CHOLINERGIC DOPAMINERGIC INTERACTION IN THE RAT STRIATUM ASSESSED FROM DRUG-INDUCED REPETITIVE ORAL MOVEMENTS

The role of striatal dopaminergic/cholinergic interactions in the regulation of oral behaviour in rats was studied using methods which resolve distinct patterns of jaw movements, allowing a more accurate quantitative and qualitative analysis. Both dopamine and acetylcholine receptor agonists given either systemically or into the ventral striatum induced repetitive oral movements. However, the cholinergic movements differed from dopaminergic movements as to pattern of activity. Oral movements induced by apomorphine (0.2 mg/kg i.v.) were potentiated by carbachol (0.1-mu-g/0.2-mu-l) injected into the dorsal striatum, while inhibition was observed when carbachol was injected into the ventral striatum. Pilocarpine (4 mg/kg)-induced oral movements were reduced by injecting flupentixol (10-mu-g/0.2-mu-l), but not a combination of SKF 38393 (3-mu-g) + quinpirole (10-mu-g/0.2-mu-l), into either the dorsal or the ventral striatum. Oral movements induced by the injection of carbachol (1-mu-g/0.2-mu-l) into the ventral striatum were enhanced by previous injection of this combination of dopamine receptor agonists into the same site and were inhibited by flupentixol. These results suggest that cholinergic and dopaminergic oral movements are separate behaviors and that the striatal dopamine/acetylcholine interaction in their regulation is neither simply antagonistic or synergistic, nor reciprocal.