N-METHYL-D-ASPARTATE RECEPTOR-1 MESSENGER-RNA DISTRIBUTION IN THE CENTRAL-NERVOUS-SYSTEM OF THE WEAKLY ELECTRIC FISH APTERONOTUS-LEPTORHYNCHUS

We have isolated a partial cDNA for the N-methyl-D-aspartate (NMDA) re ceptor 1 (NMDAR1) subunit from an Apteronotus leptorhynchus brain cDNA library. The A. leptorhynchus cDNA fragment, which corresponds to nuc leotides 135-903 within the 5' region of the rat NR1 mRNA, encodes 252 amino acids that are >80% identical to the homologous segments of the rat, human, and duck NR1 proteins. RNAse protection assays revealed t hat the A. leptorhynchus NR1 mRNA was highly enriched in the forebrain and hypothalamus, with lesser amounts in the brainstem, and very low levels in the cerebellum. In situ hybridization also demonstrated that neurons in the pallial forebrain were highly enriched in NR1 transcri pts. High levels of NR1 mRNA were found in pyramidal cells within the optic tectum and octavolateral regions. Pyramidal cells of the electro sensory lateral line lobe had the highest levels of expression, and th e NR1 mRNA was found to be selectively enriched in their apical dendri tes. (C) 1997 Wiley-Liss, Inc.