Effects of long-term low-salt alkali stress on antioxidant capacity, immune-inflammatory responses, and metabolism in the hepatopancreas of Litopenaeus vannamei

The Litopenaeus vannamei , known for its broad salinity tolerance and strong stress resistance, is an excellent candidate for aquaculture in saline-alkaline water. This experiment aimed to investigate the effects of long-term (60-day) low-salt alkali stress on the antioxidant capacity, apoptosis, inflammatory response, and immune function of the shrimp's hepatopancreas, and to analyze the underlying metabolic mechanisms through metabolomics. The results showed that the activities of SOD, CAT, and GSH-Px enzymes were significantly increased, indicating a notable enhancement in antioxidant capacity. The mRNA expression levels of apoptosis-related genes Caspase3, P53, and BAX were significantly elevated. The activities of ALT and AST enzymes were markedly increased, and the mRNA expression levels of inflammatory factors TNF, JNK, and RAB6A were significantly upregulated, suggesting potential inflammatory damage to the hepatopancreas. Meanwhile, the activities of AKP and ACP enzymes were significantly enhanced, and the mRNA expression levels of immune-related genes TRAF6, Toll, ALF and Crustin were notably increased, indicating that low-salt saline-alkaline stress may enhance immune defense. Metabolomics results indicated that arachidonic acid metabolism was significantly enriched pathway in response to low-salt alkali stress, potentially playing a key regulatory role by generating inflammatory mediators and immune signaling molecules to mediate inflammatory responses and immune activation in the hepatopancreas. Through physiological and biochemical analyses of the hepatopancreas of Pacific white shrimp, this study explores their adaptation to saline-alkaline water, providing important references and practical implications for saline-alkaline aquaculture of this species.