INCORPORATION INTO PHOSPHOLIPID CLASSES AND METABOLISM VIA DESATURATION AND ELONGATION OF VARIOUS C-14-LABELED (N-3) AND (N-6) POLYUNSATURATED FATTY-ACIDS IN TROUT ASTROCYTES IN PRIMARY CULTURE

Abstract: The incorporation and metabolism of [1‐14C]18: 3(n‐3), [1‐14C]20:5(n‐3), [1‐14C]18:2(n‐6), and [1‐14C]20:4(n‐ 6) were studied in primary cultures of trout brain astrocytes. There were no significant differences between the amounts of individual fatty acids incorporated into total lipid at 22°C. with >90% of all the fatty acids being incorporated into polar lipid classes. The distributions of 18:2(n‐6), 18:3(n‐3), and 20:5(n‐3) in individual phospholipid classes at 22°C were very similar, with 57–63 and 18–24% being incorporated into phosphatidylcholine and phosphatidylethanolamine, respectively. Approximately equal amounts of 20:4(n‐6), ∼30% of the total, were incorporated into each of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. The metabolism of the (n–3) fatty acids to longer‐chain and more unsaturated species was significantly greater than that of(n 6) acids, but Δ4‐desaturase activity was very low. A culture temperature of 10°C increased the incorporation of all the fatty acids into total lipid and that of C20 fatty acids into polar lipid. At 10°C, the incorporation of C20 fatty acids into phosphatidylethanolamine and phosphatidylinositol was increased, and the incorporation into phosphatidyicholine and phosphatidylserine was decreased. The distribution of C18 fatty acids was unchanged at the lower temperature, as was the desaturation and elongation of all the polyunsaturated fatty acids incorporated. Copyright © 1990, Wiley Blackwell. All rights reserved