Hippocampal glutamate receptors in fear memory consolidation.
It is thought that activity-dependent changes in synaptic efficacy driven by biochemical pathways responsive to the action of the excitatory neurotransmitter glutamate are critical components of the mechanisms responsible for memory formation. In particular, the early activation of the NMDA (rNMDA) and AMPA (rAMPA) subtypes of ionotropic glutamate receptors has been demonstrated to be a necessary event for the acquisition of several types of memory. In the rat, consolidation of the long-term memory for a one-trial, step-down inhibitory avoidance task is blocked by antagonists of the rNMDA and rAMPA infused into the CA1 region of the dorsal hippocampus early after training and is associated with a rapid and reversible increase in the total number of [3H]AMPA binding sites. The learning-induced increase in [[3H]AMPA is accompanied by translocation of the GluR1 subunit of the rAMPA to the post-synaptic terminal together with its phosphorylation at Ser831. In addition, learning of the mentioned fear-motivated task induces the activation and rNMDA-dependent translocation of CaMKII to the post-synaptic density. Inhibition of this protein kinase as well as blockade of the rNMDA abolishes both the learning-induced translocation of GluR1 and its phosphorylation. Our data suggest that learning of an avoidance task enhances hippocampal rAMPA signaling through rNMDA and CaMKII-dependent mechanisms.
Centro de Memória, Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos 2600--Anexo, Porto Alegre, 90035-003, RS, Brasil. mcammaro@terra.com.br
Martín
M
Cammarota
Lia R M
LR
Bevilaqua
Juliana S
JS
Bonini
Janine I
JI
Rossatto
Jorge H
JH
Medina
N
N
Izquierdo
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D001522:Behavior, Animal; D001665:Binding Sites; D015153:Blotting, Western / Q000379:methods; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D003216:Conditioning, Operant / Q000187:drug effects; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005239:Fear / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D007266:Inhibition, Psychological; D008297:Male; D008568:Memory / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D017470:Receptors, Glutamate / Q000145:classification / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium / Q000493:pharmacokinetics; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000493:pharmacokinetics
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D014316:Tritium; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases