Differential involvement of hippocampal and amygdalar NMDA receptors in contextual and aversive aspects of inhibitory avoidance memory in rats.
Adult male rats bilaterally implanted with guide canullae aimed either at the dorsal hippocampus (dHIP) or the basolateral nucleus of the amygdala (BLA) were trained in a step-down inhibitory avoidance task (IA) and tested for retention 24 h after training. Immediately after training, animals were given a bilateral infusion of the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist D,L-2-amino-5-phosphonopentanoic acid (AP5) (5.0 microg) into the dHIP or the BLA. Both intrahippocampal and intraamygdala infusions of AP5 blocked IA retention. Preexposure to the training box, but not to a different environment 24 h prior to training prevented the impairing effect of intrahippocampal infusion of AP5 on retention. Preexposure did not affect the retention impairment induced by intraamygdala infusion of AP5. These data suggest that hippocampal NMDA receptors might be involved in the contextual and spatial aspects, while amygdalar NMDA receptors might be involved in the aversive aspects of memory for IA.
Roesler
Rafael
R
GENOTOX Laboratory, Center for Biotechnology, Federal University of Rio Grande do Sul, 91501-970 Porto Alegre, RS, Brazil. rroesler@terra.com.br
Schröder
Nadja
N
Vianna
Mônica R M
MR
Quevedo
João
J
Bromberg
Elke
E
Kapczinski
Flávio
F
Ferreira
Maria Beatriz C
MB
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009473:Neuronal Plasticity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis*
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate