Fatty Acid Amide Hydrolase Inhibition by Neurotoxic Organophosphorus Pesticides

Organophosphorus (OP) compound-induced inhibition of acetylcholinesterase (AChE) and neuropathy target esterase explains the rapid onset and delayed neurotoxic effects, respectively, for OP insecticides and related compounds but apparently not a third or intermediate syndrome with delayed onset and...

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Veröffentlicht in:Toxicology and applied pharmacology 2001-05, Vol.173 (1), p.48-55
Hauptverfasser: Quistad, Gary B., Sparks, Susan E., Casida, John E.
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Sprache:eng
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Zusammenfassung:Organophosphorus (OP) compound-induced inhibition of acetylcholinesterase (AChE) and neuropathy target esterase explains the rapid onset and delayed neurotoxic effects, respectively, for OP insecticides and related compounds but apparently not a third or intermediate syndrome with delayed onset and reduced limb mobility. This investigation tests the hypothesis that fatty acid amide hydrolase (FAAH), a modulator of endogenous signaling compounds affecting sleep (oleamide) and analgesia (anandamide), is a sensitive target for OP pesticides with possible secondary neurotoxicity. Chlorpyrifos oxon inhibits 50% of the FAAH activity (IC50 at 15 min, 25°C, pH 9.0) in vitro at 40–56 nM for mouse brain and liver, whereas methyl arachidonyl phosphonofluoridate, ethyl octylphosphonofluoridate (EOPF), oleyl-4H-1,3,2-benzodioxaphosphorin 2-oxide (oleyl-BDPO), and dodecyl-BDPO give IC50s of 0.08–1.1 nM. These BDPOs and EOPF inhibit mouse brain FAAH in vitro with ≥200-fold higher potency than for AChE. Five OP pesticides inhibit 50% of the brain FAAH activity (ED50) at
ISSN:0041-008X
1096-0333
DOI:10.1006/taap.2001.9175