The distribution of the NMDA R1 subunit in the rat hippocampus--an immunocytohistochemical study.

In the present study we examined immunocytochemically the distribution of the R1 subunit of NMDA receptors in rat hippocampus. The applied antibody directed against the III-IV transmembrane region of the R1 subunit of NMDA receptors revealed a heterogeneous distribution of NMDA R1 protein which was highest in the CA1 pyramidal layer and lowest in the stratum lacunosum moleculare. The high immunoreactivity that corresponded to the presence of NMDA R1 receptor subunits was observed mainly in layers of cell bodies of hippocampal neurons, such as deep pyramidal layers of CA1, CA2 and CA3 regions and a granular cell layer of the dentate gyrus. The obtained data are discussed in terms of correlation between the receptor localization and the vulnerability of hippocampal neurons to overstimulation associated with activation of NMDA receptors.