title: Differences in glycinergic mIPSCs in the auditory brain stem of normal and congenitally deaf neonatal mice.
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.
authors.affiliation: Synaptic Structure and Function Group, Division of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra ACT 0200, Australia.
authors.forename: Richardson N
authors.initials: RN
authors.lastname: Leao
authors.forename: Sharon
authors.initials: S
authors.lastname: Oleskevich
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Melissa
authors.initials: M
authors.lastname: Bautista
authors.forename: Robert E W
authors.initials: RE
authors.lastname: Fyffe
authors.forename: Bruce
authors.initials: B
authors.lastname: Walmsley
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000502:physiology* / Q000648:ultrastructure; D003638:Deafness / Q000151:congenital* / Q000503:physiopathology*; D005998:Glycine / Q000502:physiology*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D051379:Mice; D008808:Mice, Inbred CBA; D016253:Microscopy, Immunoelectron; D009433:Neural Inhibition / Q000502:physiology*; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D005998:Glycine