These studies examined the ability of a conditioned stimulus previously pai
red with footshock to reinstate cocaine-induced conditioned place preferenc
e. Male rats were given either odor or tone in a paired (PRD group) or expl
icitly unpaired (random, RND group) manner with footshock. All rats were su
bsequently trained in a cocaine conditioned place preference (CPP) task. Co
caine CPP was demonstrated in all groups. After CPP extinction, presentatio
n of the conditioned fear stimulus produced a greater degree of reinstateme
nt in PRD rats compared to the RIND group. This was true whether the condit
ioned stimulus was odor or tone but when odor was used as the conditioned s
timulus, the RIND group also partially reinstated cocaine CPP. In rats trai
ned with tone as the conditioned stimulus, presentation of the tone during
the test for reinstatement produced robust reinstatement of cocaine CPP onl
y in the PRD, but not RIND, group. In contrast, a subsequent priming inject
ion with cocaine reinstated cocaine CPP equally in both RND and PRD groups.
These studies indicate for the first time that conditioned fear stimuli in
duce reinstatement of cocaine CPP, and suggest that stimuli associated with
prior stress may produce relapse in humans. (C) 2001 Published by Elsevier
Science B.V.