Essential fatty acid deficiency: effects of cross-fostering mice at birth on myelin levels and composition.

Female mice were assigned an essential fatty acid (EFA)-deficient diet or a control diet at mating, and litters were cross-fostered at birth to produce three groups of animals: pups fed a control diet prenatally and deficient diet postnatally (C leads to D); a deficient diet prenatally and a control diet postnatally (D leads to C); and a control diet throughout life (C leads to C). The yield of myelin, the developmental pattern of the major proteins, and the proportion of major lipids were examined in the purified myelin of the three groups at 3, 6, and 9 weeks. Myelin yield was lower at 9 weeks in both the (C leads to D) and (D leads to C) groups compared to controls. There was an alteration in the ratios of the proteins and major lipid classes in myelin from the (C leads to D) animals at 9 weeks, whereas the ratios of these components were normal in the (D leads to C) animals at this age. However, at three weeks the lipid composition of the myelin isolated from (D leads to C) animals was abnormal. The results suggest that postnatal EFA deficiency results in hypomyelination in mice and that the myelin formed is of abnormal composition during early postnatal brain development. Prenatal EFA deficiency results in less severe hypomyelination with only the earliest myelin formed being of abnormal lipid composition.