Effect of repeated treatment with desipramine in the behavioral "despair" test in rats: antagonism by "atypical" but not "classical" neuroleptics or antiadrenergic drugs.

A 7-day treatment with 20 mg/kg/day desipramine reduced the immobility time in the behavioral "despair" test in rats. The effect of DMI was antagonized by sulpiride (100 mg/kg i.p.), metoclopramide (20 mg/kg i.p.) and clopazine (20 mg/kg i.p.) but not by haloperidol (0.5 mg/kg i.p.) or chlorpromazine (5 mg/kg i.p.). Alpha-adrenoreceptor blockers (prazosin 3 mg/kg s.c.; aceperone 10 mg/kg i.p.; azapetine 24 mg/kg s.c.; phentolamine 20 mg/kg i.p.), dl-propranolol (5 mg/kg i.p.) and clonidine (0.1 mg/kg i.p.) failed to modify the anti-immobility effect of DMI. The data suggest that a particular subtype of dopamine receptors is involved in the anti-immobility effect of a 7-day treatment with DMI in the behavioral "despair" test in rats.