Neurochemical studies in aging brain. I. Structural changes in myelin lipids.

Age-related changes in the lipid chemical composition and structure of myelin and myelin subfractions have been studied in the rat brain. Myelin subfractions with a content ranging from the more mature and compact lamellae to fractions containing earlier membrane fractions were isolated from mature, old, and aged animal groups. We found changes in cholesterol-phospholipid ratios and an increasing degree of unsaturation in the longest acyl chains of major myelin glycosphingolipids. These changes suggest that increased fluidity and decreased stability occurs with age in myelin.