LIPID-PEROXIDATION AS ONE-MODE OF ACTION IN OCHRATOXIN-A TOXICITY IN RATS AND CHICKS

The objective of this study was to determine whether lipid peroxidatio n is one mode of action in ochratoxin A (OA) toxicity in vivo. Lipid p eroxidation was monitored by analyzing malondialdehyde (MDA) in differ ent tissues by HPLC. A refinement study on the MDA assay was carried o ut, which showed the importance of the addition of an iron catalyst fo r the decomposition of hydroperoxides to yield a maximum amount of MDA from a given sample. The rat experiment was designed in a 2 x 2 facto rial arrangement using 4 x 6 animals. The four different diets were fe d for 21 d and contained either 1% corn oil and 9% tallow (Diets I and III) or 10% corn oil (Diets II and IV); in groups III and IV, 5 mg OA were added per kilogram of diet. For the chick experiment 4 x 8 Legho rn cockerels received diets for 14 d with no added sunflower oil (Diet s I and III), whereas the diets of groups II and IV were supplemented with 2.5% sunflower oil. In groups III and IV, 2.5 mg OA were added pe r kilogram of diet. In both experiments OA decreased the performance o f the animals significantly. In the rat experiment an increased lipid peroxidation due to a higher dietary level of unsaturated fatty acids could be obtained, when muscle samples were oxidatively stressed with Fe3+ and ascorbic acid. In the chick experiment there were very clear effects of the dietary treatment on the MDA concentrations of differen t tissues, as both a higher supply with unsaturated fatty acids and OA increased most of the MDA values significantly. These data suggest th at lipid peroxides are formed in vivo by OA, but the effects may vary considerably from species to species, and may also be influenced by ot her factors.