Cognitive function and cholinergic neurochemistry in weanling rats exposed to chlorpyrifos

David A. Jett, Ryman V. Navoa, Rondell A. Beckles, Gabrielle L. McLemore

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


Previous studies have shown that moderate to high levels of chlorpyrifos (CPF) alter cognitive function in adult and immature rats. In the present study, we tested the hypothesis that lower-level exposure to CPF before or immediately after weaning causes deficits in cognitive function. A total of 78 Long-Evans rats were injected subcutaneously with 0, 0.3 or 7.0 mg/kg CPF every 4 days before or after weaning and were tested with the Morris swim task from postnatal day 24 through 28. Exposure to CPF before weaning did not cause signs of overt cholinergic intoxication or impaired growth nor did the exposures cause significant inhibition of regional brain cholinesterase (ChE) activity or reduction in muscarinic receptors 24 h after the last injection. However, spatial learning was impaired after 5 days of training in the group of weanling rats administered 7.0 mg/kg CPF. Rats administered 0.3 or 7.0 mg/kg CPF after weaning were also impaired in the task, without significant changes in brain ChE activity. These data indicate that low-level exposure to CPF caused deficits in cognitive function in weanling rats, and these effects did not appear to be mediated by the inhibition of brain ChE. It is suggested that the alteration of cognitive function in juvenile rats is an important functional correlate of the cellular and molecular effects of CPF in the immature brain. The mechanisms for CPF-induced cognitive dysfunction are unknown.

Original languageEnglish (US)
Pages (from-to)89-98
Number of pages10
JournalToxicology and Applied Pharmacology
Issue number2
StatePublished - Jul 15 2001
Externally publishedYes


  • Acetylcholinesterase
  • Brain development
  • Chlorpyrifos
  • Cognitive function
  • Muscarinic receptors

ASJC Scopus subject areas

  • Pharmacology
  • Toxicology


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