Oral motor performance following central dopamine receptor blockade.

Oral motor responses were recorded in water-deprived rats receiving injections of spiroperidol, the dopamine blocker, into the nucleus accumbens and caudate nucleus. Spiroperidol injected into the nucleus accumbens resulted in dose dependent decreases in lap volume and tongue extension. Injections of spiroperidol into adjacent sites or into the caudate nucleus did not significantly reduce lap volume even with an 8 fold larger dose administered into the caudate. These observations implicate the mesolimbic dopaminergic projections to the nucleus acumbens in oral motor responses and indicate the need for systematic comparisons of the contributions of mesolimbic and nigrostriatal dopaminergic systems to ingestive behaviors.