Effects of excitotoxic lesions of the basolateral amygdala on cocaine-seeking behavior and cocaine conditioned place preference in rats.
Incentive motivation for cocaine, elicited by cocaine-associated stimuli, is thought to be involved in craving and relapse. To examine the role of the basolateral amygdala complex (BLC) in this phenomenon, we assessed the effects of post-training BLC lesions on extinction of cocaine-seeking behavior and cocaine-conditioned place preference (CPP) and the effects of pre-training BLC lesions on acquisition of cocaine-CPP. In Experiment 1, rats were first trained to self-administer cocaine and then received bilateral infusions of the excitotoxin, N-methyl-D-aspartic acid (NMDA, 0.12 M; 0.3 microl/side), or vehicle into the BLC. They were then tested repeatedly for extinction of cocaine-seeking behavior (i.e. nonreinforced responses in the presence of cocaine-paired stimuli). Subsequently, they were trained and tested for acquisition of cocaine-CPP (i.e. increased time spent in a previously cocaine-paired, relative to a saline-paired, environment). Locomotion and compartment entries were also measured. In Experiment 2, rats were first trained and tested for cocaine-CPP, and then received NMDA or vehicle infusions into the BLC. Subsequently, they were tested repeatedly for extinction of cocaine-CPP. Post-training BLC lesions retarded extinction of cocaine-seeking behavior and cocaine-CPP, whereas pre-training lesions disrupted acquisition of cocaine-CPP. These effects did not appear to be related to changes in general activity. We suggest that pre-training BLC lesions disrupted acquisition of cocaine-CPP by impairing assignment of incentive value to cocaine-paired stimuli, whereas post-training BLC lesions disrupted extinction of cocaine-conditioned behaviors by impairing the assessment of the current incentive value of cocaine-paired stimuli.
Fuchs
Rita A
RA
Department of Psychology, Arizona State University, P.O. Box 871104, Tempe, AZ 85287-1104, USA.
Weber
Suzanne M
SM
Rice
Heather J
HJ
Neisewander
Janet L
JL
D000679:Amygdala / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000473:pathology / Q000503:physiopathology*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D003714:Denervation; D004193:Discrimination Learning / Q000187:drug effects* / Q000502:physiology; D005106:Exploratory Behavior / Q000187:drug effects* / Q000502:physiology; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009498:Neurotoxins / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012646:Self Administration / Q000523:psychology
D009498:Neurotoxins; D003042:Cocaine