A Developmental Shift from GABAergic to Glycinergic Transmission in the Central Auditory System
- 15 June 1998
- journal article
- Published by Society for Neuroscience in Journal of Neuroscience
- Vol. 18 (12), 4646-4655
- https://doi.org/10.1523/jneurosci.18-12-04646.1998
Abstract
GABAergic and glycinergic circuits are found throughout the auditory brainstem, and it is generally assumed that transmitter phenotype is established early in development. The present study documents a profound transition from GABAergic to glycinergic transmission in the gerbil lateral superior olive (LSO) during the first 2 postnatal weeks. Whole-cell voltage-clamp recordings were obtained from LSO neurons in a brain slice preparation, and IPSCs were evoked by electrical stimulation of the medial nucleus of the trapezoid body (MNTB), a known glycinergic projection in adult animals. GABAergic and glycinergic components were identified by blocking transmission with bicuculline and strychnine (SN), respectively. In the medial limb of LSO, there was a dramatic change in the GABAergic IPSC component, decreasing from 78% at postnatal day 3 (P3)–P5 to 12% at P12–P16. There was an equal and opposite increase in the glycinergic component during this same period. Direct application of GABA also elicited significantly larger amplitude and longer duration responses in P3–P5 neurons compared with glycine-evoked responses. In contrast, MNTB-evoked IPSCs in lateral limb neurons were more sensitive to SN throughout development. Consistent with the electrophysiological observations, there was a reduction in staining for the β2,3-GABAA receptor subunit from P4 to P14, whereas staining for the glycine receptor-associated protein gephyrin increased. Brief exposure to baclofen depressed transmission at excitatory and inhibitory synapses for ∼15 min, suggesting a GABAB-mediated metabotropic signal. Collectively, these data demonstrate a striking switch from GABAergic to glycinergic transmission during postnatal development. Although GABA and glycine elicit similar postsynaptic ionotropic responses, our results raise the possibility that GABAergic transmission in neonates may play a developmental role distinct from that of glycine.Keywords
This publication has 63 references indexed in Scilit:
- Glycine Receptors in Cultured Chick Sympathetic Neurons are Excitatory and Trigger Neurotransmitter ReleaseThe Journal of Physiology, 1997
- GABA and GABA-A receptors are maximally expressed in association with cone synaptogenesis in neonatal rabbit retinaDevelopmental Brain Research, 1996
- Spread of Synaptic Depression Mediated by Presynaptic Cytoplasmic SignalingScience, 1996
- Transient expression of GABA immunoreactivity in the developing rat spinal cordJournal of Comparative Neurology, 1992
- Spontaneous firing as an epigenetic factor in brain development — physiological consequences of chronic tetrodotoxin and picrotoxin exposure on cultured rat neocortex neuronsDevelopmental Brain Research, 1992
- Immunocytochemistry of neurotransmitter receptorsJournal of Electron Microscopy Technique, 1990
- Dendritic morphology of central auditory neurons correlates with their tonotopic positionJournal of Comparative Neurology, 1990
- Neurotrophic effects of GABA in cultures of embryonic chick brain and retinaSynapse, 1988
- Effect of low calcium and protease inhibitors on synapse elimination during postnatal development in the rat soleus muscleDevelopmental Brain Research, 1986
- Further behavioral analysis of GABA-mediated inhibition in the early chick embryoDevelopmental Brain Research, 1986