Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.6.1.2 (alanine aminotransferase)
 26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The acute hepatotoxic effects of vinylidene chloride (VDC) were evidenced by measurement of the increase in the serum levels of the aminotransferase (GPT) and sorbitol dehydrogenase (SDH), hepatic glutathione (GSH) depletion and histological examinations in rats. The hepatoprotective agents dithiocarb and (+)-cyanidanol-3 proved well able to antagonize these toxic effects of VDC. While dithiocarb inhibited the in vivo metabolism of VDC in a closed exposure system, (+)-cyanidanol-3 had no influence at all. These findings substantiate the role of the microsomal monooxygenase system in the metabolism and hepatotoxicity of VDC. The mechanisms by which dithiocarb and (+)-cyanidanol-3 act as antihepatotoxic agents are different: the inhibition of the metabolic activation by dithiocarb and free radical-scavenging by (+)-cyanidanol-3.
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PMID:Effects of dithiocarb and (+)-cyanidanol-3 on the hepatotoxicity and metabolism of vinylidene chloride in rats. 23 19

Intraperitoneal injection (50 mg/kg) of 2-nitropropane (2-NP) induced lipid accumulation, centrilobular necrosis, degranulation of rough endoplasmic reticulum, proliferation of smooth endoplasmic reticulum and mitochondrial abnormalities in rat liver 24 h after exposure. These pathological changes were accompanied by elevated serum alanine aminotransferase (ALAT) levels. Hepatic glutathione content increased rapidly in exposed rats. 2-NP depressed markedly hepatic cytochrome P-450 and microsomal monooxygenase activity while the enzyme, epoxide hydratase, UDP-glucuronosyltransferase and cytosolic glutathione peroxidase were enhanced. 2-NP caused an increase of acetylcholine esterase activity in the brain. This effect was also detected in synaptosomes isolated from exposed rats. The results suggest peroxidative damage in the cells.
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PMID:Acute effects of 2-nitropropane on rat liver and brain. 731 30

The oxidative metabolism of cocaine by the microsomal monooxygenase enzymes has been postulated to be essential for cocaine mediated hepatotoxicity (CMH). Endotoxin (lipopolysaccharide, LPS), a well-known cause of hepatic damage, previously has been demonstrated to dramatically increase CMH. The mechanism of this interaction has not been clearly elucidated, but cocaine oxidative metabolism appears to sensitize hepatocytes so that subsequent exposure to small amounts of LPS can further augment CMH. This study was conducted to investigate if dimethylaminoethyl-2,2-diphenylvalerate (SKF-525A) pretreatment inhibits LPS potentiation of CMH. For 5 consecutive days, male CF-1 mice were administered daily SKF-525A (50 mg/kg) or sterile saline followed an hour later by cocaine (20 mg/kg) or sterile saline. Four hours following the last cocaine or saline treatment, the mice were administered sterile saline 12x10(6) EU LPS/kg, i.p. The mice were sacrificed 18 h later by decapitation. Pretreatment with SKF-525A reversed the hepatic injury caused by cocaine alone or cocaine and LPS treatments, as indicated by both histologic evaluation and serum alanine transaminase (ALT) and aspartate transaminase (AST) activities. In particular, SKF-525A completely reversed the effects of cocaine alone on liver and blood reduced gluthathione (GSH), glutathione peroxidase (GPx) and catalase (CAT) and hepatic glutathione reductase (GRx) activities. However, SKF-525A was ineffective against the effect of LPS alone on liver and blood GPx and CAT or on hepatic GSH and GRx, suggesting that these effects were not mediated by cytochrome P450 oxidative metabolism. The pattern of biochemical changes persisting with SKF-525A pretreatment in the LPS and cocaine group resembled those of the LPS alone group. The results suggest that cytochrome P450 oxidative metabolism of cocaine is largely responsible for CMH with potentiation by LPS achieved through a different mechanism involving oxidative stress.
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PMID:Inhibition of cocaine oxidative metabolism attenuates endotoxin potentiation of cocaine mediated hepatotoxicity. 1220 38

The effect of acute and chronic dioxane administration on hepatic, renal, pulmonary and nasal mucosa P450 enzymes and liver toxicity were investigated in male rats. The acute treatment consisted of two doses (2 g/kg) of dioxane given for 2 days by gavage, whereas the chronic treatment consisted of 1.5% of dioxane in drinking water for 10 days. Both the acute and chronic dioxane treatments induced cytochrome P450 2B1/2- and P450 2E1-dependent microsomal monooxygenase activities (pentoxyresorufin O-depentylase and p-nitrophenol hydroxylase) in the liver, whereas in the kidney and nasal mucosa, only the 2E1 marker activities were enhanced. In addition in the liver, an induction of 2alpha-testosterone hydroxylase (associated with the constitutive and hormone-dependent P450 2C11) was also revealed, whereas the hepatic P450 4A-dependent omega-lauric acid hydroxylase was not enhanced by any dioxane treatment. These inductions were mostly confirmed by western blot analysis of liver, kidney and nasal mucosa microsomes. In the lung, no alteration of P450 activities was observed. To assess the mechanism of 2E1 induction, the hepatic, renal and nasal mucosa 2E1 mRNA levels were also examined. Following two kinds of dioxane administration, in the liver the 2E1 induction was not accompanied by a significant alteration of 2E1 mRNA levels, while both in the kidney and nasal mucosa the 2E1 mRNA increased about 2- to 3-fold, indicating an organ-specific regulation of this P450 isoform. Furthermore, dioxane was unable to alter the plasma alanine aminotransferase activity and hepatic glutathione (GSH) content, examined as an index of toxicity, when it was administered into rats with P450 2B1/2 and 2E1 preinduced by phenobarbital or fasting pretreatment. These results support the lack of or a poor formation of reactive and toxic intermediates during the biotrasformation of this solvent, even when its metabolism was enhanced by P450 inducers. The chronic administration of dioxane was also unable to induce the palmitoyl CoA oxidase, a marker of peroxisome proliferation, excluding this as a way to explain its toxicity. Thus, although the mechanism of dioxane carcinogenicity remains unclear, the present results suggest that the induction of 2E1 following a prolonged administration of dioxane might provide oxygen radical species, and thereby contribute to its organ-specific toxicity.
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PMID:Effects of dioxane on cytochrome P450 enzymes in liver, kidney, lung and nasal mucosa of rat. 1549 Jan 26