EXPRESSION OF N-METHYL-D-ASPARTATE RECEPTOR SUBUNIT MESSENGER-RNAS INTHE HUMAN BRAIN - HIPPOCAMPUS AND CORTEX

N-methyl-D-aspartate receptor (NR) activation in the hippocampus and n eocortex plays a central role in memory and cognitive function. We ana lyzed the cellular expression of the five NR subunit (NR1 and NR2A-D) mRNAs in these regions with in situ hybridization and human ribonucleo tide probes. Film autoradiograms demonstrated a distinct pattern of hy bridization signal in the hippocampal complex and the neocortex with p robes for NR1, NR2A, and NR2B mRNA. NR2C and NR2D probes yielded scatt ered signals without a distinct organization. At the emulsion level, t he NR1 probe produced high-density hybridization signals across the hi ppocampal complex. NR2A mRNA was higher in dentate granule cells and p yramidal cells in CA1 and subiculum compared to hilus neurons. NR2B mR NA expression was moderate throughout, with higher expression in denta te granule cells, CA1 and CA3 pyramidal cells than in hilus neurons. I n the hippocampal complex, the NR2C probe signal was not different fro m background in any region, whereas the NR2D probe signal resulted in low to moderate grain densities. We analyzed NR subunit mRNA expressio n in the prefrontal, parietal, primary visual, and motor cortices. All areas displayed strong NR1 hybridization signals. NR2A and NR2B mRNAs were expressed in cortical areas and layers. NR2C mRNA was ex-pressed at low levels in distinct layers that differed by region and the NR2D signal was equally moderate throughout all regions. Pyramidal cells i n both hippocampus and neocortex express NR1, NR2A, NR2B, and, to a le sser extent, NR2D mRNA. Interneurons or granular layer neurons and som e glial cells express NR2C mRNA. (C) 1995 Wiley-Liss, Inc.