Synaptic transmission at the Schaffer-CA1 synapse is blocked by 6,7-dinitro-quinoxaline-2,3-dione. An in vivo brain dialysis study in the rat.
6,7-Dinitro-quinoxaline-2,3-dione (DNQX, FG 9041), a new non-N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, has been reported to block non-NMDA receptor-mediated excitatory amino acidic responses in cultured neurons. We have perfused this compound in vivo through a dialysis fiber placed in the CA1 regions of anesthetized rats to test its effects on CA1 field-evoked potentials. Perfusions of 25-100 microM DNQX completely abolished field excitatory postsynaptic potentials (EPSP) and orthodromic population spikes (PS). This effect was dose-dependent and was reversed after washing with fresh Krebs-Ringer-bicarbonate. Antidromic population spikes and fiber volley potentials were unaffected by perfusions of DNQX up to 100 microM. On the contrary, perfusion of 50 microM D-2-amino-5-phosphonovalerate, a specific NMDA receptor antagonist, left unchanged both field EPSP and orthodromic PS. Results demonstrate that low-frequency transmission at the Schaffer collaterals-CA1 synapse is mediated by non-NMDA glutamate receptors.
Herreras
O
O
Departamento de Investigación, Hospital 'Ramón y Cajal', Madrid, Spain.
Menéndez
N
N
Herranz
A S
AS
Solis
J M
JM
Martín del Río
R
R
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*
D011810:Quinoxalines; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; C056723:FG 9041