Noncholinesterase mechanisms of chlorpyrifos neurotoxicity

Altered phosphorylation of Ca2+/cAMP response element binding protein in cultured neurons

Rosemary A. Schuh, Pamela J Lein, Rondell A. Beckles, David A. Jett

Research output: Contribution to journalArticle

116 Citations (Scopus)

Abstract

Previous studies suggest that low doses of the organophosphate insecticide chlorpyrifos (CPF) disrupt brain development and cognitive function by mechanisms that do not involve the inhibition of acetylcholinesterase (AChE). In the present study we tested the hypothesis that CPF and its metabolites alter the Ca2+/cAMP response element binding protein (CREB), a critical molecule in brain development and cognitive function. We further tested the hypothesis that changes in CREB occur independent of AChE inhibition. Western blot analysis of lysates from primary cultures of cortical neurons exposed to CPF, CPF-oxon, or trichloropyridinol (TCP) for 1 h and cultures exposed to trichloropyridinol (TCP) for 7 days indicated that all exposures increased the level of the phosphorylated (activated) form of CREB (pCREB), without significant changes in total CREB or α-tubulin. Remarkably, pCREB in cortical neurons was elevated by 300-400% of control levels with estimated EC50s of 60 pM, < 30 fM, and < 30 pM for CPF, CPF-oxon, and TCP, respectively. AChE activity and cell viability were not affected by organophosphate concentrations that caused significant increases in pCREB (up to 100 nM, 100 pM, and 10 μM of CPF, CPF-oxon, and TCP, respectively). The level of pCREB in hippocampal neurons was also elevated after exposure to CPF, but pCREB in cultured astrocytes was not affected. Inclusion of the cytochrome P-450 inhibitor SKF-525A did not inhibit the effects of CPF on pCREB levels, indicating that metabolism of CPF to CPF-oxon was not necessary to cause the increase in pCREB. The increases in neuronal pCREB observed in this study provide biochemical evidence that CPF and its metabolites are active at critical sites within the nervous system at levels far below those required to inhibit AChE, which could explain many of the reported neurodevelopmental and behavioral changes attributed to CPF toxicity.

Original languageEnglish (US)
Pages (from-to)176-185
Number of pages10
JournalToxicology and Applied Pharmacology
Volume182
Issue number2
DOIs
StatePublished - 2002
Externally publishedYes

Fingerprint

Chlorpyrifos
Cyclic AMP Response Element-Binding Protein
Phosphorylation
Neurons
Acetylcholinesterase
Organophosphates
Metabolites
Cognition
Brain
Proadifen
Level control
Neurology
Tubulin
Insecticides
Metabolism
Astrocytes
Nervous System
Toxicity
Cell Survival
Western Blotting

ASJC Scopus subject areas

  • Pharmacology
  • Toxicology

Cite this

Noncholinesterase mechanisms of chlorpyrifos neurotoxicity : Altered phosphorylation of Ca2+/cAMP response element binding protein in cultured neurons. / Schuh, Rosemary A.; Lein, Pamela J; Beckles, Rondell A.; Jett, David A.

In: Toxicology and Applied Pharmacology, Vol. 182, No. 2, 2002, p. 176-185.

Research output: Contribution to journalArticle

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