Stimulation of N-methyl-D-aspartate receptors, AMPA receptors or metabotropic glutamate receptors leads to rapid internalization of AMPA receptors in cultured nucleus accumbens neurons.
In hippocampus and other regions, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors are inserted into synapses during long-term potentiation and removed during long-term depression. However, little is known about regulation of AMPA receptor trafficking in the nucleus accumbens (NAc), despite growing evidence that glutamate-dependent forms of plasticity in the NAc contribute to drug addiction. Using postnatal rat NAc cultures and an immunocytochemical method that selectively detects newly internalized GluR1, we studied the regulation of AMPA receptor internalization in NAc neurons by glutamate agonists. Newly internalized GluR1 was detected during 15 or 30 min of incubation at room temperature, indicating a basal rate of GluR1 turnover. The rate of GluR1 internalization was increased by glutamate (50 microM) within 5 min of its addition. Glutamate-induced GluR1 internalization was partially blocked by either an AMPA receptor antagonist (CNQX; 20 microM) or an N-methyl-D-aspartate (NMDA) receptor antagonist (APV; 50 microM). Both NMDA (50 microM) and AMPA (50 microM) increased GluR1 internalization in a Ca(2+)-dependent manner. The NMDA effect was blocked by APV while the AMPA effect was blocked by APV or CNQX. We interpret these findings to suggest that NMDA and AMPA ultimately trigger GluR1 internalization through the same NMDA receptor-dependent pathway. The effect of glutamate was also partially blocked by the group 1 metabotropic glutamate receptor antagonist N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC; 50 microM), while the group 1 agonist 3,5-dihydroxyphenylglycine (DHPG; 50 microM) stimulated GluR1 internalization. These data suggest that AMPA receptors on NAc neurons may be subject to rapid regulation of their surface expression in response to changes in the activity of glutamate inputs from cortical and limbic regions.
Mangiavacchi
Simona
S
Department of Neuroscience, Rosalind Franklin University of Medicine and Science/The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064-3095, USA.
Wolf
Marina E
ME
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D009714:Nucleus Accumbens / Q000166:cytology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology*; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C056639:2-amino-5-phosphopentanoic acid; D014633:Valine; D002118:Calcium