High Abundance of GluR1 mRNA and Reduced Q/R Editing of GluR2 mRNA in Individual NADPH-Diaphorase Neurons

• Published in: Molecular and cellular neuroscience 2001-06, Vol.17 (6), p.1025-1033
• Main Authors: Kim, Doo Yeon, Kim, Sun Hee, Choi, Hyun Bum, Min, Chul-ki, Gwag, Byoung Joo
• Format: Article
• Language: English
• Subjects: alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid - pharmacology; Animals; calcium (extracellular); Calcium - metabolism; Calcium Signaling - drug effects; Calcium Signaling - physiology; Cell Membrane Permeability - drug effects; Cell Membrane Permeability - physiology; Cell Survival - drug effects; Cell Survival - physiology; Cells, Cultured; Cobalt - pharmacology; Dose-Response Relationship, Drug; Excitatory Amino Acid Agonists - pharmacology; Fetus; Gene Expression - drug effects; Gene Expression - physiology; NADPH Dehydrogenase - metabolism; Neostriatum - cytology; Neostriatum - drug effects; Neostriatum - metabolism; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Neurotoxins - pharmacology; Rats; Receptors, AMPA - agonists; Receptors, AMPA - genetics; Receptors, AMPA - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA Editing - drug effects; RNA Editing - physiology; RNA, Messenger - drug effects; RNA, Messenger - metabolism
• ISSN: 1044-7431; 1095-9327
• DOI: 10.1006/mcne.2001.0988

Striatal and cortical neurons containing NADPH-diaphorase [NADPH-d(+)] are highly vulnerable to excitotoxicity that is induced by activation of α-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 μM AMPA showed Co2+ uptake and survived AMPA challenge only in the absence of extracellular Ca2+.