Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets δ-subunit-containing GABA(A) receptors

Cristina Jiménez-González, Tiina Pirttimaki, David W. Cope, H. Rheinallt Parri

Research output: Contribution to journalArticle

Abstract

The rodent ventrobasal (VB) thalamus contains a relatively uniform population of thalamocortical (TC) neurons that receive glutamatergic input from the vibrissae and the somatosensory cortex, and inhibitory input from the nucleus reticularis thalami (nRT). In this study we describe ?-aminobutyric acid (GABA)(A) receptor-dependent slow outward currents (SOCs) in TC neurons that are distinct from fast inhibitory postsynaptic currents (IPSCs) and tonic currents. SOCs occurred spontaneously or could be evoked by hypo-osmotic stimulus, and were not blocked by tetrodotoxin, removal of extracellular Ca(2+) or bafilomycin A1, indicating a non-synaptic, non-vesicular GABA origin. SOCs were more common in TC neurons of the VB compared with the dorsal lateral geniculate nucleus, and were rarely observed in nRT neurons, whilst SOC frequency in the VB increased with age. Application of THIP, a selective agonist at d-subunit-containing GABA(A) receptors, occluded SOCs, whereas the benzodiazepine site inverse agonist ß-CCB had no effect, but did inhibit spontaneous and evoked IPSCs. In addition, the occurrence of SOCs was reduced in mice lacking the d-subunit, and their kinetics were also altered. The anti-epileptic drug vigabatrin increased SOC frequency in a time-dependent manner, but this effect was not due to reversal of GABA transporters. Together, these data indicate that SOCs in TC neurons arise from astrocytic GABA release, and are mediated by d-subunit-containing GABA(A) receptors. Furthermore, these findings suggest that the therapeutic action of vigabatrin may occur through the augmentation of this astrocyte-neuron interaction, and highlight the importance of glial cells in CNS (patho) physiology.
LanguageEnglish
Pages1471-1482
Number of pages12
JournalEuropean Journal of Neuroscience
Volume33
Issue number8
Early online date13 Mar 2011
DOIs
Publication statusPublished - Apr 2011

Fingerprint

GABA-A Receptors
Thalamus
gamma-Aminobutyric Acid
Neurons
Vigabatrin
Inhibitory Postsynaptic Potentials
GABA Plasma Membrane Transport Proteins
Geniculate Bodies
Aminobutyrates
Vibrissae
Somatosensory Cortex
Tetrodotoxin
Benzodiazepines
Neuroglia
Astrocytes
Rodentia
Pharmaceutical Preparations
Population

Keywords

  • animals
  • astrocytes
  • female
  • GABA agents
  • male
  • mice
  • knockout mice
  • neurons
  • patch-clamp techniques
  • rats
  • Wistar rats
  • GABA-A receptors
  • signal transduction
  • thalamus
  • vigabatrin
  • gamma-aminobutyric acid

Cite this

Jiménez-González, Cristina ; Pirttimaki, Tiina ; Cope, David W. ; Parri, H. Rheinallt. / Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets δ-subunit-containing GABA(A) receptors. In: European Journal of Neuroscience. 2011 ; Vol. 33, No. 8. pp. 1471-1482.
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Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets δ-subunit-containing GABA(A) receptors. / Jiménez-González, Cristina; Pirttimaki, Tiina; Cope, David W.; Parri, H. Rheinallt.

In: European Journal of Neuroscience, Vol. 33, No. 8, 04.2011, p. 1471-1482.

Research output: Contribution to journalArticle

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T1 - Non-neuronal, slow GABA signalling in the ventrobasal thalamus targets δ-subunit-containing GABA(A) receptors

AU - Jiménez-González, Cristina

AU - Pirttimaki, Tiina

AU - Cope, David W.

AU - Parri, H. Rheinallt

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AB - The rodent ventrobasal (VB) thalamus contains a relatively uniform population of thalamocortical (TC) neurons that receive glutamatergic input from the vibrissae and the somatosensory cortex, and inhibitory input from the nucleus reticularis thalami (nRT). In this study we describe ?-aminobutyric acid (GABA)(A) receptor-dependent slow outward currents (SOCs) in TC neurons that are distinct from fast inhibitory postsynaptic currents (IPSCs) and tonic currents. SOCs occurred spontaneously or could be evoked by hypo-osmotic stimulus, and were not blocked by tetrodotoxin, removal of extracellular Ca(2+) or bafilomycin A1, indicating a non-synaptic, non-vesicular GABA origin. SOCs were more common in TC neurons of the VB compared with the dorsal lateral geniculate nucleus, and were rarely observed in nRT neurons, whilst SOC frequency in the VB increased with age. Application of THIP, a selective agonist at d-subunit-containing GABA(A) receptors, occluded SOCs, whereas the benzodiazepine site inverse agonist ß-CCB had no effect, but did inhibit spontaneous and evoked IPSCs. In addition, the occurrence of SOCs was reduced in mice lacking the d-subunit, and their kinetics were also altered. The anti-epileptic drug vigabatrin increased SOC frequency in a time-dependent manner, but this effect was not due to reversal of GABA transporters. Together, these data indicate that SOCs in TC neurons arise from astrocytic GABA release, and are mediated by d-subunit-containing GABA(A) receptors. Furthermore, these findings suggest that the therapeutic action of vigabatrin may occur through the augmentation of this astrocyte-neuron interaction, and highlight the importance of glial cells in CNS (patho) physiology.

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