Formation of prostanoids and hydroxy fatty acids by stimulated peritoneal mast cells: role of the dietary fat type in rat.

To study the influence of membrane fatty acid composition on the formation of prostanoids and hydroxy fatty acids by rat peritoneal mast cells (MC), animals were fed three different types of fatty acids: mackerel oil (MO), abundant in n-3 fatty acids; sunflower seed oil (SO), rich in linoleic acid; and hydrogenated coconut oil (HCO), mainly containing saturated fatty acids. The presence of n-3 fatty acids in the diet resulted in the incorporation of 20:5(n-3), 22:5(n-3) and 22:6(n-3) in MC phospholipids. A decrease of arachidonic acid, 20:4(n-6), was observed in MC-phospholipids of the MO-fed animals. Furthermore, increasing the relative amounts of 18:2(n-6) in the diet (SO group) led to an increased incorporation of linoleic acid, 18:2(n-6) in MC phospholipids when compared to both other dietary groups. The changes in MC phospholipid fatty acid composition were (partly) reflected in the formation of prostanoids and hydroxy fatty acids upon stimulation with the calcium ionophore A23187. The decrease in arachidonic acid content in MC phospholipids of MO-fed rats resulted in a decreased formation of PGD2 when compared to both other groups. Also, the increased amounts of 18:2(n-6) in MC phospholipids of SO-fed rats resulted in an increased formation of 9- and 13-HODE upon stimulation. The results show that modifications in the fatty acid composition of the diet influences MC membrane fatty acid composition which ultimately results in changes in prostanoid and hydroxy fatty acid synthesis by MC upon stimulation with the calcium ionophore A23187.