Administered intravenously to rats, CDPcholine, significantly increases the level and the synthesis rate of dopamine, and the level of tyrosine in the corpus striatum (maximum effect for 50 mg/kg, one hour after administration). CDPcholine decreases the level of serotonin and tryptophan and the synthesis rate of serotonin in the midbrain + hypothalamus and in the brain stem. The increase of the striatum dopamine level and the decrease of the brain stem and midbrain serotonin level are correlated with the recognized antiparkinson and neurostimulant action of this nucleotide.