Yellow Sea Fisheries Research Institute, Qingdao Key Laboratory for Marine Fish Breeding and Biotechnology, Chinese Academy of Fishery Sciences, No. 106 Nanjing Road, Qingdao, 266071, People's Republic of China.
College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China.
Fish Physiol Biochem. 2024 Dec;50(6):2407-2421. doi: 10.1007/s10695-024-01398-3. Epub 2024 Aug 27.
Hypoxia affects fish's survival, growth, and physiological metabolism processes. In this study, turbot plasma glucose and cortisol contents, hepatic glycolysis (hexokinase [HK], phosphofructokinase [PFK], pyruvate kinase [PK]) and lipolysis (fatty acid synthetase [FAS], lipoprotein lipase [LPL]) enzyme activities, anti-oxidant enzyme (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px]) activities, malondialdehyde (MDA), lactate and glycogen contents, gill histological parameters (lamellar length [SLL], width [SLW], interlamellar distance [ID]), respiratory frequency (RF), the proportion of the secondary lamellae available for gas exchange (PAGE), and hifs (hif-1α, hif-2α, hif-3α) expression were determined during long-term hypoxia and reoxygenation. Results showed that long-term hypoxia (3.34 ± 0.17 mg L) significantly elevated plasma cortisol and glucose contents; increased hepatic HK, PK, PFK, FAS, and LPL activity; decreased hepatic glycogen, lactate contents, and lipid drop numbers; and caused changes of hepatocyte (vacuolation, pyknotic, and lytic nucleus) after treatment for 4 weeks. Hepatic SOD, CAT, GSH-Px activity, and MDA contents; lamellar perimeter, SLL, ID, RF, and PAGE; and hepatic hif-1α, hif-2α, and hif-3α manifested similar results. Meanwhile, hif-1α is significantly higher than hif-2α, and hif-3α. Interestingly, females and males demonstrated no sex dimorphism significantly different from the above parameters (except hepatic FAS, LPL activity, and lipid drop number) under hypoxia. The above parameters recovered to normal levels after reoxygenation treatment for 4 weeks. Thus, long-term hypoxia promotes turbot hepatic glycogenolysis and lipolysis, induces oxidative damage and stimulates hepatic antioxidant capacity, and alters gill morphology to satisfy insufficient energy demand and alleviate potential damage, while hif-1α plays critical roles in the above physiological process.
缺氧会影响鱼类的生存、生长和生理代谢过程。在这项研究中，我们测定了大菱鲆血浆葡萄糖和皮质醇含量、肝糖酵解（己糖激酶[HK]、磷酸果糖激酶[PFK]、丙酮酸激酶[PK]）和脂解（脂肪酸合成酶[FAS]、脂蛋白脂肪酶[LPL]）酶活性、抗氧化酶（超氧化物歧化酶[SOD]、过氧化氢酶[CAT]、谷胱甘肽过氧化物酶[GSH-Px]）活性、丙二醛（MDA）、乳酸和肝糖原含量、鳃组织学参数（鳃片长度[SLL]、宽度[SLW]、片间距离[ID]）、呼吸频率（RF）、可用于气体交换的次级鳃片比例（PAGE）以及缺氧诱导因子（hif-1α、hif-2α、hif-3α）表达，这些指标是在长期缺氧和复氧期间测定的。结果表明，长期缺氧（3.34±0.17mg/L）显著提高了血浆皮质醇和葡萄糖含量；增加了肝 HK、PK、PFK、FAS 和 LPL 活性；降低了肝糖原、乳酸含量和脂滴数量；并在处理 4 周后导致肝细胞（空泡化、固缩和裂解核）发生变化。肝 SOD、CAT、GSH-Px 活性和 MDA 含量、鳃片周长、SLL、ID、RF 和 PAGE 以及肝 hif-1α、hif-2α 和 hif-3α均表现出相似的结果。同时，hif-1α显著高于 hif-2α和 hif-3α。有趣的是，与上述参数（除肝 FAS、LPL 活性和脂滴数量外）相比，在缺氧条件下，雌雄鱼之间没有明显的性别二态性差异。经过 4 周的复氧处理后，上述参数恢复到正常水平。因此，长期缺氧促进大菱鲆肝糖异生和脂解，诱导氧化损伤并刺激肝抗氧化能力，并改变鳃形态以满足能量需求不足，缓解潜在损伤，而 hif-1α在上述生理过程中发挥关键作用。
