Postsynaptic activity of metabotropic glutamate receptors in the piriform cortex.
Effects of some glutamate receptor antagonists on signal propagation elicited by stimulation of association fibers in guinea pig piriform cortex slices were investigated using optical imaging. During simultaneous application of both NMDA and non-NMDA receptor antagonists (D-2-amino-5-phosphonopentanoic acid and 6-cyano-7-nitroquinoxaline-2,3-dione, respectively) the postsynaptic activity was largely suppressed, and a weak although distinct late propagation component was found to survive. This latter component was reversibly suppressed by application of low Ca(2+) solution or a group I/II specific metabotropic glutamate receptor (mGluR) antagonist (+)-alpha-methyl-4-carboxyphenylglycine. These results suggest that mGluRs mediate postsynaptic excitation, which would play a crucial role in activating the reverberating positive feedback circuit effectively.
Sugitani
Michio
M
Department of Physiology, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan.
Sugai
Tokio
T
Onoda
Norihiko
N
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000502:physiology*
D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate