RENAL EFFECTS OF FUMONISIN MYCOTOXINS IN ANIMALS

Fumonisins are mycotoxins produced worldwide by Fusarium fungi, princi pally F. moniliforme. The fungus is present in virtually all harvested corn, but the toxins produced are variable. The toxins, especially fu monisin B-1, cause mild to fatal diseases in animals, with peculiar sp ecies specificity for the dominant signs of toxicity. The mechanism of toxicity is poorly understood, but it appears to be related to interf erence with sphingolipid biosynthesis in multiple organs. Whereas brai n, lung, and liver are well-known target organs, toxic effects on the kidney are also widespread and have only recently begun to be characte rized. Increased urine volume and decreased osmolarity are early chang es associated with the toxin, as are increased excretions of high-and low-molecular-weight proteins. Enzymuria in vivo, reduced ion transpor t in vitro, and elevation of free sphinganine in renal tissue and in u rine are present. An increase in serum creatinine and blood urea nitro gen and histopathologic change in renal tubules occur later and at hig her doses. The morphologic change principally affects the junction of cortex and medulla and includes prominent apoptosis of epithelial cell s of proximal convoluted tubules. Nephrotoxicity has been reported in several species, and in rats and rabbits, the kidney appears to be the most sensitive target organ.