EFFECT OF FUMONISIN MYCOTOXINS IN ANIMALS

Fumonisins are mycotoxins produced worldwide by Fusarium fungi, princi pally F. moniliforme. While this fungus can be cultured from virtually all harvested corn, fumonisin production is highly variable. Fumonisi n ingestion induces a number of fatal diseases in animals, with the or gan specificity being species dependent. The first animal toxicoses to be characterized were leukoencephalomalacia (''moldy corn poisoning'' ) in equines and pulmonary edema in swine. Fumonisins additionally pro duce mild to fatal toxicity in liver, kidney and heart in horses, pigs , cattle, sheep, chickens, ducks, rabbits, rats and mice. Prolonged ad ministration of high doses of fumonisin B-1 causes carcinoma of hepato cytes and bile ducts in rats. In man, habitual ingestion of corn produ cts that contain a high concentration of fumonisins is associated epid emiologically with cancer of the esophagus. The pathogenesis of injury to target organs is not understood completely. Affected kidneys and l ivers are characterized by individual cell death through apoptosis, wi th the degree of injury being related to dose and time of exposure. Fu monisins decrease sphingolipid synthesis through inhibition on sphinga nine N-acetyltransferase (ceramide synthetase). This inhibition result s in the accumulation of intracellular sphinganine and sphingosine. Ex cretion of sphinganine and sphingosine into the serum and urine of ani mals serves as a biomarker of fumonisin exposure. Inhibition of the ce ramide synthase also results in decreased synthesis of complex sphingo lipids and ceramide, a potent regulator of cell growth cell differenti ation, mitogenesis and apoptosis. The most sensitive target organs pre sumably are less tolerant of sphingolipid dysregulation. Because fumon isins occur worldwide in livestock feed and human foods and are potent hepatotoxic and nephrotoxic compounds, investigators and clinicians a re prudent to remain alert to possible fumonisin-related toxicity to t hese organs in both livestock and humans.