EFFECT OF THE LONG-TERM FEEDING OF DIETARY LIPIDS ON THE LEARNING-ABILITY, FATTY-ACID COMPOSITION OF BRAIN-STEM PHOSPHOLIPIDS AND SYNAPTIC MEMBRANE FLUIDITY IN ADULT MICE - A COMPARISON OF SARDINE OIL DIET WITH PALM OIL DIET

The effect of 12 month feeding of 5% palm oil or sardine oil diet on t he maze-learning ability, fatty acid composition of brain stem phospho lipids and synaptic membrane fluidity in mice was studied. The time re quired to reach the maze exit and the number of times that a mouse str ayed into blind alleys in the maze were measured three times every 4 d ays. The time and number of mice fed on the sardine oil diet were less than those of animals fed on the palm oil diet in the first and secon d trials. The results of fatty acid composition analysis of brain stem phosphatidylethanolamine showed that the percentage of docosahexaenoi c acid (22:6, n-3; DHA) was higher, but the arachidonic acid (20:4, n- 6; AA) and docosatetraenoic acid (22:4, n-6; DTA) were lower in the sa rdine oil diet fed-mice than in the palm oil diet fed-animals. Moreove r, the microviscosity of the synaptic plasma membrane in the sardine o il diet group was lower than that in the palm oil diet group. These re sults suggest that the adult mice fed on the sardine oil diet for a lo ng period maintain higher levels of docosahe xaenoic acid in brain pho spholipids, synaptic membrane fluidity and maze-learning ability than animals fed on the palm oil diet. (C) 1998 Elsevier Science Ireland Lt d. All rights reserved.