| Title | Input-specific intrasynaptic arrangements of ionotropic glutamate receptors and their impact on postsynaptic responses. | | Author(s) | Tarusawa E, Matsui K, Budisantoso T, Molnár E, Watanabe M, Matsui M, Fukazawa Y, Shigemoto R | | Institution | Division of Cerebral Structure, National Institute for Physiological Sciences, Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8787, Japan. | | Source | J Neurosci 2009 Oct 14; 29(41):12896-908. | | MeSH | Animals
Animals, Newborn
Biophysics
Cerebral Cortex
Electric Stimulation
Excitatory Postsynaptic Potentials
Freeze Fracturing
Geniculate Bodies
Glutamic Acid
Male
Mice
Mice, Knockout
Microscopy, Electron
Neural Pathways
Rats
Rats, Long-Evans
Receptor, Muscarinic M2
Receptors, AMPA
Receptors, N-Methyl-D-Aspartate
Retina
Statistics, Nonparametric
Synapses
Vesicular Glutamate Transport Protein 1
Vesicular Glutamate Transport Protein 2
| | Abstract | To examine the intrasynaptic arrangement of postsynaptic receptors in relation to the functional role of the synapse, we quantitatively analyzed the two-dimensional distribution of AMPA and NMDA receptors (AMPARs and NMDARs, respectively) using SDS-digested freeze-fracture replica labeling (SDS-FRL) and assessed the implication of distribution differences on the postsynaptic responses by simulation. In the dorsal lateral geniculate nucleus, corticogeniculate (CG) synapses were twice as large as retinogeniculate (RG) synapses but expressed similar numbers of AMPARs. Two-dimensional views of replicas revealed that AMPARs form microclusters in both synapses to a similar extent, resulting in larger AMPAR-lacking areas in the CG synapses. Despite the broad difference in the AMPAR distribution within a synapse, our simulations based on the actual receptor distributions suggested that the AMPAR quantal response at individual RG synapses is only slightly larger in amplitude, less variable, and faster in kinetics than that at CG synapses having a similar number of the receptors. NMDARs at the CG synapses were expressed twice as many as those in the RG synapses. Electrophysiological recordings confirmed a larger contribution of NMDAR relative to AMPAR-mediated responses in CG synapses. We conclude that synapse size and the density and distribution of receptors have minor influences on quantal responses and that the number of receptors acts as a predominant postsynaptic determinant of the synaptic strength mediated by both the AMPARs and NMDARs. | | Language | eng | | Pub Type(s) | In Vitro
Journal Article
Research Support, Non-U.S. Gov't
| | PubMed ID | 19828804 |
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