| T-2 toxin, a toxic member of the group A trichothecenes, is primarily produced by various Fusarium species. It is widely scattered in cereal products and can potentially affect human and animals health upon exposure. It is very critical to know the toxic mechanism of T-2 toxin on people and animl.To explore the toxicity of T-2 toxin on animals and the apoptosis mechanism of T-2 toxin in cells, this study was conducted to investigate the effects of T-2 toxin on growth performance, hematology, nutrient apparent digestibility, liver and intestinal morphology in mice. A total of 80 BALB/c mice weighted about 20 g were randomly allotted to 4 groups with 20 replicates per group and 1 mouse per replicate. The mice were fed one of the 4 treatments(0, 0.4, 1.0, 2.5 mg/kg.bw T-2 toxin exposed daily via intragastric administration) for 28 days.To further determine the toxic mechanism of T-2toxin, HL-7702 cells were exposed for 24 hours with 0, 0.1, 1, or 10 μg/L T-2toxin. After exposure, we use Flow Cytometry and RT-PCR to investigate the toxic mechanism of T-2toxin based on gene m RNA expression levels. These conclusions were as follows:(1) Influence of T-2 toxin on performance, hematology, liver morphology and antioxidant ability in BALB/c mice. In 2.5 mg/kg.bw group, the morality rate of mice was close to 25%, and average weight gain and food intake were significantly decreased(P<0.01). However, the organ coefficients of heart, liver, spleen, lung, kidney and brain in 2.5 mg/kg.bw group were increased markedly(P<0.05 or P<0.01), but that of testis, seminal vesicle, uterus and ovaries were reduced significantly(P<0.05 or P<0.01). Compared with control, organ coefficient of liver(P<0.01), the cell count of white blood cell(WBC), lymphocyte(LY), monocytes(MO), neutrophil granulocyte(GR), and content of hemoglobin(HGB) were significantly increased in 0.4 or 1 mg/kg.bw groups(P<0.05 or P<0.01), respectively. Additionally, the cell count of monocytes, neutrophil granulocyte and platelet(PLT) in 2.5 mg/kg.bw group were significantly higher than the control group(P<0.01). However, red blood count(RBC) and hemoglobin content were reduced(P<0.05 or P<0.01), respectively. Furthermore, compared with the control group, the content of glucose(GLU), urea nitrogen(UN) and creatinine(CREA), or the enzymatic activity of alkaline phosphatase(ALP) and alanine aminotransferase(ALT) were improved remarkablely, but the content of triglyceride(TG) and albumin(ALB) were reduced(P<0.05 or P<0.01). In addition, the concentration of malondialdehyde(MDA) in liver tissue was also increased, then the activity of superoxide dismutase(SOD), catalase(CAT) and glutathione peroxidase(GSH-Px) were reduced with the improvement of T-2 toxin content. It is concluded that the supplementation of T-2 at 1 mg/kg.bw can induce the immunostimulation. Nevertheless, the excessive dose can cause the inhibition of growth performance, induce organ damage of liver, and reduce the antioxidant ability significantly with dose-effect relationship.(2) Influence of T-2 toxin on nutrient apparent digestibility and intestinal morphology in BALB/c mice. The p H value in 1.0 and 2.5 mg/kg.bw groups were significantly increased(P<0.05 or P<0.01), respectively. Compared with the control, the apparent digestibility of crude protein, ash, crude fiber and ether extract were greatly decreased in T-2 toxin treatment groups(P<0.05 or P<0.01), and the digestibility of energy in 1.0 and 2.5 mg/kg.bw groups were also lower than control(P<0.01). In addition, the apparent digestibility of mineral elements including Ca, Fe, Mg, Na and P in 0.4 mg/kg.bw group was lower than the control group. In 1.0 and 2.5 mg/kg.bw groups, the digestibility of Ca, Fe, Zn, Mg, Na, K, Mn and P were significantly decreased(P<0.05 or P<0.01), as well as that of Asp, Thr, Ser, Glu, Gly, Ala, Val, Ile, Leu, Phe, Lys, His, Arg, Pro were also observably declined(P<0.05 or P<0.01), respectively. Moreover, the digestibility of Met and Tyr in 2.5 mg/kg.bw group was markedly decreased compared with the control(P<0.01). Additionally, villous length of ileum in 0.4 mg/kg.bw group was shorter than control(P<0.05). In 1.0 and 2.5 mg/kg.bw groups, reduction of villous number and villous length, increase of crypt depth, decrease of the ratio of villus length to crypt depth were observed in the duodenum, jejunum and ileum(P<0.05 or P<0.01), respectively. It is concluded that the supplementation of T-2 toxin could induce the increase of p H value and apparent digestibility decrease of nutrient, mineral elements and amino acid with dose-effect relationship, which were associated with intestinal mucosal damage caused by T-2 toxin.(3) Study on the apoptosis mechanism of HL-7702 cells induced by T-2 Toxin. T-2 toxin reduced the cell viability and increased the apoptosis of HL-7702 cells in a concentration-dependent way. Furthermore, cell and mitochondrial morphology of HL-7702 cells were changed exposured to T-2 toxin. Low concentration of T-2 toxin could induce a concentration-dependent reduction in ATP and ?Ψm. And T-2 toxin could induce ROS accumulation in HL-7702 cells. Compared with the control, the Mfn1, Mfn2, OPA1 were increased expression significantly in 0.1 μg/L T-2 toxin group(P<0.05). However, the difference of expression of Drp1 and Fis1 in these two groups were not significant(P>0.05). T-2 toxin at the concentration of 10 μg/L could improve the m RNA expressions of Caspase-3, Caspase-7, Caspase-8, Caspase-9, cyt-c, p53, Mfn1, Mfn2, Fis1, Drp1 and OPA1 m RNA in HL-7702 cells(P<0.01). Bax was increased expression,while Bcl-2 was decreased expression in HL-7702 cells exposured to 0.1~10 μg/L(P<0.05 or P<0.01). Compared to the control, the Ratio of Bax/Bcl-2 of T-2 toxin group increased. The ratio of Bax/Bcl-2 was highest when the cells were treated with 1 μg/L T-2 toxin. The result suggest that the mitochondrial fusion play avery important role in T-2 toxin at low concentration(i.e., 0.1 μg/L) induced cell injury, which is related to mitochondrial dysfunction. While higher concentration of T-2 txoin(i.e., 10 μg/L) increased mitochondrial fission and fussion hastens mitochondrial fragmentation. Meanwhile, higher concentration of T-2 toxin pretreatment increased the expressions of apoptosis-related genes. |
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