Effects of dietary folate deficiency on developmental increase of myelin lipids in rat brain

Rats were fed a folic acid deficient purified diet from day 12 of gestation throughout the lactational period. Offsprings were fed the same diet after weaning. Control rats were given 170 microgram of folic acid per day per rat supplemented to the same diet, which was fed ad libitum or by pair-feeding. At 3 and 6 weeks of age, myelin was isolated from rat brains. It was found that in comparison with the controls, myelin yield was significantly decreased as well as the brain weight in the folic acid deficient rats at 6 weeks of age. There were no differences of gross composition of myelin, protein, ratio of cholesterol, glycolipids, phospholipids, and total lipid with or without folate deficiency either at 3 or 6 weeks of age. The hydroxy fatty acid composition of myelin lipids in brain was not changed with folate deficiency at 3 or 6 weeks of age. The developmental increase of the percentages of 22:6, 22:4, and 20:1 in nonhydroxy fatty acids of myelin lipids from the folic acid deficient rats were significantly lower at 6 weeks of age in comparison with the controls. The n-3:n-6 ratio in myelin fatty acids from the folic acid deficient rat brains was abnormally low at 3 weeks of age and was not increased at even 6 weeks of age. The implications of these findings are that folic acid may play an important role in desaturation or chain elongation of polyunsaturated fatty acids in the brain of developing rats.