Oxidative damage to the hepatocellular proteins after chronic ethanol intake in the rat

Exploration of glutaredoxin-1 oxidative modification in carbon nanomaterial-induced hepatotoxicity

Herein, we present toxicological assessments of carbon nanomaterials in HL-7702 cells, and it was found that reactive oxygen species (ROS) levels were elevated. Mass spectrometry results indicated that cysteine sulfhydryl of glutaredoxin-1 (GLRX1) was oxidized to sulfenic acids and sulfonic acids by excessive ROS, which broke the binding of GLRX1 to apoptosis signal-regulating kinase 1, causing the activation of the JNK/p38 signaling pathway and ultimately hepatocyte apoptosis. However, a lower level of ROS upregulated GLRX1 instead of sulfonation modification of its active sites. Highly expressed GLRX1 in turn enabled the removal of intracellular ROS, thereby exerting inconspicuous toxic effects on cells. Taken together, these findings emphasized that CNM-induced hepatotoxicity is attributable to oxidative modifications of GLRX1 arising from redox imbalance.

Antioxidant extract of black rice prevents renal dysfunction and renal fibrosis caused by ethanol-induced toxicity

This study was conducted to evaluate the protective role of extracted natural antioxidants from black rice and their effect on kidney failure and renal cirrhosis caused by ethanol-induced toxicity. Antioxidant activity in terms of total phenol content, flavonoid compounds and anthocyanin, as well as antioxidant capacity, was determined in an extract of black rice. The findings noted that the black rice extract contained high amounts of antioxidant activity and capacity. Total phenolic compounds from black rice extract were fractionated using HPLC and the results showed that ferulic, sinapic, ascorbic, salicylic and coumaric acids were the highest in the extract. Biological experiments were performed on male albino adult rats (40 animals, 10 rats for each group), divided into four groups. After five weeks, kidney functions and protein fractions were assessed. In addition, superoxide dismutase (SOD), glutathione (GSH) and malondialdehyde (MDA) enzyme activities were determined in all groups. The results found that kidney function, total protein, albumin and globulin were affected by renal dysfunction and renal fibrosis in the positive control (PC), whereas groups 3 and 4 noted an improvement in renal function nearly or equal to the healthy rats which were fed on a basal diet. Furthermore, the PC group showed significantly decreased levels of enzymatic antioxidants, namely SOD and GSH with a concomitant elevated MDA level compared with those in the negative rats fed on a basal diet. Groups 3 and 4 also reported improvements in enzyme activity. These results were further supported by histopathological findings which revealed a curative effect in groups 3 and 4, which avoided renal dysfunction and renal fibrosis from ethanol-induced toxicity. From the results, it can be said that the black rice extract with the highest amounts of antioxidants led to improvements in all parameters, especially kidney function, total protein, albumin, and globulin, in addition to enzyme activity. Therefore, black rice can be recommended as a benefit to general health.

Hepatoprotective Role of Eclipta alba against High Fatty Diet Treated Experimental Models - A Histopathological Study

Background

The hepatic injury due to oxidative stress was ameliorated through administration of an aqueous extract of Eclipta alba leaves and suggested that wedelolactone and demethylwedelolactone were the possible components of Eclipta alba behind the protective effect on liver as well as against liver disorders.

Objective

To study the hepato-protective effects of Eclipta alba on high fatty diet treated experimental models.

Material and methods

A total of 30 adult albino rats of Wistar strain weighing 165-215 grams, from the animal house of the Basaveshwara Medical College, Hospital and Research Centre, Chitradurga, were used for the present study: group 1 included animals fed with normal diet (control); group 2, animals treated with hyperlipidemic diet for eight weeks; group 3, animals treated with hyperlipidemic diet for eight weeks, followed by one week post treatment of Eclipta alba with normal diet; group 4, animals treated with hyperlipidemic diet for eight weeks, followed by two weeks post-treatment of Eclipta alba with normal diet; and group 5, animals treated with hyperlipidemic diet for eight weeks, followed by three weeks posttreatment of Eclipta alba with normal diet.

Results

In animals with high fat diet (30%), we observed the deposition of fat in the form of fat lobules in and around the hepatocytes, mononuclear in filtration in the liver parenchyma, dilation of blood vessels, necrotic foci and damaged hepatocytes.

Conclusion

The components of Eclipta alba like wedelolactone, demethylwedelolactone and saponins reduced fat deposition, mononuclear infiltration, and necrotic foci, and stimulated hepatocyte regeneration in the liver.

Histological, Immunohistochemical, and Biochemical Study of Experimentally Induced Fatty Liver in Adult Male Albino Rat and the Possible Protective Role of Pomegranate

Nonalcoholic fatty liver disease is a major health problem and is considered the most common worldwide liver disease. Pomegranate has many biological activities and could modify the risk of hypercholesterolemia. The objective of the current research was to study the histological changes of experimentally induced fatty liver and possible protection by pomegranate. For this purpose, 50 adult male albino rats were divided into four groups, control group, pomegranate treated group that were given pomegranate juice for six weeks, fatty liver induced group that were fed on high fat diet for six weeks and protective group that were fed on high fat diet and received pomegranate juice for six weeks. Histological changes were detected in the fatty liver induced group in the form of disturbed hepatic architecture, dilatation and congestion of central veins, blood sinusoids and portal veins. Most of hepatocytes showed variable degrees of cytoplasmic vacuolation, mitochondrial structural changes, dilatation of endoplasmic reticulum in addition to nuclear structural changes like condensed chromatin, irregular shrunken nuclei and vacuolated nuclei. All these changes were associated with inflammatory cellular infiltrations, deposition of collagen fibers around the central vein, blood sinusoids, portal areas and in between the hepatocytes in addition to significant increase in number of hepatic stellate cells that was proved by electron microscope and confirmed by immunohistochemical study. Moreover, these structural changes were much less pronounced in animals treated with pomegranate either with or before receiving high fat diet. These findings suggested that pomegranate has a protective effect against experimentally induced fatty liver.

Comparative effects of EtOH consumption and thiamine deficiency on cognitive impairment, oxidative damage, and β-amyloid peptide overproduction in the brain

The effects of chronic EtOH consumption, associated or not with thiamine deficiency (TD), on cognitive impairment, oxidative damage, and β-amyloid (Aβ) peptide accumulation in the brain were investigated in male C57BL/6 mice. We established an alcoholic mouse model by feeding an EtOH liquid diet, a TD mouse model by feeding a thiamine-depleted liquid diet, and an EtOH treatment associated with TD mouse model by feeding a thiamine-depleted EtOH liquid diet for 7 weeks. The learning and memory functions of the mice were detected through the Y-maze test. Biochemical parameters were measured using corresponding commercial kits. The Aβ expression in the hippocampus was observed by immunohistochemical staining. Several results were obtained. First, EtOH significantly reduced cognitive function by significantly decreasing the Glu content in the hippocampus; increasing the AChE activity in the cortex; and reducing the thiamine level, and superoxide dismutase (SOD), glutathione peroxidase (GPx), and choline acetyltransferase (ChAT) activities in both the hippocampus and cortex. The treatment also increased the levels of malondialdehyde (MDA), protein carbonyl, 8-hydroxydeoxyguanosine (8-OHdG), and nitric oxide (NO) and the activities of total nitric oxide synthase (tNOS), inducible nitric oxide synthase (iNOS), and monoamine oxidase B (MAO-B). Furthermore, EtOH enhanced the expression levels of Aβ_1-42 and Aβ_1-40 in the hippocampus. Second, TD induced the same dysfunctions caused by EtOH in the biochemical parameters, except for learning ability, 8-OHdG content, and GPx, tNOS, and AChE activities in the cortex. Third, the modification of MDA, protein carbonyl and NO levels, and GPx, iNOS, ChAT, and MAO-B activities in the brain induced by chronic EtOH treatment associated with TD was greater than that induced by EtOH or TD alone. The synergistic effects of EtOH and TD on Aβ_1-40 and Glu release, as well as on SOD activity, depended on their actions on the hippocampus or cortex. These findings suggest that chronic EtOH consumption can induce TD, cognitive impairment, Aβ accumulation, oxidative stress injury, and neurotransmitter metabolic abnormalities. Furthermore, the association of chronic EtOH consumption with TD causes dramatic brain dysfunctions with a severe effect on the brain.

Diosmin attenuates radiation-induced hepatic fibrosis by boosting PPAR-γ expression and hampering miR-17-5p-activated canonical Wnt-β-catenin signaling

BACKGROUND

Liver fibrosis is one of the major complications from upper right quadrant radiotherapy. MicroRNA-17-5p (miR-17-5p) is hypothesized to act as a regulator of hepatic stellate cell (HSCs) activation by activation of the canonical Wnt-β-catenin pathway. Diosmin (Dios), a citrus bioflavonoid, is known to possess potent antioxidant, anti-inflammatory, and anti-apoptotic properties.

PURPOSE

To explore the molecular mechanisms that underlie radiation-induced liver fibrosis, and to evaluate the possible influence of Dios on the miR-17-5p-Wnt-β-catenin signaling axis during fibrogenesis provoked by irradiation (IRR) in rats. Also, the effect of Dios on hepatic peroxisome proliferator activated receptor-γ (PPAR-γ) expression as a regulator for HSC activation was considered.

METHODS

We administered 100 mg·(kg body mass)^-1·day^-1 (per oral) of Dios were administered to IRR-exposed rats (overall dose of 12 Gy on 6 fractions of 2 Gy each) for 6 successive weeks.

RESULTS

Data analysis revealed that Dios treatment mitigated oxidative stress, enhanced antioxidant defenses, alleviated hepatic inflammatory responses, abrogated pro-fibrogenic cytokines, and stimulated PPAR-γ expression. Dios treatment repressed the miR-17-5p activated Wnt-β-catenin signaling induced by IRR. Moreover, Dios treatment restored the normal hepatic architecture and reversed pathological alterations induced by IRR.

CONCLUSION

We hypothesize that the stimulation of PPAR-γ expression and interference with miR-17-5p activated Wnt-β-catenin signaling mediates the antifibrotic properties of Dios.

Protective effects of Cholestin on ethanol induced oxidative stress in rats

BACKGROUND

Male Wistar rats were divided into seven groups as follows: group A, basal diet; group B, basal diet with Cholestin at 0.1667 g kg⁻¹ body weight (BW); groups C-F, oral feeding of ethanol at 7.9 g kg⁻¹ BW; groups D-F, Cholestin in diet at 0.1667, 0.3333 and 0.5 g kg⁻¹ BW respectively; group G, silymarin in diet at 200 mg kg⁻¹ BW.

RESULTS

The results showed that treatment with Cholestin for 8 weeks reduced the impact of ethanol toxicity on serum markers of liver damage: aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). The antioxidant system was significantly enhanced: plasma and hepatic thiobarbituric acid-reactive substance (TBARS) levels were lowered while hepatic superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), ethanol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities and non-enzymatic antioxidants (vitamin E, vitamin C and GSH) were elevated.

CONCLUSION

Cholestin shows a protective effect against hepatotoxicity indices in ethanol-fed rats comparable to that of silymarin, as supported by the evaluation of liver histopathology. The data suggest that Cholestin exerts its hepatoprotective effect by decreasing lipid peroxidation and improving antioxidants status, thus proving itself as an effective antioxidant in ethanol-induced oxidative damage in rats.

Sorghum-based alcoholic beverage, Burukutu, perturbs the redox status of the liver of male rats

The redox status of male rat liver following 28 days consumption of Burukutu was investigated. Twenty rats were randomized into four groups with five rats each. Burukutu consumption at 0.78 g/kg alcohol produced no significant change in the activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). However, 3.71 and 7.43 g/kg dosages resulted in significant decrease in the activities of ALP, ALT and AST with corresponding increase in serum. The activity of cytochrome P₄₅₀(CYP 2E1) increased significantly in the liver of rats following consumption of Burukutu at all doses investigated. The activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase decreased significantly (P < 0.05) in rats treat with 0.78 g/kg, 3.41 and 7.43 g/kg Burukutu. There was a significant increase in the level of glutathione disulfide (GSSG) with reduction in the levels of glutathione reduced (GSH) and GSH:GSSG. The levels of oxidative stress biomarkers, malondialdehyde, conjugated dienes, lipid hydroperoxides, protein carbonyl and percentage DNA fragmentation, increased significantly (P < 0.05). It is evident from the alterations in the activities of the hepatocellular enzymes, antioxidant enzymes and oxidative stress biomarkers that Burukutu mediated its toxicity through the depletion of the antioxidant enzymes.

Oxidative stress and lung function profiles of male smokers free from COPD compared to those with COPD: a case-control study

BACKGROUND

The mechanisms of smoking tobacco leading to chronic obstructive pulmonary disease (COPD) are beginning to be understood. However, conclusions about the role of blood or lung oxidative stress markers were disparate.

AIMS

To investigate the oxidative stress in blood or lung associated with tobacco smoke and to evaluate its effect on pulmonary function data and its relation with physical activity.

METHODS

It is a case-control study. Fifty-four male-smokers of more than five pack-years (PY) and aged 40-60 years were included (29 Non-COPD, 16 COPD). Physical activity score was determined. Blood sample levels of malondialdehyde (MDA), protein-cys-SH (PSH), and Glutathione (GSH) were measured. Fractional exhaled nitric oxide (FeNO) and plethysmographic measurements were performed. Correlation coefficients (r) evaluated the association between oxidative stress markers and independent variables (plethysmographic data and physical activity score).

RESULTS

Non-COPD (48 ± 6 years) and COPD (49 ± 5 years) groups had similar tobacco consumption patterns, that is, 27 ± 14 PY versus 30 ± 19 PY, respectively. Compared to the Non-COPD group, the COPD group had significantly lower levels of GSH and PSH, that is, mean ± SE were 40 ± 6 versus 25 ± 5 µg/mL and 54 ± 10 versus 26 ± 5 µg/g of hemoglobin, respectively. However, MDA level and FeNO values were similar. In the COPD group, none of the oxidative stress markers was significantly correlated with plethysmographic data or physical activity score. In the Non-COPD group, GSH was significantly correlated with physical activity score (r = 0.47) and PSH was significantly correlated with total lung capacity (TLC) (r = -0.50), residual volume (r = 0.41), and physical activity score (r = 0.62). FeNO was significantly correlated with TLC of the COPD group (r = -0.48).

CONCLUSION

Compared to the Non-COPD group, the COPD group had a marked decrease in blood antioxidant markers (GSH and PSH) but similar blood oxidant (MDA) or lung (FeNO) burden.

Rodent models of alcoholic liver disease: of mice and men

Alcoholic liver disease (ALD) is a major cause of acute and chronic liver disease worldwide. The progressive nature of ALD is well described; however, the complex interactions under which these pathologies evolve remain to be fully elucidated. Clinically there are no clear biomarkers or universally accepted, effective treatment strategies for ALD. Experimental models of ALD are an important component in identifying underlying mechanisms of alcohol-induced injury to develop better diagnostic markers, predictors of disease progression, and therapeutic targets to manage, halt, or reverse disease progression. Rodents remain the most accessible model for studying ALD pathology. Effective rodent models must mimic the natural history of ALD while allowing examination of complex interactions between multiple hepatic, and non-hepatic, cell types in the setting of altered metabolic or oxidative/nitrosative stress, inflammatory responses, and sensitivity to cytotoxic stress. Additionally, mode and duration of alcohol delivery influence hepatic response and present unique challenges in understanding disease pathology. This review provides an overview of rodent models of ALD, their strengths and weaknesses relative to human disease states, and provides insight of the potential to develop novel rodent models to simulate the course of human ALD.

A proteomic analysis of liver after ethanol binge in chronically ethanol treated rats

Background

Binge ethanol in rats after chronic ethanol exposure augments necrosis and steatosis in the liver. In this study, two-dimensional gel electrophoresis proteomic profiles of liver of control, chronic ethanol, control-binge, and chronic ethanol- binge were compared.

Results

The proteomic analysis identified changes in protein abundance among the groups. The levels of carbonic anhydrase 3 (CA3) were decreased after chronic ethanol and decreased further after chronic ethanol-binge. Ethanol binge alone in control rats had no effect on this protein suggesting its possible role in increased susceptibility to injury by binge after chonic ethanol treatment. A protein spot, in which both cytosolic isocitrate dehydrogenase (IDH1) and glutamine synthetase (GS) were identified, showed a small decrease after chronic ethanol binge but western blot demonstrated significant decrease only for glutamine synthetase in chronic ethanol treated rats. The level of gluathione S-transferase mu isoform (GSTM1) increased after chronic ethanol but was lower after chronic ethanol-binge compared to chronic ethanol treatment. The protein levels of the basic form of protein disulfide isomerase associated protein 3 (PDIA3) were significantly decreased and the acidic forms were increased after chronic ethanol- binge but not in chronic ethanol treated rats or ethanol binge in control rats. The significant changes in proteome profile in chronic ethanol binge were accompanied by a marked increase in liver injury as evidenced by enhanced steatosis, necrosis, increased 4-hydroxynonenal labeled proteins, CYP2E1 expression, and decreased histone H2AX phosphorylation.

Conclusions

Given the role of CA3, IDH1 and GST in oxidative stress; PDIA3 in protein quality control, apoptosis and DNA repair and decreased glutamine synthetase as a sensitive marker of pericentral liver injury this proteome study of chronic ethanol-binge rat model identifies these proteins for the first time as molecular targets with potential role in progression of liver injury by binge ethanol drinking.

Effects of alcohol consumption on biomarkers of oxidative damage to DNA and lipids in ethanol-fed pigs

Chronic alcohol consumption is known to result in tissue injury, particularly in the liver, and is considered a major risk factor for cancers of the upper respiratory tract. Here we assessed the oxidative effects of subchronic ethanol consumption on DNA and lipids by measuring biomarkers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and malondialdehyde (MDA), respectively. Physiological responses of pigs (n = 4) administered ethanol in drinking water for 39 days were compared with those of water-fed pigs (n = 4). Alcoholisation resulted in serum ethanol concentration of 1.90 g L(-1) and in a moderate but significant increase in alanine aminotransferase activity, an index of liver injury. However, between the alcoholised and control groups there were no significant differences in the levels of 8-oxodG (8-oxodG per 10(6) 2'deoxyguanosine) from leucocytes (2.52 ± 0.42 Vs 2.39 ± 0.34) or from target organs, liver, cardia and oesophagus. Serum MDA levels were also similar in ethanol-fed pigs (0.33 ± 0.04 μM) and controls (0.28 ± 0.03 μM). Interestingly, levels of 8-oxodG in cardia were positively correlated with those in oesophagus (Spearman correlation coefficient R = 1, P < 0.0001). Our results suggest that alcohol consumption may not cause oxidative damage to DNA and lipids as measured by 8-oxodG and MDA, respectively. The duration of alcoholisation and the potential alcohol-induced nutritional deficiency may be critical determinants of ethanol toxicity. Relevant biomarkers, such as factors involved in sensitization to ethanol-induced oxidative stress are required to better elucidate the relationship between alcohol consumption, oxidative stress and carcinogenesis.

The protective effect of quercetin on long-term alcohol consumption-induced oxidative stress

Long-term alcohol consumption can cause oxidative stress and cytokines induction, which are associated with free radicals. Quercetin, one of the most widely distributed flavonoids in plants, is a natural antioxidant. We investigated the hypothesis that quercetin could prevent the ethanol-induced oxidative stress and decreases tumor necrosis factor-α (TNF-α) and interferon-γ (INF-γ) as pro-inflammatory cytokines. Twenty-eight rats were randomly divided into control group (C), ethanol treatment group (EtOH) (~1 ml/day, 80%; 2 g/kg body wt), intragastrically (i.g.), quercetin treatment group (Q), (100 mg/kg-body wt per 3 days) i.g. and ethanol plus quercetin treatment group (EtOH + Q) (1 ml/day, 80% of ethanol and 100 mg/kg-body wt of quercetin per 3 days) i.g. for 30 days Plasma thiobarbituric acid reactive substance (TBARS) levels and protein carbonyl content were significantly higher in the EtOH group than the C group (P < 0.01). On the other hand, TBARS level and protein carbonyl content in the EtOH + Q group was decreased significantly by quercetin (P < 0.05, P < 0.01; respectively). While GSH levels in whole blood decreased in EtOH group compared to C group, they increased significantly by quercetin (P < 0.05). Plasma ALT, TNF-α and IFN-γ levels increased significantly in the EtOH group compared to control group (P < 0.05, P < 0.01, P < 0.01, respectively), but they decreased significantly in the EtOH + Q group in comparison with EtOH group (P < 0.05, P < 0.01, P < 0.01, respectively). Our results demonstrate that quercetin treatment may provide a protection as reflected by decreased plasma TBARS, protein carbonyls, TNF-α, INF-γ and ALT levels against ethanol-induced oxidative damage.

Chronic administration of ethanol leads to an increased incidence of hepatocellular adenoma by promoting H-ras-mutated cells

This study used tissue samples from male B6C3F1 mice treated with ethanol in drinking water (0%, 2.5%, or 5%) for 4 or 104 weeks. We tested whether chronic alcohol drinking promotes oxidative stress in the liver and characterized the mutation profile of spontaneous and ethanol-induced tumors. We show that ethanol does not cause detectable oxidative stress in the liver at any time point and acts by promoting H-ras mutated cells.

Protective effects of cysteine, methionine and vitamin C on the stomach in chronically alcohol treated rats

A chronic intake of high dose alcohol may cause oxidative stress and inflammation in the stomach. It is hypothesized that cysteine-methionine and vitamin C may neutralize harmful compounds while potentiating the antioxidant capacity of the cell or tissue. The experimental animals were fed regular diets and were maintained for 90 days in the control group, the alcoholic group, which was given 2.5 g of 50% ethanol kg(-1) body wt. administered intragastrically every other day, or the alcoholic with antioxidant supplement group, to whom 2.5 g of 50% ethanol kg(-1) body wt. + a solution that contained 200 mg vitamin C, 100 mg cysteine and 100 mg methionine was administered intragastrically every other day. After the treatments, the stomach was taken for pathological and biochemical analysis. The stomach of the alcoholic group rats had higher scores of pathological findings compared with the control group, whereas the scores of the antioxidant-supplemented group were lower than the alcoholic group. In addition, the oxidized protein and lipid content in the stomachs of the alcoholic group were significantly higher than the control, but antioxidant supplementation lowered the amount of oxidation in the antioxidant supplemented group. The amount of stomach glutathione in the alcoholic group was higher than that of the control and antioxidant-supplemented groups. Interestingly, the level of total thiol in the stomach tissue of rats with antioxidant supplement was statistically higher than that of the control and alcoholic groups. In conclusion, the scores of the pathological findings in the stomach of rats with the antioxidant supplement were lower than the chronic alcohol-treated rats, albeit the amount of total thiol was increased in this group. Moreover, chronic alcohol treatment led to an increase in the level of lipid and protein oxidation in the stomach tissue of rats. A simultaneous intake of ascorbate/l-cys/l-met along with ethanol attenuated the amount of oxidation which suggested that cysteine-methionine and vitamin C could play a protective role in the stomach against oxidative damage resulting from chronic alcohol ingestion.

Beneficial effects of nicotinamide on alcohol-induced liver injury in senescence-accelerated mice

The deleterious effects of ethanol in senescence-accelerated prone 8 mice (SAMP8) and the protective role of nicotinamide (NAM) against ethanol-induced liver injury were examined. The mice were orally administered 2 g ethanol/kg BW and 200 mg or 500 mg NAM/kg BW three times/week for 10 weeks. Results showed that ethanol elevated activity of alanine aminotransferase (ALT) significantly. Ethanol also enhanced the formation of malondialdehyde (MDA) and protein carbonyls in the liver, whereas ethanol treatment resulted in significantly lower activity of hepatic glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD). Hematoxylin and eosin staining indicated moderate to severe fatty infiltration but not fibrosis. Administration of high NAM (500 mg/kg BW) led to markedly decreased levels of hepatic MDA, protein carbonyls, fatty infiltration and the activity of ALT, and increased activity of GPx, catalase and SOD in the ethanol-fed group. Thus, using SAMP8 as animal model for ethanol-induced liver injury in the aged mice, this study demonstrates that NAM is effective in protecting such damage.

Heme oxygenase-1 upregulated by Ginkgo biloba extract: Potential protection against ethanol-induced oxidative liver damage

Oxidative stress plays a pivotal role in the pathogenesis and progression of alcoholic liver disease (ALD) and HO-1 induction is suggested to protect hepatocytes from ethanol hepatotoxicity. Here, we present the data to explore the hepatoprotective effect and underlying mechanism(s) of Ginkgo biloba extract (EGB), a naturally occurring HO-1 inducer, against ethanol-induced oxidative damage. Ethanol-fed (2.4 g/kg) male rats were pretreated by EGB (48 or 96 mg/kg) for 90 days. Liver damage was evaluated by histopathology and serum aminotransferase assay. Hepatic redox parameters were measured by spectrophotometry. Heme oxygenase-1 (HO-1) expression was determined by RT-PCR and flow cytometry on mRNA and protein level, respectively. Our results showed that EGB, especially at high dose, ameliorated ethanol-induced macrovesicular steatosis and parenchymatous degeneration in hepatocytes, and decreased serum aminotransferases level. Furthermore, EGB reduced ethanol-derived glutathione depletion and lipid peroxidation, and inhibited the inactivation of superoxide dismutase, glutathione peroxidase and catalase, although EGB itself had no influence on such parameters. Importantly, EGB induced hepatic microsomal HO-1 on mRNA, protein expression and enzymatic activity, which is paralleled to the EGB-derived hepatoprotective effect. Hence, HO-1 upregulation by EGB may enhance the antioxidative capacity against the ethanol-induced oxidative stress and maintain the cellular redox balance.

Alcohol-induced oxidative stress

Alcohol-induced oxidative stress is linked to the metabolism of ethanol involving both microsomal and mitochondrial systems. Ethanol metabolism is directly involved in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). These form an environment favourable to oxidative stress. Ethanol treatment results in the depletion of GSH levels and decreases antioxidant activity. It elevates malondialdehyde (MDA), hydroxyethyl radical (HER), and hydroxynonenal (HNE) protein adducts. These cause the modification of all biological structures and consequently result in serious malfunction of cells and tissues.

Does ascorbate/L-Cys/L-Met mixture protect different parts of the rat brain against chronic alcohol toxicity?

Chronic ingestion of high levels of alcohol may cause oxidative stress that results in the formation, through alcohol metabolism, of excess free radicals, acetaldehyde, lipid and protein oxidation, and their reactivity products. These harmful molecules may trigger oxidative damage to neurons and can cause cell death. It is hypothesized that cysteine-methionine and vitamin C may neutralize these harmful compounds while potentiating the antioxidant capacity of the cell or tissue. In the present study, rats were fed regular diets and were maintained for 90 days in (1) the control group, (2) the alcoholic group, which was given 2.5 g of 50% ethanol/kg body weight administered intragastrically every other day, or (3) the alcoholic with antioxidant supplement group, to whom 2.5 g of 50% ethanol/kg body weight + a solution that contained 200 mg vitamin C, 100 mg cysteine, and 100 mg methionine was administered intragastrically every other day. The mean blood alcohol level was raised by 40% in the alcoholic group compared with the control group, but, compared with the alcoholic group, the alcohol level was decreased by 30% in the antioxidant-supplemented group. In keeping with blood alcohol levels, oxidized protein and lipid content in the cerebrum, brain stem, and cerebellum were low in the control group, higher in the antioxidant-supplemented group, and highest in the alcoholic group. The mean total thiol level was higher in the antioxidant-supplemented group than in the alcoholic and control groups. It is interesting to note that the level of total glutathione in the cerebrum and cerebellum in the alcoholic group was lower than in the control and antioxidant-supplemented groups. In conclusion, long-term alcohol administration led to increased levels of oxidized protein and lipids in the cerebrum, brain stem, and cerebellum of rats. Simultaneous intake of ascorbate/l-cys/l-met and ethanol attenuated the amount of oxidation that occurred, which suggested that cysteine, methionine, and vitamin C may play a protective role in the central nervous system against oxidative damage caused by alcohol consumption. In addition, the mean alcohol level was increased in the alcoholic group compared with the control group. The level of total glutathione was significantly decreased in the cerebellum of the alcoholic group, and oxidative damage was noted in various parts of the brain in this group. These findings suggest that oxidative stress plays a pathogenetic role in brain damage related to chronic alcoholism.

Liver injury and hepatocyte apoptosis induced by chronic alcoholic intoxication in rats

AIM: To investigate the role of hepatocyte apoptosis in the pathogenesis of alcohol-induced liver diseases (ALD) in rats.

METHODS: The rat model of liver injury was induced by combination of drinking and gastric irrigation of ethanol. The morphological changes of the liver were observed by routine HE staining under light microscope. The hepatocyte apoptosis was examined by TUNEL, and the levels of serum alanine aminotransferase (ALT) and aspartate transaminase (AST) were detected by the rate method.

RESULTS: At the end of the 5^th week, the light and moderate steatosis appeared in ethanol-treated rat livers, the proportion of fatty degeneration was 40% (8/20); At the end of the 10^th week, the proportion was increased to 85%(17/20), and the morphological changes of alcoholic hepatitis (AH) were found in 45%(9/20) rats. The serum levels of ALT and AST (nkat/L) in ethanol-treated rats were significantly higher than those of the controls (5 wk: 1 017±267 vs 550±133, P < 0.05; 1 350±333 vs 967±150, P < 0.05; 10 wk: 1 500±267 vs 767±250, P < 0.05; 2 167±533 vs 850±183, P < 0.05), and ALT and AST levels at 10 wk were also higher than those at 5 wk (P < 0.05). The TUNEL indexes (%) in at 5 and 10 wk were 0.33±0.49 and 2.03±1.61 respectively (P < 0.05), and the index at 10 wk was significantly different from that of the controls (0.10±0.21, P < 0.05). Furthermore, the TUNEL index of alcoholic hepatitis was significantly higher than that of alcoholic fatty liver (3.24±1.50% vs 1.12±0.63%, P < 0.05). Both show the significant difference.

CONCLUSION: Chronic and excessive ethanol consumption can cause liver injury in rats. The amount and time of daily ethanol intake is closely related with the degrees of liver injury. Hepatocyte apoptosis may play an important role in the pathogenesis of ALD.

Alcohol-induced oxidative stress and reduction in oxidation by ascorbate/L-cys/ L-met in the testis, ovary, kidney, and lung of rat

Chronic exposure to high doses of alcohol results in many pathophysiologic changes in cellular function caused by the alcohol itself and the effects of its metabolism (ie, generation of acetaldehyde, nicotinamide adenine dinucleotide [NADH], free radicals, and oxidative stress). However, the role of each of these effects on the testis, ovary, kidney, and lung in chronic alcoholism must be investigated. It is hypothesized that cysteine-methionine and vitamin C might neutralize harmful compounds and potentiate the antioxidant capacity of the cell or tissue. In this study, rats were fed regular diets and were maintained in the following groups for 90 days: control group; alcoholic group (2.5 g of 50% ethanol/kg body wt administered intragastrically every other day); and alcoholic with antioxidant supplement group (2.5 g of 50% ethanol plus a solution containing 200 mg vitamin C, 100 mg cysteine, and 100 mg methionine/kg body wt administered intragastrically every other day). After treatment had been completed, rat blood, testis, ovary, kidney, and lung were taken for biochemical analysis. Mean alcohol level in the alcoholic group was raised (by 40%) compared with that in the control group, but it was lower (by 30%) in the antioxidant-supplemented group than in the alcoholic group. In accordance with the levels of alcohol, oxidized protein and lipid content in the testis, ovary, kidney, and lung were low in the control group, higher in the antioxidant-supplemented group, and highest in the alcoholic group. It is interesting to note that levels of glutathione in the testis and lung of the alcoholic group were lower than those in both the control and antioxidant-supplemented groups. In conclusion, chronic alcohol administration led to a significant increase in the level of protein oxidation in the ovary and kidney of rats. Simultaneous intake of ascorbate/L-cys/L-met, along with ethanol, partly attenuated the amount of lipid and protein oxidation that occurred in tissues with oxidative stress caused by alcohol consumption.

Lipid peroxidation and antioxidant enzyme activities in erythrocytes of type I and II alcoholics

Reduced and oxidized glutathione (GSH and GSSG), protein-bound glutathione, lipid peroxidation and antioxidant enzyme activities were determined in the erythrocyte lysates and membranes of type I and II alcoholics in order to clarify the effect of age-of-onset and the duration of the alcohol consumption on erythrocyte oxidant and antioxidant status. The osmotic fragility and susceptibility of the erythrocytes to haemolysis were also determined. Erythrocyte lipid peroxidation was significantly increased but, GSH and protein-bound GSH, GSH/GSSG ratio and antioxidant enzyme activities were markedly decreased in the erythrocytes of the alcoholic subgroups. Erythrocyte count and haemoglobin content in the blood of alcoholics were found to be decreased in accordance with the finding that erythrocytes were more fragile and less resistant to haemolysis particularly in type II alcoholics. The present study showed that ethanol-induced oxidative stress in erythrocytes can lead to haemolysis and membrane-specific injuries in erythrocytes of the alcoholic subtypes.

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The "Tuebingen desiccator" system, a tool to study oxidative stress in vivo and inhalation toxicokinetics

The "Tuebingen desiccator," a gas-tight all-glass closed chamber system (CCS), has been established in Herbert Remmer's Institute of Toxicology, University of Tuebingen, to investigate the mechanisms underlying the exhalation of endogenous volatile hydrocarbons in rats under oxidative stress. Remmer and associates confirmed the former view that ethane and n-pentane were derived from polyunsaturated fatty acids, and they demonstrated that propane, n-butane and isobutane were released from amino acids. Hydrocarbons exhaled following acute ethanol treatment of rats resulted predominantly from ethanol-dependent inhibition of their metabolism and partly from oxidation of proteins. Exhalation of alkanes in carbon tetrachloride exposed rats did not reflect liver damage, which was, however, directly linked to the amount of carbon tetrachloride metabolized. As has first been shown in Herbert Remmer's institute by investigating the fate of inhaled vinyl chloride in rats, the CSS proved to be also an excellent tool for studying toxicokinetics of inhaled gaseous xenobiotics by means of gas uptake experiments. Based on results gained by such studies, it was recently demonstrated that knowledge of compound-specific physicochemical and species-specific physiological parameters are often sufficient to predict important toxicokinetic properties of inhaled chemicals such as tissue burdens at steady state. By means of the CCS, not only kinetics of a parent gaseous substance but also of gaseous metabolites can be investigated in vivo, as exemplified for ethylene oxide and 1, 2-epoxy-3-butene, metabolites of ethylene and 1,3-butadiene, respectively. Gas uptake studies in closed chamber systems are now worldwide used for determining toxicokinetic parameters relevant for physiological toxicokinetic modeling.

Vitamin E protects against alcohol‐induced cell loss and oxidative stress in the neonatal rat hippocampus

Oxidative stress has been proposed as a possible mechanism underlying nervous system deficits associated with Fetal Alcohol Syndrome (FAS). Current research suggests that antioxidant therapy may afford some level of protection against the teratogenic effects of alcohol. This study examined the effectiveness of antioxidant treatment in alleviating biochemical, neuroanatomical, and behavioral effects of neonatal alcohol exposure. Neonatal rats were administered alcohol (5.25 g/kg) by intragastric intubation on postnatal days 7, 8, and 9. A subset of alcohol-exposed pups were co-administered a high dose of Vitamin E (2 g/kg, or 71.9 IU/g). Controls consisted of a non-treated group, a group given the administration procedure only, and a group given the administration procedure plus the Vitamin E dose. Ethanol-exposed animals showed impaired spatial navigation in the Morris water maze, a decreased number of hippocampal CA1 pyramidal cells, and higher protein carbonyl formation in the hippocampus than controls. Vitamin E treatment alleviated the increase in protein carbonyls and the reduction in CA1 pyramidal cells seen in the ethanol-exposed group. However, the treatment did not improve spatial learning in the ethanol-exposed animals. These results suggest that while oxidative stress-related neurodegeneration may be a contributing factor in FAS, the antioxidant protection against alcohol-induced oxidative stress and neuronal cell loss in the rat hippocampus does not appear to be sufficient to prevent the behavioral impairments associated with FAS. Our findings underscore the complexity of the pathogenesis of behavioral deficits in FAS and suggest that additional mechanisms beyond oxidative damage of hippocampal neurons also contribute to the disorder.