Antipanic-like effect of serotonin reuptake inhibitors in the elevated T-maze

There has been an increasing interest in the development of animal models that address different types of anxiety disorders. The elevated T-maze (ETM) was developed based on the assumption that inhibitory avoidance and one-way escape are respectively related to generalized anxiety (GAD) and panic disorder (PD). Although anxiolytic effects on the inhibitory avoidance task have been shown for drugs used in clinical settings to treat GAD, positive effects of antipanic drugs in one-way escape have been described only for imipramine. The study extends the pharmacological validation of the ETM to other serotonin reuptake inhibitors that have antipanic properties. To this end, we investigated the effects of acute and chronic (21 days) IP administration of clomipramine (3, 10 and 30 mg/kg) and fluoxetine (5, 10 and 15 mg/kg). Buspirone (0.3, 1 and 3 mg/kg) was used as a negative control since the drug is effective in GAD but not PD. Chronically, both clomipramine and fluoxetine impaired one-escape, an antipanic-like effect, not altering avoidance latencies. Clomipramine, but not fluoxetine, also affected locomotion. Acute injection of buspirone impaired avoidance, an anxiolytic-like effect. Neither acute nor chronic buspirone altered one-escape. These results corroborate the suggestion that one-way escape is related to PD.