Probing NMDA receptor GluN2A and GluN2B subunit expression and distribution in cortical neurons.
The spatial distribution of N-methyl-d-aspartate receptor (NMDAR) subunits in layer 5 (L5) neurons of the medial prefrontal cortex (mPFC) is important for integrating input-output signals involved in cognitive functions and motor behavior. In this study, focal laser scanning photostimulation of caged glutamate, slice electrophysiology, and small peptide pharmacology, were used to map the distribution of functional GluN2A and GluN2B subunits of the NMDAR from L5 neurons of wild-type (WT) and GluN2A(-/-) mice. Focal uncaging of glutamate evoked spatially-restricted glutamatergic responses on various dendritic locations of pyramidal neurons in the mPFC. Analyses of the spatial arrangements of the GluN2A and GluN2B subunits were performed by comparing inhibition of glutamatergic responses in the presence of the GluN2A-selective pharmacological antagonist, NVP-AAM077 (NVP), and the GluN2B-selective peptidic antagonist, conantokin-G (con-G). We found that apical and basal expression and distribution of GluN2A and GluN2B were similar in L5 mPFC neurons of WT mice. However, the inhibition of glutamatergic responses by NVP in brain slices of GluN2A(-/-) mice were dramatically decreased, while con-G inhibition remained similar to that observed in WT brain slices. The data obtained show that expression and spatial arrangement of GluN2B subunits is independent of GluN2A in L5 neurons of the mPFC. These findings have important ramifications for NMDAR organization and function in L5 pyramidal neurons of the mPFC, and show that specific populations of NMDARs can be antagonized, while sparing other subgroups of NMDARs, thus preserving selective NMDAR functions, an important therapeutic advantage.
W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN, USA.
Rashna D
RD
Balsara
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
Ashley N
AN
Ferreira
W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN, USA.
Deborah L
DL
Donahue
W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN, USA; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, USA. Electronic address: fcastell@nd.edu.
Francis J
FJ
Castellino
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA; Department of Pharmacology and Toxicology, Indiana University School of Medicine-South Bend, South Bend, IN, USA. Electronic address: plsheets@iupui.edu.
Patrick L
PL
Sheets
D000818:Animals; D020916:Conotoxins / Q000494:pharmacology; D003712:Dendrites / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D061848:Optical Imaging; D018408:Patch-Clamp Techniques; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D020916:Conotoxins; D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; C498554:5-(alpha-methyl-4-bromobenzylamino)phosphonomethyl-1,4-dihydroquinoxaline-2,3-dione; C121001:NR2B NMDA receptor; C055407:conotoxin GV
Conantokins; Laser-scanning photostimulation; Medial prefrontal cortex; NMDARs; Pyramidal L5 neurons; Slice electrophysiology