Immune Responses of Asian Seabass Lates calcarifer to Dietary Glycyrrhiza uralensis

Simple Summary Due to the fact of their low toxicity, small side effects, and little residue, increasing attention has been paid to herbs as environmentally friendly immunostimulants. Results from the present study indicate that adding Glycyrrhiza uralensis to the feed can improve the growth and survival of Lates calcarifer and significantly promote the expression of immune-related genes in the liver and head kidney of Lates calcarifer. The optimum inclusion level of Glycyrrhiza uralensis should be 1-3%. To understand the impacts of dietary Glycyrrhiza uralensis on the immune responses of Lates calcarifer, the expression of immune-related genes including crp, c-3, c-4, mtor, mlst-8, eif4e, hsp-70, hsp-90, il-8il-8, il-10, tgf beta 1, tnf, ifn-gamma 1, and mxf in L. calcarifer juveniles was evaluated in this study. Fish were fed experimental diets with G. uralensis levels of 0%, 1%, 3%, and 5% for 56 days. The results showed that dietary G. uralensis could improve the growth and survival of L. calcarifer and regulate the immune-related genes' expression in L. calcarifer. Dietary G. uralensis significantly upregulated the expression level of crp, mtor, hsp-90, c-3, and c-4 genes in the liver of L. calcarifer, while hsp-70 gene expression was nearly downregulated. It did not upregulate the expression of elf4e and mlst-8 in the 1% and 3% inclusion groups, but it was the exact opposite in the 5% inclusion group. G. uralensis significantly affected the expression of il-8, il-10, tnf, ifn-gamma 1, mxf, and tgf beta 1 in the head kidney of L. calcarifer. G. uralensis upregulated the expression of tnf and tgf beta 1 consistently, but ifn-gamma 1 was at a low expression level. The expression of il-8 and il-10 was upregulated in the 1% group, while it was downregulated in the 5% group. The results from the present study indicate that dietary G. uralensis appeared to improve the immune function of L. calcarifer, and the optimum inclusion level should be between 1-3%.