Alkaline water has toxicity to cultured aquatic animals that frequently lived in pH-neutral freshwater. Overfishing and habitat destruction contributed to decline the wild sturgeon population size, therefore, domestic hybrid sturgeon became an increasingly important commercial species in China. Hybrid sturgeon are widely cultured in alkaline water, but little has been known about the effects of alkalinity stress on hybrid sturgeon liver tissues. We exposed hybrid sturgeon to four alkaline concentrations (3.13-3.20 mmol/L, 7.47-7.73 mmol/L, 11.6-12.6 mmol/L and 14.4-16.67 mmol/L). Histopathology, biochemical indexes assessment, gene expression level detection and metabonomics analysis were used to investigate the negative effects on liver functions following exposure to NaHCO₃. Severe tissue injury and obvious apoptosis characteristics were shown in livers under the alkaline stress. With increased exposure concentrations, the hepatic superoxide dismutase, catalase, glutathione peroxidase and alkaline phosphatase activities significantly decreased in a dose-dependent manner. NaHCO₃ exposure up-regulated the transcriptional levels of apoptosis/ferroptosis-related genes in livers. Similarly, the expressions trends of interleukin-1β and heat shock protein genes also increased in high-alkalinity. However, the expression levels of Complement protein 3 significantly decreased (P < 0.05). Hepatic untargeted metabolomics revealed the alteration conditions of various metabolites associated with the antioxidant response, ferroptosis process and amino acid metabolism (such as beta-alanine metabolism, alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism). These data provided evidence that NaHCO₃ impaired immune functions and the integrity of hybrid sturgeon liver tissues by mediating oxidative stress-mediated apoptosis and ferroptosis. Our results would shed light on the breeding welfare of domestic hybrid sturgeon and promote the economic development of fishery in China.
 

Huso dauricus,Acipenser Schrenckii,liver,oxidative stress-mediated