Long-term functional neurotoxicity of paraoxon and chlorpyrifos:: behavioural and pharmacological evidence

Organophosphate (OP) compounds are chemicals widely used in agriculture, industry and households and even as chemical weapons. The major mechanism of acute toxic action is the inhibition of acetylcholinesterase (AChE), which is responsible for the degradation of the neurotransmitter acetylcholine. A chronic OP-induced neuropsychiatric disorder (COPIND), which could result from both long-term exposure to subclinical doses of OP and after acute intoxication, has been proposed. These reports claim to develop animal models that could parallel behavioural and cognitive effects and that could later help to elucidate the mechanisms involved in this long-term affectation of the central nervous system. The present study uses a series of behavioural tests to discern the short- and long-term effects of acute intoxications with paraoxon (Px) or chlorpyrifos (CPF). Our results suggest that months after acute exposure to these ON functional central nervous system alterations can be detected using a repeated acquisition spatial task in the water maze, for CPF, and in amphetamine-induced place preference paradigm, for both Px and CPF. (C) 2004 Elsevier Inc. All rights reserved.