Salinity stress impairs disease resistance in white shrimp, Penaeus vannamei through AMPK pathway, ameliorated by dietary glucose-mediated energy homeostasis

This study presents a comprehensive examination of the physiological adaptations of white shrimp (Penaeus vannamei) to low-salinity conditions and evaluates the effects of supplementing dietary glucose on disease resistance. Compared to the control group, shrimp cultured at a salinity of 4 psu exhibit significantly elevated expression levels of adenosine 5′-monophosphate-activated protein kinase (AMPK) in the hepatopancreas, which leads to increased energy expenditure and a corresponding reduction in resistance to infection by Vibrio alginolyticus. The suppression of AMPK via dsAMPK treatment markedly enhances disease resistance. Moreover, shrimp raised in low salinity conditions exhibit downregulation of mTOR-associated molecules, including Lipin-1 and hypoxia-inducible factor 1-α (HIF-1α), both of which are essential for immune regulation. Metabolic assessments revealed reduced ATP levels and disrupted ATP/AMP and ATP/ADP ratios, indicating energy imbalance under low salinity stress. Notably, supplementing the diet with 1 % glucose significantly increased glycogen reserves and ATP content, stabilized hemolymph glucose levels, and upregulated glycolysis-related genes, thereby optimizing energy metabolism and enhancing resilience to stress. This study underscores that AMPK activation in response to low salinity conditions leads to increased energy expenditure, which in turn lowers disease resistance. Furthermore, it underscores the critical role of strategic dietary management in maintaining energy homeostasis and improving disease resistance in white shrimp under stressful environmental conditions associated with climate change, offering valuable insights for aquaculture nutrition strategies.