Bilateral administration of ergometrine into the nucleus accumbens of rats pretreated 40 min earlier with apomorphine (0.9 mg/kg, s.c.) resulted in a shift from a predominant licking score to a predominant gnawing score. Bilateral administration of ergometrine or (3.4-dihydroxyphenylamino)-2-imidazoline into the brain of rats treated 20 min later with apomorphine (2.0 mg/kg, s.c.) resulted in a shift from a predominant licking and gnawing score to a predominant walking and sniffing score. These and related data suggest a biphasic action at a certain group of dopamine receptors within the nucleus accumbens of rats: a short-term activation and along-term inhibition following this initial activation. The predictive value of the behavioural profile triggered by ergometrine for the evaluation of antidepressant effects of centrally acting drugs is discussed.