Effects of phosphatidylcholine administration to rats on choline in blood and choline and acetylcholine in brain.

Phosphatidylcholine (PCh) administered intragastrically to rats resulted in prolonged increase of the choline (Ch) concentration in plasma and erythrocytes. Plasma Ch was increased between 1 and 24 hr after administration of 10 mmol of PCh/kg with a peak level (256% of control) occurring 6 hr after treatment. The concentration of Ch in the striatum, hippocampus and cortex was increased after PCh treatment but the acetylcholine (ACh) concentrations did not change. PCh pretreatment antagonized the depletion of ACh caused by treatment with atropine, pentylenetetrazole or fluphenazine. Oxotremorine antagonized the effect of atropine but not of pentylenetetrazole or fluphenazine. Therefore, Ch derived from PCh supports ACh synthesis under conditions in which ACh release is stimulated, whereas under normal conditions the concentration of ACh is maintained with a relatively narrow range irrespective of the Ch concentration.