Complex effects of CNQX on CA1 interneurons of the developing rat hippocampus

G. Maccaferri, R. Dingledine

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We have investigated the effect of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX), on spontaneous GABAA receptor-mediated transmission in the hippocampal CA1 subfield. On average, simultaneous recordings from CA1 str. radiatum interneurons and pyramidal cells showed that CNQX application doubled the frequency of bicuculline sensitive spontaneous inhibitory postsynaptic currents (sIPSCs) without apparently changing their amplitude. However, despite the increase in sIPSC frequency, current-clamp recording showed that CNQX application was sufficient in most cases to depolarize interneurons to firing threshold. In contrast, CNQX application could not induce firing in pyramidal cells. In the presence of tetrado-toxin (TTX), CNQX increased interneuron membrane conductance, and depolarized interneurons from resting potentials. The axons of the studied interneurons ramify widely in the CA1 region and suggest that the cells of our sample are mostly involved with control of dendritic excitability. Our results indicate that CNQX-induced increase of sIPSC frequency is not limited to excitatory cells, but also impacts GABAergic interneurons. However, despite the increase of sIPSC frequency, CNQX-induced depolarization is sufficient to selectively generate firing in interneurons and thus modify the network properties mediated by GABAA receptors in the hippocampus.

Original languageEnglish (US)
Pages (from-to)523-529
Number of pages7
JournalNeuropharmacology
Volume43
Issue number4
DOIs
StatePublished - Sep 2002

Keywords

  • Bicuculline
  • Dendrite
  • GABA receptor
  • Network
  • Quinoxaline derivatives
  • TTX

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

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