N-Methyl-D-Aspartate Receptors are Clustered and Immobilized on Dendrites of Living Cortical Neurons

• Published in: Proceedings of the National Academy of Sciences - PNAS 1993-08, Vol.90 (16), p.7819-7823
• Main Authors: Benke, Timothy A., Jones, Owen T., Collingridge, Graham L., Angelides, Kimon J.
• Format: Article
• Language: English
• Subjects: 2-Amino-5-phosphonovalerate - pharmacology; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Animals; Antibodies; Biochemistry; Biological and medical sciences; Calcium - metabolism; Cells, Cultured; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cerebral Cortex - physiology; Conotoxins; Conus geographus; Dendrites; Dendrites - drug effects; Dendrites - metabolism; Dendrites - physiology; Digital images; Electric current; Evoked Potentials - drug effects; Fluorescence; Fundamental and applied biological sciences. Psychology; Ibotenic Acid - analogs & derivatives; Ibotenic Acid - pharmacology; Image contrast; Magnesium - pharmacology; Membrane Potentials; Microscopy; Mollusk Venoms - pharmacology; N-Methylaspartate - pharmacology; Neurology; Neurons; Neurons - drug effects; Neurons - metabolism; Neurons - physiology; Neuroscience; Peptides, Cyclic - pharmacology; Pyramidal Tracts - drug effects; Pyramidal Tracts - physiology; Rats; Receptors; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - metabolism; Receptors, N-Methyl-D-Aspartate - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.16.7819

The response of nerve cells to synaptic inputs and the propagation of this activation is critically dependent on the cell-surface distribution of ion channels. In the hippocampus, Ca2+influx through N-methyl-D-aspartate receptors (NMDAR) and/or voltage-dependent calcium channels on dendrites is thought to be critically involved in long-term potentiation, neurite outgrowth, epileptogenesis, synaptogenesis, and cell death. We report that conantokin-G (CntxG), a peptide from Conus geographus venom, competitively blocked with high affinity and specificity NMDAR-mediated currents in hippocampal neurons and is a reliable probe for exploring NMDAR distribution. Fluorescent derivatives of CntxG were prepared and used to directly determine NMDAR distribution on living hippocampal neurons by digital imaging and confocal fluorescence microscopy. In hippocampal slices, the CA1 dendritic subfield was strongly labeled by CntxG, whereas the CA3 mossy fiber region was not. On CA1 hippocampal neurons in culture, dendritic CntkG-sensitive NMDAR were clustered at sites of synaptic contacts, whereas somatic NMDAR were distributed diffusely and in patches. NMDAR distribution differed from the distribution of voltage-dependent calcium channels. A significant fraction of labeled NMDAR on somata and dendrites was found to be highly mobile: rates were consistent with the possible rapid recruitment of NMDAR to specific synaptic locations. The localization of NMDAR and modulation of this distribution demonstrated here may have important implications for the events that underlie neuronal processing and synaptic remodeling during associative synaptic modification.