Acetaminophen Hepatotoxicity In Rats Research Articles

Essential oils of green cumin and chamomile partially protect against acute acetaminophen hepatotoxicity in rats.

Essential oils of green cumin (Cuminum cyminum) and chamomile (Chamomilla recutita) have antioxidant and anti-inflammatory effects. Acetaminophen, N-acetyl-p-amino-phenol, is an over-the-counter analgesic and antipyretic. Despite being safe at therapeutic doses, acetaminophen overdose is a leading cause of acute liver failure. This study aimed to compare the possible protective effects of cumin and chamomile essential oils against acute acetaminophen hepatotoxicity in male rats. Cumin oil (400 mg/kg) and chamomile oil (250 mg/kg) were orally administered for 2 weeks prior to a single acetaminophen dose (1g/kg). Serum liver function enzymes, oxidative stress markers in the liver and histopathological features were evaluated. Acetaminophen caused marked damage to hepatocytes evidenced by a significant rise in the levels of liver function enzymes, including alanine aminotransferase and aspartate aminotransferase, and disruption to the liver antioxidant protective system. Whereas the cumin oil normalized acetaminophen-induced liver enzymes elevation, the chamomile oil slightly attenuated the increase in alanine aminotransferase levels in acetaminophen-intoxicated rats. The Chamomile oil moderately ameliorated glutathione depletion and the decrease in superoxide dismutase activity in the liver of acetaminophen-administered rats. The Cumin oil preserved the liver structure to a greater extent than chamomile oil in acetaminophen-intoxicated rats. Essential oils of cumin and chamomile partially counteracted acute acetaminophen hepatotoxicity.

Determination of carbamyl phosphate synthetase-1, glutamine synthetase and arginase enzyme activities as markers of acetaminophen hepatotoxicity in rats

Determination of carbamyl phosphate synthetase-1, glutamine synthetase and arginase enzyme activities as markers of acetaminophen hepatotoxicity in rats

357 Determination of carbamyle phosphate synthetase-1, glutamine synthetase and arginase enzyme activities as markers of acetaminophen hepatotoxicity in rats

357 Determination of carbamyle phosphate synthetase-1, glutamine synthetase and arginase enzyme activities as markers of acetaminophen hepatotoxicity in rats

Acarbose alone or in combination with ethanol potentiates the hepatotoxicity of carbon tetrachloride and acetaminophen in rats.

Acarbose reduces the absorption of monosaccharides derived from dietary carbohydrates, which play an important role in the metabolism and toxicity of some chemical compounds. We studied the effects of acarbose on the hepatotoxicity of carbon tetrachloride (CCl4) and acetaminophen (AP) in rats, both of which exert their toxic effects through bioactivation associated with cytochrome P450 2E1 (CYP2E1). Male Sprague-Dawley rats were kept on a daily ration (20 g) of powdered chow diet containing 0, 20, 40, or 80 mg/100 g of acarbose, with drinking water containing 0% or 10% of ethanol (vol/vol). Three weeks later, the rats were either killed for an in vitro metabolism study or challenged with 0.50 g/kg CCl4 orally or 0. 75 g/kg AP intraperitoneally. The ethanol increased the hepatic microsomal CYP2E1 level and the rate of dimethylnitrosamine (DMN) demethylation. The 40- or 80-mg/100 g acarbose diet, which alone increased the CYP2E1 level and the rate of DMN demethylation, augmented the enzyme induction by ethanol. The 40- or 80-mg/100 g acarbose diet alone potentiated CCl4 and AP hepatotoxicity, as evidenced by significantly increased levels of both alanine transaminase (ALT) and aspartate transaminase (AST) in the plasma of rats pretreated with acarbose. Ethanol alone also potentiated the toxicity of both chemicals. When the 40- or 80-mg/100 g acarbose diet was combined with ethanol, the ethanol-induced potentiation of CCl4 and AP hepatotoxicity was augmented. Our study demonstrated that high doses of acarbose, alone or in combination with ethanol, can potentiate CCl4 and AP hepatotoxicity in rats by inducing hepatic CYP2E1.

Acute hepatotoxicity of acetaminophen in rats treated with ethanol plus isopentanol.

Acetaminophen (APAP) hepatotoxicity was investigated in rats fed ethanol and isopentanol alone or in combination in a liquid diet for 7 days. Serum levels of aspartate aminotransferase (AST) and histological examination of liver slices were used to assess hepatotoxicity. At 7 hr after intragastric administration of 0.5 or 1.0 g APAP/kg, there was no significant increase in serum levels of AST in rats treated with APAP alone, or in rats pretreated with ethanol or isopentanol alone followed by APAP. There was mild central lobular congestion in the livers of rats pretreated with ethanol alone followed by APAP. In contrast, in rats pretreated with the combination of ethanol and isopentanol, administration of APAP caused a dramatic increase in serum levels of AST, along with marked central lobular necrosis, including steatosis and ischemic changes. Hepatic glutathione levels were decreased to 40-50% of control values in APAP-treated rats that had been pretreated with ethanol either alone or in combination with isopentanol. The serum concentrations of APAP were significantly lower in rats pretreated with the combination of ethanol and isopentanol followed by 1 g APAP/kg than in rats treated with APAP alone, suggesting a greater rate of APAP metabolism. We had reported previously that combined treatment of rats with ethanol and isopentanol resulted in additive to synergistic increases in CYP3A, with no further increases in CYP2E than that caused by ethanol alone. CYP3A may, therefore, be responsible for the increased APAP hepatotoxicity caused by the combined alcohol treatment.

Disulfiram prevents acetaminophen hepatotoxicity in rats.

Hepatic necrosis due to an oral acetaminophen overdose (4.25 g/kg b.wt.) was prevented by pretreatment with disulfiram 100 mg/kg, given for 3 weeks or as a single dose. Twenty-four hours after acetaminophen the impairment of hepatic function, measured as prothrombin index, and the depletion of hepatic glutathione were prevented. Hepatic cytochrome P-450 levels were unchanged but cytochrome P-450 mediated p-nitroanisole demethylation was reduced by disulfiram pretreatment. Disulfiram pretreatment reduced 24 hour urinary excretion of acetaminophen-mercapturate and- cysteine while excretion of -sulfate and -glucuronide was unchanged. After 72 hours acetaminophen induced hepatic necrosis were prevented. Identical observations were made in animals pretreated with disulfiram for 3 weeks. Five hours after acetaminophen overdose its irreversible binding to hepatic proteins was not changed. After 24 hours, however, it was increased in animals pretreated with a single disulfiram dose and unchanged in animals pretreated for 3 weeks. The protective mechanism of disulfiram after acetaminophen overdose is not mediated via a change in overall irreversible binding of acetaminophen to hepatic protein.

Mechanism of action of N-acetylcysteine in the protection against the hepatotoxicity of acetaminophen in rats in vivo.

N-Acetylcysteine is the drug of choice for the treatment of an acetaminophen overdose. It is thought to provide cysteine for glutathione synthesis and possibly to form an adduct directly with the toxic metabolite of acetaminophen, N-acetyl-p-benzoquinoneimine. However, these hypothese have not been tested in vivo, and other mechanisms of action such as reduction of the quinoneimine might be responsible for the clinical efficacy of N-acetylcysteine. After the administration to rats of acetaminophen (1 g/kg) intraduodenally (i.d.) and of [(35)S]-N-acetylcysteine (1.2 g/kg i.d.), the specific activity of the N-acetylcysteine adduct of acetaminophen (mercapturic acid) isolated from urine and assayed by high pressure liquid chromatography averaged 76+/-6% of the specific activity of the glutathione-acetaminophen adduct excreted in bile, indicating that virtually all N-acetylcysteine-acetaminophen originated from the metabolism of the glutathione-acetaminophen adduct rather than from a direct reaction with the toxic metabolite. N-Acetylcysteine promptly reversed the acetaminophen-induced depletion of glutathione by increasing glutathione synthesis from 0.54 to 2.69 mumol/g per h. Exogenous N-acetylcysteine did not increase the formation of the N-acetylcysteine and glutathione adducts of acetaminophen in fed rats. However, when rats were fasted before the administration of acetaminophen, thereby increasing the stress on the glutathione pool, exogenous N-acetylcysteine significantly increased the formation of the acetaminophen-glutathione adduct from 57 to 105 nmol/min per 100 g. Although the excretion of acetaminophen sulfate increased from 85+/-15 to 211+/-17 mumol/100 g per 24 h after N-acetylcysteine, kinetic simulations showed that increased sulfation does not significantly decrease formation of the toxic metabolite. Reduction of the benzoquinoneimine by N-acetylcysteine should result in the formation of N-acetylcysteine disulfides and glutathione disulfide via thiol-disulfide exchange. Acetaminophen alone depleted intracellular glutathione, and led to a progressive decrease in the biliary excretion of glutathione and glutathione disulfide. N-Acetylcysteine alone did not affect the biliary excretion of glutathione disulfide. However, when administered after acetaminophen. N-acetylcysteine produced a marked increase in the biliary excretion of glutathione disulfide from 1.2+/-0.3 nmol/min per 100 g in control animals to 5.7+/-0.8 nmol/min per 100 g. Animals treated with acetaminophen and N-acetylcysteine excreted 2.7+/-0.8 nmol/min per 100 g of N-acetylcysteine disulfides (measured by high performance liquid chromatography) compared to 0.4+/-0.1 nmol/min per 100 g in rats treated with N-acetylcysteine alone. In conclusion, exogenous N-acetylcysteine does not form significant amounts of conjugate with the reactive metabolite of acetaminophen in the rat in vivo but increases glutathione synthesis, thus providing more substrate for the detoxification of the reactive metabolite in the early phase of an acetaminophen intoxication when the critical reaction with vital macromolecules occurs.

Cimmetidine protects against acetaminophen hepatotoxicity in rats

Cimmetidine protects against acetaminophen hepatotoxicity in rats

Prevention of acetaminophen hepatotoxicity by propylthiouracil in the glutathione depleted rat

1. 1. This study was designed to investigate the protective effect of PTU pretreatment against acetaminophen hepatotoxicity in rats whose hepatic GSH had been depleted by prior diethylmaleate (DEM) administration. 2. 2. A single injection of DEM depleted hepatic GSH showing lowest level after 90 min in both control and PTU pretreated rats. Triple injection schedule kept the hepatic GSH concentrations consistently very low up to 6hr. 3. 3. Whereas a toxic dose of acetaminophen administration did not effect SGOT and SGPT levels after 30 hr in PTU pretreated rats given either a single or multiple injections of DEM, the same dose of acetaminophen in the control rats raised these transaminases to a very high level. 4. 4. High activity of transaminases was associated with significant histological hepatic damage. 5. 5. Our results suggest that PTU pretreatment affords significant protection against acetaminophen hepatotoxicity even under conditions when hepatic GSH concentrations have been significantly depleted prior to acetaminophen administration.