Antagonism of monosynaptic excitations in the mouse olfactory cortex slice by 6,7-dinitroquinoxaline-2,3-dione.
The effects of 6,7-dinitroquinoxaline-2,3-dione (DNQX) have been tested in slices of olfactory cortex of the mouse against responses evoked by N-methyl-D-aspartate, kainate and quisqualate and on the surface field potentials evoked on electrical stimulation of the lateral olfactory tract. At a concentration of 5 microM, DNQX competitively antagonized responses evoked by kainate and quisqualate, with only a small reduction in the responses to N-methyl-D-aspartate. In contrast, DL-(+-)-2-amino-5-phosphonopentanoic acid (APP, 50 microM) selectively antagonized depolarizations to N-methyl-D-aspartate. The amplitude of the field potential known as the N-wave was reduced by DNQX in a concentration-dependent reversible manner (IC50 = 2.92 +/- 0.33 microM; mean +/- SE mean, n = 4). DL-(+-)-2-Amino-5-phosphonopentanoic acid (50 microM) did not significantly affect this action of DNQX. It is concluded that DNQX inhibits monosynaptic excitations in the olfactory cortex by selectively blocking kainate and/or quisqualate receptors, although it is unclear whether the receptors are located at pre- and/or postsynaptic sites.
Collins
G G
GG
University Department of Pharmacology and Therapeutics, Royal Hallamshire Hospital, Sheffield, U.K.
Buckley
K S
KS
D000818:Animals; D001224:Aspartic Acid / Q000494:pharmacology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D011712:Pyramidal Tracts / Q000166:cytology / Q000187:drug effects; D011810:Quinoxalines / Q000494:pharmacology*; D016318:Quisqualic Acid; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000378:metabolism; D012023:Reflex, Monosynaptic / Q000187:drug effects*; D013569:Synapses / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D014633:Valine / Q000494:pharmacology / Q000031:analogs & derivatives
D001224:Aspartic Acid; D016202:N-Methylaspartate; D010069:Oxadiazoles; D011810:Quinoxalines; D016318:Quisqualic Acid; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter; D014633:Valine; C056723:FG 9041; C056639:2-amino-5-phosphopentanoic acid