Prenatal drug exposures sensitize noradrenergic circuits to subsequent disruption by chlorpyrifos.

Published

Journal Article

We examined whether nicotine or dexamethasone, common prenatal drug exposures, sensitize the developing brain to chlorpyrifos. We gave nicotine to pregnant rats throughout gestation at a dose (3mg/kg/day) producing plasma levels typical of smokers; offspring were then given chlorpyrifos on postnatal days 1-4, at a dose (1mg/kg) that produces minimally-detectable inhibition of brain cholinesterase activity. In a parallel study, we administered dexamethasone to pregnant rats on gestational days 17-19 at a standard therapeutic dose (0.2mg/kg) used in the management of preterm labor, followed by postnatal chlorpyrifos. We evaluated cerebellar noradrenergic projections, a known target for each agent, and contrasted the effects with those in the cerebral cortex. Either drug augmented the effect of chlorpyrifos, evidenced by deficits in cerebellar β-adrenergic receptors; the receptor effects were not due to increased systemic toxicity or cholinesterase inhibition, nor to altered chlorpyrifos pharmacokinetics. Further, the deficits were not secondary adaptations to presynaptic hyperinnervation/hyperactivity, as there were significant deficits in presynaptic norepinephrine levels that would serve to augment the functional consequence of receptor deficits. The pretreatments also altered development of cerebrocortical noradrenergic circuits, but with a different overall pattern, reflecting the dissimilar developmental stages of the regions at the time of exposure. However, in each case the net effects represented a change in the developmental trajectory of noradrenergic circuits, rather than simply a continuation of an initial injury. Our results point to the ability of prenatal drug exposure to create a subpopulation with heightened vulnerability to environmental neurotoxicants.

Full Text

Duke Authors

Cited Authors

  • Slotkin, TA; Skavicus, S; Seidler, FJ

Published Date

  • December 2, 2015

Published In

Volume / Issue

  • 338 /

Start / End Page

  • 8 - 16

PubMed ID

  • 26419632

Pubmed Central ID

  • 26419632

Electronic International Standard Serial Number (EISSN)

  • 1879-3185

Digital Object Identifier (DOI)

  • 10.1016/j.tox.2015.09.005

Language

  • eng

Conference Location

  • Ireland