High abundance of GluR1 mRNA and reduced Q/R editing of GluR2 mRNA in individual NADPH-diaphorase neurons.
Striatal and cortical neurons containing NADPH-diaphorase [NADPH-d(+)] are highly vulnerable to excitotoxicity that is induced by activation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)- or kainate-sensitive glutamate receptors. This has been attributed to Ca2+ entry through AMPA/kainate receptors in NADPH-d(+) neurons. In this study, we applied single cell RT-PCR technique to test the hypothesis that differences in levels and processing of the GluR2 subunit would contribute to the selective vulnerability of NADPH-d(+) neurons to AMPA. The nested PCR specific for GluR1-GluR4 showed that rat striatal NADPH-d(+) neurons expressed twice as much GluR1 mRNA as NADPH-d(-) neurons did. The percentage of RNA editing at the Q/R site of GluR2 was 46% in NADPH-d(+) neurons and 92% in NADPH-d(-) neurons. These results suggest that the unedited expression of GluR2 and the reduced ratio of GluR2/GluR1 render NADPH-d(+) neurons highly sensitive to Ca2+-mediated AMPA neurotoxicity. In support of this, most NADPH-d(+) neurons exposed to 100 microM AMPA showed Co2+ uptake and survived AMPA challenge only in the absence of extracellular Ca2+.
Kim
D Y
DY
Department of Neuroscience, Ajou University School of Medicine, Suwon, Korea.
Kim
S H
SH
Choi
H B
HB
Min
C
C
Gwag
B J
BJ
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005333:Fetus; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D009252:NADPH Dehydrogenase / Q000378:metabolism*; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009498:Neurotoxins / Q000494:pharmacology*; D017393:RNA Editing / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D018091:Receptors, AMPA / Q000819:agonists / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D002118:Calcium; D003035:Cobalt; D018690:Excitatory Amino Acid Agonists; D009252:NADPH Dehydrogenase; D009498:Neurotoxins; D012333:RNA, Messenger; D018091:Receptors, AMPA; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C104722:glutamate receptor ionotropic, AMPA 2