低氧和复氧对日本沼虾抗氧化酶活力及组织结构的影响

Hypoxia and reoxygenation on antioxidant enzyme activities and histological structure of Macrobrachium nipponense

为研究低氧胁迫及恢复后日本沼虾(Macrobrachiumnipponense)抗氧化酶活力和组织结构的变化,将体重(2.0±0.2) g的日本沼虾暴露于(2.0±0.2) mg/L低氧环境中24 h,设定溶解氧(6.0±0.2) mg/L为对照组,每组设置3个重复,于低氧胁迫0 h、6 h、12 h、24 h及复氧1 h、6 h、12 h、24 h分别采集实验组及对照组鳃、肝胰腺及肌肉组织,测定这些组织的抗氧化酶活力,并进行组织切片观察。实验结果表明,低氧胁迫期间肌肉组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)活力先升高后下降, 3种酶活力在低氧胁迫12 h时显著高于对照组(P<0.05),复氧阶段肌肉组织中SOD、CAT酶活力呈波动性变化,GPX酶活力在复氧24h时显著低于对照组(P<0.05)。鳃组织中SOD、CAT和GPX酶活力在低氧胁迫12 h时显著高于对照组(P<0.05), GPX酶活力在复氧24 h时显著高于对照组(P<0.05)。在低氧胁迫期间肝胰腺SOD、CAT和GPX酶活力在低氧6 h均达到最大值并显著高于对照组(P<0.05),复氧阶段3种酶活力均呈现波动性变化,肝胰腺中丙二醛(MDA)含量在低氧及复氧阶段均显著高于对照组(P<0.05)。低氧胁迫及恢复并未对肌肉组织结构产生明显的影响。鳃组织在低氧胁迫期间鳃小片上皮细胞与支柱细胞排列发生紊乱,次级层片发生肥大的现象且有红细胞流入,泌氯细胞形态发生变化且细胞数目有所增加,但复氧后均得到一定程度的恢复。肝胰腺组织在低氧胁迫期间B细胞数量逐渐降低,胞内运转泡体积减小,复氧阶段B细胞数量及体积恢复明显。结果表明急性低氧胁迫能够导致日本沼虾肝胰腺和鳃组织结构损伤并引起抗氧化酶活力发生显著变化,且24 h恢复期不足以让日本沼虾在低氧胁迫中完全恢复。

This study examined the effects of hypoxia and reoxygenation on antioxidant enzyme activities and the change in histological structure in Macrobrachium nipponense with the body weight of (2.0±0.2) g. Experimental prawns were placed in a normal (control) group or hypoxia group with given dissolved oxygen of (6.0±0.2) mg/L and (2.0±0.2) mg/L, respectively. Each group was sampled in triplicate to measure the activities of antioxidant enzymes in the muscle, gill, and hepatopancreas under hypoxia at 0 h, 6 h, 12 h, and 24 h, and under reoxygena- tion at 1 h, 6 h, 12 h, and 24 h. The histological structures of gill, muscle, and hepatopancreas were also observed. The results showed that the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) enzymes in the muscle, gill, and hepatopancreas from the experimental group first increased and then de- clined, and the activities of the three enzymes were significantly higher than those of the control group at 12 h under hypoxia stress (P<0.05). The activities of SOD and CAT in the muscle tissue of prawns in response to re- oxygenation was fluctuated over time, and the activities of GPX under reoxygenation at 24 h was significantly lower than that of the control group (P<0.05). The activities of SOD, CAT, and GPX in gill under hypoxia at 12 h were both significantly higher than that of the control group (P<0.05), and there was significantly higher GPX enzyme activity under reoxygenation at 24 h than that of the control group (P<0.05). Compared with the control group, the significantly higher SOD, CAT, and GPX activities in the hepatopancreas of prawns were observed at 6 h (P<0.05), and the content of MDA in the hepatopancreas of prawns in response to hypoxia and reoxygenation was significantly higher than that that of the control group (P<0.05). Observation of tissue by paraffin section revealed that hypoxia and recovery did not affect muscle tissue structure. Through the observation of the tissue section of the gill, it was found that the epithelial cells and the pillar cells were disordered after 12 h of hypoxia stress, and the secondary layer was hypertrophied. After 24 h of hypoxia, the secondary layer of hypertrophy was intensified and red blood cells inflowed. The morphology of the cells changed, and the number of cells increased, but it re- covered to some extent after reoxygenation. During hypoxia stress, the number of B cells in the hepatopancreatic tissues significantly decreased, but the number and apparent volume of B cells recovered to the level of the control group after reoxygenation. The results showed that acute hypoxia can cause damage to the hepatopancreas and gill of M. nipponense, and affect the activities of antioxidant enzymes. Furthermore, the results showed that acute hy- poxia can cause damage to the hepatopancreas and gill of M. nipponense, and affect the activities of antioxidant enzymes. The 24 h recovery period was not sufficient for M. nipponense to completely recover from hypoxia stress.