Cytidine(5')diphosphocholine enhances the ability of haloperidol to increase dopamine metabolites in the striatum of the rat and to diminish stereotyped behavior induced by apomorphine.

Experiments were performed to determine whether exogenous cytidine(5')diphosphocholine (CDP-choline) could modify release of dopamine in the striatum and behavior dependent on dopamine, perhaps by providing supplemental choline for synthesis of acetylcholine. Rats received water (control) or CDP-choline orally (100 mg/kg per day, for 5 days), either alone or before injection with haloperidol (1 mg/kg, i.p.), apomorphine (0.15 mg/kg, s.c.), or both. Stereotyped behavior was measured during the hour after administration of apomorphine; levels of the dopamine metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum were assessed at the end of this period (2 hr after administration of haloperidol). In rats receiving the CDP-choline, the stereotyped behavior observed after injection of apomorphine alone (P less than 0.01), or after haloperidol plus apomorphine (P less than 0.01), was attenuated. The pretreatment with CDP-choline also significantly increased levels of HVA (by 24%) and DOPAC (by 23%) in the striatum over appropriate controls in animals receiving haloperidol, or by 29 and 59% (averaging data for all time points), respectively, in animals receiving haloperidol plus apomorphine. One mechanism by which CDP-choline may affect behavior involves contributing choline to enhance synthesis of acetylcholine.