Differential expression of NMDA receptor subunits and splice variants among the CA1, CA3 and dentate gyrus of the adult rat.

N-Methyl-d-aspartate (NMDA)-type glutamate receptors in the hippocampus are important mediators of both memory formation and excitotoxicity. It is thought that glutamatergic neurons of the CA1, CA3 and dentate gyrus regions of the hippocampus contribute differentially to memory formation and are differentially sensitive to excitotoxicity. The subunit and/or splice variant composition of the NMDA receptor controls many aspects of receptor function such as ligand affinity, calcium permeability and channel kinetics, as well as interactions with intracellular anchoring and regulatory proteins. Thus, one possible explanation of the differences in NMDA receptor-dependent processes, such as synaptic plasticity and excitotoxicity, among the hippocampal sub-regions is that they differ in subunit and/or splice variant expression. Here we report that the NMDA receptor subunits NR1 and NR2B, along with the four splice variant cassettes of the NR1 subunit are differentially expressed in the CA1, CA3 and dentate gyrus of the hippocampus. Expression of the AMPA receptor subunits GluR1 and GluR2 also differ. These differences may contribute to functional differences, such as with excitotoxicity and synaptic plasticity, that exist between the sub-regions of the hippocampus.