AGE-ASSOCIATED CHANGES IN THE CONTENT AND FATTY-ACID COMPOSITION OF BRAIN GLYCEROPHOSPHOLIPIDS

The fatty acid composition of total lipids and individual phospholipid s and the ratio of cholesterol-to-phospholipid content were studied in cerebral cortex, subcortical white matter cerebellum and medulla oblo ngata/pons in 4-, 21.5- and 28-month-old rats, The cholesterol-to-phos pholipid molar ratio in subcortical white matter, medulla oblongata/po ns and cerebellum in 28-month-old rats was found to be 17, 17 and 16% higher, respectively, than in adult rats, These alterations in the mol ar ratio were produced as a result of a net increase in cholesterol co ntent rather than by changes in the total phospholipid content, The co ntent of alkenylacylglycerophosphoethanolamine (alkenylacyl GPE) incre ased in 28-month-old rats with respect to 4-month-old rats, following the order cerebral cortex > cerebellum > medulla oblongata/pons > subc ortical white matter, The fatty acid composition of total lipids showe d an increase in monounsaturated fatty acids (MUFA) and a decrease in polyunsaturated fatty acid (PUFA) content with increasing age in all r egions studied, such changes being more marked in cerebellum medulla o blongata/pons and subcortical white matter than in cerebral cortex. Th e proportion of 22:6(n-3) in cholineglycerophospholipids in the differ ent brain regions of 28-month-old rats showed a slight decrease with r espect to that in adult rats following the order cerebellum > medulla oblongata/pons > subcortical white matter, whereas that of 20:4(n-6) d ecreased only in cerebellum, Ethanolamineglycerophospholipid fatty aci d composition was modified in 28-month-old rats through a marked incre ase in monounsaturated fatty acids (18:1(n-9) and 20:1(n-9) specifical ly) in all brain areas. The MUFA content of alkenylacyl GPE increased with increasing age in all the regions studied, in the order cerebral cortex > medulla oblongata/pons > subcortical white matter > cerebellu m, An increase in the MUFA content of diacylglycerophosphoethanolamine was observed in medulla oblongata/pons and cerebellum of aged rats wi th respect to control rats, PUFA content of alkenylacyl GPE decreased mainly in medulla oblongata/pons, cerebral cortex and subcortical whit e matter of aged rats, The PUFA content of serineglycerophospholipids was the most affected by aging, Changes occurred mainly in the content of 22:6(n-3), 22:4(n-6) and 20:4(n-6) in cerebellum acid of 22:6(n-3) and 22:4(n-6) in subcortical white matter, Changes in the inositolgly cerophospholipid fatty acid content of 28-month-old rats were observed mainly in medulla oblongata/pons, which showed a decrease in PUFA (22 :4(n-6) and 22:6(n-3)) content and an increase in MUFA (18:1 and 20:1) .