Glutathione recycling is attenuated by acute ethanol feeding in rat liver

Evaluation of the effectiveness of Piper cubeba extract in the amelioration of CCl4-induced liver injuries and oxidative damage in the rodent model

Background. Liver diseases still represent a major health burden worldwide. Moreover, medicinal plants have gained popularity in the treatment of several diseases including liver. Thus, the present study was to evaluate the effectiveness of Piper cubeba fruits in the amelioration of CCl₄-induced liver injuries and oxidative damage in the rodent model. Methods. Hepatoprotective activity was assessed using various biochemical parameters like SGOT, SGPT, γ-GGT, ALP, total bilirubin, LDH, and total protein. Meanwhile, in vivo antioxidant activities as LPO, NP-SH, and CAT were measured in rat liver as well as mRNA expression of cytokines such as TNFα, IL-6, and IL-10 and stress related genes iNOS and HO-1 were determined by RT-PCR. The extent of liver damage was also analyzed through histopathological observations. Results. Treatment with PCEE significantly and dose dependently prevented drug induced increase in serum levels of hepatic enzymes. Furthermore, PCEE significantly reduced the lipid peroxidation in the liver tissue and restored activities of defense antioxidant enzymes NP-SH and CAT towards normal levels. The administration of PCEE significantly downregulated the CCl₄-induced proinflammatory cytokines TNFα and IL-6 mRNA expression in dose dependent manner, while it upregulated the IL-10 and induced hepatoprotective effect by downregulating mRNA expression of iNOS and HO-1 gene.

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.

Protective effect of Allium neapolitanum Cyr. versus Allium sativum L. on acute ethanol-induced oxidative stress in rat liver

This study investigated the protective effect of Allium neapolitanum Cyr., a spontaneous species of the Italian flora, compared with garlic (Allium sativum L.) on liver injury induced by ethanol in rats. Male albino Wistar rats were orally treated with fresh Allium homogenates (leaves or bulbs, 250 mg/kg) daily for 5 days, whereas controls received vehicle only. At the end of the experimental 5-day period, the animals received an acute ethanol dose (6 mL/kg, i.p.) 2 hours before the last Allium administration and were sacrificed 6 hours after ethanol administration. The activities of catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR) and the levels of malondialdehyde (MDA), ascorbic acid (AA), and reduced (GSH) and oxidized glutathione in liver tissue were determined. Administration of both Allium species for 5 days (leaves or bulbs) led to no statistical variation of nonenzymatic parameters versus the control group; otherwise Allium treatment caused an increase of GSH and AA levels compared with the ethanol group and a diminution of MDA levels, showing in addition that A. neapolitanum bulb had the best protective effect. Regarding to enzymatic parameters, GR and CAT activities were enhanced significantly compared with the ethanol group, whereas SOD activity showed a trend different from other parameters estimated. However, the treatment with both Allium species followed by acute ethanol administration reestablished the nonenzymatic parameters similar to control values and enhanced the activities of the enzymes measured. These results suggest that fresh Allium homogenates (leaves or bulbs) possess antioxidant properties and provide protection against ethanol-induced liver injury.

Ultrastructural changes of cornea after ethanol ingestion in Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats

PURPOSE

To compare ethanol-induced ultrastructural changes in corneas of Otsuka Long-Evans Tokushima fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats.

METHODS

Forty, five-week-old male LETO and OLETF rats were fed an ethanol-containing liquid diet (LETO alc and OLETF alc) for 11 weeks, and another forty OLETF and LETO rats were put on a pair-fed control diet (LETO con and OLETF con) for 11 weeks. The body weight and fasting blood glucose levels, and 2-hour blood glucose levels after glucose tolerance test (GTT) were checked every week. Central corneal thickness (CCT) was measured with an ultrasound pachymeter after 11 weeks. After corneal buttons were excised, transmission electron microscopy (TEM) examination was performed.

RESULTS

The CCTs in groups LETO-alc (179.39 +/- 28.64 microm) and OLETF-alc (189.46 +/- 44.44 microm) were significantly thicker than those in groups LETO-con (168.07 +/- 15.57 microm) and OLETF-con (179.28 +/- 14.68 microm) respectively (P < 0.05). The percentage of basement membrane occupied by hemidesmosome (HD/BM) in the LETO-alc (43.2 +/- 3.7%) and OLETF-alc (35.3 +/- 4.1%) was lower than that in the LETO-con (51.5 +/- 2.6%) and OLETF-con (41.6 +/- 3.5%) group respectively (P < 0.05). Descemet's membrane thickness of the LETO-alc (4.45 +/- 0.3 microm) and OLETF-alc (4.98 +/- 0.5 microm) was greater than that of the LETO-con (4.11 +/- 0.2 microm) and OLETF-con (4.57 +/- 0.3 microm) group respectively (P < 0.05). In the OLETF group, the hemidesmosomes and endothelial tight junctions were less electron-dense; interstromal edema was more prominent than that in the LETO group.

CONCLUSIONS

Corneal ultrastructural damage can develop in the pre-diabetic stage and when alcohol is ingested chronically in rats.

The effect of trans-ferulic acid and gamma-oryzanol on ethanol-induced liver injury in C57BL mouse

The effects of the oral administration of trans-ferulic acid and gamma-oryzanol (mixture of steryl ferulates) with ethanol (5.0 g per kg) for 30 days to c57BL mice on ethanol-induced liver injury were investigated. Preventions of ethanol-induced liver injury by trans-ferulic acid and gamma-oryzanol were reflected by markedly decreased serum activities of plasma aspartate aminotransferase, alanine aminotransferase and significant decreases in hepatic lipid hydroperoxide and TBARS levels. Furthermore, the trans-ferulic acid- and gamma-oryzanol-treated mice recovered ethanol-induced decrease in hepatic glutathione level together with enhancing superoxide dismutase activity. These results demonstrate that both trans-ferulic acid and gamma-oryzanol exert a protective action on liver injury induced by chronic ethanol ingestion.

The pharmacological potential of Sorbus commixta cortex on blood alcohol concentration and hepatic lipid peroxidation in acute alcohol-treated rats

The effect of Sorbus commixta cortex, a traditional herbal medicine used for the treatment of bronchitis, gastritis and dropsy, on blood alcohol concentration (BAC) and hepatic lipid peroxidation was examined in acute alcohol-treated rats. A 30-min pretreatment with a methanol extract of S. commixta cortex (SC) at concentrations higher than 200 mg kg(-1) resulted in a significant decrease in BAC and the ethyl acetate fraction (SE) of the extract showed the highest potency, with a maximum of a 46% decrease at 150 mg kg(-1) 2 h after alcohol administration (3.0 g kg(-1)) compared with the control group (P < 0.005). The rapid reduction in BAC did not appear to be due to the protection or activation of hepatic alcohol dehydrogenase (ADH) activity by SE. Hepatic malondialdehyde (MDA) levels were significantly increased by acute alcohol administration within 6 h, although pretreatment with the SE caused a significant decrease in MDA levels compared with alcohol treatment alone. Hepatic glutathione (GSH) levels and superoxide dismutase (SOD) activity remained unchanged by alcohol, SE alone or by the combined treatment of alcohol and SE. However, catalase activity was significantly reduced by acute alcohol administration and pretreatment with the SE led to significant protection of its activity. These results suggest that pretreatment with SE reduces hepatic lipid peroxidation by decreasing the bioavailability of alcohol and its oxidative metabolites, such as H2O2, at least partly, through the protection of hepatic catalase in acute alcohol-treated rats.

Ethanol administration generates oxidative stress in the pancreas and liver, but fails to induce heat-shock proteins in rats

BACKGROUND

Heat-shock proteins (HSP) play an essential role in the sequestration and reparation of denatured cellular proteins. Because ethanol treatment can result in oxidative stress-induced protein damage, it is possible that expression of HSP is altered after ethanol consumption. Dose-response and time-course studies were performed to investigate whether acute and chronic intragastric ethanol administration can induce tissue damage, oxidative stress and expression of the heat-shock proteins HSP60 and HSP72 in the pancreas and liver of male Wistar rats.

METHODS

Laboratory and morphological analysis of pancreatic and liver damage were investigated. The degree of oxidative stress was assessed by measurement of the reduced glutathione content, lipid peroxidation and protein oxidation. The levels of HSP were examined by western blot analysis.

RESULTS

Ethanol administration dose- and time-dependently elevated the serum ethanol concentration and hepatic enzyme activities. Chronic ethanol treatment also resulted in morphological damage of the liver. We observed that acute and chronic ethanol consumption had markedly different effects on the oxidative parameters in the pancreas and liver. Acute ethanol administration caused oxidative stress in the liver, whereas there was no such effect in the pancreas. In contrast, chronic ethanol feeding resulted in oxidative stress in both the pancreas and the liver. Furthermore, neither acute nor chronic ethanol intake induced the synthesis of HSP, a major defense system against cellular damage in the examined organs.

CONCLUSION

Ethanol administration generates oxidative stress in the pancreas and liver, but fails to induce HSP in rats.

Effect of zinc on hepatic lipid peroxidation and antioxidative enzymes in ethanol-fed rats

A 3-ml aliquot of 30% ethanol was fed daily to normal as well as zinc-treated (227 mg l(-1)) rats for periods of 2, 4 and 8 weeks. A highly significant increase in the levels of hepatic lipid peroxidation was observed in ethanol-fed rats after 4 and 8 weeks of treatment. On the other hand, the levels of lipid peroxidation came down significantly following ethanol feeding to zinc-treated rats. The activities of glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) in liver were elevated significantly after ethanol administration to rats for durations of 2, 4 and 8 weeks. Interestingly, zinc treatment to rats given ethanol was able to bring down the elevated levels of SOD, catalase and GPx to within normal limits, However, zinc administration alone did not cause any significant alteration in the activities of these antioxidative enzymes.

Ethanol enhances the formation of endogenously and exogenously derived adducts in rat hepatic DNA

To investigate the role of ethanol in chemically-induced carcinogenesis, we exposed Wistar rats to ethanol, either as an acute dose or for prolonged periods in a liquid diet and looked for effects on endogenously and exogenously derived DNA adducts. Changes in the cytochrome P450 protein (CYP 2E1) and its catalytic demethylase activity were also followed in order to provide a sequence of relatively well understood changes that are associated with free radical production and, therefore, potentially capable of affecting DNA. The exocyclic DNA adducts, ethenodeoxyadenosine (varepsilondA) and ethenodeoxycytidine (varepsilondC), known to arise from oxidative stress and lipid peroxidation (LPO) sources, were detected in the liver DNA of Wistar rats at background concentrations of 4-6 (varepsilondA) and 25-35 (varepsilondC) adducts per 10(9) parent bases. When rats were given either an acute dose of ethanol (5g/kg, i.g.) or exposed for 1 week to ethanol in a liquid diet (5%, w/v), etheno adduct levels were increased approximately 2-fold and this was statistically significant for varepsilondC (P<0.05 and P<0.02, respectively) for the two separate treatments.In N-nitrosodimethylamine (NDMA)-treated rats, acute ethanol treatment significantly increased the level of O(6)-methylguanine (O(6)-MeG) in hepatic DNA and this was paralleled by a decrease in O(6)-alkylguanine DNA alkyltransferase (ATase) activity; immunohistochemistry confirmed this increase of O(6)-MeG in both hepatic and renal nuclei. When rats were given ethanol in the diet and treated with NDMA, O(6)-MeG levels in hepatic DNA increased at 1 week which coincided with the peak of CYP 2E1-dependent NDMA-demethylase activity. Single cell gel electrophoresis of liver cells showed that after 1 week of exposure to ethanol, there was a small but significant increase in the frequency of DNA strand breaks induced by NDMA (P<0.05); after 4 weeks the increase was 1.4-fold (P<0.01). Our results indicate that exposures to ethanol, which resulted in blood ethanol concentrations similar to those seen in chronic alcoholics and increased levels of expression of the CYP 2E1 protein can exacerbate the DNA damaging effects of endogenous and exogenous alkylating agents. These observations provide indications of possible mechanisms for the carcinogenic or co-carcinogenic action of ethanol.

Dose response of ethanol on antioxidant defense system of liver, lung, and kidney in rat

This study investigated the alterations in levels of glutathione, lipid peroxidation, and antioxidant enzyme activity in the liver, lung, and kidney of rats treated with acute doses of ethanol. Male Fisher-344 rats were randomly divided into four groups, and were treated as follows: (1) vehicle (saline) control; (2) ethanol 2 g/kg, p.o.; (3) ethanol 4g/kg, p.o.; and (4) ethanol 6 g/kg, p.o. The animals were sacrificed 1 h after treatment, and tissues were isolated and analyzed. The hepatic GSH levels significantly decreased (73, 68, and 66% of control) due to ethanol ingestion at 2, 4, and 6g/kg, respectively. The hepatic GSH/GSSG ratio also decreased with increasing doses indicating stress response due to ethanol. The hepatic SOD activity significantly decreased (70, 75 and 71% of control) with graded doses of ethanol ingestion. The hepatic CAT/SOD and GSH-Px+CAT/SOD ratios significantly increased (147, 169 and 177% of control) and (140, 167 and 178% of control), respectively with increasing doses of ethanol. In the lung, graded doses of ethanol increased GSH-Px activity (120, 114 and 141% of control) and decreased GR activity (98, 89 and 89% of control), respectively. The MDA concentrations in the lung also increased after higher ethanol ingestion. Most of the antioxidant enzyme ratios increased with increasing doses of ethanol in the lung. In the kidney, GSH-Px activity increased (139, 119 and 151% of control), whereas GR activity decreased (84, 85 and 83% of control). GSH-Px/SOD and GSH-Px+CAT/SOD ratios increased whereas GR/GSH-Px ratio decreased after graded doses of ethanol. GSH levels in the kidney decreased after ethanol ingestion. MDA concentrations increased with increasing dose of ethanol in the kidney. These results showed the dose dependant and tissue specific changes in the antioxidant system after ethanol ingestion. Ethanol exerts oxidative stress on antioxidant systems of liver, lung and kidney in proportion to the amount of ethanol ingestion.