| Melamine and cyanuric acid in itself are important organic chemical intermediates. Poisoning incident, Lin Xiangmei, Jia Guangle and the others do the melamine and cyanuric acid in mice acute toxicity test results showed that both the low toxicity of substances. Recently, some of the fish, pigs, cats, rats in the acute animal experiments showed that melamine or cyanuric acid alone have shown low toxicity,but melamine and cyanuric acid when mixed will result in renal failure. Thus, we investigated the mixture of melamine and cyanuric acid toxicity effects of the feed and food safety has a great significance.Objectives:To investigate melamine and its homologue of cyanuric acid caused kidney damage cells and molecules, the control of melamine provide experimental evidence for harm to animals.Methods:Male SD rats were randomized into 6 groups, n= 20, weighing 20-30g. Control group, gavaged distilled water, exposure group gavaged for the next day, melamine alone group 50mg/kg·bw, cyanuric acid alone group 50mg/kg·bw, melamine and cyanuric acid mixture (Melamine+Melamine mixed acid equivalent) of high, middle and low dose groups were by 50 mg/kg·bw, l0mg/kg·bw,2 mg/ kg·bw gavage, continuous 30d. Cervical dislocation with experimental animals in each group were sacrificed, eyes do blood serum isolated renal function test, renal tissue obtained for pathological histology, cell lipid peroxidation measured with detection of apoptosis and immunohistochemistry, the other will be part of the kidney put in-70℃frozen and stored for the detection of gene expression and determination ofRT-PCR.Results:Renal function test results show that compared with the control, mixed high-dose group serum BUN, CRE was significantly higher. SOD activity, MDA content of the test results:MDA increased with increasing dose, which mixed low-dose group compared with the control group there was significant differences (P <0.05), mixed in the middle-dose group and the high-dose group were significantly different (P<0.01); SOD activity was reduced accordingly, as compared with the control group, mixed middle-dose group and mixed high-dose group were significantly different (P<0.01); histological examination showed mixed high-dose group vacuolar degeneration of tubular epithelial cells significantly, Some nuclei have dissolved, then appear in the tubular type, protein leakage, some renal tubular epithelial cell swelling, tube may have crystal appear, all exposure groups there were vacuolation of renal tubular epithelial cells. TUNEL assay results of renal cell apoptosis:the mixed dose groups have different levels of apoptosis, and with the dose increased, the apoptosis rate increased gradually, mixed middle-dose group and mixed high-dose group compared with the control group, significant difference (P<0.01). Using RT-PCR, renal Bax, Bcl-2, Cyt-c gene expression results:melamine and cyanuric acid mixture group Bax, Cyt-c expression were higher, while Bcl-2 was lower than control group. Immunohistochemistry results showed that renal Bax, Bcl-2, Cyt-c protein expression is also consistent with the gene expression results.Experimental conclusion:(1) Melamine and cyanuric acid mixture of sub-chronic toxicity in mice can cause significant kidney damage in a dose related. Kidney function tests and pathology can be seen, the main site of injury in renal tubular epithelial cells. (2) Lipid peroxidation of melamine and cyanuric acid is a mixture of the main cause of renal injury. It can SOD activity in mouse kidney tissue MDA levels decreased and increased, and the higher dose, the effect became. (3) Apoptosis of melamine and cyanuric acid mixture is another way of renal injury, it is by promoting the expression of Bax and Cyt-c, inhibit the expression of Bcl-2 to induce apoptosis of renal tubular epithelial cells.
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