Role of NMDA and non-NMDA receptors in synaptic transmission in rat piriform cortex.
The pharmacology of synaptic transmission was studied in slices of rat piriform cortex using the selective non-NMDA glutamate receptor antagonist 6.7-dinitroquinoxaline-2,3-dione (DNQX) and the selective NMDA receptor antagonist D-2-amino-5-phosphonopentanoate (D-AP5). DNQX produced a dose-dependent blockade of synaptic transmission at both lateral olfactory tract and associational system synapses with half-maximal effects at about 2.5 microM. D-AP5 had no significant effects on field potentials recorded in medium containing 2.5 mM Mg++. However in low Mg++ (100-200 microM) medium, D-AP5 did reduce a slow component of postsynaptic responses in both synaptic systems. In Mg(++)-free medium, 20 microM DNQX did not completely block transmission; the remaining response components were blocked by D-AP5. These results suggest that normal synaptic transmission in the two main inputs to the superficial layers of piriform cortex is mediated by non-NMDA receptors but that NMDA receptors can also participate under conditions where the Mg++ block of the NMDA channel is alleviated.
Jung
M W
MW
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717.
Larson
J
J
Lynch
G
G
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009830:Olfactory Bulb / Q000502:physiology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D011810:Quinoxalines; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; C056723:FG 9041; D015763:2-Amino-5-phosphonovalerate; D008274:Magnesium