三聚氰胺形成肾结晶体机制与肾损伤关系的研究

Mechanism of crystals’formation induced by melamine in kidney and the relationship between crystals and kidney injury

目的探讨三聚氰胺致大鼠肾损伤机制。方法将清洁级Wistar大鼠随机分为三聚氰胺染毒组和对照组,经口染毒后分别于染毒不同时间取肾脏大体观察、组织病理学、血清生化学检查;采用液相色谱-质谱联机、X射线衍射(XRD)法对肾脏中形成的结晶体进行定性定量分析;体外结晶体反应放热测定,分析结晶体与肾小管损伤的关系。结果 大鼠染毒一定时间后,血清肌酐(CRE)、尿素氮(BUN)、三酰甘油(TG)增高;肾脏外观异常改变;肾脏厚切片解剖镜下观察可见弥漫性分布的泥沙样阴影;组织病理检查肾小管中可见大量晶体、肾小管上皮继发性损伤;液相色谱-质谱分析证实肾脏中含有三聚氰胺147.3μg/g,三聚氰酸122.6μg/g;XRD法确认肾脏中的结晶体为三聚氰胺和三聚氰酸的结合晶体。体外晶体结晶过程生成75 kJ/mol的热量。结论在本试验条件下,经口给大鼠染毒三聚氰胺后可在肾小管中产生结晶体;由于肾小管中的大量结晶体的挤压造成肾组织严重缺血缺氧;结晶体堵塞肾小管致重吸收功能障碍;三聚氰胺-三聚氰酸结晶过程生成热致小管上皮变性。3者共同作用可能是导致肾损伤的原因。

Objective To research the mechanism of renal injury induced by melamine in rats.Methods The Wistar rats of clean grade were randomly divided into the exposure groups and the control group,the kidney samples were collected after different exposure times and tested by visual inspection,pathological examination and serum biochemical detection.The crystals formed in kidney were qualitatively and quantitatively analyzed by Lc-mc and X-ray diffraction（XRD）.According to the reaction heat of melamine and cyanuric in vitro,the relationship of crystals formation to tubular injury was analyzed.Results After exposure,the serum creatinine（CRE）,blood urea nitrogen（BUN）,triglyceride（TG） were increased.The renal appearance showed abnormal changes and the renal thick sections were observed under dissection microscope,it showed that diffuse distribution of sediment-like foreign bodies’shadow.Pathological examination showed crystals in renal tubules and the epithelial secondary injury of renal tubules.The melamine concentration was 147.3 μg/g and the cyanuric acid concentration was 122.6 μg/g in renal tissue tested by Lc-mc.The renal crystals were confirmed to be crystal combination of melamine and cyanuric acid by X-ray diffraction.The results of melamine and cyanuric acid reaction heat test showed that 94KJ/mol was produced during forming crystals.Conclusion The crystals can formed in tubules after oral exposure.Crystals blocked the renal tubular,which led to re-absorption dysfunction;and a large number of crystals caused severe kidney ischemia and hypoxia;the instantaneous reaction heat of melamine-cyanuric acid can lead to the renal tubular degeneration.The combined action of these three lead to renal injury.