EFFECTS OF FEEDING LUNARIA OIL-RICH IN NERVONIC AND ERUCIC ACIDS ON THE FATTY-ACID COMPOSITIONS OF SPHINGOMYELINS FROM ERYTHROCYTES, LIVER,AND BRAIN OF THE QUAKING MOUSE MUTANT

Feeding an oil from Lunaria biennis rich in 22:1n-9 and 24:1n-9 to hom ozygous quaking (qk.qk) mice caused a large increase in the percentage of 24:1 n-9 and corresponding decreases in the percentage of 24:0 and 22:0 in sphingomyelins from liver, erythrocytes, and milk. Brain sphi ngomyelin from 2-wk-old qk.qk pups born to qk.qk mothers maintained on the Lunaria oil had essentially normal percentage of 24:1n-9 and 18:0 , in contrast to pups born to mothers maintained on a control oil rich in 78:1n-9 whose brain sphingomyelin had a markedly reduced percentag e of 24.1n-9 and an increased percentage of 18:0. After 2 wk and up to and beyond weaning, the qk.qk pups from Lunaria-fed mothers weaned on to the Lunaria diet had a markedly decreased percentage of 24:1n-9 in their brain sphingomyelin, accompanied by an increased percentage of 18:0, as compared to heterozygous quaking mice. However, the percentag e of 24:1n-9 in brain sphingomyelin in qk.qk pups weaned on to the Lun aria diet continued throughout this period (2-8 wk postbirth) to be si gnificantly higher than in qk.qk pups weaned on to the control diet. W e conclude that dietary 24:1n-9 influences the fatty acid composition of brain sphingomyelin in qk.qk mice, but only via the mother in pre- or early postnatal animals. We further consider that the dietary effec ts may be elicited mainly in the sphingomyelin of nonmyelinated brain cells, and that the nervonic acid in myelin sphingomyelin may be forme d mainly by chain elongation in oligodendrocytes from shorter chain fa tty acid precursors.