辛基酚胁迫对雄性泥鳅抗氧化酶及卵黄蛋白原的影响

为研究辛基酚(OP)对雄性泥鳅抗氧化酶活性及血清卵黄蛋白原(VTG)含量的影响,将雄性泥鳅分别暴露于4种不同质量浓度OP(0.12、0.19、0.32、0.52 mg/L)中持续7、14、21 d和28 d,采用试剂盒检测肝脏超氧化物歧化酶(SOD)与过氧化氢酶(CAT)的含量,采用碱不稳定性蛋白结合磷法检测血清VTG的含量。结果表明,0.12 mg/L OP胁迫14 d,肝脏SOD和CAT含量均无显著变化,但是随着胁迫剂量增大和时间延长,SOD和CAT含量降低极其显著,在0.52 mg/L OP胁迫28 d时降到最低水平;泥鳅在0.12 mg/L OP中暴露7 d时,血清VTG含量就有极其显著升高,且随着胁迫剂量增大和时间的延长,VTG含量呈升高趋势。提示OP胁迫对SOD和CAT活性有显著的抑制作用,并随胁迫剂量增大和时间延长而抑制加剧,造成氧化损伤;OP胁迫可诱导VTG合成,并随暴露剂量增大和时间延长而诱导增强,具有明显的雌激素效应,这可能与其氧化损伤有密切关系。

Incidence of antioxidant enzymes and vitellogenin induced in male loach (Misgurnus anguillicaudatus) exposed to octylphenol

Octylphenol (OP), a group of alkylphenol polyethenoxy ethers (APEs), is usually present in polluted water. OP has strong estrogenic activity, is easily concentrated and is difficult for animals to degrade; therefore, it may affect the function of the liver of Misgurnus anguillicaudatus. The antioxidant enzyme system is an important protection mechanism in the body that prevents oxidative damage during metabolism of oxygen free radicals. Although some studies of the toxicity of many phenolic contaminations have been conducted in fish and mammals, few data are currently available regarding the oxidative damage and estrogenic activity of OP in fish. To investigate the damage and activity of M. anguillicaudatus, the median lethal concentration (LC₅₀) of OP for 24, 48, 72 and 96 hours and safe concentration (SC) were calculated by the single factor toxicity test. The LC₅₀ for 24, 48, 72, and 96 hours were 3.26, 2.69, 2.12 and 1.82 mg/L, and the SC was 0.54 mg/L. Based on the SC values, male loaches were exposed to OP at four different concentrations (0.12, 0.19, 0.32 and 0.52 mg/L) and the activities of antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) in the liver were determined at 7, 14, 21 d and 28 d. Additionally, the levels of serum vitellogenin (VTG) were examined by measuring the alkali-labile phosphorus content of the lipid-free protein fraction at 7, 14, 21 d and 28 d. The results showed that the activities of SOD did not differ significantly in response to 0.12 mg/L of OP during 14 d, but that they declined significantly with increased exposure time and concentration, with the lowest activity being observed in response to exposure to 0.52 mg/L of OP for 28 d. The CAT activities showed a similar pattern. When compared to the control group (0 mg/L), the levels of serum VTG increased significantly in response to 0.12 mg/L of OP at 7 d, and increased further with increasing concentration. As the exposure time increased, the total VTG activity in the four concentration groups also increased, with the maximum value being observed in response to exposure to 0.52 mg/L of OP for 28 d. These findings indicated that OP had high toxicity toward M. anguillicaudatus and that moderate and high concentrations of OP were able to induce oxidative stress and exert a significant negative impact on SOD and CAT activities of M. anguillicaudatus. Moreover, the inhibition intensified remarkably as the exposure concentration and time increased, resulting in the hepatic defense function of antioxidant enzymes being reduced. This, in turn, caused excess reactive oxygen species (ROS) accumulation, which can lead to oxidative damage of M. anguillicaudatus. The serum VTG could be induced in male loaches treated by OP and the induction intensified greatly with exposure, indicating that OP possesses estrogenic activity that intensified as the exposure concentration and time increased, leading to damage to the reproductive system of M. anguillicaudatus. These results indicate that the estrogenic effect of OP may be closely correlated with oxidative damage in M. anguillicaudatus.