Distinct roles of the different ionotropic glutamate receptors within the nucleus accumbens in passive-avoidance learning and memory in mice.
Research on the role of the nucleus accumbens in behaviour has been largely focused on the functions of this structure in conditioning to appetitive stimuli. It has been suggested that a network comprising the nucleus accumbens and its convergent inputs might mediate dissociable functions in the acquisition, the consolidation and the retrieval of information. However, findings related to a role of this structure in aversive conditioning are somewhat contradictory, and its involvement in this form of learning is still under debate. Moreover, very little evidence is available on the step of information processing mediated by the accumbens. Thus the purpose of this study was to investigate the effects of the blockade of the AMPA and NMDA glutamate receptors, which have been suggested to mediate the transmission of information from the limbic system to this structure, on a classical aversive conditioning task - the one-trial step through inhibitory avoidance paradigm (24 h interval between training and testing). Intra-accumbens focal injections of AP-5 and DNQX (NMDA and AMPA antagonists, respectively) were performed immediately after training, before training and before testing in mice. The NMDA antagonist (37.5, 75 and 150 ng per side) impaired animal performance only if administered immediately after but not before training or before testing. Conversely, DNQX (0.5, 1.0 and 5.0 ng per side) reduced the step through latencies when administered before training and before testing. These findings suggest that NMDA receptor activation within the accumbens is necessary in formation but not expression of memory for inhibitory avoidance. AMPA receptors, instead, are necessary for the acquisition and the expression but not consolidation of inhibitory avoidance memory.
De Leonibus
Elvira
E
Dipartimento di Genetica e Biologia Molecolare, Università di Roma 'La Sapienza', P .le Aldo Moro 5, 00185, Rome, Italy.
Costantini
Vivian J A
VJ
Castellano
Claudio
C
Ferretti
Valentina
V
Oliverio
Alberto
A
Mele
Andrea
A
D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D011930:Reaction Time; D017470:Receptors, Glutamate / Q000502:physiology*; D013194:Staining and Labeling; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D017470:Receptors, Glutamate; C056723:FG 9041; C056639:2-amino-5-phosphopentanoic acid; D014633:Valine