Melamine Induced Renal Injury And Crystallization In Rats

Objective:To investigate renal injury and crystallization in melamine—administered rats.Methods:There were two parts the investigation.1,Kidney lesions induced by administration of melamine were investigated in male SD rats. Animals,6 weeks old at the beginning of the experiment, received 3%(W/W) melamine in the diet for 12 weeks. After 3 months executed all rats observation biochemical indicators and pathological analysis.2,Kidney lesions and urinary calculus formation induced by administration of melamine were investigated in male SD rats. Animals,6 weeks old at the beginning of the experiment, received 3% (W/W) melamine in the diet for 12 weeks followed by a 4 week period without chemicals, the total observation time being 16 weeks.Results:Compared with blank group, the levels of melamine and protein in urine were increased with the drug exposure time, urine creatinine excretion and creatinine clearance were reduced, kidney/weight ratio were increased, but each urine pH and uric acid were no difference obviously in the melamine rats. Stone appeared in bladder one month after the induction, in which the composition were confirmed for melamine phosphate by electrospray mass spectrometry and infrared spectral analysis. Uric acid was not found to exist otherwise. Pathological analysis showed crystal deposition, epithelial and stromal damage in the kidney. Melamine crystals were mainly concentrated in renal tubular cavity, and interstitial damage apparently in kidney. Progressive inflammation and fibrosis in kidney were developed with the increase of drug exposure time. Bladder tumor was not found at the four month's research. No melamine values were existed in urine at the time of 3 month's induction following 2 week's withdrawal for melamine. After discontinuation to melamine for 4 weeks, bladder calculi were not found in all the rats, the function were improved obviously and pathological damage were significantly reduced in kidney. In addition, rats admitted potassium—sodium citrate shown much improvement in renal function with much lower in serum creatinine levels. But taurine improved without apparent change in renal function, and H2O2 and mitochondrial oxidative reagent SOD,GSH-PX were not difference in the melamine rats with and without taurine intakesConclusions:Renal crystals and injury were induced with melamine exposure time and concentration, in which mainly appeared in renal tubular cavity. The composition of crystals was melamine phosphate. Renal function in melamine intake rats would be improved with the intake together with potassium sodium citrate. Taurine did not improve renal function in melamine intake rats shown the oxidative stress were not the mainly mechanism for the renal injury induced by melamine.