Evidence of Dopamine Involvement in the Effect of Repeated Treatment with Various Antidepressants in the Behavioural 'despair' Test in Rats

Daily treatment for 7 days with 5 mg/kg nomifensine, 20 mg/kg amineptine, 10 mg/kg mianserin or 20 mg/kg iprindole reduced the immobility time in the behavioural 'despair' test in rats. No stimulation of motor activity was found with any of the drugs, and iprindole and mianserin actually reduced the activity of rats in an open field. The anti-immobility effect of the various antidepressants was significantly counteracted by 0.5 mg/kg haloperidol or 100 mg/kg sulpiride. These doses of neuroleptics alone did not significantly modify the immobility time of rats not treated with the antidepressant compounds. As previously found for desipramine and amitriptyline, the data suggest that dopamine is involved in the anti-immobility effect in rats of repeated treatment with nomifensine, amineptine, mianserin and iprindole.