镉致黑斑蛙肝脏中ROS生成及其蛋白质氧化损伤作用

Reactive oxygen species generation and protein oxidative damage in the liver of Rana nigromaculata exposed to cadmium

在实验条件下,将健康性成熟黑斑蛙(Rana nigromaculata)暴露于0.005、0.010、0.050和0.100mg·L-1浓度的镉溶液中30d,采用2,4二硝基苯肼比色法测定肝组织蛋白质羰基含量,KCl-SDS沉淀法测定DNA-蛋白质交联含量,并测定了肝组织中活性氧自由基(ROS)的水平,以探讨镉对黑斑蛙肝组织蛋白质的氧化损伤作用及其作用机制.结果表明,随染镉浓度的增加,黑斑蛙肝线粒体中的ROS水平明显升高,各染毒组与对照组相比有显著性差异;肝蛋白质羰基(PCO)含量和DNA-蛋白质交联(DPC)也随镉暴露浓度的增加而升高,且均呈明显的浓度-效应关系,但这种升高仅在镉浓度为0.05、0.10mg.L-1时才具有显著意义.结果还显示,低浓度镉的长期暴露可引起黑斑蛙肝蛋白质氧化损伤和DNA损伤,诱导产生大量自由基可能是导致蛋白质和DNA产生损伤的主要机制之一.

To explore the degree of protein oxidative damage and its molecular mechanism in the liver of Rana nigromaculata upon exposure to cadmium, healthy adult frogs were exposed to 0.005, 0.010,0.050 or 0.100 mg·L^-1 cadmium for 30 days. The protein carbonyl content was assessed with 2,4-dinitrophenylhydrazine and the amount of DNA-protein crosslinking was assayed with KCl-SDS. The level of reactive oxidizing species （ROS） in the liver was also detected. The results showed that the ROS level in mitochondria increased with the cadmium dose and there were significant differences between each cadmium-treated group and the control. Liver protein carbony1 （PCO） content and DNA content crosslinked with protein increased significantly with cadmium concentration, displaying an obvious concentration-effect relationship, but only at 0.05 and 0.1 mg·L^-1 was the increase markedly significant. The results suggest that cadmium can induce protein oxidative damage and DNA damage; the primary mechanism may be generation of free radicals, followed by protein oxidative damage and DNA damage.