Inherent desensitisation-preventing properties of a novel, subtype-selective AMPA receptor agonist, (S)-CPW 399, as a possible explanation for its excitotoxic action in cultured cerebellar granule cells

C Sinclair, H Reavy, A Grieve, A Schousboe, E Morelli, E Novellino, G Campiani, Roger Griffiths

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The synthesis and pharmacological characterisation of (S)-CPW 399 as a novel, potent and subtype-selective agonist of the AMPA receptor was recently reported. Studies have been extended to investigate its excitotoxic action in primary cultures of mouse cerebellar granule cells. (S)-CPW 399 induced neuronal cell death in a time- and concentration-dependent manner (EC50 similar to70 muM) at 24-h exposure. (S)-CPW-induced neuronal death could be prevented by co-administration with either of the AMPA/kainate selective receptor antagonists 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX) and 6-nitro-7-sulphamoylbenzo[f]quinoxaline-2,3-dione (NBQX) or by the 2,3-benzodiazepine, GYKI 53655 (a selective AMPA receptor antagonist); while no protection was afforded by either the NMDA receptor antagonist D,L(+/-)-2-amino-5-phosphonopentanoate (APV) or by nifedipine (an L-type calcium channel antagonist) when used alone or in combination. Cyclothiazide, which blocks AMPA receptor desensitisation, caused minimal potentiation of (S)-CPW 399-induced neuronal death, supporting accumulating evidence that (S)-CPW 399 is a full AMPA receptor agonist that markedly prevents a receptor desensitised conformation. (S)-AMPA, (S)-willardiine (a naturally-occurring heterocyclic excitatory amino acid) and its halogenated derivative, (S)-5-fluorowillardiine, had no deleterious effect on neuronal viability when used alone but each, in the presence of cyclothiazide, induced a concentration-dependent excitotoxic cell death with a rank order of potency (fluorowillardiine >> AMPA = willardiine). (S)-CPW 399 stimulated an increase in intracellular free-calcium levels ([Ca2+](i)) in a concentration-dependent fashion (EC50 similar to5 muM) attaining a value of six-fold that of 'resting' cells at maximum stimulation; achieved at similar to100 muM (S)-CPW 399. The (S)-CPW 399-stimulated increase in [Ca2+](i) was virtually abolished by GYKI 53655, NBQX, CNQX and by cobalt ions; markedly inhibited by nifedipine and marginally affected by D-APV. These results suggest that (S)-CPW 399 may be used as a pharmacological tool to aid in the investigation of the role of AMPA receptors in excitotoxicity and their molecular mechanisms of desensitisation. (C) 2002 Elsevier Science Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)499-510
Number of pages12
JournalNeurochemistry International
Volume42
Issue number6
DOIs
Publication statusPublished - May 2003

Keywords

  • excitotoxicity
  • cultured cerebellar granule cells
  • AMPA receptors
  • desensitisation
  • METHYL-D-ASPARTATE
  • EXCITATORY AMINO-ACIDS
  • RAT HIPPOCAMPAL-NEURONS
  • CENTRAL-NERVOUS-SYSTEM
  • KAINATE RECEPTORS
  • GLUTAMATE-RECEPTOR
  • NEOCORTICAL NEURONS
  • SUBUNIT EXPRESSION
  • CA2+ PERMEABILITY
  • CORTICAL-NEURONS

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