auriculata, particularly at 200 mg/kg. To sum up, all these results indicated the hepatoprotective properties of both extracts, as well as their antifibrotic effect was evidenced by reduction in hepatic collagen deposition. However, additional experiments are required to isolate their individual secondary metabolites, assess the toxicity of the extracts and explore the involved mechanism of action.

Probiotic mixture containing Lactobacillus spp. and Bifidobacterium spp. attenuates 5-fluorouracil-induced intestinal mucositis in mice

Lactobacillus spp. and Bifidobacterium spp. was used to protect against gastrointestinal disorders. The present study evaluated the effects of probiotic mixture (PM) containing Lactobacillus spp. and Bifidobacterium spp. on intestinal mucositis induced by 5-fluorouracil (5-FU). Swiss male mice (25-30 g) were treated with 5-FU (450 mg/kg, ip) and were orally administered (PM). Probiotic mixture 1 (PM-1) is a mixture of two probiotics (Lactobacillus acidophilus and Bifidobacterium lactis) and probiotic mixture 2 (PM-2) is a mixture of four probiotics (Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus rhamnosus, and Bifidobacterium lactis). PM-1 and PM-2 decreased histopathological scores in the duodenum and jejunum after mucositis. PM-2 attenuated 5-FU-induced weight loss. On the other hand, PM-1 did not exert a significant effect on weight loss. Both probiotics mixture increased the villus/crypt ratio in all intestinal segments, increased GSH levels in the duodenum and jejunum, and reduced the MDA, MPO, TNF-α, and IL-6 levels in the duodenum, jejunum, and ileum. PM-2 attenuated the delay in gastric emptying. PM-1 and PM-2 prevented epithelial injury in intestinal mucositis by 5-FU, demonstrating the potential use of these probiotics as therapeutic agents against intestinal mucositis.

Mechanistic role of cAMP and hepatocyte growth factor signaling in thioacetamide-induced nephrotoxicity: Unraveling the role of platelet rich plasma

Chronic kidney diseases occur as result of exposure to wide range of deleterious agents as environmental pollutants, toxins and drug. Currently, there is no effective protective therapy against renal damage, fibrosis and its sequel of end stage renal disease. Platelet-rich plasma (PRP) has a progressively gained consideration in wound healing, repair/regeneration of damaged tissues and conservation of organ function. However, its impact on thioacetamide (TAA) induced chronic renal damage has not been elucidated yet. So, the present study was carried out to evaluate the possible protective and regenerative effect of PRP against TAA induced renal damage and their potential underlying mechanism. PRP treatment improved redox state, renal function disturbed histologicl features; decreased monocyte chemo-attractant protein-1 (MCP-1) level; increased Peroxisome proliferator-activated receptor gamma co-activator-1α (PGC-1α) marker of mitochondrial biogenesis and metabolism; cyclic adenosine monophosphate (cAMP); hepatocyte growth factor (HGF) and autophagy protein beclin-1 level. In addition, PRP treatment decreased apoptosis and fibrosis as evidenced by decreased active caspase3 and α-SMA expression and immunoreactivity, respectively. In conclusion, PRP could potentially protect against TTA-induced chronic kidney damage by alleviating oxidative stress, improving, mitochondrial biogenesis, autophagy, disruption of the inflammatory, apoptotic and fibrotic response induced by TTA.

Chemical induction of hepatic apoptosis in rodents

The urge of identifying new pharmacological interventions to prevent or attenuate liver injury is of critical importance and needs an expanded experimental toolbox. Hepatocyte injury and cellular death is a prominent feature behind the pathology of liver diseases. Several research activities focused on identifying chemicals and hepatotoxicants that induce cell death by apoptosis, in addition to presenting its corresponding signaling pathway. Although such efforts provided further understanding of the mechanisms of cell death, it has also raised confusion concerning identifying the involvement of several modes of cell death including apoptosis, necrosis and fibrosis. The current review highlights the ability of several chemicals and potential hepatotoxicants to induce liver damage in rodents by means of apoptosis while the probable involvement of other modes of cell death is also exposed. Thus, several chemical substances including hepatotoxins, mycotoxins, hyperglycemia inducers, metallic nanoparticles and immunosuppressant drugs are reviewed to explore the hepatic cytotoxic spectrum they could exert on hepatocytes of rodents. In addition, the current review address the mechanism by which hepatotoxicity is initiated in hepatocytes in different rodents aiding the researcher in choosing the right animal model for a better research outcome.

An integrative analysis of chemically-induced cirrhosis-associated hepatocarcinogenesis: Histological, biochemical and molecular features

This study aimed the integrative characterization of morphological, biochemical and molecular features of chemically-induced cirrhosis-associated hepatocarcinogenesis. Thus, male Wistar rats were submitted to a diethylnitrosamine (DEN)/thioacetamide (TAA)-induced model. Liver tissue was processed for global gene expression, histopathological and collagen evaluations; as well as immunohistochemical and oxidative stress analysis. Gene Ontology and functional analysis showed the upregulation of extracellular matrix deposition genes, such as collagen type I alpha 1 and 2 (Col1α1 and Col1α2) and tissue inhibitor of metalloproteinase 1 and 2 genes (Timp1 and Timp2). In agreement these findings, animals presented extensive liver cirrhosis with increased collagen deposition (Sirius red). Besides, the animals developed many glutathione S-transferase pi (GST-P)-positive preneoplastic lesions showing high cell proliferation (Ki-67), in keeping with the Gstp1 and Gstp2 increased gene expression. DEN/TAA-treated rats also showed the upregulation of tumorigenesis-related annexin A2 gene (Anxa2) and few neoplastic lesions (hepatocellular adenomas, carcinomas, and cholangiocarcinoma). In contrast, gene expression and activity of antioxidant enzymes were decreased (glutathione peroxidase, total glutathione-S-transferase, and catalase). The model featured remarkable similarities to human hepatocarcinogenesis. Our findings could bring up new molecular insights into cirrhosis-associated hepatocarcinogenesis, and provide a suitable animal model for the establishment of further diagnostic, preventive and therapeutic approaches.

Adefovir dipivoxil loaded proliposomal powders with improved hepatoprotective activity: formulation, optimization, pharmacokinetic, and biodistribution studies

The present study aimed to prepare proliposomal formulae for improving the oral bioavailability of adefovir dipivoxil (AD), a nucleoside reverse transcriptase inhibitor effective against hepatitis B virus (HBV). The prepared proliposomal formulae were characterized for entrapment efficiency (E.E.%), vesicle size and in vitro drug release after reconstitution to conventional liposomes. The optimized formula (F9) with a maximum desirability value of 0.858 was selected having E.E.% of 71 ± 3.3% with an average vesicle size of 164.6 ± 5 nm. Moreover, the crystallization of AD within the optimized formula investigated via powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the presence of the drug in an amorphous state within the lipid vesicles with enhanced stability over a storage period of 12 months. Thioacetamide-induced liver damage in rats evidenced by elevated liver enzymes was significantly improved after treatment with the optimum formula. Pharmacokinetic and biodistribution studies of formula F9 showed a higher accumulation of AD in the liver with enhanced bioavailability compared to AD suspension which highlights its potential advantage for an effective treatment of chronic HBV. Hence, proliposomal drug delivery is considered as a better choice for the oral delivery of AD.

Inhibitory effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at early stage of steroid-induced femoral head necrosis

Apoptosis and DNA oxidative damage serve significant roles in the pathogenesis of steroid-induced femoral head necrosis. Vitamin E demonstrates anti-apoptotic and anti-oxidant properties. Therefore, the present study investigated the effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at an early stage of steroid-induced femoral head osteonecrosis. Japanese white rabbits were randomly divided into three groups (steroid, vitamin E-treated, and control groups), each comprising 12 rabbits. Those in the steroid group (group S) were initially injected twice with an intravenous dose of 100 µg/kg Escherichia coli endotoxin, with a 24 h interval between the two injections, and then with an intramuscular dose of 20 mg/kg methylprednisolone, three times at intervals of 24 h in order to establish a rabbit model of osteonecrosis. The vitamin E treated group (group E) received the same treatment as group S, and were administered 0.6 g/kg/d vitamin E daily from the beginning of modeling. The control group (group C) was injected with normal saline at the equivalent dosage and times as the aforementioned two groups. Two time points, weeks 4 and 6 following the completion of modeling, were selected. Osteonecrosis was verified by histopathology with hematoxylin-eosin staining. The apoptosis rate of osteonecrosis was analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The apoptosis expression levels of caspase-3 and B-cell lymphoma 2 (Bcl-2), and DNA oxidative damage of bone marrow hematopoietic cells were analyzed by immunohistochemistry. At weeks 4 and 6 following the completion of modeling, the vacant bone lacunae rates of group E were 15.87±1.97 and 25.09±2.67%, respectively, lower than the results of 20.02±2.21 and 27.79±1.39% for group S; and the osteocyte apoptosis indexes of group E were 20.99±2.95 and 33.93±1.62%, respectively, lower than the results of 26.46±3.37 and 39.90±3.74% from group S. In addition, the Bcl-2 expression at week 4 in the femoral head tissues of group E was higher compared with group S; and the proportion of Bcl-2-positive cells of group E was 9.81±1.01%, higher compared with group S at 8.26±1.13%. The caspase-3 staining data at week 4 in femoral head tissues demonstrated that in the 12 femoral heads of group S, four were negative (32%) and eight were positive (68%); in group E, five were negative (45%) and seven were positive (55%); and in group C, 11 were negative (95%) and one was positive (5%). In addition, the DNA oxidative damage rate at week 4 in the bone marrow hemopoietic cells of group E was (7.24±1.44%), lower compared with group S (11.80±1.26%), and higher compared with group C (5.75±1.47%). Vitamin E is effective in intervening in apoptosis through decreasing caspase-3 expression and upregulating Bcl-2 expression, and by alleviating DNA oxidative damage in bone marrow hemopoietic cells at the early stage of steroid-induced femoral head necrosis in rabbit models.

Effect of undifferentiated versus hepatogenic partially differentiated mesenchymal stem cells on hepatic and cognitive functions in liver cirrhosis

Liver cirrhosis is the outcome of chronic liver injury. The current study aimed to investigate the therapeutic effect of undifferentiated mesenchymal stem cells versus in vitro partially differentiated mesenchymal stem cells on liver cirrhosis and hepatic encephalopathy. 50 adult male albino rats constituted the animal model and were divided into the following groups: control, thioacetamide, undifferentiated mesenchymal stem cells and hepatocyte growth factor-differentiated mesenchymal stem cells groups. Cognitive assessment was achieved by open field test and Y-maze task. We measured serum alanine aminotransferase, albumin and transforming growth factor-beta1, gene expression of α-smooth muscle actin, matrix metalloprotein-2, its tissue inhibitor and apoptotic markers: Bax and Bcl2, brain glial fibrillary acidic protein, synaptophysin, and dopaminergic receptors.

Liver toxicity of thioacetamide is increased by hepatocellular iron overload

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

Sulfated polysaccharide isolated from Ulva lactuca attenuates d-galactosamine induced DNA fragmentation and necrosis during liver damage in rats

Abstract Context: Ulva lactuca Linnaeus (Chlorophyceae), a commonly distributed seaweed, is rich in polysaccharide but has not been studied extensively. Objective: The present study investigated the effects of crude fraction of Ulva lactuca polysaccharide (ULP) on d-galactosamine (d-Gal)-induced DNA damage, hepatic oxidative stress, and necrosis in rats. Materials and methods: The rats were treated with ULP (100 mg/kg, orally) for 4 weeks before a single intraperitoneal injection of d-Gal (500 mg/kg). In addition to liver cell necrosis and DNA damage, antioxidant parameters, such as lipid peroxide (LPO), superoxide dismutase, and catalase, and histopathology of liver tissue were evaluated. Results: ULP pre-treatment significantly attenuated a d-Gal-induced decrease in DNA and RNA levels (3.67 ± 0.38) and (5.42 ± 0.46), respectively. Comet tail length and acridine staining confirmed the number of cells undergoing necrosis were relatively lower in ULP treated rats (30 µm and 8-10% of counted cells) compared to rats treated with d-Gal (60 µm and 16% of counted cells). Biochemical (LPO, SOD and CAT) and histological evaluation (p < 0.01) confirmed the anti-hepatotoxic and antioxidant property of crude polysaccharide against d-Gal-induced elevation of LPO and infiltration of inflammatory cells into liver tissue. Discussion and conclusion: Although our previous studies have reported on the protective role of ULP against liver toxicity, our present findings show that ULP improved the hepatic antioxidant defense system against d-Gal-induced DNA damage and necrosis in rats.

Protective Role of Phyllanthus niruri Extract against Thioacetamide-Induced Liver Cirrhosis in Rat Model

A preclinical study was performed to determine if the extract from Phyllanthus niruri (PN) plays a protective role against liver cirrhosis induced by thioacetamide (TAA) in rats. Initially, acute toxicity was tested and the results showed that the extract was benign when applied to healthy rats. Next, the therapeutic effect of the extract was investigated using five groups of rats: control, TAA, silymarin, and PN high dose and low dose groups. Significant differences were observed between the TAA group and the other groups regarding body and liver weights, liver biochemical parameters, total antioxidant capacity, lipid peroxidation, and oxidative stress enzyme levels. Gross visualization indicated coarse granules on the surface of the hepatotoxic rats' livers, in contrast to the smoother surface in the livers of the silymarin and PN-treated rats. Histopathological analysis revealed necrosis, lymphocytes infiltration in the centrilobular region, and fibrous connective tissue proliferation in the livers of the hepatotoxic rats. But, the livers of the treated rats had comparatively minimal inflammation and normal lobular architecture. Silymarin and PN treatments effectively restored these measurements closer to their normal levels. Progression of liver cirrhosis induced by TAA in rats can be intervened using the PN extract and these effects are comparable to those of silymarin.

Once initiated, how does toxic tissue injury expand?

Once initiated, how tissue injury expands after high toxicant doses, even after their complete elimination, is not understood. Free-radical generation was initially proposed to mediate progression of injury. However, mechanisms proposed thus far have remained unsubstantiated. Necrotic injury is characterized by loss of osmoregulation, cell swelling, blebbing, and cell rupture. This exposes cytosolic enzymes, including proteases, phospholipases, and lysosomal Ca(2+)-dependent enzymes, to high extracellular calcium (Ca(2+)). Activated hydrolytic enzymes, termed 'death proteins,' hydrolyze their substrates in the plasma membrane of neighboring cells, commencing self-perpetuated injury progression. Likewise, ischemia-reperfusion injury exposes the hydrolytic enzymes to high Ca(2+), fuelling the progression of tissue injury. This mechanism is independent of the offending toxicant that initiates the injury. I present here a case for therapeutic intervention with inhibitors directed against death proteins as a means to avert organ failure and death well after the poisoning event.

Increasing evidence for and regulation of a human placental endogenous digitalis-like factor

Endogenous digitalis-like factors (EDLFs) appear to be hypertensiogenic and increased in the serum and placenta of women with preeclampsia (PE), a complication of pregnancy. Digibind, an anti-digoxin antibody Fab fragment, reverses in vitro effects of EDLF and in vivo features of PE. We used Digibind in a radioimmunoassay to measure EDLF and compared this to a bio-functional assay of EDLF with good agreement. These methods confirmed that human placenta was a source of EDLF, synthesizing and releasing EDLF into the media of cultured human placental tissue. Ketoconazole, a steroid synthesis inhibitor, and 17-OH progesterone, a possible substrate of steroid synthesis, were shown to inhibit or increase EDLF release respectively, suggesting overlap of synthetic pathways. Abnormalities of PE such as placental hypoxia, increased reactive oxygen species and increased pro-inflammatory cytokines were demonstrated to increase placental EDLF release. These findings strongly support placental production of EDLF with increased release due to features of PE.

Sterically stable liposomes improve the therapeutic effect of hepatic stimulator substance on fulminant hepatic failure in rats

BACKGROUND AND AIMS

Few drugs have been confirmed to be effective for fulminant hepatic failure (FHF). The purpose of this study was to prepare sterically stable liposomes (SSL) encapsulating hepatic stimulator substance (HSS) and determine their therapeutic effect on FHF.

METHODS

HSS were encapsulated into SSL (HSS-SSL). FHF was induced in rats by thioacetamide (TAA) injection (400mg/kg, three times with a 24-h interval). The agents, including HSS-SSL, SSL, HSS, and sodium chloride (NS), were each injected intravenously 2h after the second and the third TAA injection.

RESULTS

Freshly prepared HSS-SSL had a mean size of 93.59nm and the average encapsulation efficiency was 37.20%. HSS encapsulated in SSL showed a longer half life and more potent target to injured livers than free HSS. Twenty-four hours after the third TAA-injection, the survival rate of HSS-SSL-treated rats (80%) was significantly higher than that of rats treated with NS (20%), SSL (25%), or HSS (50%). Histopathologic examination showed that there was the least necrosis and inflammation in the livers of HSS-SSL-treated rats. The incidence of stage 3 or 4 hepatic encephalopathy in HSS-SSL-treated rats was significantly lower than that in rats treated with other agents. The serum pro-inflammatory cytokine levels and hepatic lipid peroxidation levels were both markedly reduced, while hepatocyte proliferative rate was markedly increased after HSS-SSL treatment.

CONCLUSION

Encapsulation by SSL markedly improved the therapeutic effect of HSS on FHF in rats. Encapsulation by SSL may be an effective approach to enhance the therapeutic potency of drugs for FHF.

Hepatoprotective Effects of Orthosiphon stamineus Extract on Thioacetamide-Induced Liver Cirrhosis in Rats

Orthosiphon stamineus as medicinal plant is commonly used in Malaysia for treatment of hepatitis and jaundice; in this study, the ethanol extracts were applied to evaluate the hepatoprotective effects in a thioacetamide-induced hepatotoxic model in Sprague Dawley rats. Five groups of adult rats were arranged as follows: Group 1 (normal control group), Group 2 Thioacetamide (TAA) as positive control (hepatotoxic group), Group 3 Silymarin as a well-known standard drug (hepatoprotective group), and Groups 4 and 5 as high and low dose (treatment groups). After 60-day treatment, all rats were sacrificed. The hepatotoxic group showed a coarse granulation on the liver surface when compared to the smooth aspect observed on the liver surface of the other groups. Histopathological study confirmed the result; moreover, there was a significant increase in serum liver biochemical parameters (ALT, AST, ALP, and Bilirubin) and the level of liver Malondialdehyde (MDA), accompanied by a significant decrease in the level of total protein and Albumin in the TAA control group when compared with that of the normal group. The high-dose treatment group (200 mg/kg) significantly restored the elevated liver function enzymes near to normal. This study revealed that 200 mg/kg extracts of O. stamineus exerted a hepatoprotective effect.

An antibody of TNF-alpha did not prevent thioacetamide-induced hepatotoxicity in rats

Tumor necrosis factor (TNF)-α antibodies have been shown to reduce liver damage in different models. We investigated the effects of infliximab (a TNF-α antibody) on liver damage in thioacetamide (TAA)-induced hepatotoxicity in rats. Group 1 (n = 8) was the control group. In group 2 (n = 8), the TAA group, the rats received 300 mg/kg intraperitoneal (ip) TAA daily for 2 days. In group 3 (n = 8), the TAA + Infliximab (INF) group, infliximab (5 mg/kg ip daily) was administered 48 hours before the first dose of TAA daily for 2 days and was maintained for 4 consecutive days. In group 4 (n = 8), the INF group, the rats received only ip infliximab (5 mg/kg) daily. Livers were excised for histopathological and biochemical tests (thiobarbituric-acid-reactive substances [TBARS], and myeloperoxidase [MPO]). Serum ammonia, aspartate transaminase (AST), alanine transaminase (ALT), TNF-α, liver TBARS and MPO levels, and liver necrosis and inflammation scores in the TAA group were significantly higher than in the control and INF groups (all p < 0.01). All parameters except AST were not significantly different between TAA and TAA + INF. In conclusion, our results suggest that oxidative stress plays an important role in TAA-induced hepatotoxicity, and infliximab does not improve oxidative liver damage.

Effect of carnosine against thioacetamide-induced liver cirrhosis in rat

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Oxidative stress has been proposed to be involved in thioacetamide (TAA)-induced liver cirrhosis in rats, that is similar to human disease. In this study we aimed to investigate the role of carnosine on the development of TAA-induced cirrhosis. 200mg TAA/kg body weight has been given i.p. twice a week for three months to female wistar rats. Another group received same dose of TAA in the same pattern plus 2g carnosine/L of drinking water for three months. TAA administration resulted in hepatic fibrosis, significant increases in plasma transaminase activities as well as hepatic hydroxyproline and lipid peroxide levels, while liver glutathione (GSH) and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) protein expressions and activities decreased. Carnosine was found to behave as an antioxidant reducing malondialdehyde (MDA) and diene conjugate (DC) levels although it was not effective on increased transaminase activities and decreased antioxidants. It also did not affect the histopathological changes observed in TAA group. Thus our findings indicate that carnosine appears to attenuate peroxidation as an antioxidant itself but does not seem to prevent the development of TAA-induced cirrhotic process.

Induction of GST-P-positive proliferative lesions facilitating lipid peroxidation with possible involvement of transferrin receptor up-regulation and ceruloplasmin down-regulation from the early stage of liver tumor promotion in rats

To elucidate the role of metal-related molecules in hepatocarcinogenesis, we examined immunolocalization of transferrin receptor (Tfrc), ceruloplasmin (Cp) and metallothionein (MT)-1/2 in relation to liver cell foci positive for glutathione-S-transferase placental form (GST-P) in the early stage of tumor promotion by fenbendazole (FB), phenobarbital, piperonyl butoxide or thioacetamide in a rat two-stage hepatocarcinogenesis model. To estimate the involvement of oxidative stress responses to the promotion, immunolocalization of 4-hydroxy-2-nonenal, malondialdehyde and acrolein was similarly examined. Our findings showed that MT-1/2 immunoreactivity was not associated with the cellular distribution of GST-P and proliferating cell nuclear antigen, suggesting no role of MT-1/2 in hepatocarcinogenesis. We also found enhanced expression of Tfrc after treatment with strong tumor-promoting chemicals. With regard to Cp, the population showing down-regulation was increased in the GST-P-positive foci in relation to tumor promotion. Up-regulation of Tfrc and down-regulation of Cp was maintained in GST-P-positive neoplastic lesions induced after long-term promotion with FB, suggesting the expression changes occurring downstream of the signaling pathway involved in the formation of GST-P-positive lesions. Furthermore, enhanced accumulation of lipid peroxidation end products was observed in the GST-P-positive foci by promotion. Post-initiation treatment with peroxisome proliferator-activated receptor alpha agonists did not enhance any such distribution changes in GST-P-negative foci. The results thus suggest that facilitation of lipid peroxidation is involved in the induction of GST-P-positive lesions by tumor promotion from an early stage, and up-regulation of Tfrc and down-regulation of Cp may be a signature of enhanced oxidative cellular stress in these lesions.

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.

Neutral sphingomyelinase-induced ceramide accumulation by oxidative stress during carbon tetrachloride intoxication

Ceramide is a biologically active lipid causing apoptosis in a variety of cells. In this study, we examined the effect of CCl4 on the ceramide metabolism and indicators of oxidative stress. After 12 h of oral administration of CCl4 (4 ml/kg body weight as a 1:1 mixture of CCl4 and mineral oil) to rats, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were increased. Antioxidants such as vitamins C and E were decreased in the liver and kidney. In addition, the ratio of GSH/GSSG in the liver, plasma, kidney, and brain decreased at 2h. The total ceramide in the liver significantly increased as early as 2h after CCl4 administration. After 24 and 36 h, the total ceramide in plasma and the kidney was also augmented. In the brain, the total ceramide dramatically increased at 36 h. These results suggested that the increased ceramide in plasma was transferred to the kidney and the brain. The activity of neutral sphingomyelinase (SMase), which was reported to be enhanced by the decrease of GSH, was significantly increased after CCl4 treatment in the liver, kidney, and brain. However, acid SMase activities were not increased in the liver and kidney. Thus, the activation of neutral SMase via oxidative stress induced the increase of ceramide during CCl4 intoxication in not only the liver but also other tissues. These results suggested that the excess accumulation of ceramide causes damage in other organs including the kidney and brain during fulminant hepatic failure.

Chronic High Doses of Thioacetamide Followed by Vitamin A Modify Dolichol, Dolichol Isoprenoids, and Retinol Content in Rat Liver Cells

Our line of researches follows the hypothesis that dolichol and retinol metabolism might be interrelated and involved in liver fibrosis. To this end, in this study rats were subjected to chronic treatment with thioacetamide (TAA) (300 mg/L liquid diet) for 1 and 2 months and, after liver damage had occurred, supplemented with vitamin A before sacrifice. Dolichol, dolichol isoprene units, and retinol content were determined in isolated parenchymal and sinusoidal liver cells (hepatic stellate cells; Kupffer cells; sinusoidal endothelial cells). Dolichol increased in hepatocytes after TAA treatment, with or without vitamin A. Dolichol decreased in the other cells. Retinol in general decreased. In hepatocytes, retinol decreased only on normal nutrition, while the vitamin A load was taken up normally. The percentages of dolichol isoprene units (Dol-16 to Dol-20, in rats) confirm that Dol-18, which was not modified in percentage by TAA on normal nutrition, did not increase after vitamin A, as it did in control cells (7-12%). The behavior of Dol-18 was similar in all the cells studied. Vitamin A might reveal a latent damage produced by TAA on dolichol homologues. These data support previous hypotheses that the action of TAA depends on the administration modality, the dosage, and the diet, and that Dol-18 might have different functions and compartmentalization in the cells. Furthermore, the results support the hypothesis that dolichol chain length might be interrelated with retinol metabolism, perhaps through their metabolites.

Combination of selenium and three naturally occurring antioxidants administration protects D-galactosamine-induced liver injury in rats

D-Galactosamine (D-GaIN) is a highly selective hepatotoxin that causes liver injury similar to human viral hepatitis via depletion of uridine nucleotides, which subsequently diminishes synthesis of RNA and proteins. The aim of this study was to investigate the role of selenium, ascorbic acid, beta-carotene, and alpha-tocopherol on D-GaIN-induced liver injury of rats by morphological and immunohistochemical means. In this study, Sprague-Dawley female rats were divided into four groups. Group I consists of rats injected physiologic saline solution intraperitoneally. Group II consists of rats given selenium (0.2 mg/kg per day), ascorbic acid (100 mg/kg per day), beta-carotene (15 mg/kg per day), and alpha-tocopherol (100 mg/kg per day) for 3 days via gavage method. Group III consists of the single dose of D-GaIN (500 mg/kg)-injected animals. Group IV are the D-GaIN-injected animals given the same antioxidant combination. In situ terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling (TUNEL) assay was applied to determine apoptosis for paraffin sections of the liver samples. Moreover, caspase-3 and proliferating cell nuclear antigen antibody were applied for paraffin sections. In the group given D-GaIN, apoptotic cells with TUNEL assays and caspase-3 activity, which are liver injury markers induced by D-GaIN, the hepatocyte proliferation with cell proliferation assay increased. However, selenium and other three antioxidants combination clearly suppressed an increase in apoptotic cells with TUNEL assay and caspase-3 activity. In addition, it suppressed D-GaIN-induced cell proliferation in the liver. As a result, these results indicate that selenium and three naturally occurring antioxidants shows a protective effect against liver injury induced by D-GaIN. These results suggest that supplementation with the combination of selenium, ascorbic acid, beta-carotene, and alpha-tocopherol may help prevent the development of liver injury.

Role of carnosine in preventing thioacetamide-induced liver injury in the rat

Carnosine (beta-alanyl-L-histidine) is a dipeptide with antioxidant properties. Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). In this study, we investigated the effect of carnosine treatment on TAA-induced oxidative stress and hepatotoxicity. Rats were injected intraperitoneally with TAA (500 mg/kg) and carnosine (250 mg/kg, intraperitoneal) was co-administered with TAA. All animals were killed 24 h after injections. TAA administration resulted in hepatic necrosis, significant increases in plasma transaminase activities as well as hepatic lipid peroxide levels. In addition, hepatic antioxidant system was found to be depressed following TAA administration. When carnosine was co-administered with TAA in rats, plasma transaminase activities were found to approach to normal values in rats. Histological findings also suggested that carnosine has preventive effect on TAA-induced hepatic necrosis. Carnosine treatment caused significant decreases in lipid peroxide levels in TAA-treated rats without any changes in enzymatic and non-enzymatic antioxidants except vitamin E in the liver of rats. Our findings indicate that carnosine, in vivo may have a preventive effect on TAA-induced oxidative stress and hepatotoxicity by acting as an non-enzymatic antioxidant itself.

Preventing hypoxia/reoxygenation damage to hepatocytes by p66(shc) ablation: up-regulation of anti-oxidant and anti-apoptotic proteins

BACKGROUND/AIMS

Ischemia/reperfusion damage to the liver remains a serious concern in many clinical situations. Major mechanisms for this certainly include oxidative stress.

METHODS

The effects of ablating the p66 isoform of ShcA (p66(shc)) on hypoxia/reoxygenation (H/R)-induced oxidative stress and cell injury in hepatocytes were investigated.

RESULTS

Immediately after reoxygenation, AML12 cells were clearly under oxidative stress; many cells underwent apoptosis. However, knockdown of p66(shc) by specific RNAi markedly decreased cellular oxidative stress and H/R-induced apoptosis, as well as conferring resistance to H(2)O(2) insult. These data suggest that prevention of apoptosis conferred by ablation of p66(shc) results from changed ROS-scavenging, but not inhibition of ROS generation. These data were also confirmed in fibroblasts from p66(shc) knockout mice. Anti-oxidant molecules, such as MnSOD and Ref-1 and the anti-apoptotic molecule Bcl-xL were up-regulated, and pro-apoptotic FLICE was down-regulated, by ablation of p66(shc). Interestingly, catalase expression was not affected in p66(shc)-knockdown-AML12 cells although it is a major target in other cell types.

CONCLUSIONS

Our findings suggest that in hepatocytes, ablation of p66(shc) is cytoprotective against H/R-induced oxidative stress, with MnSOD and Ref-1 playing critical roles, and with up-regulation of Bcl-xL and down-regulation of FLICE contributing jointly to preventing cells from undergoing oxidant-induced apoptosis.

Antioxidant therapy for chronic hepatitis C after failure of interferon: Results of phase II randomized, double-blind placebo controlled clinical trial

AIM: To assess the safety and efficacy of antioxidant therapy for patients with chronic hepatitis C virus (HCV) infection.

METHODS: One hundred chronic HCV infection patients failed in interferon treatment were enrolled and randomly assigned to receive combined intravenous and oral antioxidants or placebo, or oral treatment alone. Primary end points were liver enzymes, HCV-RNA levels and histology.

RESULTS: Combined oral and intravenous antioxidant therapy was associated with a significant decline in ALT levels in 52% of patients who received antioxidant therapy vs 20% of patients who received placebo (P = 0.05). Histology activity index (HAI) score at the end of treatment was reduced in 48% of patients who received antioxidant therapy vs 26% of patients who received placebo (P = 0.21). HCV-RNA levels decreased by 1-log or more in 28% of patients who received antioxidant therapy vs 12% who received placebo (P = NS). In part II of the trial, oral administration of antioxidants was not associated with significant alterations in any of the end points.

CONCLUSION: Antioxidant therapy has a mild beneficial effect on the inflammatory response of chronic HCV infection patients who are non-responders to interferon. Combined antiviral and antioxidant therapy may be beneficial for these patients.

Effect of dimethyl sulphoxide on oxidative stress, activation of mitogen activated protein kinase and necrosis caused by thioacetamide in the rat liver

Thioacetamide (400 mg/kg body weight, i.p.) was administered to rats. After 12 h the activity of plasma glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) was significantly higher than that of the control group, and after 24 h plasma GOT and GPT activities strongly increased. These results indicated that the necrotic process was initiated at about 12 h and developed thereafter. By co-administration of dimethyl sulphoxide (DMSO, 18 and 1 h before, and 8 h after administration of thioacetamide: each time, 2.5 ml/kg body weight, p.o.), plasma GOT and GPT were significantly decreased and were even comparable to the control group, showing that DMSO totally prevented the necrotic action of thioacetamide. After 12 and 24 h of thioacetamide administration, the hepatic level of vitamin C, the most sensitive chemical indicator of oxidative stress, decreased significantly, indicating that oxidative stress was significantly enhanced 12 h after thioacetamide intoxication and thereafter. DMSO totally restored the liver vitamin C level, demonstrating that DMSO effectively ameliorated the oxidative stress caused by thioacetamide, resulting in the prevention of necrosis of the liver. Phosphorylated c-Jun NH(2)-terminal kinase (JNK) significantly increased transiently 12 h after treatment with thioacetamide. These results indicated that oxidative stress and the activation of JNK took place almost simultaneously. Phosphorylated extracellular signal-related kinase (ERK) 2 was significantly increased 6-12 h after thioacetamide injection. Phosphorylated p38 MAPK (mitogen activated protein kinase) was significantly decreased 24 h after administration of thioacetamide. DMSO treatment inhibited the change of these MAPKs by thioacetamide, corresponding with the prevention of the liver necrosis as well as the attenuation of oxidative stress.

Protective effects of Gingko biloba on thioacetamide-induced fulminant hepatic failure in rats

Gingko biloba (GB) has antioxidant and platelet-activating factor (PAF) antagonistic effects. We investigated the protective effects of GB on thioacetamide (TAA)-induced fulminant hepatic failure in rats. Fulminant hepatic failure was induced in treatment groups by three intraperitoneal (ip) injections of TAA (350 mg/kg) at 24-hour intervals. Treatments with GB (100 mg/kg per day, orally) and N-acetylcysteine (20 mg/kg twice daily, sc) were initiated 48 hours prior to TAA administration. The liver was removed for histopathological examinations. Serum and liver thiobarbituric acid-reactive substance (TBARS) levels were measured for assessment of oxidative stress. Liver necrosis and inflammation scores and serum and liver TBARS levels were significantly higher in the TAA group compared to the control group (P < 0.001, < 0.001, 0.001, < 0.001, respectively). Liver necrosis and inflammation scores and liver TBARS levels were significantly lower in the GB group compared to the TAA group (P < 0.001, < 0.001 and 0.01, respectively). GB ameliorated hepatic damage in TAA-induced fulminant hepatic failure. This may be due to the free radical-scavenging effects of GB.

Activation of mitogen activated protein kinase (MAPK) during carbon tetrachloride intoxication in the rat liver

Carbon tetrachloride (CCl(4): 4 ml/kg body weight as a 1:1 mixture of CCl(4) and mineral oil) was orally administered to rats. After 12 h the activity of plasma AST (aspartate aminotransferase) and ALT (alanine aminotransferase) was significantly higher than that of the control group and plasma AST and ALT activities increased thereafter. These results indicated that the necrotic process was active at about 12 h and developed thereafter. After 2-24 h of CCl(4) administration, the hepatic level of vitamin C, the most sensitive indicator of oxidative stress, decreased significantly, indicating that oxidative stress was significantly enhanced as early as 2 h after CCl(4) intoxication and thereafter. Phosphorylated JNK (c-Jun NH(2)-terminal kinase) and phospho-ERK1/2 (extracellular signal-regulated kinase1/2) were significantly increased transiently 1-3 h after treatment with CCl(4), while phosphorylated p38 decreased significantly 1-24 h after CCl(4) treatment. These results indicated that the change in MAPKs (mitogen activated protein kinases) slightly preceded that in vitamin C, the most sensitive chemical indicator of oxidative stress.

Vitamin E and Apoptosis

Vitamin E is a generic term that refers to a family of compounds that is further divided into two subgroups called tocopherols and tocotrienols. All natural forms of tocopherols and tocotrienols are potent antioxidants that regulate peroxidation reactions and controls free radical production within the body. However, it is now firmly established that many of the biological actions mediated by individual vitamin E isoforms are not dependent on their antioxidant activity. Furthermore, synthetic ether derivatives of vitamin E that no longer possess antioxidant activity also display a wide range of biological activities. One of the most intriguing therapeutic applications for natural vitamin E and vitamin E derivatives currently being investigated is their use as anticancer agents. Specific forms of vitamin E display potent apoptotic activity against a wide range of cancer cell types, while having little or no effect on normal cell function or viability. Experimental studies have also determined that the intracellular mechanisms mediating the apoptotic effects of specific vitamin E compounds display great diversity in different types of caner cells and has been found to restore multidrug resistant tumor cells sensitivity to chemotherapeutic agents. These findings strongly suggest that some natural and synthetic analogues of vitamin E can be used effectively as anticancer therapy either alone or in combination to enhance the therapeutic efficacy and reduce toxicity of other anticancer agents.

Involvement of P53 and Bax/Bad triggering apoptosis in thioacetamide-induced hepatic epithelial cells

AIM: Thioacetamide (TAA) has been used in studying liver fibrosis and cirrhosis, however, the mechanisms of TAA-induced apoptosis in liver are still unclear. The hepatic epithelial cell line clone 9 was cultured and treated with TAA to investigate the causes of cell death.

METHODS: The cell viability of TAA-induced clone 9 cells was determined using MTT assay. Total cellular GSH in TAA-induced clone 9 cells was measured using a slight modification of the Tietze assay. The activity of caspase 3 in TAA-induced clone 9 cells was monitored by the cleavage of DEVD-p-nitroanaline. TUNEL assay and flow cytometry were applied for the determination of DNA fragmentation and the proportion of apoptosis in TAA-induced clone 9 cells, respectively. The alterations of caspase 3, Bad, Bax and Phospho-P53 contents in TAA-induced clone 9 cells were measured by Western blot.

RESULTS: The experimental data indicated that TAA caused rat hepatic epithelial cell line clone 9 cell death in a dose-and time-dependent manner; 60% of the cells died (MTT assay) within 24 h after 100 mg/L TAA was applied. Apoptotic cell percentage (TUNEL assay) and caspase 3 activities were highest after 100 mg/L TAA was added for 8 h. The release of GSH and the elevation in caspase content after TAA treatment resulted in clone 9 cell apoptosis via oxidative stress and a caspase-dependent mechanism. The phospho-p53, Bax and Bad protein expressions in clone 9 cells were increased after TAA treatment.

CONCLUSION: These results reveal that TAA activates p53, increases caspase 3, Bax and Bad protein contents, perhaps causing the release of cytochrome c from mitochondria and the disintegration of membranes, leading to apoptosis of cells.

Activation of mitogen activated protein kinase (MAPK) during D-galactosamine intoxication in the rat liver

A significant increase in plasma glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase was observed 6 h after intraperitoneal administration of D-galactosamine (D-Galn). Three hours after administration of D-Galn, the vitamin C concentration in the liver decreased significantly compared to that in a control group and thereafter the hepatic vitamin C concentration remained at a significantly lower level. Phosphorylated JNK (c-Jun NH2-terminal kinase) and phosphorylated ERK (extracellular signal-regulated kinase) started increasing 3 h after D-Galn treatment and remained at a high level for 6-12 h after the treatment, while phosphorylated p38 MAPK increased significantly 6 h after D-Galn administration. These results indicated that oxidative stress and the activation of JNK and ERK took place almost simultaneously, followed by the activation of p38 MAPK.

Synergistic protection by S-adenosylmethionine with vitamins C and E on liver injury induced by thioacetamide in rats

Free radicals are involved in the pathogenesis of acute liver injury induced by thioacetamide (TAA). We investigated the effects of S-adenosylmethionine (SAMe) combined with/without vitamins C and E on TAA-induced acute liver injury in rats. TAA was given intraperitoneally (200 mg kg-1). Antioxidant treatments (SAMe, 25 mg kg-1; vitamin C, 100 mg kg-1; vitamin E, 200 mg kg-1, intraperitoneal) were given 1 h later. Liver histology, enzymology, and ability to release hepatic insulin-sensitizing substance (HISS) were assessed. TAA caused liver tissue injury, increased liver enzymes, and decreased insulin sensitivity (p<0.01). Blockade of HISS release by atropine did not further decrease insulin sensitivity in rats with TAA insult, indicating that the decrease in insulin sensitivity was HISS dependent. Treatment with SAMe alone or vitamins C+E slightly improved liver histology but not the changes in liver enzymes and insulin sensitivity. Combined treatment with SAMe plus vitamins C+E greatly protected the liver from tissue injury, the increase in liver enzymes, and the decrease in insulin sensitivity. In conclusion, acute liver injury causes HISS-dependent insulin resistance (HDIR). There are synergistic antioxidative effects among the antioxidants, SAMe and vitamins C and E, that protect the liver from TAA-induced HDIR, suggesting that antioxidant treatment may best be done using a balanced "cocktail."

Curcumin ameliorates acute thioacetamide-induced hepatotoxicity

BACKGROUND AND AIM

Increased production of reactive oxygen species and nitric oxide and activation of nuclear factor kappa B are implicated in the pathogenesis of various liver diseases, including fulminant hepatic failure. Curcumin is a naturally occurring anti-oxidant that reduces oxidative stress and inhibits nuclear factor kappa B and nitric oxide formation. The aim of the present study is to assess curcumin's therapeutic potential in acute thioacetamide hepatotoxicity, a rat model of fulminant hepatic failure.

METHODS

Fulminant hepatic failure was induced by two intraperitoneal (i.p.) injections of 300 mg/kg thioacetamide (TAA) at 24-h intervals. The experimental groups received a low-dose (200 mg/kg per day, i.p.) or a high-dose (400 mg/kg per day) of curcumin, initiated 48 h prior to the first TAA injection. A fourth group was administered neither TAA nor curcumin and served as a control.

RESULTS

The survival rate was higher in both curcumin-treated groups compared to the TAA only treated group. Biochemical parameters of liver injury, blood ammonia and hepatic necroinflammation were lower in the low-dose curcumin group compared to TAA controls, and were further reduced in the high-dose group (P < 0.05 and P < 0.01, respectively). Curcumin treatment also reduced the TAA-induced elevated hepatic levels of thiobarbituric acid-reactive substances (TBARS), and inhibited the nuclear binding of nuclear factor kappa B (NFkappaB) and inducible nitric oxide (iNOS) protein expression.

CONCLUSIONS

Curcumin improved survival and minimized oxidative stress, hepatocellular injury and hepatic necroinflammation, NFkappaB binding and iNOS expression in a rat model of FHF. These findings support the role of ROS, NFkappaB and iNOS in mediating liver insult due to TAA, and that of curcumin as a hepato-protectant.

Treatment of chronic hepatitis C virus infection via antioxidants: results of a phase I clinical trial

BACKGROUND

The pathogenesis of chronic hepatitis C virus (HCV) infection is associated with a defective host antiviral immune response and intrahepatic oxidative stress. Oxidative stress and lipid peroxidation play major roles in the fatty liver accumulation (steatosis) that leads to necro-inflammation and necrosis of hepatic cells. Previous trials suggested that antioxidative therapy may have a beneficial effect on patients with chronic HCV infection.

AIMS

To determine the safety and efficacy of treatment of chronic HCV patients via a combination of antioxidants.

METHODS

Fifty chronic HCV patients were treated orally on a daily basis for 20 weeks with seven antioxidative oral preparations (glycyrrhizin, schisandra, silymarin, ascorbic acid, lipoic acid, L-glutathione, and alpha-tocopherol), along with four different intravenous preparations (glycyrrhizin, ascorbic acid, L-glutathione, B-complex) twice weekly for the first 10 weeks, and followed up for an additional 20 weeks. Patients were monitored for HCV-RNA levels, liver enzymes, and liver histology. Assessment of quality of life was performed using the SF-36 questionnaire.

RESULTS

In one of the tested parameters (eg, liver enzymes, HCV RNA levels, or liver biopsy score), a combination of antioxidants induced a favorable response in 48% of the patients (24). Normalization of liver enzymes occurred in 44% of patients who had elevated pretreatment ALT levels (15 of 34). ALT levels remained normal throughout follow-up period in 72.7% (8 of 11). A decrease in viral load (one log or more) was observed in 25% of the patients (12). Histologic improvement (2-point reduction in the HAI score) was noted in 36.1% of the patients. The SF-36 score improved in 26 of 45 patients throughout the course of the trial (58% of the patients). Treatment was well tolerated by all patients. No major adverse reactions were noted.

CONCLUSIONS

These data suggest that multi antioxidative treatment in chronic HCV patients is well tolerated and may have a beneficial effect on necro-inflammatory variables. A combination of antiviral and antioxidative therapies may enhance the overall response rate of these patients.

Evaluation of cultured, precision-cut rat liver slices as a model to study drug-induced liver apoptosis

The precision-cut liver slice culture model has been used widely to investigate drug metabolism and drug-induced necrosis. However, apoptosis, a key mediator of liver toxicity remains to be studied in this model. We evaluated apoptosis induced by thioacetamide (TAA) in rat liver slices, and in livers taken from TAA-treated rats as a control. Rat liver slices were treated with 50, 75 and 100 mM of TAA for 15 h. Histopathological examination of the liver slices revealed specific centrilobular localization of apoptotic hepatocytes at 75 mM but randomly distributed at 100 mM. Apoptosis in centrilobular hepatocytes was confirmed by appearance of cleavage products of caspase-3 and DNA fragmentation studied by TUNEL method. A concentration-dependent release of cytochrome c was observed in the slices, suggesting a role for mitochondria in the apoptosis triggered by TAA. The in vitro results were compared to the data obtained in male Sprague-Dawley rats given a single ip injection of 40 mg/kg TAA and sacrificed 1, 2, 3 and 6 h after dosing. Histopathological analyses showed specific centrilobular localization of apoptosis after 6 h treatment. Caspase-3 activation, DNA fragmentation and cytochrome c release were also observed in the liver of rats treated with TAA. Overall these data indicated that precision-cut liver slices provide a valuable in vitro system to study drug-induced liver apoptosis.

Specific type IV phosphodiesterase inhibitor ameliorates thioacetamide-induced liver injury in rats

BACKGROUND AND AIMS

Rolipram is a specific type IV phosphodiesterase inhibitor that suppresses the activity of immune cells and the production of pro-inflammatory cytokines. In this study, we assessed the effect of rolipram on acute liver injury using thioacetamide (TAA)-induced liver injury in rats as a model.

METHODS

Rats were treated with rolipram (0.5-5 mg/kg, intraperitoneally) or vehicle and injected 30 min later with TAA (100 mg/kg, subcutaneously). Serum transaminase concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) levels were measured and livers were examined for microscopic changes. Dose-dependent protection against TAA liver injury was based on transaminase levels and inflammatory cytokine production, and was measured 9 h after TAA when the peak release of cytokines occurred.

RESULT

Rolipram suppressed liver injury based on serum aspartate transaminase (AST), alanine transaminase (ALT) and histology and reduced TNF-alpha, IL-1beta and GRO/CINC-1 levels. Rolipram, at doses of 0.5-5 mg/kg, suppressed serum transaminase and TNF-alpha production in a dose-dependent manner, and these effects were significant at doses of 2.5 and 5 mg/kg.

CONCLUSION

In our rodent model of acute liver injury, rolipram clearly reduced liver damage and inhibited pro-inflammatory cytokine production. These results suggest that specific type IV phosphodiesterase inhibitors, such as rolipram, have potent hepatoprotective effects that are associated with suppressing inflammatory cytokine production.

Liver necrosis and fulminant hepatic failure in rats: protection by oxyanionic form of tungsten

The hepatic lesion produced as a result of oxidative stress is of wide occurrence. In the present study, the effect of tungsten on liver necrosis and fulminant hepatic failure (FHF) has been studied in rats treated with various compounds known to produce oxidative stress. Supplementation of animals with sodium tungstate for 7 weeks before the induction of liver injury by chemicals including thioacetamide (TAA), carbon tetrachloride (CCl(4)), or chloroform (CHCl(3)) could protect progression of hepatic injury. Various biochemical changes associated with liver damage and oxidative stress were measured. Hepatic malondialdehyde content, endogenous tripeptide, and reduced glutathione were measured as oxidative stress markers. The activity of xanthine oxidase, which generates reactive oxygen species (ROS) as a by-product, was also determined and found to be perturbed. Tungsten supplementation to rats caused a significant decrease in lipid peroxidation and lowered the levels of the biochemical markers of hepatic lesions produced by TAA, CCl(4) (CCl(4)), or CHCl(3). Tungsten could also cause an increase in the survival rate in rats receiving lethal doses of TAA, CCl(4), or CHCl(3). The protective effect of tungsten, however, is suggested to be limited to the conditions where the hepatic lesion is reported to be due to the generation of ROS. The progression of liver injury produced by the compounds causing oxidative stress without initiating the generation of free radicals such as bromobenzene (BB), or acetaminophen (AAP), could not be inhibited by tungsten. The possible mechanism explaining the role of oxyanionic form of tungsten in free radical-induced hepatic lesions is discussed.

Change in the concentration of vitamins C and E in rat tissues by paraquat administration

Paraquat causes lung injury by oxidative stress. After 48 h of intraperitoneal administration of paraquat (50 mg/kg of body weight) to rats, the vitamin C concentration in the lungs was significantly decreased, while lung vitamin E content was increased after 12 h. These results indicate that vitamin C directly reflected the oxidative stress in the lungs.