Effects of long-chain monounsaturated and n-3 fatty acids on fatty acid oxidation and lipid composition in rats

Long-chain n-3 fatty acids and fat fish are reported, among multiple physio logical properties, to enhance peroxisomal beta -oxidation and effect triac ylglycerol status. Long-chain n-3 and monounsaturated fatty acids are the m ain portion of fatty acids in fat fish. The individual effect of long-chain monounsaturated fatty acids on beta -oxidation and fatty acid composition was tested and compared to the effect of n-3 polyunsaturated and saturated fatty acids in a 3-week feeding experiment of rats. To explore the contribu tion from long-chain monounsaturated fatty acids in these aspects, the effe ct of long-chain n-3 and monounsaturated fatty acids on mitochondrial and p eroxisomal beta -oxidation was compared, as well as fatty acid composition of adipose tissue, liver and serum. Fatty acid oxidase, palmitoyltransferas e I and II activities, the amount of serum lipids, and the fatty acid compo sition of lipid fractions from the organs were analysed. The peroxisomal be ta -oxidation was enhanced by the n-3 fatty acids, whereas a small, signifi cant increase with the monounsaturated fatty acids was observed. There was a stimulation of the mitochondrial oxidation with the n-3 fatty acids, but monounsaturated fatty acids gave a small, nonsignificant decrease. With n-3 fatty acids there was a considerable decrease in the levels of serum triac ylglycerol, phospholipids, free fatty acids and total cholesterol, while th ere were only minor effects of monounsaturated fatty acids. As judged from the fatty acid composition data, there was a mobilization on n-3 fatty acid s from the adipose tissue to liver and plasma with the n-3 diet. This obser vation was also seen with the monounsaturated fatty acid-enriched diet. In conclusion, monounsaturated fatty acids seemed to stimulate peroxisomal bet a -oxidation and to increase plasma triacylglycerol, whereas the mitochondr ial oxidation was slightly decreased. Copyright (C) 2001 S. Karger AG, Base l.