食品添加剂诱导8-羟基鸟嘌呤糖基酶的实验研究

DNA Damage Induced by Food Additive in Rat Kidney

目的 探讨食品添加剂KBrO3对哺乳类组织中 8 羟基鸟嘌呤糖基酶的氧化诱导作用。方法 比较用KBrO3处理大鼠后 ,其肾和肝中修复酶活性的变化规律。酶活性分析用高效液相色谱 电化学检测法。结果 腹膜下给予 80mg kg剂量KBrO3后 ,在肾脏发现酶活性在 3h时显著升高 ,而在 6h时 ,其活性达到高大值 (1 2 5± 0 14 )pmol,该值是 0h的 6倍。然后 ,活性开始下降并在 12h回到 0h水平 ;不加处理时 ,其活性只有 (0 2 0± 0 0 6 )pmol,而在 2 0、4 0、80及 16 0mg kgKBrO3腹膜下给予时 ,其活性分别是 (0 33± 0 0 9)、(0 5 3± 0 10 )、(0 75± 0 13)及 (1 30± 0 0 8)pmol,在 4 0mg kg以上时活性显著增高 ,且显示剂量反应关系。在肾中观察到该酶活性变化是时间与剂量依赖性的 ,而在肝中未发现这种变化。结论 哺乳类组织中 8 羟基鸟嘌呤糖基酶能被氧化诱导 ,提示DNA中氧化损伤的修复是机体在有氧环境中生存的重要过程。

Objective To explore the oxidative inducibility of oh+8Gua glycosylase in mammalian tissues. Methods Treated with potassium bromate (KBrO-3), the activity changes of this enzyme in the kidney and the liver of rats were measured and compared by HPLC/ED. Results With a single dose of KBrO-3 (80 mg/kg,ip), the activity in the kidney was found to increase significantly at 3h. At 6h, activity peaked, showing a 6-fold increase over that at zero time. Thereafter, it decreased and returned to its zero time level at 12h. With increasing doses of KBrO-3 (up to 160 mg/kg,ip),activity increased linearly with increased dosage, and over 40mg/kg, the activity increased to a level significantly higher than that in the control. But no significant changes were observed in the liver on the same conditions. Conclusion oh+8Gua glycosylase can be induced oxidatively in mammalian tissues and it implies that the repair of oh+8Gua residues in DNA is a process important for the survival of organisms in an aerobic environment.