Transcriptional analysis reveals antioxidant, ion transport, and glycolysis mechanisms in Litopenaeus vannamei gills involved in the response to high alkali stress

Saline-alkali aquacultural systems have an important role in improving the economic output of the aquacultural industry. However, the survival rate of shrimp in intensive aquacultural systems is affected by alkalinity fluctuations. This study explored the ion transport and molecular responses of the whiteleg shrimp Litopenaeus vannamei to short-term high alkaline stress (96 h). The results showed that survival rate decreased significantly with time, hemolymph osmotic pressure and oxygen consumption dropped sharply after peaking at 48 h, and ammonia excretion followed a non-monotonic pattern, with an initial decline followed by a subsequent increase. Analysis of key physiological indicators revealed that urea nitrogen continued to accumulate, antioxidant (SOD and CAT) and glycolytic (PFK and LDH) enzymes were significantly activated, but ion regulatory enzymes (Na⁺/K⁺-ATPase) were severely suppressed. Gill histopathology showed typical injuries (such as gill filament shrinkage, vacuolation, and hemocytopenia). Furthermore, transcriptome analysis confirmed that high alkali stress activated insulin signaling pathway and glycolysis-related genes (e.g., upregulating PFK and GLUT expression). These results indicate that the high alkalinity causes an ion imbalance, changes the ammonia transport process, and activates the glycolysis pathway. These conclusions provide a theoretical basis for the subsequent development for the saline-alkaline aquacultural of Litopenaeus vannamei.