Dendritic compartmentation of NMDA receptor mRNA in cultured hippocampal neurons

THE intracellular localization of mRNA encoding the obligatory subunit for the N-methyl-D-aspartate (NMDA) receptor complex (NMDAR1) was determined in cultured hippocampal neurons by in situ hybridization. From the time at which dendrites begin to develop, labelling for NMDAR1 mRNA extended beyond cell somata into incipient dendritic processes. By 10 days in culture, label was found throughout dendritic arbors in a distribution pattern similar to that for microtublin associated proteins 2 mRNA, but contrasted sharply with that for GluR1 or beta-actin mRNAs, both of which were restricted to cell somata. NMDAR1 mRNA was also expressed in astrocytes, where it was diffusely localized throughout the cytoplasm. These data suggest that transport of NMDAR1 mRNA may serve as a mechanism to target and manipulate local concentrations of NMDA receptors.