Hepatotoxicity and renal toxicity in rats of corn samples associated with field cases of equine leukoencephalomalacia.

Currently there is no convenient bioassay to determine the potential toxicity of corn naturally contaminated with Fusarium moniliforme. A short-term bioassay would be useful for future investigations aimed at isolating as yet unidentified toxins produced by this fungus. Two groups of five male Sprague-Dawley rats were each fed one of two F. moniliforme contaminated corn samples, designated CS-1 and CS-2, that were associated with separate field cases of equine leukoencephalomalacia (ELEM). A control group, also consisting of five male rats, was fed uncontaminated seed corn. All animals survived to the end of the study and there were no apparent differences in appearance or behaviour among groups. Weight loss and irregular food consumption occurred in all groups and probably resulted from nutritional deficiencies inherent in the corn diets. Hepatocellular degeneration, necrosis and hyperplasia as well as biliary hyperplasia were found in the test groups only and were attributed to F. moniliforme. Serum transaminase and alkaline phosphatase activities in animals fed CS-1 and CS-2 for 4 wk were significantly increased compared with the controls, while serum bilirubin concentration was increased only in the CS-1 group. Tubular nephrosis was also present in the renal cortex of all animals fed CS-1 and CS-2. These effects may have been related to fumonisins B1 and B2, recently discovered metabolites of F. moniliforme, that were found in both CS-1 and CS-2. Short-term studies of this type may be useful in screening naturally-contaminated grains and other materials for hepatotoxic metabolites produced by F. moniliforme.