Adenosine A2A receptor-induced inhibition of NMDA and GABA A receptor-mediated synaptic currents in a subpopulation of rat striatal neurons

Kerstin Wirkner, Zoltan Gerevich, Thomas Krause, Albrecht Günther, Laszlo Köles, Dietmar Schneider, Wolfgang Nörenberg, Peter Illes

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The function of adenosine A2A receptors, localized at the enkephalin-containing GABAergic medium spiny neurons of the striatum, has been discussed controversially. Here we show that, in the absence of external Mg 2+, the adenosine A2A receptor agonist CGS 21680 postsynaptically depressed the NMDA, but not the non-NMDA (AMPA/kainate) receptor-mediated fraction of the electrically evoked EPSCs in a subpopulation of striatal neurons. Current responses to locally applied NMDA but not AMPA were also inhibited by CGS 21680. However, in the presence of external Mg 2+, the inhibition by CGS 21680 of the GABAA receptor-mediated IPSCs led to a depression of the EPSC/IPSC complexes. The current response to the locally applied GABAA receptor agonist muscimol was unaltered by CGS 21680. Whereas, the frequency of spontaneous (s)IPSCs was inhibited by CGS 21680, their amplitude was not changed. Hence, it is suggested that under these conditions the release rather than the postsynaptic effect of GABA was affected by CGS 21680. In conclusion, under Mg2+-free conditions, CGS 21680 appeared to postsynaptically inhibit the NMDA receptor-mediated component of the EPSC, while in the presence of external Mg2+ this effect turned into a presynaptic inhibition of the GABAA receptor-mediated IPSC.

Original languageEnglish
Pages (from-to)994-1007
Number of pages14
JournalNeuropharmacology
Volume46
Issue number7
DOIs
Publication statusPublished - Jun 1 2004

Keywords

  • A receptor
  • GABA receptor
  • NMDA receptor

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

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