Trans fatty acids: Positional specificity in brain lecithin

Fifteen-day-old rats were divided into three groups: one group received an intracerebral injection of 5 μ Ci of 9-trans, 12-trans 1-¹⁴C] octadecadienoic acid; the second group was given 5 μCi of the same compound plus an equal wt of nonradioactive allcis arachidonic acid; the third group was given 5 μCi of 9-trans 1-¹⁴C] octadecenoic acid. All animals were sacrificed 8 hr after injection. Glycerophosphocholine (GPC) was isolated and partically deacylated with phospholipase A₂ fromCrotalus Adamanteus venom. The results of this study were as follows: 1) aftert 1-¹⁴C] 18∶1 injection, there was twice as much radioactivity in the 1-position as in the 2-position; 2) whentt 1-¹⁴C] 18∶2 was injected, more than 90% of the total radioactivity was found in the 2-position; 3) followingtt1-¹⁴C]-18∶2 +nonradioactive arachidonate injection, ca. 75% of the total radioactivity still remained in the 2-position; and 4) all of the injected 1-¹⁴C]-tracers showed evidence of undergoing β-oxidation to form acetyl-CoA, which was converted to radioactive palmitate. The possibility is discussed that the observed distribution pattern of the injected radioactive tracers may be attributed to tissue metabolic specificity. Ramifications of the deposition of dietarytrans fatty acids in the brain during the developmental stage of the central nervous system are also discussed.