Immune Responses of Asian Seabass Lates calcarifer to Dietary Glycyrrhiza uralensis

Abstract

To understand the impacts of dietary <i>Glycyrrhiza uralensis</i> on the immune responses of <i>Lates calcarifer</i>, the expression of immune-related genes including <i>crp</i>, <i>c-3</i>, <i>c-4</i>, <i>mtor</i>, <i>mlst-8</i>, <i>eif4e</i>, <i>hsp-70</i>, <i>hsp-90</i>, <i>il-8il-8</i>, <i>il-10</i>, <i>tgfβ1</i>, <i>tnf</i>, <i>ifn-γ1</i>, and <i>mxf</i> in <i>L. calcarifer</i> juveniles was evaluated in this study. Fish were fed experimental diets with <i>G. uralensis</i> levels of 0%, 1%, 3%, and 5% for 56 days. The results showed that dietary <i>G. uralensis</i> could improve the growth and survival of <i>L. calcarifer</i> and regulate the immune-related genes' expression in <i>L. calcarifer</i>. Dietary <i>G. uralensis</i> significantly upregulated the expression level of <i>crp</i>, <i>mtor</i>, <i>hsp-90</i>, <i>c-3</i>, and <i>c-4</i> genes in the liver of <i>L. calcarifer</i>, while <i>hsp-70</i> gene expression was nearly downregulated. It did not upregulate the expression of <i>elf4e</i> and <i>mlst-8</i> in the 1% and 3% inclusion groups, but it was the exact opposite in the 5% inclusion group. <i>G. uralensis</i> significantly affected the expression of <i>il-8, il-10, tnf, ifn-γ1, mxf,</i> and <i>tgfβ1</i> in the head kidney of <i>L. calcarifer</i>. <i>G. uralensis</i> upregulated the expression of <i>tnf</i> and <i>tgfβ1</i> consistently, but <i>ifn-γ1</i> was at a low expression level. The expression of <i>il-8</i> and <i>il-10</i> was upregulated in the 1% group, while it was downregulated in the 5% group. The results from the present study indicate that dietary <i>G. uralensis</i> appeared to improve the immune function of <i>L. calcarifer</i>, and the optimum inclusion level should be between 1-3%.