Stress reinstates nicotine seeking but not sucrose solution seeking in rats

Rationale: Intermittent footshock stress effectively reinstates extinguished heroin-, cocaine- and alcohol-taking behaviors, but not behaviors previously maintained by food reinforcers. Here we tested further the generality of the phenomenon of stress-induced reinstatement by determining the effect of footshock on reinstatement of operant responding previously maintained by nicotine or palatable sucrose solutions. Methods: Groups of rats were trained to self-administer either nicotine (0.03 mg/kg per infusion, 14 days) or sucrose (10 or 30% w/v, 14-20 days). After extinction of the nicotine- or the sucrose-reinforced behaviors for 5-15 days, the rats were exposed to intermittent footshock stress (5 and 15 min, 0.8 mA) during tests for reinstatement. Results: Footshock reliably reinstated nicotine seeking after extinction of the drug-reinforced behavior. In contrast, the same parameters of footshock stress did not consistently reinstate operant responding previously maintained by sucrose solutions. Conclusions: These and previous data suggest that stressors may be more effective stimuli for reinstatement of behaviors previously maintained by drug reinforcers as compared with non-drug reinforcers.