NMR Studies Of The Effects Of T-2 Toxin On Animal’s Metabonome

T-2 toxin, produced by Fusarium molds, is a member of type-A subgroup of trichothecenes and is a common contaminant in grains and animal feedstuff. Due to its high toxicity and relative stability during storage, cooking and processing of food, T-2 toxin contaminated cereal crops or the consumption of meat from livestock and poultry contaminated by T-2 toxin or its metabolites directly or indirectly poses a significant potential risk to human health. Previous study demonstrated that T-2 toxin is capable of causing severe damage through several toxicity mechanisms, namely, high affinity for the 60S ribosomal subunit and resulting inhibition of protein synthesis, inhibition DNA/RNA synthesis, causing oxidative stress and inducing apoptosis. However, there is no report about the investigation of the global endogenous metabolic alterations caused by T-2 toxin in bio-fluid and multiple organs of animals. In addition, a great species discrepancy was reported for the toxicity of T-2 toxin amongst animals exposed to T-2 toxin due to the differences of anatomy, enzyme type and levels, transformation mechanism of drug between animals. However, no investigation reported the similarity or discrepancy of metabolic alterations occurred in animals following T-2 toxin exposure. Moreover, it is not clear what endogenous metabolic changes occurred in animals following long term T-2 toxin exposure. Hence, we performed the following research using NMR-based metabonomics approach and multivariate data analysis.Firstly, we investigate systemic metabolic alteration in rat bio-fluid and multiple organs in response to a single low (0.5 mg/kg.bw), moderate (2 mg/kg.bw) and high dose (4 mg/kg.bw) of acute T-2 toxin exposure. The results showed that all dosages of T-2 toxin influenced the urinary metabonome, and the influence extent is positive correlated with the dosage of T-2 toxin. Besides, the metabolic profiling of liver, thymus, spleen and stomach in rat were significantly changed following high dose of T-2 toxin treatment. The observation of higher levels of GSSG in thymus of T-2 toxin treated rats, lower level of taurine in spleens of T-2 toxin treated rats and lower level of 1-methylnicotinate and 1-methylnicotinamide in urine of T-2 toxin treated rats suggested the oxidative stress induced by T-2 toxin. High dose of T-2 toxin caused the depletion of PC, PE in the spleen and PE in the thymus, accompanied by the increase of GPC in liver, suggesting that T-2 toxin can disrupt the integrity and function of cellular membranes. The decrease in urinary succinate and citrate and fumarate in the liver, accompanied by the increase in NAD observed in T-2 toxin exposed rats suggested that T-2 toxin influence mitochondrial function and consequently suppressed the rate of the tricarboxylic acid cycle (TCA cycle). The decrese levels of glucose accompanied by the increase levels of pyruvate in the plasma of T-2 toxin treated rats suggested that T-2 toxin stimulated glycolytic activity. The increase of 3-hydroxybutyrate and acetoacetate in the plasma of T-2 toxin exposed rats signify that T-2 toxin induced the beta-oxidation of lipids to meet the energy needs. The changes of amino acids and nucleotides in multiple organs of T-2 toxin treated rats signify that T-2 toxin induce the perturbation of amino acid and nucleotide metabolism. In addition, the increase of phenylacetylglycine, p-cresol glucuronide and p-cresol sulfate accompanied by the decrease in hippurate observed in the urine of T-2 exposed rats suggested that T-2 toxin disturbed the gut microbial ecosystem. However, the effects of T-2 toxin on the activity of xenobiotic detoxification enzyme cannot be ruled out.Secondly, we analyzed the metabolic alterations induced by a single intravenous injection of T-2 toxin (0.5 mg/kg.bw) in piglets and broilers. The results showed that T-2 toxin treatment induced the increase of amino acids, reaching maximum levels at 2 hour and 4 hour post-dose in the plasma of broilers and piglets, together with a reduction of glucose and lipid. Moreover, T-2 toxin influences the metabolic profiling of broiler liver, kidney and spleen. The modulated metabolites include amino acids, nucleotides, energy-related metabolites, and so on. Amongst our observations, one of the most interesting findings was the alteration of plasma tryptophan concentration, which from below the limit of NMR detection in the control broilers increased to considerable levels in the T-2 toxin-treated broilers. The significant alteration of plasma tryptophan levels may have implication of T-2 toxin being a neurotoxic compound. In addition, T-2 toxin induced alterations of nucleotides were relatively lagging behind that of amino acids in the liver, kidney and spleen of broilers, which may provide an evidence for a previous assumption that the effects of T-2 toxin on DNA are a secondary result of its effects on protein synthesis.Lastly, we analyzed the effects of 12 weeks T-2 toxin exposure (low dose,0.1 mg/kg.bw; moderate dose,0.5 mg/kg.bw; high dose,2.0 mg/kg.bw) on metabolic profiling of Wistar rats. The results show that multiple rats died during 2 weeks T-2 toxin exposure. Low dose of T-2 toxin has no significant impact on the metabonome of rat urine, plasma and multiple organs. However, moderate dose of T-2 toxin exposure significantly influenced urinary metabonome and serum clinical biochemistry, namely, ALT, Glc, and ALKP. In all, the adverse toxicity influences induced by a single low dose of T-2 toxin exposure may be repaired by a long time of xenobiotic metabolism in the living organisms; while the effects of long term T-2 toxin exposure on living being is non-negligible; and high level of T-2 toxin have the ability of causing death. Therefore, practically the level of T-2 toxin in grains and animal source foods should be under strict control.In summary, our studies provide systematic metabonomic information concerning the T-2 toxin exposure on the metabolic profiling of biofluids and multiple organs, deepen our understanding of the toxicity mechanisms of T-2 toxin, and provide a reference for food safety assessment.