The role of the mesolimbic dopaminergic system in the desipramine effect in the forced swimming test.

The effects of sulpiride isomers injected into the nucleus accumbens on the anti-immobility activity of desipramine in rats were studied to clarify the role of dopamine receptors. (-)-Sulpiride 100 ng/0.5 microliters injected bilaterally into the nucleus accumbens 5 min before testing reduced the effect of a 7-day treatment with 10 mg/kg per day desipramine in the swimming test but 5 micrograms/0.5 microliter (+)-sulpiride injected in the same area had no effect. Fluphenazine, 5 micrograms/0.5 microliter, or 6-hydroxydopamine-induced depletion of dopamine in the nucleus accumbens also reduced the anti-immobility effect of desipramine. The data further support the hypothesis that dopamine transmission in the nucleus accumbens has a permissive role in the effect of desipramine in the forced swimming test.