Effects of dopamine receptor antagonists on ongoing maternal behavior in rats.

The effects of different peripheral doses of four dopamine (DA) receptor antagonists on general activity and maternal behavior were examined in lactating female rats. Administration of the classic D1-like and D2-like DA receptor blocker haloperidol (0.1 and 0.05 mg/kg) disrupted pup retrieval and nest-building behaviors and reduced motor activity. Pimozide (0.5 and 0.2 mg/kg), which has more affinity for DA D2-like receptors, mildly disrupted pup retrieval while showing no significant influence on open-field behaviors. The putative DA D(4) receptor blocker, clozapine (1.5 and 1.0 mg/kg) reduced motor activity significantly, while only 1.0 mg/kg dose significantly decreased percent of rats displaying nest building. The DA D1-like receptor blocker SKF-83566 (0.2 and 0.1 mg/kg) significantly reduced pup retrieval, nest building and motor activity. These results suggest a role for DA receptors in ongoing maternal behavior that correlates directly with general activity.