Desipramine and restraint stress induce odor conditioned aversion in rats: suppression by repeated conditioning.

Rats exposed to one, three, or seven conditioning sessions defined by an olfactory conditioned stimulus and stress or antidepressant administration as unconditioned stimulus were later tested for their preference for the conditioned olfactory stimulus. A significant reduction of the time spent in the conditioned stimulus was observed in animals exposed to one and three pairings with stress or three pairings with desipramine. A lack of conditioned aversion was observed in animals exposed to seven pairings with either reinforcer. These data could indicate that the adaptative mechanisms elicited by repeated stress or desipramine may be involved in the decrease of conditioned aversion.