[Phospholipid composition of the cerebral proteolipids of rats of different ages]

Some properties and phospholipid composition of proteolipids (PL) of brain of 10, 20, 30 and 120--180 days old rats were studied following their isolation by the emulsion centrifugation method of Folch. The content of crude and purified PL and the phospholipids bound to them gradually increased with age. The PL isolated from brains of 10-day old rats are different in their properties and composition from that of PL of adult brain. Their optical density is 2-2,5 times smaller (E1% 1cm lambda 278 mmk). This may be due to their lower content of cyclic amino acids. The content of lecithin and monophosphoinositides in PL decreases with age while that of serienphosphatides and especially polyglycerophosphatides increases. The content of acidic phosphatides tightly bound to PL protein also increases. All of these changes occur mainly between the 10th and 20th days after birth. It would seem that this period is important for the formation of PL and their involvement in the composition of membranes.