Accumulation and depletion of trans octadecenoic acid in rat peripheral nerve phospholipid

The accumulation and depletion of trans 18:1 acids in the sciatic nerve phospholipids was studied in rats fed a diet containing 18% partially hydrogenated soybean oil of which 45% was trans 18:1. The nerve phospholipid of rats fed partially hydrogenated soybean oil beginning at weaning age reached a maximum incorporation of trans 18:1 or 0.8% in 4 weeks; whereas the nerve phospholipid of 18-day-old pre-weanling pups of mothers fed the partially hydrogenated soybean oil diet since their weaning contained 3.3% trans 18:1. The trans content decreased rapidly after the weaning of these second-generation rats to a steady-state level 50% higher than the maximum level reached in the first generation. Upon removal of partially hydrogenated soybean oil from the diet, the trans 18:1 of nerve phospholipid decreased much more slowly than from liver or heart phospholipid. Essential fatty acid deficiency had no influence on incorporation or removal of trans 18:1 in nerve phospholipid. The accumulation and depletion of trans 18:1 in nerve phospholipid of second-generation partially hydrogenated soybean oil-fed rats paralleled the changes of polyunsaturated fatty acids and was quite different from the changes observed in 18:0 and cis 18:1. Polyunsaturated fatty acids increased in nerve phospholipid from second but not first-generation rats fed partially hydrogenated soybean oil and declined rapidly when partially hydrogenated soybean oil was removed from the diet.