Characterization and regulation of a high affinity [3H]CNQX labelled AMPA receptor in rat neocortex.
We have characterized a high affinity site of the alpha-amino-3 hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor in in vitro living slices of adult rat neocortex using [3H]CNQX, and AMPA antagonist. [3H]CNQX labelled multiple binding sites with a Bmax of a high affinity site of approximately 470 fmol/mg protein and an apparent Kd of 11.3 nM. The high affinity site of the AMPA receptor could be down-regulated (36%) by 2 h preincubations in quisqualate, an AMPA agonist. Increases in electrical activity induced by a combination of veratridine and glutamate also led to an average decrease of the high affinity AMPA receptor number of 17%. In addition, preincubations with muscimol, a GABAA agonist, as well as glutamate agonists kainate and N-methyl-D-aspartate (NMDA) led to an average increase in high affinity AMPA receptor number of 17%, 14%, and 37%, respectively. The present results show that a ligand-gated high affinity AMPA receptor can be regulated by agonist stimulation as well as changes in neural activity.
Department of Ophthalmology, University of British Columbia, Vancouver, Canada.
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D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000378:metabolism; D008297:Male; D009118:Muscimol / Q000378:metabolism; D016202:N-Methylaspartate / Q000378:metabolism; D010069:Oxadiazoles; D011810:Quinoxalines / Q000378:metabolism*; D016318:Quisqualic Acid / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D014316:Tritium
D010069:Oxadiazoles; D011810:Quinoxalines; D018091:Receptors, AMPA; D017981:Receptors, Neurotransmitter; D014316:Tritium; D009118:Muscimol; D016202:N-Methylaspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D016318:Quisqualic Acid; D007608:Kainic Acid