GABAA receptors at hippocampal mossy fibers

Neuron. 2003 Sep 11;39(6):961-73. doi: 10.1016/s0896-6273(03)00559-2.


Presynaptic GABAA receptors modulate synaptic transmission in several areas of the CNS but are not known to have this action in the cerebral cortex. We report that GABAA receptor activation reduces hippocampal mossy fibers excitability but has the opposite effect when intracellular Cl- is experimentally elevated. Synaptically released GABA mimics the effect of exogenous agonists. GABAA receptors modulating axonal excitability are tonically active in the absence of evoked GABA release or exogenous agonist application. Presynaptic action potential-dependent Ca2+ transients in individual mossy fiber varicosities exhibit a biphasic dependence on membrane potential and are altered by GABAA receptors. Antibodies against the alpha2 subunit of GABAA receptors stain mossy fibers. Axonal GABAA receptors thus play a potentially important role in tonic and activity-dependent heterosynaptic modulation of information flow to the hippocampus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • GABA-A Receptor Agonists
  • Guinea Pigs
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Hippocampus / ultrastructure
  • In Vitro Techniques
  • Male
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Mossy Fibers, Hippocampal / drug effects
  • Mossy Fibers, Hippocampal / metabolism*
  • Mossy Fibers, Hippocampal / ultrastructure
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-A / metabolism*
  • Receptors, GABA-A / ultrastructure
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*
  • gamma-Aminobutyric Acid / metabolism


  • GABA-A Receptor Agonists
  • Receptors, GABA-A
  • gamma-Aminobutyric Acid