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 microCi of 9-trans,12-trans [1-(14)C] octadecadienoic acid; the second group was given 5 microCi of the same compound plus an equal wt of nonradioactive all cis arachidonic acid; the third group was given 5 microCi of 9-trans [1-(14)C] octadecenoic acid. All animals were sacrificed 8 hr after injection. Glycerophosphocholine (GPC) was isolated and partically deacylated with phospholipase A2 from Crotalus Adamanteus venom. The results of this study were as follows: 1) after t[1-(14)C]18:1 injection, there was twice as much radioactivity in the 1-position as in the 2-position; 2) when tt[1-(14)C] 18:2 was injected, more than 90% of the total radioactivity was found in the 2-position; 3) following tt[1-(14)C]-18:2 + nonradioactive arachidonate injection, ca. 75% of the total radioactivity still remained in the 2-position; and 4) all of the injected [1-(14)C]-tracers showed evidence of undergoing beta-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 dietary trans fatty acids in the brain during the developmental stage of the central nervous system are also discussed.