The effect of vitamin B-6 deficiency on the fatty acid composition of the major phospholipids in the rat.

We have studied the effect of vitamin B-6 deficiency in the rat on the fatty acid spectrum of phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and phosphatidylethanolamine (PE) in liver, plasma and kidneys. In general, vitamin B-6 deficiency decreased the proportion of arachidonic acid in the phospholipid fraction studies and increased that of linoleic acid. These changes seem to be greatest in the liver, whose changes were reflected quite faithfully in the plasma and were least in the kidneys, especially in the case of PE. These differences of order of magnitude may be due to differences in the site of synthesis, in the function or in the turnover of these phospholipids in the different tissues. We have attempted to explain these changes on the basis of a decrease in the synthesis of PC by the pathway of methylation of PE, a pathway which leads mainly to the information of arachidonoyl-PC. The relative importance of the de novo pathway, via CDP-choline, which produces mainly linoleoyl PC would thus increase. This mechanism, associated or not with a decrease in the synthesis of arachidonic acid from linoleic acid, could produce the effects observed on the fatty acid spectrum of the various phospholipids.