NMDA antagonist AP-5 increase environmentally induced cocaine-conditioned locomotion within the nucleus accumbens.
An environment previously associated with cocaine use can elicit cravings, even in the absence of the drug, which may be due to the formation of strong associations between the environment and the drug. These associations can result from motor learning and reinforcing effects of cocaine, and may be mediated in part by ionotropic glutamate receptors in the nucleus accumbens (N.Acc.). To determine whether NMDA receptor activity in the N.Acc. affects the expression of conditioned locomotion, rats were trained using an environment-elicited cocaine-conditioning paradigm. Rats trained to pair a cocaine injection with an environment showed an increased locomotor activity when tested in the drug-paired environment, whereas rats injected with cocaine in their home cages did not exhibit greater locomotion. Significantly greater locomotor activity occurred in trained animals that received an infusion of AP-5, a NMDA receptor antagonist, into the N.Acc. These results suggest that animals trained to associate environmental cues with cocaine become conditioned to this environment. Furthermore, our finding demonstrates that NMDA receptor activation within the N.Acc. modulates cocaine-induced conditioning.
Rodríguez-Borrero
Enrique
E
University of Puerto Rico, Río Piedras Campus, Biology Department, San Juan, Puerto Rico.
Bernardo Colón
Alexandra
A
Burgos-Mártir
Melissa A
MA
Alvarez Carillo
José E
JE
del Campo
Yaniré Estrada
YE
Abella-Ramírez
Cynthia
C
Maldonado-Vlaar
Carmen S
CS
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects*; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate; D003042:Cocaine