Dietary trilinoelaidate: effects on the in vitro biosynthesis of different prostaglandins in brain, lung and stomach fundus of rats

Linoleic acid requirement of rats fed trans fatty acids

The amount of linoleic acid required to prevent undesirable effects of C18 trans fatty acids was investigated. In a first experiment, six groups of rats were fed diets with a high content of trans fatty acids (20% of energy [en%]), and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four groups of rats were fed diets designed to compare trans fatty acids with saturated and cis-monounsaturated fatty acids of the same chain length at the 2 en% linoleic acid level. After 9-14 weeks, the oxygen uptake, lipid composition and ATP synthesis of heart and liver mitochondria were determined. The phospholipid composition of the mitochondria did not change, but the fatty acid compositions of the two main mitochondrial phospholipids were influenced by the dietary fats. Trans fatty acids were incorporated in all phospholipids investigated. The linoleic acid level in the phospholipids, irrespective of the dietary content of linoleic acid, increased on incorporation of trans fatty acids. The arachidonic acid level had decreased in most phospholipids in animals fed diets containing 2 en% linoleic acid. At higher linoleic acid intakes, the effect of trans fatty acids on the phospholipid arachidonic acid level diminished. However, in heart mitochondrial phosphatidylethanolamine, trans fatty acids significantly increased the arachidonic acid level. Despite these changes in composition, neither the amount of dietary linoleic acid nor the addition of trans fatty acids influenced the mitochondrial function. For rats, a level of 2 en% of linoleic acid is sufficient to prevent undesirable effects of high amounts of dietary C18 trans fatty acids on the mitochondrial function.

Prostanoid synthesis in peripheral nerve

The transformation of [1-14C]arachidonic acid into radiolabeled prostanoids was studied with homogenates and desheathed sciatic nerves of rats and frogs. All of the preparations studied were shown to synthesize prostaglandins; the specific prostanoids made were characterized by their migration on thin-layer chromatograms in three separate solvent systems. Both desheathed rat nerve and homogenates synthesize prostaglandin E2, prostaglandin F2 alpha, prostaglandin D2, 6-ketoprostaglandin F1 alpha and thromboxane B2. With preparations from frog nerve, prostaglandin E2 was the major prostanoid product formed. Several conditions were able to modulate the production of prostaglandin E2 with desheathed frog nerve. Electrical stimulation at high frequency (100 Hz) for 30 min increased the formation of labeled prostaglandin E2. Inclusion of glutathione also affected prostaglandin E2 formation. A lower concentration (0.1 mM) stimulated prostaglandin synthesis, while 1 mM glutathione was partially inhibitory. In both the rat and frog system, prostanoid synthesis was suppressed by indomethacin and aspirin.