NMDA receptor content of synapses in stratum radiatum of the hippocampal CA1 area.

Racca, C., Stephenson, F.A., Streit, P., Roberts, J.D. and Somogyi, P. (2000) NMDA receptor content of synapses in stratum radiatum of the hippocampal CA1 area. Journal of Neuroscience, 20 (7). pp. 2512-2522.

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Official URL: http://www.jneurosci.org/content/20/7/2512

Abstract

Glutamate receptors activated by NMDA (NMDARs) or AMPA (AMPARs) are clustered on dendritic spines of pyramidal cells. Both the AMPAR-mediated postsynaptic responses and the synaptic AMPAR immunoreactivity show a large intersynapse variability. Postsynaptic responses mediated by NMDARs show less variability. To assess the variability in NMDAR content and the extent of their coexistence with AMPARs in Schaffer collateral-commissural synapses of adult rat CA1 pyramidal cells, electron microscopic immunogold localization of receptors has been used. Immunoreactivity of NMDARs was detected in virtually all synapses on spines, but AMPARs were undetectable, on average, in 12% of synapses. A proportion of synapses had a very high AMPAR content relative to the mean content, resulting in a distribution more skewed toward larger values than that of NMDARs. The variability of synaptic NMDAR content [coefficient of variation (CV), 0.64-0.70] was much lower than that of the AMPAR content (CV, 1.17-1.45). Unlike the AMPAR content, the NMDAR content showed only a weak correlation with synapse size. As reported previously for AMPARs, the immunoreactivity of NMDARs was also associated with the spine apparatus within spines. The results demonstrate that the majority of the synapses made by CA3 pyramidal cells onto spines of CA1 pyramids express both NMDARs and AMPARs, but with variable ratios. A less-variable NMDAR content is accompanied by a wide variability of AMPAR content, indicating that the regulation of expression of the two receptors is not closely linked. These findings support reports that fast excitatory transmission at some of these synapses is mediated by activation mainly of NMDARs.

Item Type:Article
Uncontrolled Keywords:hippocampus spine immunocytochemistry electron microscopy NMDA receptor AMPA receptor glutamate receptor spine apparatus
Departments, units and centres:Department of Pharmaceutical and Biological Chemistry > Department of Pharmaceutical and Biological Chemistry
ID Code:2542
Journal or Publication Title:Journal of Neuroscience
Deposited By:Library Staff
Deposited On:25 Nov 2011 11:13
Last Modified:25 Nov 2011 11:13

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