Repeated treatment with imipramine and amitriptyline reduced the immobility of rats in the swimming test by enhancing dopamine mechanisms in the nucleus accumbens.

Bilateral injections of 1 microgram sulpiride in the rat nucleus accumbens antagonized the effect of a seven-day treatment with 20 mg kg-1 day-1 imipramine or amitriptyline in the swimming test. The data suggest that dopamine mechanisms in the limbic regions of the rat brain are involved in the effect of repeated treatment with imipramine and amitriptyline in that test.