Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Protective role of heme oxygenase-1 induction in carbon tetrachloride-induced hepatotoxicity

Reductive metabolism of carbon tetrachloride (CCl(4)) is thought to cause lipid peroxidation which results in hepatic injury. Heme oxygenase-1 (HO-1) (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is known to be induced by oxidative stress and to confer protection against oxidative tissue injuries. In this study, we examined the role of HO-1 induction in a rat model of CCl(4)-induced acute liver injury. CCl(4) treatment (1 mL/kg, intraperitoneally) produced severe hepatic injury in rats as revealed by significant increases in serum alanine transaminase (ALT) (EC 2.6.1.2) activity and hepatic malondialdehyde (MDA) content, severe liver cell injury, and increases in hepatic tumor necrosis factor-alpha (TNF-alpha) mRNA expression and DNA binding activity of nuclear factor-kappa B (NF-kappa B). Following CCl(4) treatment, hepatic HO-1 expression was markedly increased both at transcriptional and protein levels in hepatocytes, especially around the central vein. HO-1 induction was mediated in part through a rapid increase in microsomal free heme concentration presumably derived from hepatic cytochrome P450. Inhibition of HO activity by tin-mesoporphyrin (Sn-MP), which resulted in a sustained increase in microsomal free heme concentration, exacerbated liver injury, as judged by the sustained increase in serum ALT activity, extensive hepatocytes injuries, a more pronounced expression of hepatic TNF-alpha mRNA and an enhanced NF-kappa B activation. These findings indicate that induction of HO-1 is an adaptive response to CCl(4) treatment, and it may be critical in the recovery of hepatocytes from injury. Our findings also suggest that HO-1 induction may play an important role in conferring protection on hepatocytes from oxidative damage caused by free heme.

Clinical usefulness of edaravone for acute liver injury

BACKGROUND

Edaravone, a newly synthesized radical scavenger, has shown an excellent effect on treating stroke patients. The effect of edaravone on carbon tetrachloride (CCl4)-induced acute liver injury was examined.

METHODS

Six rats were injected with CCl4 alone and six rats were intravenously injected with edaravone immediately after and 3 h after injection of CCl4. Another six rats were injected with olive oil alone. The animals were killed at 24 h after the CCl4 injection.

RESULTS

Injection of CCl4 was followed by a marked increase in serum alanine aminotranferase (ALT) level (CCl4, 1630.6 +/- 606.8 IU/L; olive oil, 21.0 +/- 2.6 IU/L; P < 0.001), lactate dehydrogenase (LDH) level (CCl4, 5068.0 +/- 2956.4 IU/L; olive oil, 203.6 +/- 30.5 IU/L; P < 0.005), and total bilirubin (TB) level (CCl4, 0.88 +/- 0.48 mg/dL; olive oil, 0.37 +/- 0.05 mg/dL; P < 0.01), whereas in the edaravone-treated rats, the ALT (119.4 +/- 113.5 IU/L, P < 0.001), LDH (369.7 +/- 288.2 IU/L, P < 0.005), and TB values (0.29 +/- 0.16 mg/dL, P < 0.01) were significantly decreased. Histological examination of the liver by hematoxylin and eosin and oil red O staining showed a marked reduction of steatosis in the CCl4 and edaravone-treated rats compared with the CCl4-injected rats. Significant inhibition of hepatocytic apoptosis was demonstrated by the terminal deoxynucleotidyl transferase-mediated UTP nick-end labeling (TUNEL) method in the edaravone-treated rats.

CONCLUSIONS

These results suggest that edaravone has a marked preventive effect on oxidative stress-induced acute liver injury.

Protective effects of fermented filtrate from Antrodia camphorata in submerged culture against CCl4-induced hepatic toxicity in rats

The protective effects and the possible mechanisms of dry matter of fermented filtrate (DMF) from Antrodia camphorata in submerged culture (ACSC) on H(2)O(2)-induced cytotoxicity in HepG2 and carbon tetrachloride (CCl(4))-induced hepatotoxicity in Sprague-Dawley rats were investigated. The results showed that the inhibitory effect of DMF and its crude triterpenoids on lipid peroxidation occurred in a dose-response manner in an AAPH/linoleic acid system. When HepG2 cells were pretreated with DMF at the concentration of 0.10 mg/mL for 4 h and then induced by 1 h of treatment with H(2)O(2) (100 microM), lipid peroxidation was significantly (p < 0.05) decreased, as measured by the formation of malondialdehyde. The oral pretreatment with DMF [0.25 and 0.50 mg/kg of body weight (bw)] for 5 consecutive days prior to the administration of a single dose of 40% CCl(4) (0.10 mL/100 g of bw, ip) significantly prevented the increase in serum levels of hepatic enzyme markers (alanine and aspartate aminotransferase) and liver lipid peroxidation (p < 0.05). Histopathological evaluation of the rat liver revealed that DMF reduced the incidence of liver lesions, including neutrophil infiltration, hydropic swelling, and necrosis induced by CCl(4) in rats. Moreover, reduced glutathione (GSH)-dependent enzymes (glutathione peroxidase, glutathione reductase, and glutathione S-transferase) and the GSH/GSSG ratio were significantly improved in the oral pretreatment DMF of rats (p < 0.01). The results suggest that DMF may play a role in preventing oxidative damage in living systems by up-regulating hepatic GSH-dependent enzymes to preserve the normal GSH/GSSH ratio and scavenging free radicals formed during CCl(4) metabolism.

Efficacy of treatment with glycosaminoglycans on experimental collagen-induced arthritis in rats

To evaluate the antioxidant activity of the glycosaminoglycans hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S), we used a rat model of collagen-induced arthritis (CIA). Arthritis was induced in Lewis rats by multiple intradermal injections of 250 microl of emulsion containing bovine type II collagen in complete Freund's adjuvant at the base of the tail and into three to five other sites on the back. Rats were challenged again with the same antigen preparation 7 days later. Disease developed about 11 days after the second immunization. The effects of treatment in the rats were monitored by biochemical parameters and by macroscopic and histological evaluations in blood, synovial tissue and articular cartilage. Arthritis produced the following symptoms: severe periarticular erythema, edema and inflammation in the hindpaws; membrane peroxidation in the cartilage of the joints; endogenous antioxidant wasting; high tumour necrosis factor-alpha (TNF-alpha) plasma levels; and synovial neutrophil accumulation. Treatment with HYA and C4S, starting at the onset of arthritis for 10 days, limited the erosive action of the disease in the articular joints of knee and paw, reduced lipid peroxidation, restored the endogenous antioxidants reduced glutathione (GSH) and superoxide dismutase, decreased plasma TNF-alpha levels, and limited synovial neutrophil infiltration. These data confirm that erosive destruction of the joint cartilage in CIA is due at least in part to free radicals released by activated neutrophils and produced by other biochemical pathways. The beneficial effects obtained with the treatment suggest that HYA and C4S could be considered natural endogenous macromolecules to limit erosive damage in CIA or as a useful tool with which to study the involvement of free radicals in rheumatoid arthritis.

Protective mechanism of salvia miltiorrhiza on carbon tetrachloride-induced acute hepatotoxicity in rats

The purpose of this study was to investigate the possible mechanisms of Salvia miltiorrhiza (Sm) in carbon tetrachloride (CCl(4))-induced acute hepatotoxicity in rats. Male Wistar rats received a single dose of CCl(4) (2 ml/kg in corn oil, intraperitoneally). Three hours after CCl(4) intoxication, rats received either Sm (100 mg/kg) or silymarin (100 mg/kg) by gastrogavage twice a day for 2 consecutive days. CCl(4)-induced liver damage was shown by significant elevation of serum aminotransferase levels. Additionally, a significant decrease was observed in hepatic microsomal P450 2E1 protein content and hepatic concentrations of antioxidant enzymes. In contrast, rats given both Sm and silymarin supplement had less elevation of serum aminotransferase concentrations associated with less severe lobular damage of hepatocytes than rats receiving CCl(4) alone. Sm administration restored the reduction of hepatic microsomal P450 2E1 protein content as well as inducing an increase in hepatic glutathione concentration. On the other hand, administration of silymarin resulted in an elevation of hepatic superoxide dismutase levels. Moreover, both Sm and silymarin treatment inhibited the elevation of hepatic inducible nitric oxide (iNOS) protein content and nitrite concentration in liver homogenate 24 h after CCl(4) intoxication. We concluded that administration of Sm is effective in amelioration of CCl(4)-induced hepatotoxicity. This effect may be due to its ability to decrease the metabolic activation of CCl(4) by an increase in P450 2E1 protein content and its antioxidant activity associated with less increase in hepatic iNOS protein content.

Protective effect of a lignan-containing flaxseed extract against CCl(4)-induced hepatic injury

Carbon tetrachloride (CCl(4)) -induced hepatotoxicity is a commonly used model for investigating lipid peroxidation-related tissue injury. In the present study, the effect of flaxseed extract was observed on histological sections, glutathione-content and DNA strand breaks. Lignan-containing flaxseed extract (1.6 g/kg body weight/day) was daily administered with intragastric injection to rats for three days, on the fourth day, CCl(4) (2 g/kg) was intraperitoneally injected. Liver tissue was sampled at 24 hr after administering CCl(4). Liver-necrosis was observed in CCl(4)-injected rats without pretreatment of flaxseed extract. Pretreatment of flaxseed extract reduced extent of the necrosis found 24 hr after the intraperitoneal administration of CCl(4). Pretreatment of flaxseed extract protect against CCl(4)-induced decrease of reduced glutathione-content measured from reactions with 5,5'-dithiobis-(2-nitrobenzoic acid) and also protect against the elevation of DNA strand breaks in the liver cells measured by comet assay. Flaxseed-extract appears to protect liver cells against CCl(4)-induced necrosis.

Hepatoprotective effects of 18beta-glycyrrhetinic acid on carbon tetrachloride-induced liver injury: inhibition of cytochrome P450 2E1 expression

The protective effects of 18beta-glycyrrhetinic acid (GA), the aglycone of glycyrrhizin (GL) derived from licorice, on carbon tetrachloride-induced hepatotoxicity and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with GA prior to the administration of carbon tetrachloride significantly prevented an increase in serum alanine, aspartate aminotransferase activity and hepatic lipid peroxidation in a dose-dependent manner. In addition, pretreatment with GA also significantly prevented the depletion of glutathione (GSH) content in the livers of carbon tetrachloride-intoxicated mice. However, reduced hepatic GSH levels and glutathione-S-transferase activities were unaffected by treatment with GA alone. Carbon tetrachloride-induced hepatotoxicity was also prevented, as indicated by a liver histopathologic study. The effects of GA on the cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation, were also investigated. Treatment of mice with GA resulted in a significant decrease of the P450 2E1-dependent hydroxylation of p-nitrophenol and aniline in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. GA also showed antioxidant effects upon FeCl(2)-ascorbate-induced lipid peroxidation in mice liver homogenate and upon superoxide radical scavenging activity. These results show that protective effects of GA against the carbon tetrachloride-induced hepatotoxicity may be due to its ability to block the bioactivation of carbon tetrachloride, primarily by inhibiting the expression and activity of P450 2E1, and its free radical scavenging effects.

Protective effect of Platycodi radix on carbon tetrachloride-induced hepatotoxicity

The protective effects of a Platycodi radix (Changkil: CK), the root of Platycodon grandiflorum A. DC (Campanulaceae) on carbon tetrachloride (CC14)-induced hepatotoxicity and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with CK prior to the administration of CC14 significantly prevented the increased serum enzymatic activities of alanine and aspartate aminotransferase in a dose-dependent manner. In addition, pretreatment with CK also significantly prevented the elevation of hepatic malondialdehyde formation and the depletion of reduced glutathione content in the liver of CC14-intoxicated mice. However, hepatic reduced glutathione levels and glutathione S-transferase activities were not affected by treatment with CK alone. CC14-induced hepatotoxicity was also essentially prevented, as indicated by a liver histopathologic study. The effects of CK on the cytochrome P450 (P450) 2E1, the major isozyme involved in CC14 bioactivation were also investigated. Treatment of mice with CK resulted in a significant decrease of P450 2E1-dependent p-nitrophenol and aniline hydroxylation in a dose-dependent manner. CK showed antioxidant effects in FeCl2-ascorbate-induced lipid peroxidation in mice liver homogenate and in superoxide radical scavenging activity. Our results suggest that the protective effects of CK against CC14-induced hepatotoxicity possibly involve mechanisms related to its ability to block P450-mediated CC14 bioactivation and free radical scavenging effects.