Acute Hypoxia Stress in the Mudskipper (Boleophthalmus pectinirostris): Effects of Puerarin and Dexamethasone

The intensification of aquaculture often leads to dissolved oxygen depletion, posing a significant hypoxic stress to aquatic organisms such as the mudskipper (Boleophthalmus pectinirostris). Identifying compounds that can mitigate hypoxic damage is therefore of great importance. This study investigated the protective effects of puerarin and dexamethasone against acute hypoxic stress in mudskippers. Four experiment groups were formulated: fish in the control group (HC) and the hypoxia group (HH) were injected with NaCl, fish in the puerarin group (HP) were injected with puerarin, and fish in the dexamethasone group (HD) were injected with dexamethasone, then the HH, HP, and HD groups were treated with a hypoxia condition sustained for 48 h. Compared with the HC and HP groups, the HH group showed significantly reduced activities of protein kinase B (Akt), glycogen synthase kinase (GSK-3β), lactate dehydrogenase (LDH), and pyruvate kinase (PK) in the liver at 24 and 48 h. The gene transcription levels of GSK-3β and Akt in the liver and gill of mudskipper were the smallest, but p53, VEGF, HIF-1, and BNIP3 in the liver of fish in the HH group were significantly highest. The gene transcription levels of GSK-3β and Akt in the liver of mudskippers in the HP group were observably lower than those of mudskippers in the HD group at 24 h, but HIF-1 was significantly higher. On the contrary, at 48 h, the mRNA expression levels of GSK-3β and Akt in the liver of fish in the HP group were significantly higher than those of fish in the HD group, but HIF-1 was significantly lower. The results indicated that mudskippers suffering from hypoxia led to oxygen homeostasis disturbances and apoptosis, but exogenous puerarin or dexamethasone could mitigate the adverse effects. The mRNA of HIF-1 regulation has an important role in enhancing hypoxia tolerance.