Effects of high-temperature stress on serum biochemical indexes,liver sod gene and heat shock protein gene expression of juvenile Siniperca chuatsi

【Objective】 To explore the changes in serum biochemical indicators, immune indicators, and liver antioxidant related gene expression of juvenile Siniperca chuatsi under high-temperature environment, clarify their effects on high temperature and tolerance limits, and provide reference for scientific cultivation of S. chuatsi under high-temperature environment.【Method】 Using 21℃ as the control group, three high-temperature groups of 25, 29 and 33℃ were set up to carry out a 96 h high-temperature stress test on juvenile S. chuatsi. The serum biochemical and immune indexes were determined by serum biochemical indicator kit, and the expressions of antioxidant related genes in liver of juvenile S. chuatsi were detected by real-time fluorescent quantitative PCR.【Result】 Under high-temperature stress, the serum glucose(Glu) concentration, triglyceride(TG) concentration, total cholesterol(TC) concentration, alanine aminotransferase(ALT) activity, and aspartate aminotransferase(AST) activity of juvenile S. chuatsi changed in varying degrees, and the same biochemical index had great differences at different stress temperatures at the same time. With the prolongation of stress time, the serum Glu concentration of juvenile S. chuatsi showed a trend of decreasing first and then increasing;the concentrations of TG and TC showed a downward trend on the whole, and the concentrations of TG and TC in the serum of each high-temperature treatment group were lower than those of the control group after 96 h of stress;the serum TP concentration in the 33℃ treatment group also showed a trend of decreasing first and then increasing, but there was no significant difference between the high-temperature treatment groups and the control group(P>0.05, the same below). The serum ALT activity in the 25℃ treatment group significantly increased at 48 h of stress(P<0.05, the same below), while the serum AST activity in the 29℃ treatment group significantly increased at 24 h of stress;the activity of serum lysozyme(LZM) in each high-temperature treatment group was basically higher than that in the control group, and the serum immunoglobulin M(IgM) concentration in each high-temperature treatment group was generally lower than that in the control group after 48 h of stress. The relative expression of sod gene in the liver of juvenile S. chuatsi generally increased with the increase of stress temperature, the relative expression of hsp90α gene basically increased first and then decreased with the prolongation of stress time or the increase of stress temperature, the relative expression of hsp70α gene showed a downward trend overall.【Conclusion】 High-temperature environment causes a strong stress response in juvenile S. chuatsi. In order to avoid oxidative damage caused by stress, juvenile S. chuatsi self-regulate by increasing the expression of sod gene, increasing energy utilization, and reducing the synthesis and secretion of IgM. However, in the late stage of stress, due to prolonged stress or stress intensity exceeding its regulatory capacity, the S. chuatsi undergoes tissue damage. Since high-temperature stress has a significant impact on the physiological metabolism of juvenile S. chuatsi and reduces their non-specific immunity, it is necessary to strengthen the cultivation management of S. chuatsi during the high-temperature season, avoid adverse effects caused by rapid changes in water temperature, and prevent S. chuatsi from diseases.