The time course of NMDA-and kainate-induced cGMP elevation and glutamate release in cultured neuron

Seikwan Oh, Chang Sik Shin, Hack Seang Kim

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3 Scopus citations


The levels of extracellular glutamate, intracellular Ca2+ ([Ca2+]i) and cGMP were determined for 1 h with the excitatory amino acids, N-methyl-D-aspartate (NMDA) or kainate in cultured cerebellar granule cells. Both NMDA and kainate produced a time-dependent release of glutamate, and kainate was more potent than NMDA in glutamate elevation. The elevation of extracellular glutamate was not purely governed by intracellular Ca2+ concentration. However, in opposite to the time-dependent elevation of glutamate, the elevation of cGMP by NMDA and kainate were at maximum level in short-time (1 min) incubation then remarkably decreased with longer incubation times. Post-applications (30 min after agonist) of EAA antagonst did not block EAAs-induced glutamate elevation. However, NMDA antagonist, phencyclidine (PCP), blocked NMDA-induced cGMP elevation at pre- or post-application, but kainate antagonist, 6,7-dinitroquinoxaline-2,3-dione (DNQX), paradoxically augmented kainate-induced cGMP elevation for 1 h incubation. These results show that NMDA or kainate induces time-dependent elevations of extracellular glutamate, while the elevations of cGMP by these EAAs are remarkably decreased with longer incubation times. However, NMDA- and kainate-induced glutamate release was blocked by pre-application of each receptor antagonist but not by post-application while EAA-induced [Ca2+]i was blocked by post-application of antagonist. These observations suggest that EAA-induced elevation of [Ca2+]i is not parallel with elevation of glutamate release or cGMP.

Original languageEnglish
Pages (from-to)153-158
Number of pages6
JournalArchives of Pharmacal Research
Issue number3
StatePublished - Jun 1995


  • Ca influx
  • Excitatory amino acids
  • Kainate
  • NMDA
  • cGMP


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