title: Neuronal activity regulates protein and gene expressions of GluR2 in postnatal rat visual cortical neurons in culture.
abstract: Ionotropic glutamate receptors, the principal excitatory neurotransmitter receptors in the CNS, are classified into NMDA and non-NMDA subtypes. Previously, we found a direct relationship between neuronal activity and NMDA receptor subunit 1 in rat primary neuronal cultures and monkey visual cortex. The present study focused on the relationship between neuronal activity and subunit 2 of AMPA glutamate receptor, GluR2. GluR2 controls Ca(2+) permeability of AMPA receptors, and the transcription of its gene is activated by nuclear respiratory factor 1, which also activates the transcription of a few subunit genes of cytochrome oxidase (CO). Primary neuronal cultures of postnatal rat visual cortex were subjected to impulse blockade with tetrodotoxin (TTX) for 6 days, or 20 mM KCl depolarizing treatment for 1, 2, 5, 10, 20, 30, and 40 hrs. After 20 hrs of KCl treatment, GluR2 immunoreactivity and CO activity were significantly increased above controls (P < 0.01), and both remained high at 30 and 40 hrs of treatment. However, GluR2 mRNA level as shown by in situ hybridization was already up-regulated above controls after 10 hrs of KCl treatment (P < 0.01) and remained elevated with longer periods of depolarization. TTX blockade, on the other hand, induced a significant down-regulation of GluR2 immunoreactivity, GluR2 gene expression as well as CO activity (P < 0.01 for all). Our results indicate that both protein and mRNA expressions of GluR2 in cultured visual cortical neurons are tightly controlled by neuronal activity.
authors: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.
authors: Xuetao
authors: X
authors: Bai
authors: Margaret T T
authors: MT
authors: Wong-Riley
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D018091:Receptors, AMPA / Q000096:biosynthesis* / Q000235:genetics; D013779:Tetrodotoxin / Q000494:pharmacology; D014793:Visual Cortex / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D018091:Receptors, AMPA; D013779:Tetrodotoxin; C104722:glutamate receptor ionotropic, AMPA 2