Number and Density of AMPA Receptors in Single Synapses in Immature Cerebellum

The number of ionotropic receptors in synapses is an essential factor for determining the efficacy of fast transmission. We estimated the number of functional AMPA receptors at single postsynaptic sites by a combination of two-photon uncaging of glutamate and the nonstationary fluctuation analysis i...

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Bibliographic Details
Published in:The Journal of neuroscience 2005-01, Vol.25 (4), p.799-807
Main Authors: Tanaka, Jun-ichi, Matsuzaki, Masanori, Tarusawa, Etsuko, Momiyama, Akiko, Molnar, Elek, Kasai, Haruo, Shigemoto, Ryuichi
Format: Article
Language:English
Subjects:
Animals
Cellular/Molecular
Cerebellum - growth & development
Cerebellum - metabolism
Cerebellum - ultrastructure
Excitatory Postsynaptic Potentials - drug effects
Excitatory Postsynaptic Potentials - physiology
Freeze Fracturing - methods
Glutamates
Immunohistochemistry
In Vitro Techniques
Indoles
Kinetics
Purkinje Cells - physiology
Rats
Rats, Sprague-Dawley
Receptors, AMPA - metabolism
Synapses - metabolism
Synapses - physiology
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Summary:The number of ionotropic receptors in synapses is an essential factor for determining the efficacy of fast transmission. We estimated the number of functional AMPA receptors at single postsynaptic sites by a combination of two-photon uncaging of glutamate and the nonstationary fluctuation analysis in immature rat Purkinje cells (PCs), which receive a single type of excitatory input from climbing fibers. Areas of postsynaptic membrane specialization at the recorded synapses were measured by reconstruction of serial ultrathin sections. The number of functional AMPA receptors was proportional to the synaptic area with a density of approximately 1280 receptors/microm2. Moreover, highly sensitive freeze-fracture replica labeling revealed a homogeneous density of immunogold particles for AMPA receptors in synaptic sites (910 +/- 36 particles/microm2) and much lower density in extrasynaptic sites (19 +/- 2 particles/microm2) in the immature PCs. Our results indicate that in this developing synapse, the efficacy of transmission is determined by the synaptic area.
ISSN:0270-6474
1529-2401
DOI:10.1523/JNEUROSCI.4256-04.2005