Effects of anxiogenic drugs in rat forced swimming test.

The effect of antidepressants and anxiogenics in the forced swimming (Porsolt') test was investigated in rats. On the second day of an experiment, desipramine (10 mg/kg), pentylenetetrazole (20 mg/kg), picrotoxin (2.5 mg/kg), and clonidine (1.0 mg/kg) shortened while buspirone (1.0 mg/kg), yohimbine (2.5 mg/kg), DMCM (1.0 mg/kg), and Ro-15-4513 (1.0 mg/kg) prolonged the time of immobility or behavioral despair; fluoxetine (10 and 20 mg/kg), citalopram (10 mg/kg), and flumazenil (10 mg/kg) were ineffective. While clonidine, given in a subeffective dose (0.1 mg/kg), augmented the effect of desipramine (10 mg/kg), buspirone (1.0 mg/kg) had an opposite effect. The picrotoxin (2.5 mg/kg) challenge prominently shortened the time of immobility after desipramine (10 mg/kg) or citalopram (10 mg/kg) treatment. In conclusion, our results indicate that pharmacologically enhanced anxiety interacts with the effects of acute drug treatment in the forced swimming test.