Although clinical attempts have been made to treat patients with senile dementia using phosphatidylcholine (PC) or acetylcholine (Ach) esterase inhibitors to restore central cholinergic transmission by increasing Ach contents in the brain, definite positive results have yet to be obtained. To investigate further the influence of the systemic administration of PC on brain Ach, we measured choline (Cho) and Ach contents in discrete brain regions of rat by HPLC with an electrochemical detector, following an acute administration of PC. Cho contents increased in the frontal cortex, striatum and substantia innomimata after acute intraperitoneal administration of soybean PC in liposome form. Cho contents were not affected in any region after acute injection of egg PC. Ach contents were not affected significantly in any brain region after acute administration of each PC substance. It thus follows that Cho contents increase by the systemic administration of highly purified PC, and PC may possibly pass the blood brain barrier. However, PC administration is not capable of accelerating Ach synthesis in the brain.
