6533b823fe1ef96bd127f3ff

RESEARCH PRODUCT

The Homeostasis of Brain Choline

subject

description

The interest in the homeostasis of brain choline is reinforced by the role of choline as immediate precursor of acetylcholine, phosphatidylcholine and other phospholipids in the brain. In order to obtain a comprehensive view of the mochanisms of homeostasis it appeared necessary to elucidate the negative arteriovenous difference of choline across the brain (net release), a phenomenon that has been known for 20 years and is present in mammals and in man. This finding prompted an intense search for a de novo synthesis of choline in the brain. We detected in anaesthetized rats a reversal of the net release into a net uptake (positive arterio-venous difference), when the plasma level of choline was elevated spontaneously (presumably due to dietary intake) or after i.p. injection of choline. In these experiments, the newly taken up choline was rapidly removed from the extracellular space of the brain by cellular uptake and subsequent phosphorylation. The newly generated phosphocholine was trapped in brain cells and was only slowly incorporated into phosphatidylcholine, which in turn appears to serve as a reservoir for free choline. Surplus choline in a free or bound form may be cleared from the brain by net release.