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BACKGROUND Rats given extended access to cocaine develop several symptoms of addiction, including a gradual escalation of drug intake, whereas rats given limited access do not. We asked here whether extended access to cocaine also produces drug-induced sensitization, a form of neurobehavioral plasticity implicated in addiction. METHODS Rats were given(More)
Women are at greater risk for cocaine addiction than are men, and female rats similarly show a greater propensity to self-administer cocaine than do male rats. This could be due to the intrinsic sex differences in brain organization, to the activational effects of circulating gonadal hormones, or both. For example, estradiol enhances dopamine release in the(More)
Contextual stimuli associated with drug exposure can modulate various effects of drugs, but little is known about their role in relapse to drug seeking. Using a renewal procedure, the authors report that drug-associated contextual stimuli play a critical role in relapse to drug-seeking previously maintained by a heroin-cocaine mixture (speedball). Rats were(More)
We recently found that in rats trained to self-administer a heroin-cocaine mixture, exposure to the drug self-administration environment, after extinction of the drug-reinforced behavior in a different context, leads to renewal of drug seeking. Here we further explored the role of contextual stimuli in drug seeking by characterizing the effect of(More)
We studied the influence of rate of intravenous infusion of cocaine or amphetamine on drug-taking and seeking behavior. First, drug-naive rats were tested for acquisition of self-administration of increasing doses of amphetamine or cocaine infused over 5 or 100 s. Second, self-administration of cocaine or amphetamine infused over 5-100 s was assessed on(More)
Both the acute psychomotor response and the development of sensitization to amphetamine are attenuated if i.p. injections are given in the cage where animals live (HOME), relative to when injections are given in a novel (NOVEL), but otherwise physically identical cage. It was suggested that this effect of environment on sensitization may be due to the(More)
Doses of amphetamine or cocaine that fail to induce psychomotor sensitization when given to a rat in its home cage can produce robust sensitization if given immediately following placement into a relatively novel, distinct environment. A drug-associated context can serve as a conditioned stimulus, and therefore may promote robust sensitization by(More)
Incentive motivation theory ascribes a critical role to reward-associated stimuli in the generation and maintenance of goal-directed behavior. Repeated psychomotor stimulant treatment, in addition to producing sensitization to the psychomotor-activating effects, can enhance the incentive salience of reward-associated cues and increase their ability to(More)
Behavioral sensitization following repeated intermittent cocaine administrations is thought to involve alterations in cocaine regulation of neural activity within the accumbens and caudate brain regions. Although Fos immunohistochemistry and c-fos in situ hybridization have frequently been used to assess changes in cocaine-induced neural activity following(More)
In humans, exposure to environmental contexts previously associated with drug intake often provokes relapse to drug use, but the mechanisms mediating this relapse are unknown. Based on early studies by Bouton & Bolles on context-induced 'renewal' of learned behaviours, we developed a procedure to study context-induced relapse to drug seeking. In this(More)