Effect of dietary koumine on the immune and antioxidant status of carp (Cyprinus carpio) after Aeromonas hydrophila infection.

Abstract

Koumine (KM) has anxiolytic, anti-inflammatory and growth-promoting effects in pigs and sheep. Based on the growth-promoting and immunological effects of koumine, the present study was conducted on Cyprinus carpio (C. carpio) with four KM concentrations: 0&#xa0;mg/kg, 0.2&#xa0;mg/kg, 2&#xa0;mg/kg, and 20&#xa0;mg/kg for 10 weeks, followed by a 1-week Aeromonas hydrophila (A. hydrophila) infection experiment. The effect of KM on the immunity of A. hydrophila infected carp was analyzed by histopathology, biochemical assay, and qRT-PCR to assess the feasibility of KM in aquaculture. The results showed that the presence of KM alleviated pathogen damage to carp tissues. At 2&#xa0;mg/kg and 20&#xa0;mg/kg concentrations of KM successively and significantly elevated (p&#xa0;<&#xa0;0.05) the SOD activities in the intestinal tract, hepatopancreas and kidney of carp. The expression levels of hepatopancreatic antioxidant genes Nrf2 and IGF-1 were significantly up-regulated in the same group (p&#xa0;<&#xa0;0.05), while the expression levels of immune genes IL-8 and IL-10 were down-regulated. In summary, KM at concentrations of 2&#xa0;mg/kg and 20&#xa0;mg/kg could regulate the expression of antioxidant and immune genes in various tissues in an orderly and rapid manner, and significantly improve the antioxidant and immune abilities of carp, which is conducive to the improvement of the resilience of carp.