Regional distribution of low affinity kainate receptors in brain of Macaca fascicularis determined by autoradiography using [3H](2S,4R)-4-methylglutamate.
Binding of [3H](2S,4R)-4-methylglutamate, a novel low affinity kainate receptor agonist, was studied in brain sections of a Macaca fascicularis monkey. In cerebellar sections, [3H](2S,4R)-4-methylglutamate bound to a single population of sites (KD = 20 nM) and was inhibited by various glutamate receptor ligands: kainate > 6-cyano-7-nitroquinoxaline-2,3-dione > L-glutamate >> AMPA. (S)-5-lodowillardiine and (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid (ATPA), drugs selective for the GluR5 subunit, displaced 50% and 40% of binding, respectively. Autoradiography revealed topographic binding of [3H](2S,4R)-4-methylglutamate. Binding in cortex was highest in layer 5 and restricted to CA2/3 in hippocampus. Levels of binding were high in septum and hypothalamus. Moderate densities of binding were found in caudate-putamen, cerebellar granular layer, nucleus tractus solitarius, cuneate nucleus and area postrema. Binding in spinal cord was concentrated in dorsal horn. [3H](2S,4R)-4-Methylglutamate shows differential binding throughout primate brain and is a valuable new ligand for low affinity kainate receptors.
Carroll
F Y
FY
Department of Pharmacology, Monash University, Clayton, Victoria, Australia.
Finkelstein
D I
DI
Horne
M K
MK
Lawrence
A J
AJ
Crawford
D
D
Paxinos
G
G
Beart
P M
PM
D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D008252:Macaca fascicularis; D008297:Male; D018092:Kainic Acid Receptors / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism; D014018:Tissue Distribution; D014316:Tritium
D005971:Glutamates; D018092:Kainic Acid Receptors; D014316:Tritium; C046105:4-methylglutamic acid