Dietary Lysine Levels Improved Antioxidant Capacity and Immunity via the TOR and p38 MAPK Signaling Pathways in Grass Carp, Ctenopharyngodon idellus Fry

Abstract

An 8-week rearing trial was designed to appraise the dietary lysine levels on intestinal antioxidant capacity and immunity of grass carp fry. Six practical diets were prepared with graded levels of lysine (1.44, 1.79, 1.97, 2.44, 2.56 and 2.87% dry matter), and these diets were fed to grass carp fry. The results showed that the activities of intestinal antioxidant factors including catalase and glutathione peroxidase were markedly improved by the 2.44% dietary lysine compared with the control diet (1.44% dietary lysine) (P < 0.05). In terms of antioxidants, compared with the control diet, the 2.44% diet markedly upregulated the mRNA expression levels of target of rapamycin, S6 kinase1 and nuclear factor erythroid 2-related factor 2 pathway-related antioxidant genes, containing catalase and glutathione peroxidase 1α (P < 0.05) and downregulated the mRNA levels of Kelch-like ECH-associated protein 1 (P > 0.05). The mRNA levels of 4E-binding protein 2 showed the opposite trend compared with those of target of rapamycin, and the minimum value was observed in the group of 1.97% dietary lysine (P < 0.05). In terms of immunity, compared with the 1.44% diet, the 2.44% diet markedly suppressed the intestinal p38 mitogen-activated protein kinase and interferon γ2 mRNA levels (P < 0.05). Moreover, nuclear factor-kappa B p65, tumor necrosis factor α, interleukin 6, interleukin 8, and interleukin 15 mRNA levels all exhibited the same trend as p38 mitogen-activated protein kinase and interferon γ2; however, the difference among all the lysine treatments groups was not significant (P > 0.05). The anti-inflammatory cytokines transforming growth factor β2 and interleukin 4/13B mRNA levels in the intestine were remarkably upregulated by high dietary lysine levels (2.56 and 2.87%) (P < 0.05), and when the dietary lysine level reached 2.44%, the interleukin 4/13A mRNA levels were strikingly increased (P < 0.05). Overall, the data suggested that 2.44% dietary lysine could strengthen the immune and antioxidant capacities of grass carp fry via activating the target of rapamycin (TOR) signaling pathway, and suppressing the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway, which then improve the survival rate.

Dietary lysine modulates growth performance, haemato‐biochemical indices, non‐specific immune response, intestinal enzymatic activities and antioxidant properties of rainbow trout, Oncorhynchus mykiss fingerlings

“…Similar statements were seen in other fish species such as silveryblack porgy, S. hasta (Yaghoubi et al, 2018) and grass carp, C. idella (Huang et al, 2021;Li et al, 2014). Fazio et al (2017) in their studies on flathead mullet, Mugil cephalus and gilt-head sea bream, Sparus aurata reported that the oxidative status and relationship between total oxidant status (TOS) and total antioxidant capacity (TAC) in serum are presumably reliant upon the fish species and are influenced by different feeding habits and the presence of appropriate nutrient.…”

“…Several past workers have suggested that dietary Lys has a key role in the regulation of antioxidant response in fish, which could influence the actions of different antioxidant enzymes (Huang et al, 2021;Li et al, 2014). Superoxide dismutase (SOD) is treated as one of the main antioxidant defence pathways, which plays a significant part in disease resistance and immunity (Li et al, 2014).…”

“…antioxidant status, growth performance, immune response, lysine requirement, Oncorhynchus mykiss (Dawood et al, 2020;Fazio et al, 2012), while investigation of plasma parameters also adds information regarding the physiological condition of fish and its overall health conditions (Ahmad, Ahmed, Dar, 2021 ;Ahmad, Ahmed, Fatma, et al, 2021). In the past, several studies reported that appropriate concentrations of dietary Lys can regulate metabolism and immunity in mammals and in fish species (Huang et al, 2021;Wu, 2010). Therefore, in addition to growth parameters, the study of haemato-biochemical parameters of fish would be useful in establishing the requirement of nutrient in fish.…”

Effects of Dietary Phospholipids on Growth Performance, Digestive Enzymes Activity and Intestinal Health of Largemouth Bass (Micropterus salmoides) Larvae

“…In the present study, the inclusion of dietary phospholipids significantly decreased the expression of rela in a quadratic manner, followed a similar pattern with that of the proinflammatory cytokines. Moreover, nf-κb is a downstream target of the p38 MAPK signaling pathway, which is involved in the regulation of inflammation in mammals ( 22 ) and is suggested to influence the intestinal immune function of grass carp ( 24 , 74 ). In the present study, the transcription of p38 mapk , mapk 13 and mapk 14, was repressed with the inclusion of dietary phospholipids.…”

“…The nuclear factor kappa B (Nf-κB), a downstream target of the p38 MAPK signaling pathway, is a major signaling molecule in the regulation of cytokines production ( 23 ). Therefore, it has been suggested that, in teleosts, the p38 MAPK/Nf-κB pathway participates in the regulation of inflammation response ( 20 , 24 ). However, it is yet unclear whether dietary phospholipids can alleviate the intestinal inflammation response in fish larvae through the p38 MAPK/Nf-κB pathway.…”