Differential incorporation of precursor moieties into cerebral cortex and cerebellum glycerophospholipids during aging.

The incorporation of polar and non-polar moieties into cerebral cortex (CC) and cerebellum (CRBL) phospholipids of adult (3.5-month-old) and aged (21.5-month-old) rats was studied in a minced tissue suspension. The biosynthesis of acidic phospholipids through [3H]glycerol appears to be slightly increased with respect to that of zwitterionic or neutral lipids in CC of aged rats with respect to adult rats. On the contrary, the synthesis of phosphatidylcholine (PC) from [3H]choline was inhibited. However, the incorporation of [14C]serine into phosphatidylserine (PS) was higher in CC and CRBL in aged rats with respect to adult rats. The synthesis of phosphatidylethanolamine (PE) from PS was not modified during aging. Saturated ([3H]palmitic) and polyunsaturated ([3H]arachidonic) acids were incorporated successfully by adult and aged brain lipids. In addition [3H]palmitic, [3H]oleic and [3H]arachidonic acid were employed as glycerolipid precursors in brain homogenate from aged (28.5 month old) and adult (3.5 month old) rats. [3H]oleic acid incorporation into neutral lipids (NL) and [3H]arachidonic acid incorporation into PC, PE and phosphatidylinositol (PI) were increased in aged rats with respect to adult rats. Present results show the ability and avidity of aged brain tissue in vitro to incorporate unsaturated fatty acids when they are supplied exogenously. They also suggest a different handling of choline and serine by base exchange enzyme activities to synthesize PC and PS during aging.