Non-NMDA excitatory amino acid receptors in a subcellular fraction enriched in cerebellar glomeruli.

Article date: 1991/4/1

PubMed ID: 784912

Journal name: Neurochemical research (ISSN: 0364-3190)


In the internal granular layer of the cerebellar cortex the polysynaptic complexes called glomeruli consist mainly of homogeneous populations of glutamatergic and GABAergic synapses, both located on granule cell dendrites. A subcellular fraction enriched in glomeruli was prepared from rat cerebellum, and the distribution of the different types of NMDA and non-NMDA glutamate binding sites was studied in the membranes derived from this fraction (fraction G) as compared to that in the membranes prepared from a total cerebellar homogenate (fraction T). Cl-/Ca2+ independent [3H]glutamate binding sites were not abundant and could be reliably measured only in fraction G. Cl- dependent/Ca2+ activated [3H]glutamate binding sites were more abundant and exhibited a single KD in both fractions G and T. Quisqualate, NMDA, kainate, L-AP4 and trans-ACPD inhibited [3H]glutamate binding to different extents in the two membrane fractions. Quisqualate sensitive sites were predominant in all cases but more abundant in fraction T than in fraction G. An opposite distribution was observed for the NMDA sensitive binding sites while kainate sensitive binding sites were scarce everywhere. Trans-ACPD, a ligand presumed selective for metabotropic glutamate binding sites, displaced [3H]glutamate from fraction T but nor from fraction G, suggesting the absence of these sites from glomeruli. Similarly, no L-AP4 sensitive sites were present in fraction G while they were abundant in fraction T. Binding sites associated with ionotropic receptors of the quisqualate type were determined by measuring [3H]AMPA binding. The density of the high affinity [3H]AMPA binding sites in fraction T was twice as high as in fraction G, indicating that these sites are abundant in structures other than glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)

Author List: Viennot F, de Barry J, Gombos G

Publication Types: Journal Article

Substances mentioned in the article: Glutamates; Receptors, AMPA; Receptors, Glutamate; Receptors, Kainic Acid; Receptors, Neurotransmitter; Ibotenic Acid; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Kainic Acid;

Mesh terms: Animals; Binding, Competitive; Cells, Cultured; Cerebellum/metabolism; Female; Glutamates/metabolism; Ibotenic Acid/analogs & derivatives; Kainic Acid/metabolism; Kinetics; Male; Rats; Rats, Inbred Strains; Receptors, AMPA; Receptors, Glutamate; Receptors, Kainic Acid; Receptors, Neurotransmitter/metabolism; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

Citations: - 6121375

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