Differences in glycinergic mIPSCs in the auditory brain stem of normal and congenitally deaf neonatal mice

J Neurophysiol. 2004 Feb;91(2):1006-12. doi: 10.1152/jn.00771.2003. Epub 2003 Oct 15.

Abstract

We have investigated the fundamental properties of central auditory glycinergic synapses in early postnatal development in normal and congenitally deaf (dn/dn) mice. Glycinergic miniature inhibitory postsynaptic currents (mIPSCs) were recorded using patch-clamp methods in neurons from a brain slice preparation of the medial nucleus of the trapezoid body (MNTB), at 12-14 days postnatal age. Our results show a number of significant differences between normal and deaf mice. The frequency of mIPSCs is greater (50%) in deaf versus normal mice. Mean mIPSC amplitude is smaller in deaf mice than in normal mice (mean mIPSC amplitude: deaf, 64 pA; normal, 106 pA). Peak-scaled fluctuation analysis of mIPSCs showed that mean single channel conductance is greater in the deaf mice (deaf, 64 pS; normal, 45 pS). The mean decay time course of mIPSCs is slower in MNTB neurons from deaf mice (mean half-width: deaf, 2.9 ms; normal, 2.3 ms). Light- and electron-microscopic immunolabeling results showed that MNTB neurons from deaf mice have more (30%) inhibitory synaptic sites (postsynaptic gephyrin clusters) than MNTB neurons in normal mice. Our results demonstrate substantial differences in glycinergic transmission in normal and congenitally deaf mice, supporting a role for activity during development in regulating both synaptic structure (connectivity) and the fundamental (quantal) properties of mIPSCs at central glycinergic synapses.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Brain Stem / physiology*
  • Brain Stem / ultrastructure
  • Deafness / congenital*
  • Deafness / physiopathology*
  • Glycine / physiology*
  • Immunohistochemistry
  • In Vitro Techniques
  • Mice
  • Mice, Inbred CBA
  • Microscopy, Immunoelectron
  • Neural Inhibition / physiology*
  • Synapses / physiology
  • Synapses / ultrastructure
  • Synaptic Transmission / physiology*

Substances

  • Glycine