Morphologic, digestive enzymes and immunological responses of intestine from Litopenaeus vannamei after lipopolysaccharide injection.

The shrimp intestine barrier serves as the first line of the host defense against pathogen infection. Lipopolysaccharide (LPS) is the cell wall component of gram-negative bacteria, which known as endotoxin and induce the intestine inflammation. In this study, the acute toxicity effects of LPS injection on the morphology, digestive enzymes and immunological responses of intestine from Litopenaeus vannamei was investigated. HE stain showed that LPS injection damaged the intestine connective and epithelium tissue. Specifically, a decrease in the activities of digestive enzymes including of amylase, lipase, trypsin and pepsin was observed. Moreover, LPS injection increased the content of oxidative stress parameters (O generation capacity, LPO, MDA and PC), and the expression of HIF-1α gene. Alternatively, the antibacterial activities (PO and T-NOS), and the expression of the antibacterial genes (proPO, ALF, Toll and Imd) and pathogen pattern recognition genes (LGBP and Lec) increased at first and then decreased. Significant variations in anitioxidant enzyme activity of T-AOC, and the expression of the anitioxidant-related genes (SOD, HSP70 and Trx). These results revealed that LPS injection harmed the intestine barrier of L. vannamei by damaging intestine mucosal structure, increasing oxidative stress, and suppressing the digestive and immune status.