The effects of fluoxetine and zimeldine on the behavior of olfactory bulbectomized rats

Previous work has shown that subchronic administration of antidepressant drugs can reverse the behavioral and physiological changes produced by removal of the olfactory bulbs of rats. It has also been reported that acute administration of drugs believed to enhance serotonergic transmission can improve passive avoidance performance in bulbectomized rats. In order to follow up this observation the effects of the serotonin reuptake inhibitor, fluoxetine, were studied in bulbectomized and control rats. Fluoxetine produced a dose-related improvement in the passive avoidance behavior of bulbectomized rats in a step-down task and in a Y-maze. The effect of fluoxetine on step-down avoidance was blocked by metergoline and was also shown by zimeldine, another inhibitor of serotonin reuptake. However, in tests of active avoidance responding in a shuttle box and exploratory locomotion, fluoxetine produced similar disruptions of behavior in both bulbectomized and control animals. Thus, the effects of fluoxetine on the behavior of bulbectomized rats are dependent upon the behavioral test.