The reproductive toxicity of melamine in the absence and presence of cyanuric acid in male mice.

Melamine, a chemical compound, was used widely in the manufacture of amino resins and plastics. Cyanuric acid related structurally to melamine was used as a water stabilizer in swimming pools. The combination of melamine and cyanuric acid was thought to be responsible for renal impairment in mammals. In the present work, we investigated the reproductive toxicity of melamine in the absence and presence of cyanuric acid in male mice. Pathological damages in different degrees were observed in the testis of male mice treated with different doses of both melamine alone and combination of melamine and cyanuric acid in a dose-dependent manner. Based on the TUNEL assay, the mice treated with high dose of melamine (50 mg/kg/day) had a significant increase in apoptotic index of spermatogenic cells (p<0.05) compared with the control group. Sperm abnormality test indicated that melamine alone resulted in abnormal sperm morphology. The mice from co-administration groups of melamine and cyanuric acid were not eating, and were most likely in renal failure. The combined exposure to melamine and cyanuric acid was revealed to have certain toxic effects on testis of male mice at a relative low dose (each at 1 mg/kg/day). Also, in comparison to melamine treated groups, more severe apoptosis was observed in co-administration groups of melamine and cyanuric acid with both middle (each at 5 mg/kg/day) and high doses (each at 25 mg/kg/day). However, all mice administrated with combination of melamine and cyanuric acid (each at 206, 412, or 824 mg/kg/day) died before day 6 from which no data were obtained on sperm abnormality. These results from this study demonstrated that melamine had certain toxic effects on testes of male mice, especially when ingested in high concentration. These results might be useful in evaluating the toxicity of melamine on reproductive system of male animal, and they also would be a supplement to the existing toxic profile of melamine.