A behavioural profile of fluoxetine-induced anorexia

Fluoxetine is a specific and long-lasting inhibitor of serotonin reuptake. In free-feeding rats a dose of 10 mg/kg reduced meal size but had no significant effect on meal frequency. Feeding rate during meals was also reduced. Direct observation of behaviour associated with eating suggested that fluoxetine did not act by enhancing sleep or other behaviour patterns that interfere with eating, although the transition from feeding to sleep occurred more rapidly after drug treatment. Enhancement of satiety or interference with the sustaining of meals by fluoxetine would be consistent with these data. Rebound feeding after anorexia was not observed in either the meal pattern study or in a separate experiment using schedule fed animals. There was also no clear development of tolerance to the anorectic effect of fluoxetine, and we discuss possible reasons for an association of these two properties.