Phospholipid fatty acids in brains of normal sheep and sheep with ceroid-lipofuscinosis.

The ceroid-lipofuscinoses are a group of inherited diseases of humans and animals characterised by brain atrophy and the storage of a fluorescent lipopigment. Brain grey matter phospholipid fatty acids of diseased sheep are compared with those of normal sheep. Phosphatidylethanolamine of diseased sheep contains more 18:1(n-9) and less 22:6(n-3) than normal and their phosphatidylcholine less 16:0. Other differences are minor. All differences are in the same direction as those reported for the infantile form of human ceroid-lipofuscinosis, but are smaller. Normal sheep grey matter phosphatidylinositol contains 8.5% 20:4(n-6) and 24.6% 22:6(n-3), in contrast to 28.5 and 4.6%, respectively, in humans. The other sheep phospholipids have similar fatty acid profiles to those from humans. Apart from low levels of 20:3(n-9) and 22:3(n-9) they contain no additional non-essential fatty acid derived species. No sign of essential fatty acid deficiency occurs in either diseased or normal sheep. It is concluded that sheep must conserve their restricted essential fatty acid supply for structural functions, and that an abnormality in fatty acid metabolism is not primarily involved in the pathogenesis of ceroid-lipofuscinosis. The results also call into question the primary role of peroxidation of polyunsaturated fatty acids in lipopigment formation in this disease.