Sánchez-Nuño Sergio, Sanahuja Ignasi, Fernández-Alacid Laura, Ordóñez-Grande Borja, Fontanillas Ramon, Fernández-Borràs Jaume, Blasco Josefina, Carbonell Teresa, Ibarz Antoni
Departament de Biologia Cel⋅Lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
Skretting Aquaculture Research Centre, Stavanger, Norway.
Front Physiol. 2018 Jul 17;9:923. doi: 10.3389/fphys.2018.00923. eCollection 2018.
Aquaculture is a growing industry that is increasingly providing a sizable proportion of fishery products for human consumption. Dietary energy and temperature fluctuations affect fish health and may even trigger mortality, causing great losses in fish production during winter. To better understand this unproductive winter period in aquaculture, the redox status in a cultured marine species, the gilthead sea bream, was analyzed for the first time by inducing controlled temperature fluctuations and reducing dietary lipid content. Two groups of fish (by triplicate), differing in their dietary lipid content (18% vs. 14%), were subjected to 30 days at 22°C (Pre-Cold), 50 days at 14°C (Cold) and then 35 days at 22°C (Recovery). Plasma and liver redox metabolites (oxidized lipid, oxidized protein and thiol groups), liver glutathione forms (total, oxidized and reduced) and liver antioxidant enzyme activities were measured. Reducing dietary lipid content did not affect gilthead sea bream growth, glutathione levels or enzyme activities, but did reduce the amount of oxidized lipids. A sustained low temperature of 14°C showed a lack of adaptation of antioxidant enzyme activities, mainly catalase and glutathione reductase, which subsequently affected the glutathione redox cycle and caused an acute reduction in total hepatic glutathione levels, irrespective of diet. Antioxidant enzyme activities were gradually restored to their pre-cold levels, but the glutathione redox cycle was not restored to its pre-cold values during the recovery period used. Moreover, the lower lipid diet was associated with transiently increased liver oxidized protein levels. Thus, we propose that fish should be fed a low lipid diet during pre-cold and cold periods, which would reduce oxidized lipid levels without affecting fish growth, and a higher energy diet during the recovery period. Moreover, diets supplemented with antioxidants should be considered, especially during temperature recovery.
水产养殖是一个不断发展的行业，越来越多地为人类消费提供相当比例的渔业产品。饮食能量和温度波动会影响鱼类健康，甚至可能引发死亡，导致冬季鱼类生产遭受巨大损失。为了更好地了解水产养殖中这个无生产效益的冬季，首次通过诱导可控的温度波动并降低饮食脂质含量，对养殖的海洋物种金头鲷的氧化还原状态进行了分析。两组鱼（每组三个重复），饮食脂质含量不同（18%对14%），先在22°C下饲养30天（预冷期），然后在14°C下饲养50天（低温期），最后在22°C下饲养35天（恢复期）。测量了血浆和肝脏中的氧化还原代谢物（氧化脂质、氧化蛋白质和硫醇基团）、肝脏谷胱甘肽形式（总谷胱甘肽、氧化型谷胱甘肽和还原型谷胱甘肽）以及肝脏抗氧化酶活性。降低饮食脂质含量并未影响金头鲷的生长、谷胱甘肽水平或酶活性，但确实减少了氧化脂质的量。持续14°C的低温显示抗氧化酶活性缺乏适应性，主要是过氧化氢酶和谷胱甘肽还原酶，这随后影响了谷胱甘肽氧化还原循环，并导致肝脏总谷胱甘肽水平急剧下降，与饮食无关。抗氧化酶活性逐渐恢复到预冷水平，但在所用的恢复期内，谷胱甘肽氧化还原循环并未恢复到预冷值。此外，低脂质饮食与肝脏氧化蛋白质水平短暂升高有关。因此，我们建议在预冷期和低温期应给鱼投喂低脂质饮食，这将降低氧化脂质水平而不影响鱼类生长，在恢复期投喂能量更高的饮食。此外，应考虑添加抗氧化剂的饮食，尤其是在温度恢复期间。
