BIOCHEMICAL MATURATION OF CENTRAL NERVOUS SYSTEM .I. LIPID CHANGES

Lipid studies have been carried out on rabbit neural tissue at ages 1, 5, 8, 9, 14, 30, 60, 90, 120, and 170 days, and the findings correlated to development. Comparison has been made: (1) between brain and myelin prepared from it; (2) between brain and cord myelins; and (3) between myelins from various species, using our results together with data from the literature. It was found that the consistency of the myelin prepared from brain and cord in the early stage of development - 1, 5, 8, and 9 days - differs greatly from the myelin repared from adult neural tissue. This 'immature' myelin is characterized by high phospholipids and low cholesterol and cerebroside. The greatest changes take place between the 1st and 14th days. There is a 5-fold increase in cholesterol and 12-fold in cerebroside; and after this date, there is an even, but moderate, increase. The total lipid at maturation in the myelin is 73.9%; in the brain, 53.3%. Since the lipid composition of the myelin from cord has not been investigated before, we analyzed the cord myelin at ages 5, 8, 9, 14, and 170 days. The lipid compositions of the myelin from cord and brain during development are not exactly parallel. The cord myelin had a higher phospholipid content during development, although ethanolamine glycerophosphatide at maturity was higher in the brain (difference = 2 mole%). The same applies to cholesterol; on the other hand, cerebroside was higher in the cord. The lipid compositions of the myelin of various species - rabbit, bovine, rat, guinea-pig and human-were compared and found at maturity to be similar. © 1969.