Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of repeated exposure to N,N-dimethylformamide (DMF) on hepatic microsomal monooxygenase system and glutathione metabolism were investigated. DMF was administered to Wistar male rats by subcutaneous (s.c.) injection at 0.5 ml/kg body weight daily for 1 week. Macroscopically, mild liver swelling was observed and liver weights significantly increased after 1 week of exposure to DMF. Hematological changes were not detected. In exposed rats, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, cholinesterase and total cholesterol significantly increased. Hepatic microsomal cytochrome P-450 and protoheme decreased by 34% and 24%, respectively, while microsomal protein and cytochrome b5 were not affected. NADH-ferricyanide reductase activity decreased by 24% while NADPH-cytochrome c reductase activity showed no change. Glutathione reductase (GR) activity showed a significant decrease after the first injection and remained depressed throughout the study, with no change in glutathione peroxidase (GPx) activity. Glutathione S-transferase (GST) activity showed a significant increase at 3 days after DMF treatment and gradually increased by 66% at 1 week. In a subsequent experiment with a single administration of DMF (4 ml/kg), reduced glutathione (GSH) in the liver was decreased by 28% at 8 h, but recovered to control levels by 24 h. These results indicate that DMF alters the hepatic microsomal monooxygenase system and glutathione metabolism. These findings may greatly contribute to the elucidation of the pathogenesis of DMF hepatotoxicity.
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PMID:Effects of dimethylformamide on hepatic microsomal monooxygenase system and glutathione metabolism in rats. 153 72

Previous studies have shown that a single oral pretreatment of rats with the organophosphorus insecticide 2-chloro-1-(2,4-dichlorophenyl)vinyl diethyl phosphate (chlorfenvinphos, CVP) afforded protection against the toxicity of a subsequent challenge with the same compound within 24 hr. This protection may be due to the reduction in brain cholinesterase inhibition caused by the decrease in plasma CVP concentration. The purpose of this study was to investigate the mechanism of the decrease in plasma CVP concentration in relation to metabolic induction. CVP was preferentially metabolized by a liver microsomal fraction with an NADPH-generating system, compared with serum or kidney subcellular fractions. A single oral 24-hr pretreatment with CVP (15 mg/kg) increased the oral LD50 of its next dosage to threefold. The same treatment also increased CVP metabolism (to 178%), cytochrome P450 content (to 130%), cytochrome P450 reductase activity (to 130%), cytochrome b5 content (to 121%), and cytochrome P450-linked activities such as aminopyrine demethylase (to 140%) and aniline hydroxylase (to 127%) in the hepatic microsomal fraction. A single oral 24-hr pretreatment of phenobarbital (50 mg/kg), which is known as an inducer of cytochrome P450, increased the oral LD50 of CVP and all the related metabolic parameters listed above in an order of magnitude similar to that of CVP, although the increments induced by the phenobarbital treatment were greater than those induced by the CVP treatment. These results indicate that the increase in hepatic CVP metabolism may be due to the induction of the hepatic cytochrome P450 system caused by the single oral short-term treatment with CVP. This induction may be one of the reasons for the decrease in plasma CVP concentration which may be responsible for the reduction in toxicity of its next dosage.
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PMID:Metabolic induction of the hepatic cytochrome P450 system by chlorfenvinphos in rats. 176 23

Chlorpyrifos-oxon (CPO), a metabolite of chlorpyrifos, is a potent inhibitor of acetylcholinesterase and, although the neurotoxicological impact of this organophosphorus compound has been broadly studied both in vitro and in vivo, there are few studies of metabolic interactions of CPO with other xenobiotics. CPO significantly activated the production of 1-naphthol (5-fold), 2-naphthol (10-fold), trans-1,2-dihydro-1,2-naphthalenediol (1.5-fold), and 1,4-naphthoquinone from naphthalene by human liver microsomes (HLM). It was further demonstrated that the production of naphthalene metabolites by CYP2C8, 2C9*(1), 2C19, 2D6*(1), 3A4, 3A5, and 3A7 was activated by CPO, while the production of naphthalene metabolites by CYP1A1, 1A2, 1B1, and 2B6 was inhibited by CPO. CPO inhibited CYP1A2 production of naphthalene metabolites, while activating their production by CYP3A4. Similarly, CPO inhibited the production of N,N-diethyl-m-hydroxymethylbenzamide (BALC) from DEET by human liver microsomes, but activated the production of N-ethyl-m-toluamide (ET) from this substrate. CYP2B6, the most efficient isoform for BALC production, was inhibited by CPO, while CYP3A4, the most efficient isoform for ET production, was activated by CPO. CPO inhibited CYP2B6 production of both BALC and ET from DEET, but activated CYP3A4 production of ET, while inhibiting CYP3A4 BALC production. CPO appears to facilitate the binding of naphthalene to CYP3A4. This metabolic activation is independent of cytochrome b5, suggesting that activation of CYP3A4 by CPO is associated with a conformational change of the isoform rather than facilitating electron transfer.
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PMID:The effect of chlorpyrifos-oxon and other xenobiotics on the human cytochrome P450-dependent metabolism of naphthalene and deet. 1844 1