N-methyl-D-aspartate receptor 1 mRNA distribution in the central nervous system of the weakly electric fishApteronotus leptorhynchus

Abstract

We have isolated a partial cDNA for the N-methyl-D-aspartate (NMDA) receptor 1 (NMDAR1) subunit from an Apteronotus leptorhynchus brain cDNA library. The A. leptorhynchus cDNA fragment, which corresponds to nucleotides 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 that 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 transcripts. High levels of NR1 mRNA were found in pyramidal cells within the optic tectum and octavolateral regions. Pyramidal cells of the electrosensory lateral line lobe had the highest levels of expression, and the NR1 mRNA was found to be selectively enriched in their apical dendrites.

SK Channels Provide a Novel Mechanism for the Control of Frequency Tuning in Electrosensory Neurons

“…The primers used were as follows: forward, 5Ј-ATCTTYGGIATGTTYGGIATIGT-3Ј, and reverse, 5Ј-TATAGATIAGCCAIGTYTCY-3Ј, where Y is CϩT and I is inosine. PCR was performed on brain cDNA from A. leptorhynchus (Bottai et al, 1997). The product of the degenerate reverse transcription-PCR (900 bp) was cloned into the pGEM-T vector (Promega, Madison, WI).…”

Excitatory Amino Acid Receptors of the Electrosensory System: The NR1/NR2BN-Methyl-d-Aspartate Receptor

“…Especially prominent coexpression of NMDA receptors (NR1 subunit) and CaMKII is evident in ELL pyramidal cells and in neurons of the dorsal forebrain (Bottai et al 1997;Maler and Hincke 1999); preliminary studies (in situ hybridization) have demonstrated that the AptNR2B subunit is also abundant at both sites (R. Dunn, unpublished observations.). It will therefore be interesting to determine whether the activity-dependent association of AptNR2B and CaMKII is part of the molecular basis of adaptive sensory filtering in ELL (Bastian 1999).…”

“…Recent studies have demonstrated that the dorsolateral forebrain of teleost fish is essential for spatial memory (Rodriguez et al 2002) and have suggested that this region is similar to mammalian hippocampus. In Apteronotus, this brain region has very high levels of NR1 (Bottai et al 1997), AptNR2B (R. Dunn and L. Maler, unpublished observations), and CaMKII (Bottai et al 1997). Both spatial memory and synaptic plasticity (long-term potentiation) in the hippocampus require intact interactions between NR2B and CaMKII (Malenka and Nicoll 1999); given the relative simplicity of teleost forebrain, our results suggest that this may prove to be a useful preparation for investigating the cellular basis of spatial memory.…”

“…In A. leptorhynchus, sequence analysis of the NMDA receptor subunit NR1 (AptNR1) indicated strong sequence conservation with its mammalian orthologs, including some of the alternative splice variants (Bottai et al 1997(Bottai et al , 1998. Here, we present the sequence of the apteronitid NR2B subunit (AptNR2B).…”

“…In situ hybridization and immunohistochemical analyses have demonstrated prominent expression of NMDA receptors in both primary afferent and feedback synapses of the ELL (Berman et al 2001;Bottai et al 1997). Furthermore, the plasticity of synaptic responses involved in the adaptive filtering of predictable electorsensory signals (Bastian 1996ab;Bell et al 1997) is inhibited by pharmacological blockade of these NMDA receptors (Han et al 2000;J.…”