IMPORTANCE OF SPHINGOLIPIDS AND INHIBITORS OF SPHINGOLIPID METABOLISMAS COMPONENTS OF ANIMAL DIETS

Sphingolipids are highly bioactive compounds that participate in the r egulation of cell growth, differentiation, diverse cell functions, and apoptosis. They are present in both plant and animal foods in appreci able amounts, but little is known about their nutritional significance . Recent studies have shown that feeding sphingomyelin to female CF1 m ice treated with a colon carcinogen (1,2-dimethylhydrazine) reduced th e number of aberrant colonic crypt foci; longer-term feeding also affe cted the appearance of colonic adenocarcinomas. Therefore, dietary sph ingolipids should be considered in studies of the relationships betwee n diet and cancer. Sphingolipids have also surfaced as important facto rs in understanding the mechanism of action of a recently discovered f amily of mycotoxins, termed fumonisins. Fumonisins are produced by fun gi commonly found on maize and a few related foods, and their consumpt ion can result in equine leukoencephalomalacia, porcine pulmonary edem a and a number of other diseases of veterinary animals and, perhaps, h umans. A cellular target of fumonisins is the enzyme ceramide synthase , and disruption of sphingolipid metabolism by fumonisins has been est ablished by studies with both cells in culture and animals that have c onsumed these toxic mycotoxins. These findings underscore the ways in which sphingolipids and agents that affect sphingolipid utilization sh ould be given consideration in selecting animal diets for nutritional and toxicological studies.