Functional NMDA Receptor Subtype 2B Is Expressed in Astrocytes after IschemiaIn Vivoand AnoxiaIn Vitro
| Autor: | Lynn A. Raymond, Claire A. Sheldon, Herman B. Fernandes, Claudia Krebs, Kenneth G. Baimbridge |
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| Rok vydání: | 2003 |
| Předmět: |
Male
Agonist N-Methylaspartate medicine.drug_class Synaptogenesis Biology Hippocampus Receptors N-Methyl-D-Aspartate Brain Ischemia chemistry.chemical_compound Piperidines Glial Fibrillary Acidic Protein Excitatory Amino Acid Agonists medicine Ifenprodil Animals ARTICLE Rats Wistar Receptor Long-term depression Cells Cultured Neurons musculoskeletal neural and ocular physiology General Neuroscience Glutamate receptor Axotomy Immunohistochemistry Cell Hypoxia Rats Cell biology medicine.anatomical_structure 2-Amino-5-phosphonovalerate nervous system chemistry Astrocytes NMDA receptor Calcium Excitatory Amino Acid Antagonists Neuroscience Astrocyte |
| Zdroj: | ResearcherID |
| ISSN: | 1529-2401 0270-6474 |
| Popis: | NMDA-type glutamate receptors play a critical role in neuronal synaptogenesis, plasticity, and excitotoxic death. Recent studies indicate that functional NMDA receptors are also expressed in certain glial populations in the normal brain. Using immunohistochemical methods, we detected the presence of the NMDA receptor 2B (NR2B) subunit of the NMDA receptor in neurons but not astrocytes in the CA1 and subicular regions of the rat hippocampus. However, after ischemia-induced neuronal death in these regions, double immunohistochemical labeling revealed that NR2B subunits colocalized with the astrocyte marker glial fibrillary acid protein and with NR1 subunits that are required for functional NMDA receptors. NR2B expression was first observed 3 d after ischemia and reached a peak at 28 d. At 56 d, only a few NR2B-expressing astrocytes were still present. In vitro, when postnatal hippocampal cultures were subjected to 5 min of anoxia, it resulted in NR2B expression on astrocytes in the glial feed layer. Imaging of intracellular calcium with postanoxic cultures and astrocytes isolated acutely from the ischemic hippocampus revealed a rise in intracellular [Ca(2+)] after stimulation with the specific agonist NMDA. The response could be blocked reversibly with the competitive antagonist 2-amino-5-phosphonovalerate and attenuated by the NR2B-selective antagonist ifenprodil. Control astrocytes were not responsive to NMDA but responded to glutamate. An understanding of the role of astrocytes that express functional NMDA receptors in response to ischemia may guide development of novel stroke therapies. |
| Databáze: | OpenAIRE |
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