Quisqualate and N-methyl-D-aspartate synergistically excite cerebellar Purkinje cells as a long-term effect.
Interactions between the excitatory amino acids (EAAs) quisqualate (QUIS) and N-methyl-D-aspartate (NMDA) were investigated in order to explore mechanisms which may help to explain long-term changes in synaptic efficacy induced by these agents. In 93% of the cerebellar Purkinje (Pnj) cells recorded extracellularly which responded to iontophoretic application of QUIS with increases in discharge of up to 100% above spontaneous levels. NMDA administration sensitized the neuron to further QUIS stimulation by 40-200% over control levels of response. NMDA-enhanced QUIS responses reached maximal levels after termination of NMDA application and persisted for up to 2 h post-NMDA. The NMDA receptor blocker 2-amino-5-phosphonovalerate (APV) prevented the observed effect only when administered before but not after NMDA application, suggesting that a long-lasting post-receptor mechanism may be involved in the observed synergistic interaction of QUIS and NMDA.
Smith
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Department of Anatomy, Hahnemann University, Philadelphia, PA 19102-1192.
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology*; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D016318:Quisqualic Acid; D051381:Rats
D010069:Oxadiazoles; D001224:Aspartic Acid; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D016318:Quisqualic Acid