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NEUROBEHAVIORAL EFFECTS OF CHRONIC DIETARY AND REPEATED HIGH-LEVEL SPIKE EXPOSURE TO CHLORPYRIFOS IN RATS.
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.
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.
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Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
NEUROBEHAVIORAL TOXICOLOGY BRANCH