Protection against carbon tetrachloride hepatotoxicity by pretreatment with indole-3-carbinol

The effects of administering indole-3-carbinol (I-3-C) on carbon tetrachloride (CCl4)-induced hepatotoxicity were examined. Mice received by gavage 0-150 mg I-3-C/kg body wt in methanol-extracted corn oil, followed 1 h later by 15 microliters CCl4/kg body wt in corn oil. Animals were sacrificed 24 h after receiving CCl4. Pretreatment with I-3-C reduced the degree of centrolobular necrosis, as observed histologically. Additionally, CCl4-mediated elevated serum enzymes were reduced by I-3-C. Although I-3-C induced elevated levels of cytochrome P-450 and associated mixed-function oxidase activity, the CCl4 depression of these parameters was not clearly reversed by I-3-C. However, CCl4 produced decreases in hepatic levels of glutathione (GSH), total reducing equivalents, and protein sulfhydryls, all of which were restored to control levels by I-3-C. Using mouse liver microsomes in an NADPH-fortified reaction mixture, I-3-C inhibited, in a concentration-dependent manner, CCl4-initiated lipid peroxidation, with 50% inhibition at 35-40 microM I-3-C. When mice were treated by gavage with 50 mg [14C]I-3-C/kg body wt, concentrations of radiolabel in the liver were greater than 100 microM after 1 hr. This was five times the level of radioactivity measured in blood and three times the concentration of I-3-C necessary for 50% inhibition of CCl4-mediated lipid peroxidation in vitro. The data are consistent with the hypothesis that I-3-C intervenes in CCl4-mediated hepatic necrosis by combining with reactive free radical metabolites of CCl4, thereby protecting critical cellular target sites.     

The effect of a dose of dimethylnitrosamine on the toxicity of a subsequent dose and on the toxicity of carbon tetrachloride in mice.

Mice were given a first dose of dimethylnitrosamine (DMN) and the LD50 of a second dose determined at various times later. The total dose (sum of the 2 doses) tolerated under these conditions increased slowly as the interval between the 2 doses increased, to a maximum that was maintained until the 6th day. The LD50 of the second dose then returned slowly to normal by the 10th day. The data suggest that the biochemical lesion in DMN induced liver necrosis developed relatively slowly.     

Effect of tryptophan on toxic cirrhosis induced by intermittent carbon tetrachloride intoxication in the rat

The effects of the administration of tryptophan on toxic cirrhosis induced by intermittent carbon tetrachloride (CCl4) intoxication in the rat were investigated. Rats received CCl4 (0.45 ml/100 g body wt ip) twice weekly for 10-14 weeks. Tryptophan (30 mg/100 g body wt) by stomach tube was administered 1 hr before killing. Tryptophan improved hepatic polyribosomal aggregation and [14C]leucine incorporation into protein in vitro of control rats as well as long-term CCl4-treated rats that had developed toxic cirrhosis. However, the effects were more marked in control than in experimental rats. Tryptophan administration induced an increase in labeled nuclear RNA release in vitro and a decrease in labeled tryptophan binding to nuclear protein in vitro of livers of rats receiving long-term CCl4 and of control rats. The results indicate that the stimulatory effects of a single administration of tryptophan in toxic cirrhotic livers are similar to, but somewhat less than, those which occur in livers of normal, control rats.     

Diverse mechanisms of hepatocellular injuries due to chemicals: evidence in rats administered carbon tetrachloride or dimethylnitrosamine.

Differences in acute hepatotoxicity of carbon tetrachloride (CCl4) and dimethylnitrosamine (DMN) have been tested in normal foetal, newborn and adult rats, foetal, newborn and adult rats pretreated with phenobarbitone and partially hepatectomized adult rats. While CCl4 is non-toxic to the foetal and newborn liver, DMN induces identical necrosis at all ages. Prior dosing with phenobarbitone augments CCl4 toxicity only in the adult and the newborn but the foetus continues to be resistant. Such pretreatment, on the other hand, significantly reduces the effects of DMN on liver in all animals. Partial hepatectomy makes the liver less susceptible to CCl4 and more so to DMN. Such diversities of hepatic response to the two toxins can be accounted for by the levels of the respective toxifying enzymes in the liver cell in different situations.     

Hypericum perforatum protects against hepatic injury induced by carbon tetrachloride

Extracts of Hypericum perforatum (St. John’s wort) have gained much interest for their antidepressant effects. The aim of the present study was to investigate the effect H. perforatum on the development of liver injury induced by treatment with carbon tetrachloride (CCl₄) in rats. Liver damage was induced by administration of carbon tetrachloride (2.8?ml/kg in olive oil). H. perforatum (25, 50, and 100?mg/kg) alone or combined with silymarin (25?mg/kg) was given once daily orally simultaneously with CCl₄ and for 14?days thereafter. Liver damage was assessed by determining serum enzyme activities and hepatic histopathology. In CCl₄-treated rats given H. perforatum at 25?mg/kg per day for 2?weeks, the elevations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in serum were significantly less than in the CCl₄ control group. Serum ALT level decreased by 14.4% and AST level by 16.6% of their corresponding control value, respectively. Serum alkaline phosphatase (ALP) level was not significantly reduced by H. perforatum at 25?mg/kg. The addition of silymarin at the dose of 25?mg/kg to H. perforatum resulted in further decrease in liver enzymes compared with H. perforatum treatment alone. Serum ALT decreased by 40.2%, AST by 37.9%, and ALP by 38.1% of the control value, respectively, after combining H. perforatum at 25?mg/kg and silymarin. On the other hand, treatment with H. perforatum at 50 or 100?mg/kg reduced serum ALT levels by 37.9–52.6%, AST levels by 30.2–53.2%, and ALP by 48.5–51.5%, respectively. Silymarin given in combination with the above doses of H. perforatum reduced serum ALT by 58.7–63.3%, AST by 56.6–60.9%, and ALP levels by 54.7–58.8%, respectively. Meanwhile, silymarin alone decreased serum ALT by 56.8%, AST by 62.6%, and ALP levels by 55.1%, respectively. The administration of CCl₄ resulted in marked increase in nitric oxide level in serum (the concentrations of nitrite/nitrate) as compared to the normal group. Treatment with H. perforatum resulted in a dose-dependent decrease in serum nitric oxide level compared with the CCl₄ control group. Blood levels of reduced glutathione were markedly decreased in CCl₄-treated rats. Reduced glutathione levels were increased significantly by 100?mg/kg H. perforatum and restored to near normal values by silymarin treatment. Histopathological examination also indicated that CCl₄-induced liver injury was less severe in the H. perforatum-treated groups. Taken together, the present results show that H. perforatum reduces the extent of hepatic injury caused by CCl₄ in rats and this effect is increased by co-administration of silymarin. This suggests the beneficial effect of silymarin administration to depressed patients with liver disease treated with H. perforatum.     

Danshensu-mediated protective effect against hepatic fibrosis induced by carbon tetrachloride in rats

The culprit of hepatic fibrosis (HF) is linked to suprathreshold deposition of collagen. Thus, collagen reduction by improved metabolism contributes to HF management. In this study, we aimed to investigate the hepatoprotective effects of Danshensu (DSS) against carbon tetrachloride (CCl₄)-induced HF rats. The results showed that DSS-administrated rats resulted in decreasing in hepatosomatic indexes, and lowering serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Meanwhile, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) were increased, while the content of malonaldehyde (MDA) was lessened in liver tissue of DSS administration group. In addition, the pro-fibrotic markers of hydroxyproline (Hyp), type III procollagen (PCIII) and hyaluronic acid (HA) contents were decreased. Histopathological examination confirmed that the hepatotoxicity in CCl₄-injured rats was alleviated following the DSS administration. Furthermore, intrahepatic protein expressions of alpha-smooth muscle actin (α-SMA), phosphorylated JAK2 (p-JAK2) and phosphorylated STAT3 (p-STAT3) were effectively down-regulated, respectively. Overall, this work demonstrates that DSS played the protective effect against CCl₄-induced cytotoxicity in liver tissue, which the probable mechanism is associated with attenuation of lipid peroxidation, collagen accumulation and enhancement of anti-oxidative defense capability, as well as regulation of intrahepatic JAK/STAT pathway for maintaining collagenic homoeostasis.     

Potentiation of carbon tetrachloride hepatotoxicity by hypoxia.

To determine the cause of hepatic injury in patients with hypoxaemia, the persistence of liver susceptibility to toxic injury after hypoxia was investigated in rats. Centrilobular necrosis and marked elevation of serum glutamic-pyruvic transaminase (SGPT) and serum glutamic-oxaloacetic transaminase (SGOT) activities were induced by carbon tetrachloride (0.1 ml/kg body weight) given in the period between 3 h before and 21 h after exposure to 7% oxygen for 3 h. This observation, that a short period of hypoxia results in a prolonged sensitivity to carbon tetrachloride-induced liver injury, has not been described previously. The mechanism of the phenomenon is obscure. These observations suggest that the hepatic injury in patients with hypoxaemia may be caused not only by the hypoxia per se or chemicals administered before or during hypoxia, but also by chemicals given within 24 h of hypoxaemia.     

Acute liver toxicity by carbon tetrachloride in HSP70 knock out mice

The effects of carbon tetrachloride (CCl(4)) treatment on acute liver damage in knock out (heat shock proteins -- HSP70-/-) mice and wild-type (C57BL/6) mice were examined. Acute liver injury was induced by a single intraperitoneal injection of 0.3 ML/kg CCl(4) in olive oil. Mice were sacrificed at 12, 24, 48 and 72 h after treatment. To assess hepatotoxicity, alanine transaminase, neutrophil infiltration and degree of necrosis were measured. Western blot analysis was employed for heat shock proteins. The result revealed that HSP70-/- mice showed higher alanine transaminase levels and a more severe degree of neutrophilic infiltration and necrosis than those of wild-type mice. Furthermore, HSP70-/- mice recovered more slowly from CCl(4) treatment. In HSP70-/- mice, HSP47 was overexpressed. Therefore, HSP70-/- mice could be an adequate model of acute liver toxicity study.     

Protection of mice against mouse hepatitis virus by Corynebacterium parvum.

C57BL/6 mice that are highly susceptible to infection with mouse hepatitis virus type 3 were protected against intraperitoneal viral infection by simultaneous intraperitoneal injection of Corynebacterium parvum. No protection was observed when C. parvum was given intravenously or when it was injected intraperitoneally 3 days before viral infection. Protective effects were, however, consistently found when C. parvum was given 2 h before or 2 h after viral infection. Activity was seen only against 10 50% lethal doses and not against 100 50% lethal doses. C. parvum also caused a significant decrease of virus type 3. These data suggest a direct effect of C. parvum on virus-susceptible cells. Injection of C. parvum in mice caused activation of natural killer (NK) cells and of interferon production. However, these two effects were equally demonstrable at high and low doses of C. parvum, whereas protection against mouse hepatitis virus type 3 was not demonstrable at low doses of C. parvum. Thus, antiviral protection may be dissociated from activation of NK cells and induction of interferon.     

含硒藻蓝蛋白抗小鼠实验性肝损伤的作用

目的:观察含硒藻蓝蛋白(Se-SPC)对四氯化碳(CCl₄)致小鼠急性肝损伤的拮抗作用。方法:以2%CCl₄油灌胃复制小鼠急性肝损伤模型,各组分别腹腔注射Se-SPC、藻蓝蛋白(SPC)、无机硒(Se)7d,测定血及肝组织中Se、谷胱甘肽过氧化物酶(GPx)、超氧化物歧化酶(SOD)、丙二醛(MDA)、谷丙转氨酶(ALT)、一氧化氮(NO)水平,分析Se-SPC、SPC、无机Se对上述指标的影响。结果:Se-SPC组比CCl₄组血和肝中Se、GPx、SOD水平显著增高(P<0.05),血ALT、血和肝中MDA及NO₂^-/NO₃^-水平显著降低(P＜0.05),高剂量Se-SPC组对Se含量、GPx、MDA、NO₂^-/NO₃^-等指标的影响更为显著(P＜0.01),在相同蛋白或硒剂量下,Se-SPC组比SPC组和无机Se组对上述指标作用更大。相关分析发现小鼠血Se水平与GPx活性呈显著正相关(r=0.705),血GPx活性与MDA、NO₂^-/NO₃^-、ALT水平呈明显负相关(r=－0.629,r=－0.336,r=－0.457),血ALT活性与MDA及NO₂^-/NO₃^-呈显著正相关(r=0.519,r=0.641)。结论:Se-SP可能结合增高硒酶活性及抗炎双重功效,对CCl₄致小鼠肝脏的氧化损伤具有拮抗作用。     

Responses of fatty livers of mice to carbon tetrachloride

Female mice of the Taconic Swiss stock were fed one of the three diets described below then injected subcutaneously with 0.035 cm³CCl₄/100 gm body weight in a mineral oil solution. One group was fed an adequate commercial laboratory ration, then mice were killed 12, 24 and 48 hours after CCl₄; another a cholinedeficient, high-fat, low-protein diet for 14 days, then injected with CCl₄, and killed 12, 24 and 48 hours later; and another group, a choline-supplemented (2 gm choline chloride/100 gm diet), high-fat, low-protein diet for 14 days, then injected with CCl₄ and killed 24 hours later. In the group fed the normal diet, the polyhalogen produced within 24 hours the expected centrolobular necrosis and glycogen depletion, involving one-third to one-half of the lobular areas. In fatty livers produced by feeding the choline-deficient diet, necrosis at 24 hours post injection was limited in a majority of instances to a zone one or two cells thick immediately surrounding the central vein. Despite this decreased necrosis in fatty livers centrolobular glycogen depletion still involved one-third to one-half of lobules and there was an infiltration of inflammatory cells immediately adjacent to the central vein. The hepatic necrosis at 12 and 48 hours paralleled that in the normal dietary group. Feeding of the choline-supplemented, high-fat, low-protein diet for two weeks produced an extremely limited parenchymal liposis. In such relatively non-fatty livers CCl₄ produced hepatic necrosis comparable to that in mice receiving normal diets. The extent of protection from the necrogenic actions of CCl₄ was clearly associated with extensive intracytoplasmic liposis of hepatic parenchyma.     

Protection against herpes simplex virus infection in mice by Corynebacterium parvum.

Corynebacterium parvum administered in mice prior to herpes simplex virus (HSV) infection significantly protected them against lethal encephalitis. This was seen both with a mouse strain highly susceptible to HSV and with one relatively resistant to HSV. Mice immunosuppressed by cyclophosphamide and showing an increased mortality after HSV infection were also protected by C. parvum pretreatment. However, C. parvum given simultaneously with or after HSV infection did not exert a therapeutic effect.     

Protection of mice against Giardia muris infection.

Strains of mice showing relatively rapid (BALB/c) and defective (C3H/He) spontaneous elimination of Giardia muris displayed marked differences in the degree of resistance to infection induced by prior injection of trophozoites in Freund complete adjuvant.