LINOLEIC AND LINOLENIC ACIDS ARE SELECTIVELY SECRETED IN TRIACYLGLYCEROL BY HEPATOCYTES FROM NEONATAL RATS

To determine whether specific fatty acids are metabolized differently by neonatal liver, hepatocyte cultures from neonatal (age: 5, 11, and 21 days) and adult rats were incubated with radiolabeled 18:1, 18:2, or 18:3. At each age, the rate of oxidation was highest for 18:3 and lowest for 18:1. Conversely, esterification was highest for 18:1 and lowest for 18:3. Fatty acid esterification was of the order: day 5 > day 11 > adult > day 21. When incubations contained each of two of the above fatty acids, one radiolabeled and the other not, 18:1 inhibited oxidation of radiolabeled 18:2 by up to 45% in neonatal hepatocytes. In addition, added 18:1 increased glycerolipid accumulation from 18:2 and 18:3. Under these conditions, the relative proportion of triacylglycerol secreted in the medium, compared with that accumulated in the cells, was two- to fourfold higher for day 11 and 21 rat; hepatocytes. The results suggest that a specific mechanism exists in the livers of neonatal rats to spare n-3 and n-6 fatty acids from oxidation and instead secrete them in triacylglycerol.