镉、汞暴露在中华绒螯蟹卵巢中的富集及其氧化应激反应

EFFECTS OF CADMIUM AND MERCURY ON OXIDATIVE STRESS INDEXES IN THE OVARY OF ERIOCHEIR SINENSIS

研究以中华绒螯蟹(Eriocheir sinensis)为实验对象,用不同浓度的Cd^(2+)溶液(0、0.63、1.26、2.52、5.04和10.07 mg/L)或Hg^(2+)溶液(0、0.06、0.11、0.23、0.46和0.91 mg/L)对其分别进行染毒, 6d后解剖取其卵巢,检测卵巢中Cd和Hg的富集量以及氧化应激相关指标的变化情况。结果显示,随着Cd^(2+)或Hg^(2+)染毒浓度的升高,卵巢中Cd和Hg的富集量显著增加; H_2O_2、MDA和NO含量、MT mRNA表达量及NOS活性均随着Cd^(2+)和Hg^(2+)浓度的增加出现上升的趋势,但SOD、CAT和GPx活性呈先升后降的趋势。这说明镉、汞均可引起卵巢组织产生过量的自由基和脂质过氧化,并诱导氧化应激酶及MTmRNA的表达以抵抗不良的环境。总之,MT对中华绒螯蟹卵巢中重金属的解毒发挥着重要作用,抗氧化酶能有效地消除活性氧自由基(ROS),维持机体的氧化还原处于平衡状态,共同保护膜脂免受氧化损伤。

Cadmium (Cd) and mercury (Hg) are the most common pollutants found in water environment to cause tissue damages and induce apoptosis in invertebrates. To investigate the toxicological effects of Cd and Hg on the ovary of Eriocheir sinensis, the crabs were exposed to different concentrations of Cd ^2+(0, 0.63, 1.26, 2.52, 5.04 and 10.07 mg/L) or Hg ^2+(0, 0.06, 0.11, 0.23, 0.46 and 0.91 mg/L) for 6 days. The accumulation of Cd^2+ and Hg in the ovary increased significantly with the increased concentrations. The extent of oxidative stress caused by Cd^2+ or Hg^2+ was investigated by determining the oxidative stress indexes in the crab ovary. MDA, H2O2 and NO contents, MT (Metallothionein) mRNA levels and NOS activity in the ovary increased with the increased concentrations of Cd and Hg . SOD, CAT and GPx activities initially increased, and then decreased with the increased Cd^2+ or Hg^2+. The result suggest that Cd ^2+ and Hg^2+ can cause excessive accumulation of free radicals in ovary which lead to lipid peroxidation, and that MT induction in the ovary is a protective response against oxidative damage via detoxification of the ovary of E. sinensis. The induced antioxidant enzymes by Cd^2+ and Hg^2+ could effectively eliminate reactive oxygen species (ROS) from the tissues and maintain a redox-balance system to provide protection against Cd^2+ and Hg^2+-induced oxidative stress.