Turnover of ethanolamine phosphoglycerides in different brain areas of adult and aged rats.

The turnover of ethanolamine glycerophospholipids (EGP) has been determined in six different cerebral areas of 4-month and 22-month-old rats, by injecting [3H]glycerol together with [14C]ethanolamine into the lateral ventricle of the brain. The areas examined behave quite differently in respect to their utilization of the most simple precursors of phosphoglyceride biosynthesis. The incorporation of both glycerol and ethanolamine is already complete as early as 2-4 hours and then reutilization begins, at least for the so called fast pools of phosphoglycerides. The different slopes of the specific activity of the two precursors in EGP suggest a high degree of variance among catabolic rates in the different brain regions. In aged rats the utilization of the water-soluble precursors of EGP synthesis decreases in all brain areas and these data suggest that aging may have a different effect on the catabolic activities as well as phospholipid biosynthesis.