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BEHAVIORAL AND NEUROCHEMICAL EFFECTS OF ACUTE CHLORPYRIFOS IN RATS: TOLERANCE TO PROLONGED INHIBITION OF CHOLINESTERASE
Citation:
Bushnell, P., C. Pope, AND S. Padilla. BEHAVIORAL AND NEUROCHEMICAL EFFECTS OF ACUTE CHLORPYRIFOS IN RATS: TOLERANCE TO PROLONGED INHIBITION OF CHOLINESTERASE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/041 (NTIS PB94137130).
Description:
Chlorpyrifos (CPF), a commercially prevalent organophosphate (OP) pesticide, inhibits blood and brain cholinesterase for up to 10 weeks after acute s.c. injection in rats. his prolonged inhibition suggested that acute CPF may affect muscarinic receptors and behavior as does repeated treatment with the shorter-acting OP diisopropylfluorophosphate (DFP) (Bushnell et al., 1991). eight-maintained, adult male Long-Evans rats were trained to perform an appetitive operant task which allowed daily quantification of working memory (accuracy of delayed matching-to-position, DMTP), reference memory (accuracy of visual discrimination, VD), and motivation/motor function (trail completion, lever press latency and nosepoke inter-response time [IRT] during delay). he rats were then injected s.c. with 0, 60, 125, or 250 mg/kg CPF in peanut oil and were tested on the DMTP/VD task 5 days/week for 7 weeks; unconditioned behavior was also rated for overt signs of toxicity. hE activity in whole blood was inhibited in a dose-related manner for more than 53 days. hE activity in four brain regions was inhibited 60% - 80% 7 days after 60 mg/kg CPF., and 80% - 95% 7 days after 250 mg/kg,