Synapses with a segmented, completely partitioned postsynaptic density express more AMPA receptors than other axospinous synaptic junctions
Section snippets
Animals
Experimental protocols employed in this study were described in detail earlier (Ganeshina et al., 2004). Briefly, four young adult male rats of Fischer-344×Brown Norway strain were acquired from Harlan (Indianapolis, IN, USA). All experiments were performed in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and approved by Northwestern University's Animal Care and Use Committee. The number of rats used in the present study was kept to a minimum
Identification of SCP synapses in electron micrographs of serial sections
Examination of serial sections obtained from tissue conventionally prepared for transmission electron microscopy showed that SCP synapses were encountered rarely in the CA1 stratum radiatum where their proportion was estimated to be 2.0% of the entire axospinous synaptic population and 12.8% of all perforated axospinous synapses. Synapses belonging to the SCP subtype could be readily identified in such preparations by a complex of specific ultrastructural features. These included the presence
Discussion
The present study demonstrates that SCP synapses are characterized by an exceptionally high AMPAR immunoreactivity as compared with other axospinous synapses in the rat CA1 stratum radiatum. The number of immunogold particles for AMPARs in SCP synapses markedly and significantly exceeds that in other axospinous synaptic junctions (Table 1). Our data also show that the PSD area is significantly larger in SCP synapses than in other synaptic subtypes (Table 1). Despite this, the density of
Acknowledgements
The authors would like to thank Dr. N. P. Spruston for helpful discussions. This work was supported by a grant from NIH/NIA AG17139.
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