Persistent increases in cocaine-seeking behavior after acute exposure to cold swim stress.

Background: Acute and chronic stress reinstates drug-seeking behavior. Current animal models show that these effects are contingent (temporally, contextually, or both) on the drug-conditioning environment. To date, no paradigm exists to model the common human situation in which stressors that are distinct from the experience of drugs can lead to relapse.

Methods: Rats were allowed to self-administer cocaine or saline over 8 days. They then underwent extinction training, during which responding was not reinforced with drug infusions. After 16 days of extinction, rats were submitted to a brief cold swim stress and then tested for seeking behavior (responding not reinforced with drug infusions) for 4 days.

Results: All rats developed self-administration behavior. Following extinction, cold swim stress induced reinstatement of drug-seeking behavior in cocaine-trained rats, an effect that was still present 3 days after stress exposure.

Conclusions: This study indicates that cold swim stress can have long-term effects on drug-seeking behavior and may provide us with a suitable model to study the latent effects of stress on relapse to drug abuse.