Homeostatic control of membrane fatty acid composition in the rat after dietary lipid treatment

Abstract

Diets in which both the lipid content and composition (polyunsaturated to saturated fatty acid ratio) were varied were fed to rats for 20 weeks, and the effects on the tissue lipid profiles were determined. The fatty acid profile of the plasma lipids, and the phospholipid fatty acids of the mitochondrial and microsomal fractions of liver, heart, kidney and brain, as well as erythrocyte membranes were determined. Despite large differences in the level and type of lipid present in the experimental diets and in the proportion of saturated fatty acids in the plasma lipids in response to the various diets, there was little effect on the proportion of saturated to unsaturated fatty acids in the phospholipids of the various membranes examined. The major effect of altering the dietary level of polyunsaturated to saturated fatty acids was on the ratio of the omega 6/omega 3 series of unsaturated fatty acids in the membrane lipids. This change occurred in all tissues except the brain, in which only a small response to altered dietary lipid intake was observed. The omega 6/omega 3 ratio was elevated upon feeding a diet rich in omega 6 polyunsaturated fatty acids, but decreased when a diet rich in saturated fatty acids was fed. The failure to significantly alter membrane lipid saturation/unsaturation in the tissues examined would suggest that a homeostatic mechanism is operative in biological membranes and may act to buffer membranes from the effects of changes in the nature of the dietary lipid intake.

Cold acclimation or grapeseed oil feeding affects phospholipid composition and mitochondrial function in duckling skeletal muscle

“…Results of experiment 2 indicate that in birds, as in mammals (21), the mitochondrial membrane FA composition can be manipulated by the FA composition of the diet. However, the enrichment in membrane PUFA is lower than what could be expected from the diet composition, indicating some homeostatic control of the membrane lipid composition already noted by others (34). Because the diet similarly affected the FA profile of mitochondrial phospholipids of the three tissues investigated, it follows that the tissue-specific changes observed after cold acclimation are precisely regulated and, for instance, are not dependent on the higher food intake or alterations in the supply of blood lipids (35).…”

Ileal and colonic fatty acid profiles in patients with active Crohn's disease.

“…This second mechanism is known in the regulation of structural-functional homoeostasis of membranes. '9 22 Evidence of both mechanisms is provided by studies in rats.22 23 To clarify this finding, however, it is necessary to define the mucosal compartments or cell types, which are the predominant site of changes in individual fatty acids and to elucidate their metabolic interactions. The change in the fatty acid profile led to an increase of the unsaturation index in the inflamed mucosa.…”

Comparative Effects of Feeding Different Fats on Fatty Acid Composition of Major Individual Phospholipids of Rat Hearts

“…It has been recently shown that the balance be tween (n-6) and (n-3) fatty acids plays an important role in modification of desaturase enzymes responsible for synthesis of 20:5 (n-3) and 22:6 (n-3) from 18:3 (n-3) [27], Thus, earlier reports have demonstrated that (n-3) fatty acids inhibit the metabolism of (n-6) fatty acids especially at the desatura tion steps [28,29]. In this way, the reduction in the ratio (n-6)/(n-3) observed in fish oilfed rats might be due to an inhibition of the metabolism of (n-6) fatty acids produced by (n-3) fatty acids, possibly through competi tion at the desaturation steps [28,29], which could lead to decreased formation of throm boxane A2, a proaggregatory agent [30].…”