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NEUROBEHAVIORAL EFFECTS OF CHRONIC DIETARY AND REPEATED HIGH-LEVEL SPIKE EXPOSURE TO CHLORPYRIFOS IN RATS.
Citation:
Moser, V C., P. M. Phillips, K. L. McDaniel, R S. Marshall, D L. Hunter, AND S. Padilla. NEUROBEHAVIORAL EFFECTS OF CHRONIC DIETARY AND REPEATED HIGH-LEVEL SPIKE EXPOSURE TO CHLORPYRIFOS IN RATS. Presented at International Neurotoxicology Association, Portugal, 6/17-22, 2001.
Description:
This study aimed to model long-term subtoxic human exposure to an organophosphorus pesticide, chlorpyrifos, and to examine the influence of that exposure on the response to intermittent high-dose acute challenges. Adult Long-Evans male rats were maintained at 350g body weight by limited access to food pellets to produce an intake of 0, 1, or 5 mg/kg/day. During the year-long exposure, half of the rats in each dose group received bi-monthly challenges (spikes) of chlorpyrifos, and the other half received vehicle. Rats were periodically tested using a neurological battery of evaluations and motor activity, to evaluate the magnitude of the acute response (spike days) as well as recovery and ongoing chronic effects (non-spike days). During the eleventh month, rats were tested in a Morris water maze. In non-spiked rats, the lower dose produced blood but no brain cholinesterase inhibition, whereas the higher dose produced about 50% brain cholinesterase inhibition. The diet alone (high dose) lowered activity counts and produced slight ataxia. Effects of the spikes differed as a function of dietary level for several endpoints (e.g., gait abnormality, tremor, lacrimation). In general, the high-dose feed groups showed greater effects of the spike doses. There were no clear cognitive deficits observed on any water maze measure; however, the high-dose feed groups showed more tendency to swim in the outer annulus of the tank. Thus, chronic chlorpyrifos exposure produced neurobehavioral changes and altered the response to acute challenges.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.