低溶氧胁迫对刺参(Apostichopus japonicus)氧化应激指标的影响

为探明低氧胁迫对刺参(Apostichopus japonicus)抗氧化能力的影响以及刺参的低氧逆境响应机制，给低氧环境条件下的刺参养殖提供指导，本研究通过设置低氧胁迫实验，将刺参在水体低氧(2.0±0.2) mg/L]8 h 处理后恢复常氧(7.0±0.2) mg/L]2.5 h，取低氧和常氧不同时间段的刺参肌肉、呼吸树和消化道组织，对各组织的乳酸(LD)、丙二醛(MDA)和抗氧化酶系等应激参数进行测定和变化趋势分析。结果显示，与对照组相比，在低氧胁迫8 h 内，随着低氧暴露时间的延长，刺参肌肉、呼吸树和消化道等组织中的 LD 含量、抗氧化能力(T-AOC)、过氧化氢酶(CAT)、谷胱甘肽-S-转移酶(GST)活力显著上升；超氧化物歧化酶(SOD)活力显著下降；肌肉组织中的 MDA 含量显著降低，呼吸树和消化道中的 MDA 含量显著上升。在恢复常氧阶段，各氧化应激指标逐渐恢复到正常水平。低氧胁迫使刺参的有氧代谢减弱，无氧代谢增强，以维持机体能量需求。低氧胁迫造成刺参机体各种应激生化指标上升或下降，这是机体为适应低氧环境刺激而作出的一种抗氧化策略。

Effects of Hypoxic Stress on Oxidative Stress Indices in Apostichopus japonicus

Apostichopus japonicus that usually habits in the temperate zone, is one of the important aquaculture species at northern China coast. Dissolved oxygen, known as the oxygen content in water, is necessary for the survival of aquatic organisms and directly affects the enzyme activity, metabolism, and growth of aquatic organisms. Therefore, low dissolved oxygen during the hot weather is very harmful for sea cucumber aquaculture and has become an urgent issue. Here we investigated the effects of hypoxic stress on antioxidant capacity of A. japonicus. The experimental group was exposed to hypoxia (2.0±0.2) mg/L] for 8 h, followed by reoxygenation (7.0±0.2) mg/L] for 2.5 h. Then tissues from the muscle, respiratory tree, and digestive tract were collected at different time points. Levels of lactic acid, malondialdehyde (MDA), and activities of the antioxidant enzyme system in different tissues and time points were analyzed. It was found that during the exposure to hypoxia, the lactic acid content and activities of total antioxidant capacity (T-AOC), catalase (CAT) and glutathione-S-transferase (GST) were significantly higher compared with the control group (P<0.05), whereas the activity of superoxide dismutase (SOD) became lower (P<0.05) with the extension of hypoxic exposure. The level of MDA in the muscle tissue was significantly lower than in the control group (P<0.05), however, was higher in the respiratory tree and digestive tract. All of the oxidative stress indices gradually returned to normal levels during reoxygenation. These results indicated that as the aerobic metabolism was inhibited during hypoxia, the anaerobic metabolism was increased to maintain the energy supply. The elevated T-AOC, CAT and GST activities and declined SOD activity caused by hypoxia might be an antioxidant strategy to adapt to the hypoxic environment. Our study may provide useful information for the control of hypoxic conditions in sea cucumber aquaculture.