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Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood.

Publication ,  Journal Article
Slotkin, TA; Ryde, IT; Levin, ED; Seidler, FJ
Published in: Brain Res Bull
March 28, 2008

The developmental neurotoxicity of organophosphate pesticides targets serotonin (5HT) systems, which are involved in emotional and appetitive behaviors. We exposed neonatal rats to daily doses of diazinon on postnatal days 1-4, using doses (0.5 or 2mg/kg) spanning the threshold for barely-detectable cholinesterase inhibition. We then evaluated the effects on 5HT(1A) and 5HT(2) receptors, and on the 5HT transporter in cerebral cortical regions and the brainstem in adolescence through adulthood. Diazinon evoked a lasting deficit in 5HT(1A) receptors in males only, whereas it caused a small but significant increase in 5HT transporters in females; neither effect showed a significant regional selectivity. This pattern differed substantially from that seen in earlier work with another organophosphate, chlorpyrifos, which at pharmacodynamically similar doses spanning the threshold for cholinesterase inhibition, evoked a much more substantial, global upregulation of 5HT receptor expression; with chlorpyrifos, effects on receptors were seen in females, albeit to a lesser extent than in males, and were also regionally distinct. The effects of diazinon were nonmonotonic, showing larger alterations at the lower dose, likely reflecting positive trophic effects of cholinergic stimulation once the threshold for cholinesterase inhibition is exceeded. Our results reinforce the idea that different organophosphates have fundamentally distinct effects on the developmental trajectories of specific neurotransmitter systems, unrelated to their shared action as cholinesterase inhibitors. The effects on 5HT circuits expand the scope of behavioral endpoints that need to be considered in evaluating the developmental neurotoxicity of organophosphates.

Duke Scholars

Published In

Brain Res Bull

DOI

ISSN

0361-9230

Publication Date

March 28, 2008

Volume

75

Issue

5

Start / End Page

640 / 647

Location

United States

Related Subject Headings

  • Sex Factors
  • Serotonin Plasma Membrane Transport Proteins
  • Serotonin
  • Receptors, Serotonin, 5-HT2
  • Receptor, Serotonin, 5-HT1A
  • Rats, Sprague-Dawley
  • Rats
  • Pregnancy
  • Neurotoxicity Syndromes
  • Neurology & Neurosurgery
 

Citation

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Slotkin, T. A., Ryde, I. T., Levin, E. D., & Seidler, F. J. (2008). Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood. Brain Res Bull, 75(5), 640–647. https://doi.org/10.1016/j.brainresbull.2007.10.008
Slotkin, Theodore A., Ian T. Ryde, Edward D. Levin, and Frederic J. Seidler. “Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood.Brain Res Bull 75, no. 5 (March 28, 2008): 640–47. https://doi.org/10.1016/j.brainresbull.2007.10.008.
Slotkin, Theodore A., et al. “Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood.Brain Res Bull, vol. 75, no. 5, Mar. 2008, pp. 640–47. Pubmed, doi:10.1016/j.brainresbull.2007.10.008.
Journal cover image

Published In

Brain Res Bull

DOI

ISSN

0361-9230

Publication Date

March 28, 2008

Volume

75

Issue

5

Start / End Page

640 / 647

Location

United States

Related Subject Headings

  • Sex Factors
  • Serotonin Plasma Membrane Transport Proteins
  • Serotonin
  • Receptors, Serotonin, 5-HT2
  • Receptor, Serotonin, 5-HT1A
  • Rats, Sprague-Dawley
  • Rats
  • Pregnancy
  • Neurotoxicity Syndromes
  • Neurology & Neurosurgery