Effects of ethanolamine (Etn) administration on Etn and choline (Ch) levels in plasma, brain extracellular fluid (ECF) and brain tissue, and on brain phospholipid levels in rats: an in vivo study.

The sources and fates of brain ethanolamine (Etn) are poorly known and the effects of its administration have not been investigated, even though cortical levels are known to be reduced in certain neurodegenerative diseases. We studied the effect of different Etn doses (10(-3), 5 x 10(-3) and 10(-2) mol/kg, i. p.) on its and choline's (Ch) levels in arterial plasma and brain extracellular fluid (ECF) of awake rats. We also studied its effects on brain levels of Etn, Ch, and their respective major phospholipids. Etn administration caused dose dependent increases in Etn levels within both plasma and brain ECF. For the 10(-2) mol/kg dose, Etn levels were significantly (p<0.01) greater than pre-injection values in both the plasma and ECF. Whole brain Etn and phosphatidylethanolamine were also significantly (p<0.05) increased by 10(-2) mol/kg Etn. Exogenous Etn significantly (p<0.05) increased Ch levels in plasma and whole brain; Etn also increased brain ECF Ch levels. Our data show for the first time that circulating Etn can act as a source of brain Ch. Metabolic pathways that might mediate the increases in Etn and Ch are discussed, as are possible mechanisms of the decreases in brain Eth seen in Alzheimer's disease.