Effects of Hypoxia Stress on Antioxidant and Apoptotic in the Heart of Rainbow Trout(Oncorhynchus mykiss)
Rainbow trout(Oncorhynchus mykiss)is extremely sensitive to hypoxia,and its antioxidant capacity and apoptosis are affected by hypoxia environments.To understand the effects of hypoxia stress on the heart of rainbow trout,antioxidant and apoptotic gene expression were measured using enzyme activity assay and qRT-PCR during moderate hypoxia(4.5±0.1 mg/L)and severe hypoxia(3.0±0.1 mg/L)stress for 4,8,12,24 h,1 month,and reoxygenation(8.5±0.1 mg/L)for 12 and 24 h.The results showed that total superoxide dismutase(T-SOD)and catalases(CAT)activities were significantly reduced at 24 h and 1 month,malondialdehyde(MDA)content was significantly increased at 12 h(P<0.05)under severe hypoxia stress;T-SOD,CAT and total antioxidant capacity(T-AOC)activities were gradually increased under moderate hypoxia stress.Compared with the control group,total protein(TP)content was significantly decreased after 1 month of hypoxia stress(P<0.05).The expression of antioxidant-related genes Cu/Zn-SOD(cu/zn-sod)and Mn-SOD(mn-sod)were significantly decreased under severe hypoxia and moderate hypoxia stress compared with the control group(P<0.05);the expression of cat was significantly decreased at 4,8 and 12 h under severe hypoxia(P<0.05).After severe hypoxia stress,the expression of apoptosis-related gene B-cell lymphoma-2(Bcl-2)increased significantly under short-term hypoxia stress compared with the control group,while the expression of Bcl-2-associated X(Bax)showed no significant difference,and the expression of caspase-3(casp3)and tumor suppressor gene 53(p53)decreased significantly at 12 h(P<0.05).Acid phosphatase(ACP)and alkaline phosphatase(AKP)were significantly higher than those of the control group at 12 h under severe hypoxia stress and moderate hypoxia stress(P<0.05).The above results suggested that rainbow trout heart could reduce oxidative damage by regulating the activities of antioxidant enzymes and the expression of apoptosis-related genes under different concentrations of hypoxia.This study provides a theoretical basis for further elucidating the oxidative stress mechanism in rainbow trout heart under hypoxia stress.
Rainbow troutHypoxiaPhysiological and biochemical indicatorsOxidative stressApoptosis