Reduction by pretreatment with dibenamine of hepatotoxicity induced by carbon tetrachloride, thioacetamide or dimethylnitrosamine

Pretreatment with dibenamine (25 mg/kg sc 48 and 24 hr before the administration of a hepatotoxic agent) protected rats against the hepatotoxicity of CCl₄, thioacetamide, or dimethylnitrosamine, but not against allyl alcohol or bromobenzene. Protection was evident from reduced activity of plasma glutamic-pyruvic transaminase and reduced liver necrosis as demonstrated by histologic evaluations. In rats pretreated with dibenamine, LD50 values for CCl₄ and thioacetamide were elevated and liver triglycerides after CCl₄ and dimethylnitrosamine were reduced. Dibenamine protection against hepatotoxicity did not correlate with alpha-adrenergic receptor blockade. Similar pretreatment with 3 other alpha-adrenergic blocking agents, tolazoline, phenoxybenzamine, and EEDQ (N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline), failed to protect rats against CCl₄-induced hepatotoxicity.     

Antidotal effects of deferrioxamine in experimental liver injury--role of lipid peroxidation

Pretreatment with deferrioxamine (DFO, 125-500 mg/kg i.p.) protected male mice against CCl4- or CBrCl3-induced hepatotoxicity which is closely related to an inhibition of iron-dependent lipid peroxidation monitored by ethane exhalation. For allyl alcohol, 1,1-dichloroethylene, dimethylnitrosamine, thioacetamide, bromobenzene and paracetamol no hepatoprotection was achieved with DFO indicating that lipid peroxidation is not involved as a primary mechanism of toxicity. In the case of bromobenzene a marked in vivo lipid peroxidation was observed, which was unaffected by DFO and appears therefore to be iron-dependent.     

Potentiation of CCl4 of hepatotoxicity in rats by a metabolite of 2-butanone: 2,3-butanediol

The role of ketone metabolism in 2-butanone-induced potentiation of carbon tetrachloride (CCl₄) hepatotoxicity was studied in rats. The blood concentrations of 2-butanol, 3-hydroxy-2-butanone and 2,3-butanediol were determined by gas chromatographic analysis after the oral administration of 2-butanone (2.1 ml/kg). The concentrations of 2-butanol, 3-hydroxy-2-butanone and 2,3-butanediol detected 4 h after dosing were 3.2 mg/100 ml, 2.4 mg/100 ml and 8.6 mg/100 ml, respectively. Eighteen hours after 2-butanone, the concentration of 2,3-butanediol rose to 25.6 mg/100 ml, while the concentrations of 2-butanol and 3-hydroxy-2-butanone declined to 0.6 mg/100 ml and 1.4 mg/100 ml, respectively. A 16-h pretreatment with either 2-butanone (2.1 ml/kg, p.o.) or 2,3-butanediol (2.12 ml/kg, p.o.) markedly enhanced the hepototoxic response to CCl₄ (0.1 ml/kg, i.p.), as measured by serum glutamic pyruvic transaminase activity and hepatic triglyceride content. In vivo, limited formation of 3-hydroxy-2-butanone occurred after this dose of 2,3-butanediol. These data suggest that the production of 3-hydroxy-2-butanone and 2,3-butanediol via 2-butanone metabolism may participate in the augmented necrogenic effect of CCl₄ seen after pretreatment with 2-butanone.     

The influence of ethanol pretreatment on the effects of nine hepatotoxic agents

The hepatotoxic effects of carbon tetrachloride (0.01 ml/kg i.p.), thioacetamide (50 mg/kg intraperitoneally), paracetamol (0.5 g/kg intraperitoneally), and allyl alcohol (0.05 ml/kg intraperitoneally) as estimated by determination of serum enzyme activities (GOT, GPT, SDH) were enhanced in mice treated with one oral dose of 4.8 g/kg ethanol 16 hrs. previously. Pretreatment of mice with ethanol did not increase the hepatotoxic actions of bromobenzene (0.25 ml/kg intraperitoneally), phalloidin (1.5 mg/kg intraperitoneally), alpha-amanitin (0.75 mg/kg intraperitoneally), and praseodymium (12 mg/kg intravenously) though there was a trend to higher enzyme activities in the case of bromobenzene. In guinea-pigs ethanol also aggravated CCl4-induced liver damage, but only strengthened the hepatotoxic activity of D-galactosamine (150 mg/kg intraperitoneally). Treatment with 4.8 g/kg ethanol did not influence liver glutathione levels in mice but increased aniline hydroxylation in the 9000 x g liver homogenate supernatant of mice and guinea-pigs. A dose of 2.4 g/kg ethanol, on the other hand, neither increased aniline hydroxylase activity nor enhanced carbon tetrachloride-induced hepatotoxicity in mice. It is assumed that the enhanced sensitivity to hepatotoxic agents after treatment with ethanol may be due to an enhanced microsomal activation of these substances.     

Effect of dithiocarb on metabolism and covalent binding of carbon tetrachloride.

Rat liver microsomes catalyze covalent binding of ¹⁴CCl₄ metabolites to the microsomal protein; this binding was inhibited by dithiocarb at an I50 of 2.3 × 10^?5m. With mouse liver microsomes, the I50 was 6 × 10^?5m. The inhibiting potency of dithiocarb on the metabolic activation of carbon tetrachloride was comparable to that of 1-naphthyl-4(5)-imidazole, and was much greater than that of benzothiadiazoles or of SKF 525-A. In vivo, the effect of dithiocarb on the metabolic transformation of carbon tetrachloride was studied in rats and mice exposed to CCl₄ vapor in a closed system. Dithiocarb effectively inhibited metabolic elimination of carbon tetrachloride at a dose of 100 mg/kg. The data suggest that the proven antagonism of dithiocarb with the hepatotoxic effects of carbon tetrachloride should be related to inhibition of metabolic activation of the latter.     

Effects of dithiocarb and (+)-catechin against carbon tetrachloride-alcohol-induced liver fibrosis

Treatment of male rats with carbon tetrachloride (CCl4, 2 x weekly 0.2 ml/kg p.o.) and a 5% alcohol solution, instead of drinking water, for 4 weeks led to marked increases in serum enzyme activities (GOT, GPT, SDH), hepatic triglyceride and hydroxyproline content. Diethyl dithiocarbamate (dithiocarb, 200 mg/kg p.o.) simultaneously applied with CCl4 totally suppressed the elevation in serum enzyme activities and hepatic hydroxyproline concentration, and partially suppressed that of the triglyceride content. (+)-Catechin (50-300 mg/kg p.o.) simultaneously applied with CCl4 had no influence on the enhanced serum enzymes, but depressed the augmented content of both hepatic triglyceride and hydroxyproline in a dose-dependent way. The most effective dose with respect to the reduction of the hydroxyproline concentration was 100 mg/kg (+)-catechin; the highest dose (300 mg/kg), however, enhanced the CCl4-alcohol-induced hydroxyproline augmentation.     

Studies on protective effect of DA-9601,Artemisia asiatica extract, on acetaminophen- and CCI4-induced liver damage in rats

The hepatoprotective effect of DA-9601, a quality-controlled extract ofArtemisia asiatica, on liver damage induced by acetaminophen (APAP) and carbon tetrachloride (CCI₄) was investigated by means of serum-biochemical, hepatic-biochemical, and histopathological examinations. Doses of DA-9601 (10, 30, or 100mg/kg) were administered intragastrically to each rat on three consecutive days i.e. 48 h, 24 h and 2 h before a single administration of APAP (640 mg/kg, i.p.) or CCl₄ (2 ml/kg, p.o.). Four h and 24 h after hepatotoxin treatment, the animals were sacrificed for evaluation of liver damage. Pretreatment of DA-9601 reduced the elevation of serum ALT, AST, LDH and histopathological changes such as centrilobular necrosis, vacuolar degeneration and inflammatory cell infiltration dose-dependently. DA-9601 also prevented APAP- and CCl₄-induced hepatic glutathione (GSH) depletion and CCl₄-induced increase of hepatic malondialdehyde (MDA), a parameter of lipid peroxidation, in a dose-dependent manner. These findings suggest that pretreatment with DA-9601 may reduce chemically induced liver injury by complex mechanisms which involve prevention of lipid peroxidation and preservation of hepatic GSH.     

The curative effects of cysteamine,cysteine, and dithiocarb in experimental paracetamol poisoning

In a curative test (i.p. injection 1 hr after administration of paracetamol) cysteamine (100 mg/kg), cysteine (200 mg/kg), and dithiocarb (100 mg/kg) reduced the death rate from paracetamol poisoning (1.5g/kg p.o.) in male mice from 67 to 10, 15 or 10%, respectively. A reduction of mortality rate to 30 or 35% was induced by glutathione (100 mg/kg) and thiazolidine carboxylic acid (50 mg per kg), respectively, whereas penicillamine, thioctic acid, silymarin, and dimercaprol were ineffective. When given 2 or 4 hrs after paracetamol, cysteine, unlike cysteamine, had a curative effect on paracetamol toxicity.Hepatotoxic activity of paracetamol (0.5 g/kg p.o.) was evident by high increases in the levels of serum enzymes (GOT, GPT, GLDH, SDH). Paracetamol-induced enzyme elevations were prevented completely by treatment with cysteamine (50 mg/kg) or cysteine (100 mg/kg) and partially by treatment with dithiocarb (100 mg/kg) 1 hr after paracetamol. LD₅₀ values (i.p. injection) were 450 mg per kg for cysteamine, 660 mg/kg for cysteine, and 1800 mg/kg for dithiocarb. With regard to the therapeutic index cysteamine, cysteine, and dithiocarb can be recommended as antidotes for paracetamol poisoning.A nearly total depletion of hepatic glutathione occurred after paracetamol (0.5 g/kg p.o.). Administration of cysteine (100 mg/kg), one hr after paracetamol, induced a complete repletion of liver glutathione whereas cysteamine (100 or 200 mg/kg) and dithiocarb (100 mg/kg) induced a partial repletion. Glutathione repletion probably accounts for the antidote efficiency of cysteine, cysteamine, and dithiocarb. Its mechanism, however, remains obscure.     

Hepatoprotection by malotilate against carbon tetrachloride-alcohol-induced liver fibrosis

Subchronic treatment of male rats with carbon tetrachloride (CCl4, twice weekly 0.2 ml/kg p.o.) and feeding a 5% alcohol solution instead of drinking water led to a nearly complete liver cirrhosis in all animals within 4 weeks. This was also documented by a three fold increase in hepatic total hydroxyproline content. Steatosis was quantified by enhanced liver triglyceride concentrations and acute necroses by increments of serum enzyme activities (GPT, SDH). Daily oral treatment with malotilate (100 mg/kg) totally prevented the development of liver cirrhosis, hepatic hydroxyproline accumulation and increases in serum enzyme activities induced by CCl4-alcohol. In cianidanol-treated rats (100 mg/kg p.o.) only portoseptal fibrosis was seen, however hydroxyproline and triglyceride accumulation as well as enhanced serum enzyme activities were not suppressed. D-penicillamine (300 mg/kg p.o.) and colchicine (50 micrograms/kg i.p.) failed to protect rats against CCl4-alcohol induced fibrosis, necrosis and steatosis in this model.     

Protective effects of Digera muricata (L.) Mart. on testis against oxidative stress of carbon tetrachloride in rat

Oxidative stress induced by carbon tetrachloride (2 ml/kg body weight i.p.) in rat substantially decreases the increase in body weight and relative testis weight. It also markedly increases the level of TBARS and nitrites along with corresponding decrease in reduced glutathione and various antioxidant enzymes in testis, i.e., catalase, peroxidase, superoxide dismutase and glutathione peroxidase. Serum level of testosterone, luteinizing hormone and follicle stimulating hormone was significantly decreased while estradiol and prolactin were increased with carbon tetrachloride treatment. Histopathology of CCl₄-treated rats indicated the partial degeneration of germ and Leydig cells along with deformities in spermatogenesis. Supplementation of Digera muricata (100, 150, 200 mg/kg body weight orally) once a week for 16 weeks results in decrease of TBARS and nitrite, while increase in antioxidant enzymes; catalase, peroxidase, superoxide dismutase, GSH-Px and GSH contents. Serum level of testosterone, luteinizing hormone, follicle stimulating hormone, estradiol, prolactin, histology, body weight and relative testis weight was also concomitantly restored to near normal level by D. muricata supplementation to carbon tetrachloride intoxicated rat. The results clearly demonstrate that D. muricata treatment augments the antioxidants defense mechanism against carbon tetrachloride induced toxicity and provides evidence that it may have a therapeutic role in free radical mediated diseases.     

Effect of aging on liver glutathione levels and hepatocellular injury from carbon tetrachloride, allyl alcohol or galactosamine

Severity of liver damage 24 hr after i.p. administration of carbon tetrachloride (0.2 ml/kg), allyl alcohol (0.036 ml/kg) or galactosamine (400 mg/kg) was evaluated in male rats at 4-5, 14-15 or 24-25 months of age. Allyl alcohol hepatotoxicity, as judged by light microscopy and serum alanine aminotransferase levels, increased markedly as a function of age. In contrast, carbon tetrachloride and galactosamine toxicities were unchanged or slightly diminished in old rats. Hepatic glutathione (GSH) concentrations were unaffected by aging; thus, the age-dependent increase in susceptibility to allyl alcohol toxicity was not a result of diminished GSH availability in old age. Hepatotoxicant-induced changes in GSH were observed in allyl alcohol-treated old rats (20% increase) and in galactosamine-treated young-adult and middle-aged rats (30% decrease).     

Protective potential of Royal Jelly against carbon tetrachloride induced-toxicity and changes in the serum sialic acid levels

Royal Jelly (RJ) is used in the Turkish folk medicine for the treatment of number of disorders. The present study describes the hepatoprotective and antioxidant activities of the RJ against carbon tetrachloride (CCl₄)-induced acute liver damage. Sprague–Dawley rats were used for the experiment. CCl₄ (0.8 ml/kg; s.c.) and RJ (50, 100, 200 mg/kg; orally) were given every other day, for 20 days. Malondialdehyde, reduced glutathione in whole blood and tissues; ceruloplasmin, sialic acid, ascorbic acid, retinol, β-carotene and liver enzymes levels in serum were measured. Additionally, histopathological alterations in the liver were examined. RJ exerted the significant protective effect on liver damage as well as on oxidative stress induced by CCl₄, resulting in reduced lipid peroxidation and improved endogenous antioxidant defence systems. It also reduced the elevated levels of liver enzymes. Histopathological study further confirmed the hepatoprotective effect of RJ, when compared with the CCl₄ treated control groups. In conclusion, present study reveals biological evidence that supports the use of RJ in the treatment of chemical-induced hepatotoxicity.     

Hepatotoxic interactions of ethanol with allyl alcohol or carbon tetrachloride in rats.

To assess whether potential toxic interactions occur between ethanol and allyl alcohol or carbon tetrachloride following subacute, concurrent chemical exposure, male Fischer 344 rats, approximately 70 d of age, were given ethanol at 0, 0.05, 0.1, 0.2, or 0.5 ml/kg in corn oil daily by gavage for 14 d (ETOH group), or the same levels of ethanol with 21 mg allyl alcohol/kg (ALAC group), or the same levels of ethanol with 20 mg carbon tetrachloride/kg (CCL4 group). Hepatic response was assessed 24 h after the last dose. Interactions were evaluated by comparing the ETOH group with either the ALAC group or the CCL4 group using multivariate analysis of variance procedures. No statistically significant interaction was seen between the ETOH group and the ALAC group at the dosages used. Although an interaction between ethanol and carbon tetrachloride given simultaneously was not statistically significant, a small interactive effect on weight gain from d 0 to termination was apparent (p = .057). Exposure to ethanol alone resulted in a concentration-dependent decrease in absolute and relative liver weight, with a threshold between 0.05 and 0.1 ml/kg. There was no histopathological evidence of hepatic damage with ethanol alone, and no effect on hepatic cytochrome P-450 and glutathione levels or on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALK). Exposure to allyl alcohol alone resulted in significant increases in absolute and relative liver weights, liver glutathione, and periportal hepatocellular vacuolar degeneration. Exposure to carbon tetrachloride alone resulted in significant increases in absolute and relative liver weight, serum levels of ALT, AST, and ALK, and centrilobular hepatocellular vacuolar degeneration and necrosis. These observations indicate that subacute, concurrent exposure of ethanol with carbon tetrachloride or allyl alcohol at ethanol levels comparable to those reported in gavage vehicles did not result in interactive toxicity.     

Effects of standardized bilberry fruit extract (Mirtoselect®) on resolution of CCl4-induced liver fibrosis in mice

Bilberry (Vaccinium myrtillus L) has been traditionally used in the treatment of various liver disorders. The aim of this study was to investigate the effects of bilberry fruit extract (BE) on carbon tetrachloride (CCl₄)-induced hepatic fibrosis. Male Balb/C mice were treated with CCl₄ dissolved in olive oil (20% v/v, 2 ml/kg) intraperitoneally (i.p.), twice a week for 7 weeks. BE (1, 5, and 10 mg/kg) was given to mice for next 15 days, 72 h after the last dose of CCl₄. The CCl₄ administration increased oxidative stress as well as the expression of tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) in the liver. Furthermore, increased α-smooth muscle actin (α-SMA) expression and hydroxyproline levels indicated activation of hepatic stellate cells (HSCs) and enhanced collagen production. BE 10 mg/kg markedly attenuated oxidative stress, decreased TNF-α, TGF-β1, and α-SMA expression, and eliminated hepatic collagen deposits. These results indicate that BE, in a dose dependent manner, induces the resolution of liver fibrosis by decreasing oxidative stress and inactivating HSCs via down-regulation of fibrogenic cytokines, TGF-β1 and TNF-α.     

Silymarin,the antioxidant component and Silybum marianum extracts prevent liver damage

Liver disorders are one of the common recent problems affects on the human health. These disorders due to many environmental polluted sources. Many herbal, medicinal and pharmaceutical plants and their extracts are widely studied by many researchers. Silybum marianum got a bright reputation in relieve the liver diseases, and that might be for the potent silymarin mixture. Mechanism of action for silymarin conducted mainly to the antiradical and anticarcinogenic roles. Ethyl acetate (100 mg/kg bw) and ethanol seed extracts for S. marianum (100 mg/kg bw) were tested against the injection (i.p.) by carbon tetrachloride (2 ml/kg bw) the inducer of liver damage. Their activity were compared with standard hepatic drug hepaticum (100 mg/kg bw) for 10 days. Ethanolic extract showed the most significantly decrease in the liver enzymes. For the oxidative experiments, ethyl acetate showed the most increase for glutathione level and the risk factor HDL/LDL significantly. Hepaticum was the most powerful group for the significant decreasing for malondialdehyde and fucosidase activity. Some equal improvements were noticed in the histopathological studies for the protective groups.     

Diverse response of cycloheximide-treated rats to liver injury elicited by dimethylnitrosamine,thioacetamide, bromobenzene,allyl alcohol or aflatoxin B1

Cycloheximide (1.5 $\text{mg}\text{kg}$, i.p. 30 min before hepatotoxins) inhibits d,l-[¹⁴C]leucine incorporation in liver microsomal proteins and prevents liver necrosis induced by allyl alcohol or bromobenzene but not that elicited by dimethylnitrosamine (DMN), thioacetamide (TAC) or aflatoxin B₁ (AFT). The hypothesis that protein synthesis plays an active role in the production of cellular damage may not have general validity.     

Hepatoprotective effect of methylsulfonylmethane against carbon tetrachloride-induced acute liver injury in rats

This study evaluated the effect of methylsulfonylmethane (MSM) on carbon tetrachloride (CCl₄)-induced acute liver injury in rats. A single injection of CCl₄ (2 ml/kg, i.p.) increased serum aminotransferases (ALT and AST) activities. In addition, CCl₄ treatment led to elevation of hepatic malondialdehyde (MDA) content as well as decrease in superoxide dismutase (SOD) and catalase (CAT) activities. Furthermore, cytochrome P450 2E1 (CYP2E1) content was suppressed while proinflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels increased in liver tissue after CCl₄ administration. We showed that acute CCl₄-induced damage was accompanied by a rise in Bax/Bcl₂ ratio indicating apoptosis. Pre-treatment with MSM (400 mg/kg) inhibited the increases of serum ALT and AST activities, decreased hepatic MDA, TNF-α, IL-6 and Bax/Bcl₂ ratio compared to CCl₄ treated group. On the other hand, MSM raised SOD and CAT activities as well as CYP2E1 level in liver tissues. The present study shows that MSM possesses a hepatoprotective effect against CCl₄-induced liver injury in rats. This protective effect might be through its antioxidant, anti-inflammatory and antiapoptotic properties.     

Enhanced hepatotoxicity of carbon tetrachloride, thioacetamide, and dimethylnitrosamine by pretreatment of rats with ethanol and some comparisons with potentiation by isopropanol.

Elevated plasma glutamic-pyruvic transaminase (GPT) activity induced by carbon tetrachloride (CCl₄), thioacetamide, or dimethylnitrosamine in male rats was increased by pretreatment with four doses (each 5 ml/kg) of ethanol orally 48, 42, 24, and 18 hr before the hepatotoxic agent. The potentiated hepatotoxicity of CCl₄ was confirmed by histologic evaluation. During the pretreatment, blood ethanol concentrations fluctuated between 0 and 300 mg/100 ml, but were less than 5 mg/100 ml when a hepatotoxic agent was injected ip. Pretreatment with ethanol did not affect the hepatic concentrations of CCl₄ or its metabolite, chloroform (CHCl₃), at 1 hr after administration of CCl₄. The CCl₄-induced diene conjugation tended to increase after ethanol pretreatment and was significantly potentiated by pretreatment with isopropanol or pyrazole and a single dose of ethanol. In rats pretreated with ethanol, covalent binding of ¹⁴CCl₄ to liver protein and lipid in vivo was significantly greater at 6 and 24 hr, but not during the first 3 hr, than in control rats. The in vitro binding of ¹⁴CCl₄, ¹⁴CHCl₃, and ¹⁴CBrCl₃ to hepatic microsomal protein was increased by ethanol pretreatment. Ethanol pretreatment also doubled the in vitro rate of demethylation of dimethyl-nitrosamine by liver microsomes, but did not affect the amount of microsomal protein and cytochrome P-450, NADPH c reductase activity nor the rate of N-demethylation of ethylmorphine. The similarities in microsomal effects of pretreatment with isopropanol and pretreatment with four doses of ethanol suggest that similar mechanisms are involved in their potentiation of CCl₄-induced hepatotoxicity. The potentiation by pretreatment with ethanol, but not with isopropanol, of the hepatotoxicity of thioacetamide and dimethylnitrosamine suggests that ethanol pretreatment also activates some additional mechanisms.     

Normalization by antipsychotic drugs of biochemically induced abnormal behavior in rats

Male rats were trained to perform a conditioned avoidance response combined with a successive discrimination in a modified shuttle box. The administration of l-Dopa, 100 mg/kg i.p., after inhibition of peripheral aromatic amino acid decarboxylase, or apomorphine, 2 mg/kg i.p., was found to disrupt the discriminative but not the avoidance behavior. The dopamine receptor antagonist pimozide (0.5 mg/kg i.p.), but not the noradrenaline receptor antagonist phenoxybenzamine (10 or 20 mg/kg i.p.) completely antagonized the l-Dopa-induced abnormal behavior, indicating an involvement of central dopamine mechanisms. The present data show that antipsychotic drugs not only inhibit behavior but can also improve behavior in animals with a disturbed function.