| Metabolism and residues, toxicity of melamine on Channel catfish (Ictalurus punctatus) were studied. At first, A Ultra performance liquid chromatography (UPLC) method about detecting melamine content in plasma and tissues was established. Chromatographic conditions:BeHC 18(2.1×100 mm,1.7μm),10 mmol/L heptanesulfonate sodium+10 mmol/L citric acid:acetonitrile (V/V=94:6), the column temperature for 30℃, the sample temperature for 18℃, velocity of 0.3 mL/min, the injection volume for 10μL. UV detector wavelength was at 240 nm. Standard curve existed good correlation and the correlation coefficient amounted to 0.9879 above. The average recovery in plasma, muscle, liver, kidney was more than 76%. The recovery from these tissues was blood (99.50±4.69)%, liver (87.00±5.46)%, kidney (84.10±9.71)%, muscle (76.37±4.37)%, respectively. And the highest recovery was from plasma, the lowest from muscle. The coefficient of variations were less than 10%. The limit of detection was 0.05 mg/L,0.10,0.05,0.05 mg/kg, respectively.Secondly, Studies on the metabolism of melamine (80 mg/kg) mixed feeding with the Channel catfish at (21±1)℃. Samples were collected at different time. The samples were detected by using UPLC. Experiment datas were analyzed with 3P97 pharmacokinetic software process. Results show that the plasma concentration-time data fits to a one-compartment open model with absorption, C=3.952660(e-0.027279t—e-0.127279t). Absorption and elimination half-life were 5.447h,25.409h, respectively. The time to peak plasma concentration(Tp) was 15.405 h and peak concentration(Cmax) was 20.399 mg/L. The apparent volume of distribution(Vd) was 2.576 (mg/kg)/(mg/L). Melamine in plasma were high concentration and wide distribution, but eliminated slowly. Parameters in muscle, liver, kidney:Absorption half-life were 3.558,4.188,5.440 h, respectively. Elimination half-life were 50.808, 23.350,23.724 h. The time to peak plasma concentration(Tp) were 14.677,12.652, 14.997 h. The peak concentration(Cmax) were 7.645,22.925,40.605 mg/L. The apparent volume of distribution(Vd) were 8.566,2.397,1.271 (mg/kg)/(mg/L). The results showed:The absorption of melamine in the tissues was rapid, and kidney> liver> muscle. The concentration maintained higher, distributed widely and eliminated the more slowly but which in muscles was faster than others. The time to peak concentration was no large difference. But the peak concentration in kidney was the highest, which in muscles was the lowest.Thirdly, the residues of melamine in the.Channel catfish with repeatedly mixed feeding was Studied. Melamine in tissues in general showed the kidney> liver> muscle.In the 1st day, the content of melamine was the highest, and kidney(39.617 mg/kg), liver (9.920 mg/kg), muscles (8.354 mg/kg),respectively.7 days after drug withdrawal,the melamine content in tissues was lower than the maximum residue limit of melamine 2.5mg/kg.Fourth, The damage of melamine on red blood cells was studied at different concentrations of melamine (80,800,2000 mg/kg) and different exposure time (5,6, 7 d). The results showed that micronuclei and nuclear anomalies rate were higher in most of experiment groups than the negative control group. The peak value appeared in the first 6 d, the micronucleus rate was 0.88%o, nuclear anomalies rate was 17.854‰. Micronuclei and nuclear anomalies in trial groups were no significant difference (P>0.05). The results indicated that melamine was no significant genotoxic effects on channel catfish.Fifth, the effect of melamine on serum biochemical indexes in Ictalurus punctatus were studied,80 Ictalurus punctatus were randomly divided into a negative group and three treatment groups. The results showed:the triglycerides (TG) and total cholesterol (T-CHO) content in the whole experiment phase had no big change. Compared with control, there were no significant difference (P>0.05). In the 8th day, alkaline phosphatase (ALP) (21.33,35.00,50.67 U/L), aspertate aminotransferase (AST) (49.00,66.67,75.67 U/L), alanine aminotransferase (ALT) (10.67,26.00, 35.67 U/L) vitality rised with poisonous doses. Compared with control group, low concentration had no significant difference (P>0.05), and the other groups were significantly difference (P<0.05). In the 13th day and 20th day, three serum enzyme content dropped significantly, and the same dose groups had little change. Creatinine (CRE) overall declined, but the difference was not significant (P>0.05). In the same sampling time points, different doses groups had no significant difference (P>0.05). In the 8th day, serum urea nitrogen (BUN) of high dose groups were obviously higher than the-control group, there were significance (P<0.05) and a very significant difference (P<0.01), low dose groups were non-significance difference (P>0.05). After the 13th day and 20th day, compared with the control groups,BUN content of each dose group had no significant difference (P>0.05). |
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