White Shrimp Litopenaeus vannamei That Have Received Gracilaria tenuistipitata Extract Show Early Recovery of Immune Parameters after Ammonia Stressing

White shrimp Litopenaeus vannamei immersed in seawater (35‰) containing Gracilaria tenuistipitata extract (GTE) at 0 (control), 400, and 600 mg/L for 3 h were exposed to 5 mg/L ammonia-N (ammonia as nitrogen), and immune parameters including hyaline cells (HCs), granular cells (GCs, including semi-granular cells), total hemocyte count (THC), phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, lysozyme activity, and hemolymph protein level were examined 24~120 h post-stress. The immune parameters of shrimp immersed in 600 mg/L GTE returned to original values earlier, at 96~120 h post-stress, whereas in control shrimp they did not. In another experiment, shrimp were immersed in seawater containing GTE at 0 and 600 mg/L for 3 h and examined for transcript levels of immune-related genes at 24 h post-stress. Transcript levels of lipopolysaccharide and β-1,3-glucan binding protein (LGBP), peroxinectin (PX), cytMnSOD, mtMnSOD, and HSP70 were up-regulated at 24 h post-stress in GTE receiving shrimp. We concluded that white shrimp immersed in seawater containing GTE exhibited a capability for maintaining homeostasis by regulating cellular and humoral immunity against ammonia stress as evidenced by up-regulated gene expression and earlier recovery of immune parameters.