Dietary Taraxacum mongolicum polysaccharide ameliorates the growth, immune response, and antioxidant status in association with NF-κB, Nrf2 and TOR in Jian carp (Cyprinus carpio var. Jian)

Taraxacum mongolicum polysaccharide (TMP) is a highly effective anti-inflammatory and antioxidant agent, but it has not been studied in aquatic feed. Here, the objective of this study was to evaluate the effects of dietary TMP on the growth, digestive enzyme activity, immune response, antioxidant status, and the NF-κB, Nrf2 and TOR signalling pathway-related genes in Jian carp. The juvenile fish were randomly distributed into four groups according to the TMP concentrations (0, 0.5, 1.0 and 2.0 g/kg) for 56 days. Our results indicated that the growth, enzyme activity and immune factors in fish increased in a concentration-dependent manner, and the dietary supplementation with TMP (1.0 g/kg) increased the WG, SGR, PER, amylase, lipase and protease activity. Meanwhile, the serum immune response (except for ACP) and hepatopancreas antioxidant enzyme activity were positively regulated by TMP. However, MDA, PC, COR and LDH contents were negatively correlated with the dietary supplementation with TMP. Furthermore, the trend in the expression of genes related to the NF-κB, Nrf2 and TOR signalling pathways were similar to that of the enzyme activity, which increased with the increase in dietary supplementation with TMP (except for proinflammatory factors, tgf-β and keap1). Among them, il-10, il-2, ho-1, nrf2, sod-(Cu-Zn) and gpx showed sharp increases. These results elucidate that dietary supplementation with TMP may greatly ameliorate the growth, digestive enzyme activity, immune response and antioxidant status and regulate the expression of NF-κB, Nrf2 and TOR signalling pathway-related genes in Jian carp.