Objective: Study the toxicology damage of melamine(cyanuric acid) to rats’ kidney.Methods: Divided the newborn rats and adult rats into high dose group of melamine(NM

M)

low dose group of melamine(Nm

m)

high dose group of cyanuric acid(NA

A)

low dose group of cyanuric acid(Na

a)

high dose group of melamine-cyanuric acid(NMA

MA)

low dose group of melamine-cyanuric acid(Nma

ma) and normal control group(NN

N).The corresponding dose of melamine(cyanuric acid) was given by oral gavage and lasted two months.Rats were killed at 3 day

15 day and 60 day.The body weight and kidney weight were collected.Renal function was detected and the microscopic and ultra-microscopic renal histology structural changes were observed.Results: The body weight of NMA group and Nma group increased first

and then reduced.The body weight of MA group and ma group reduced gradually.The number of kidney crystal increased with the administration time extension.The electron microscope demonstrated that the tubules which contained stones microvilli reduced or disappeared

granulocyte infiltration and other inflammatory response.The kidney weight/body weight

urea nitrogen

creatinine

uric acid value increased in administration groups.Conclusion: Melamine(cyanuric acid) could produce insoluble crystals in rat kidney and lead to renal dysfunction.The toxicity of melamine(cyanuric acid) was greater in adult rats than in newborn.The number of melamine(cyanuric acid) crystals was positively correlated with dose and time.The toxicity of melamine was greater than cyanuric acid.Melamine(cyanuric acid) mixture toxicity was greater than the monomer.Melamine(cyanuric acid) toxicity had individual differences and brood diffenence.