Oxotremorine-induced cholinergic syndrome: modifications by levodopa and/or oral cytidine diphosphocholine.

A peripheral and cerebral cholinergic syndrome was induced in mice by oxotremorine administration; pretreatment orally with cytidine diphosphocholine (CDP-choline) does not potentiate this syndrome and even antagonizes oxotremorine-induced salivation. Levodopa antagonizes the oxotremorine-induced cerebral symptoms (akinesia + tremor); however this antagonism disappears when mice are chronically pretreated orally with CDP-choline, confirming the action of CDP-choline on dopaminergic pathways. The proven efficacy of CDP-choline in Parkinsonism could then be mediated by a hypersensitivity of some cerebral dopamine receptors, and not by a direct stimulating effect of the striatal dopaminergic receptors.