Effects of fusarium moniliforme isolates on tissue and serum sphingolipid concentrations in horses

Disruption in sphingolipid (SL) metabolism is a biomarker of exposure to fumonisins. The role of altered SL metabolism in the pathogenesis of fumonisin toxicoses is not understood. A 27-d feeding trial in horses compared the toxic effects of 3 strains of Fusarium moniliforme: RRC 415, cultured from corn in MS; AU 2/3, cultured from feed associated with clinical signs of duodenitis-proximal jejunitis (DPJ) in horses in AL; and MRC 826, cultured from corn in South Africa and shown to cause equine leukoencephalomalacia (ELEM). These were cultured on corn and diluted with clean corn and grain mixed with molasses (sweet feed) to final concentrations of < 1, 65-130 and 200 mg fumonisin B1 (FB1)/kg, respectively. None of the horses developed DPJ, but horses fed MRC 826 had intestinal lesions consistent with DPJ and horses fed AU 2/3 and MRC 826 developed ELEM. Serum SL concentrations were analyzed in horses fed control and F moniliforme culture material, in brain and/or intestinal tissues in healthy horses (euthanized in AL and IL), and in horses fed AU 2/3 and MRC 826. Serum sphinganine (Sa): sphingosine (Szero) ratios were significantly elevated in horses fed AU 2/3 and MRC 826. Sphinganine concentrations were significantly elevated in the hypothalamus-dentate gyrus and brain stem in horses fed AU 2/3, compared to healthy horses. Sphingosine concentrations were significantly elevated in the proximal duodenum and ileum of MRC 826 horses compared to healthy horses. The brain and intestinal tissues in horses with and without pathological lesions did not have changed Sa:S(zero).