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 th ough cortical levels are known to be reduced in certain neurodegenerat ive 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 respect ive major phospholipids. Etn administration caused dose dependent incr eases in Etn levels within both plasma and brain ECF. For the 10(-2) m ol/kg dose, Etn levels were significantly (p<0.01) greater than pre-in jection values in both the plasma and ECF. Whole brain Etn and phospha tidylethanolamine 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 E tn and Ch are discussed, as are possible mechanisms of the decreases i n brain Etn seen in Alzheimer's disease.