Effect of Pyridoxine Deficiency on Fatty Acid Composition of Carcass and Brain Lipids in the Rat

Female rats were fed diets containing 10% of corn oil (with or without added pyridoxine). Signs of severe pyridoxine deficiency were observed after 10 weeks in rats that received the diets deficient in pyridoxine. These animals and the pyridoxine-supplemented controls were then sacrificed and the fatty acid composition of the carcass and brain lipids was determined. Under ad libitum feeding conditions the percentage of stearic acid was higher and of linoleic acid lower in carcass fats of the deficient animals compared with fats of the supplemented controls. When the feed consumption of both groups was the same, the carcass fat of the deficient animals contained a higher percentage of stearic acid and a lower percentage of palmitoleic acid than the carcass fat of the controls, but the degree of unsaturation of the fat from rats in both groups was the same. These results were interpreted to indicate that there is no sparing of unsaturated fatty acids and little change in fatty acid composition of carcass fat in pyridoxine deficiency unless the rats are also deficient in essential fatty acids. It is suggested that the effects of pyridoxine deficiency on fat metabolism are of a secondary nature mediated by changes in protein and carbohydrate metabolism. No differences in normal and α-hydroxy fatty acid composition of brain lipids from pyridoxine-deficient and pyridoxine-supplemented rats were observed. If pyridoxine deficiency causes changes in neural lipid metabolism, they are not sufficiently marked to be observable when fatty acids from total brain lipid are examined.