Herbal extracts interfere with bacterial adhesion and support apoptosis-dependent exfoliation to protect mammals against bacterial infection. In this study, juvenile yellow catfish were fed with control diet or Acanthopanax senticosus extracts (AS)supplemented diet. After 60 days, AS (180 ml/kg feed) significantly elevated fish growth and feed utilization, with higher weight gain and feed efficiency. After challenged with Edwardsiella ictaluri, survival rate of AS-supplemented fish (65%) was significantly higher than control fish (30%). Control fish exhibited obvious skin lesions since 1 day post-infection (dpi) and decreased thickness of epidermis with prolonged days, while AS-supplemented fish skin structure showed better integrity. Moreover, length of secondary branchial filaments of AS-supplemented fish was higher than control fish that showed obvious occlusion between adjacent lamellae. Unlike its proinflammatory role in spleen, AS significantly inhibited gill inflammation at 4 dpi via regulating TLRs-NFκB pathway. Moreover, haematoxylin-eosin staining exhibited that AS delayed the liver vasculitis and necrotic hepatitis of yellow catfish. Further study by TUNEL assay, caspase-3 activity and mRNA expression indicated that AS significantly promoted hepatic apoptosis at 1 dpi to prevent further necrosis, which process was regulated by JAK/STAT pathway. All results demonstrated AS modulated inflammation and apoptosis to protect yellow catfish against Edwardsiella ictaluri infection.

Non-nutritional stress during early life period has been reported to promote the metabolic programming in fish induced by nutritional stimulus. Sodium chloride (NaCl) and hydrogen peroxide (H2O2) have been widely applied during fish egg hatching, but the influences on health and metabolism of fish in their later life remain unknown. In the present study, H2O2 treatment at 400mg/L but not 200mg/L significantly increased the loach hatchability and decreased the egg mortality, while NaCl treatment at 1,000 and 3,000mg/L showed no significant influences on the loach hatchability nor egg mortality. Further studies indicated that 400mg/L H2O2 pre-treatment significantly enhanced the antioxidant capacity and the mRNA expression of genes involved in immune response of loach larvae, accompanied by the increased expression of genes involved in fish early development. However, the expression of most genes involved in lipid metabolism, including catabolism and anabolism of loach larvae, was significantly upregulated after 200mg/L H2O2 pre-treatment. NaCl pre-treatment also increased the expression of antioxidant enzymes; however, only the expression of C1q within the detected immune-related genes was upregulated in loach larvae. One thousand milligram per liter NaCl pre-treatment significantly increased the expression of LPL and genes involved in fish early development. Thus, our results suggested the programming roles of 400mg/L H2O2 pre-treatment during egg hatching in enhancing antioxidant capacity and immune response of fish larvae via promoting fish early development.