EFFECTS OF DIETARY PURIFIED EICOSAPENTAENOIC ACID (20/5(N-3)) AND DOCOSAHEXAENOIC ACID (22/6(N-3)) ON FATTY-ACID DESATURATION AND OXIDATION IN ISOLATED RAT-LIVER CELLS

The effects of dietary supplementation of eicosapentaenoic acid (20:5(n - 3), EPA) and docosahexaenoic acid (22:6(n - 3), DHA) on the metabolism of polyunsaturated fatty acids were studied in isolated rat liver cells. Both pure EPA and pure DHA and a mixture of the two n - 3 fatty acids in different doses were used. The supplementation of moderate amounts of n - 3 fatty acids suppressed the activity of DELTA-6-desaturase (50%) and to a smaller extent of the DELTA-5-desaturase (60-70%) compared to controls. When higher doses of dietary purified EPA and DHA were used, this inhibitory effect on the DELTA-6- and DELTA-5-desaturase activities disappeared. The DELTA-4-desaturase activity seemed to be unaffected by the feeding conditions used. The supplementation of the n - 3 fatty acids in the diet at all dose levels used increased the beta-oxidation of all the polyunsaturated fatty acids, especially of linoleic acid, linolenic acid and eicosapentaenoic acid. The results suggest an increase both in peroxisomal and mitochondrial beta-oxidation. The peroxisomal beta-oxidation of n - 3 fatty acids seemed to be particularly increased.