Assay of Chicken Brain Neurotoxic Esterase Activity Using Leptophosoxon as the Selective Neurotoxic Inhibitor

Hen brain mlcrosomel preparation has phenyl velerete-hydrolyzlng activity associated with neurotoxlc ester-ase activity. Part of that activity Is due to peraoxon-lnsensltlve estereses end 9 sub-part of this Is sensitive to neurotoxlc orgenophosphates, i.e., mlpa-fox and leptophosoxon. This neurotoxlc agent senslt-Ive esterase activity is referred to as neurotoxlr esterase (NTE). Because of the commercial unavell-ability and high toxicity of mlpefox, which Is usually used as the selective Inhibitor for assaying NTE, lepto-phosoxon was used as an alternative to mlpafox. Results Indicated that the NTE fraction of hen brain mlcrosomel PV-hydrolyzlng activity Is the same target for either mlpafox or leptophosoxon. The Inhibitory effect of leptophosoxon against that fraction was much higher than that of mlpafox. The availability of lepto-phos/leptophosoxon makes this assay very useful for screening organophosphorus esters for neurotoxlc effects. In t roduct ion Delayed neuropathy, or "toxic distal axonopathy " (l) is one of the most serious effects of some organophos-shorus (OP) compounds. This special toxic neuropathy is accompanied by axonal degeneration and demyelination of both the central and peripheral nerve axons of certain species of vertebrates (2). Briefly, in man, chicken, and cat, the most sensitive species, there is a delay period of 8-12 days after "Correspondence and requests for reprints should be sent to Dr. S.A. Sollman