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An Isolated Semi-intact Preparation of the Mouse Vestibular Sensory Epithelium for Electrophysiology and High-resolution Two-photon Microscopy
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An Isolated Semi-intact Preparation of the Mouse Vestibular Sensory Epithelium for Electrophysiology and High-resolution Two-photon Microscopy

Published on: June 13, 2013

Excitatory actions of GABA in developing chick vestibular afferents: effects on resting electrical activity

Celso Cortes1, Fabian Galindo, Salvador Galicia

  • 1Facultad de Medicina, Benemérita Universidad Autónoma de Puebla, Av. 13 Sur 2702 Colonia Volcanes CP, 72410, Puebla, Pue., México.

Synapse (New York, N.Y.)
|February 13, 2013
PubMed

Insights

Gamma-aminobutyric acid (GABA) enhances vestibular afferent activity during chicken development. This excitatory effect of GABA diminishes with age, suggesting a role in regulating spontaneous activity and glutamate release.

Area of Science:

  • Neuroscience
  • Developmental Biology
  • Auditory and Vestibular Systems

Background:

  • Vestibular afferents are crucial for balance and spatial orientation.
  • The role of neurotransmitters like GABA in vestibular development is not fully understood.
  • Understanding developmental changes in neurotransmission is key to deciphering sensory system maturation.

Purpose of the Study:

  • To investigate the developmental effects of gamma-aminobutyric acid (GABA) on vestibular afferent activity.
  • To characterize the role of GABAergic signaling in the inner ear during embryonic and early postnatal development.
  • To elucidate the mechanisms underlying GABA's influence on vestibular afferent excitability.

Main Methods:

  • Isolated inner ear preparations from embryonic (E15-E21) and postnatal (P5) chickens.
  • Application of GABA and muscimol to record multiunit activity of vestibular afferents.
  • Use of GABAA receptor antagonists (bicuculline, picrotoxin) and chloride channel blockers (9-AC).
  • Co-application with glutamatergic antagonists (CNQX, MCPG, 7ClKyn) to assess presynaptic interactions.

Main Results:

  • GABA and muscimol increased the basal discharge frequency of vestibular afferents in a dose-dependent manner.
  • The excitatory effect of GABA was strongest in early embryonic stages (E15-E17) and decreased significantly by later embryonic (E21) and postnatal (P5) stages.
  • GABAA receptor antagonists and chloride channel blockers reduced the excitatory effect of GABA, indicating a GABAA receptor-mediated mechanism.
  • Glutamatergic antagonists also reduced basal discharge and GABA's effect, suggesting presynaptic involvement.

Conclusions:

  • GABA exerts an excitatory influence on vestibular afferent resting activity during development, likely mediated by GABAA receptors.
  • This excitatory role diminishes with developmental progression, possibly due to changes in chloride ion gradients.
  • GABA acts presynaptically, potentially facilitating spontaneous activity and modulating glutamate release, but is not the primary neurotransmitter in these synapses.

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