Influence of developmental nicotine exposure on spike-timing precision and reliability in hypoglossal motoneurons

J Neurophysiol. 2015 Mar 15;113(6):1862-72. doi: 10.1152/jn.00838.2014. Epub 2014 Dec 30.

Abstract

Smoothly graded muscle contractions depend in part on the precision and reliability of motoneuron action potential generation. Whether or not a motoneuron generates spikes precisely and reliably depends on both its intrinsic membrane properties and the nature of the synaptic input that it receives. Factors that perturb neuronal intrinsic properties and/or synaptic drive may compromise the temporal precision and the reliability of action potential generation. We have previously shown that developmental nicotine exposure (DNE) alters intrinsic properties and synaptic transmission in hypoglossal motoneurons (XIIMNs). Here we show that the effects of DNE also include alterations in spike-timing precision and reliability, and spike-frequency adaptation, in response to sinusoidal current injection. Current-clamp experiments in brainstem slices from neonatal rats show that DNE lowers the threshold for spike generation but increases the variability of spike-timing mechanisms. DNE is also associated with an increase in spike-frequency adaptation and reductions in both peak and steady-state firing rate in response to brief, square wave current injections. Taken together, our data indicate that DNE causes significant alterations in the input-output efficiency of XIIMNs. These alterations may play a role in the increased frequency of obstructive apneas and altered suckling strength and coordination observed in nicotine-exposed neonatal humans.

Keywords: development; intrinsic properties; motoneuron; nicotine; spike-timing precision; spike-timing reliability.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials*
  • Animals
  • Female
  • Ganglionic Stimulants / pharmacology*
  • Hypoglossal Nerve / drug effects*
  • Hypoglossal Nerve / embryology
  • Hypoglossal Nerve / physiology
  • Male
  • Motor Neurons / drug effects*
  • Motor Neurons / physiology
  • Nicotine / pharmacology*
  • Pregnancy
  • Prenatal Exposure Delayed Effects
  • Rats
  • Rats, Sprague-Dawley
  • Reaction Time

Substances

  • Ganglionic Stimulants
  • Nicotine