Co- and Post-Treatment with Lysine Protects Primary Fish Enterocytes against Cu-Induced Oxidative Damage

Abstract

The aim of the work was primarily to explore the protective activity pathways of lysine against oxidative damage in fish in vivo and in enterocytes in vitro. First, grass carp were fed diets containing six graded levels of lysine (7.1–19.6 g kg-1 diet) for 56 days. Second, the enterocytes were treated with different concentrations of lysine (0–300 mg/L in media) prior to (pre-treatment), along with (co-treatment) or following (post-treatment) with 6 mg/L of Cu for 24 h. The results indicated that lysine improved grass carp growth performance. Meanwhile, lysine ameliorated lipid and protein oxidation by elevating the gene expression and activity of antioxidant enzymes (superoxide dismutase (SOD), glutathioneperoxidase (GPx), glutathione-S-transferase (GST) and reductase (GR)), and nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA levels in fish intestine. The in vitro studies showed that co- and post-treatment with lysine conferred significant protection against Cu-induced oxidative damage in fish primary enterocytes as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) OD values, along with alkaline phosphatase (ALP) and lactate dehydrogenase activities, and the depletion of protein carbonyl (PC), malondialdehyde (MDA) and 8-hydroxydeoxyguanosine contents. Moreover, lysine co-treatment decreased the activities and mRNA level of cellular SOD, GPx, GST and GR compared with the Cu-only exposed group. Gene expression of the signalling molecule Nrf2 showed the same pattern as that of SOD activity, whereas Kelch-like ECH-associated protein 1b (Keap1b) followed the opposite trend, indicating that co-treatment with lysine induced antioxidant enzymes that protected against oxidative stress through Nrf2 pathway. In addition, post-treatment with lysine increased proteasomal activity and blocked the Cu-stimulated increase in mRNA levels of GST and associated catalase (CAT) and GST activities (P<0.01 and P<0.001). GR activity and gene expression, and glutathione (GSH) content followed an opposite trend to GST activity (P<0.05). Thus, post-treatment of lysine elevated protein and DNA repair abilities and ameliorated the cellular redox state of enterocytes. The overall results suggest that lysine plays a significant role in the protection of fish intestine in vivo and in vitro through the induction of key antioxidant protection.

Lysine deficiency impaired growth performance and immune response and aggravated inflammatory response of the skin, spleen and head kidney in grown-up grass carp (Ctenopharyngodon idella)

“…The dietary lysine requirement was estimated to be 47.27 g/kg of dietary protein for maximum of PWG. This value was similar to our previous research for on-grown grass carp, which was 47.30 g/kg of dietary protein ( Li et al., 2016a , Li et al., 2016b ). Additionally, previous studies have indicated that challenge with A. hydrophila could lead to histopathological change ( Abdelhamed et al., 2017 ) and skin haemorrhage and lesions in fish ( Wang et al., 2018 ).…”

“…The MDA content is used as a biomarker to measure the level of oxidative damage ( Wang et al., 2010 ). Our previous study reported that lysine excess could increase the content of MDA levels in grass carp intestine ( Li et al., 2016a , Li et al., 2016b ). These results help to explain our findings.…”

“…One previous study reviews adverse effects of arginine (essential amino acid) deficiency on the immune organ's immune function of fish ( Chen et al., 2015 ). In grass carp, lysine enhanced the growth performance and intestinal antioxidant capacity of fish ( Li et al., 2016a , Li et al., 2016b ; Li et al., 2013 ). Fish growth is often correlated with the immune organ's immune function ( Liu et al., 2018 ).…”

“…Grass carp is the major component of global aquaculture ( Zhong et al., 2019 ). One previous study evaluated the lysine requirement in grown-up grass carp based on PWG alone ( Li et al., 2016a , Li et al., 2016b ). However, the requirement of essential amino acids (such as arginine) varies with different indices ( Chen et al., 2015 ).…”

Anti-Oxidative Effect of L-Lysine on Post Thaw Quality of Nili-Ravi Buffalo Bull Semen (Bubalus Bubalis)

“…The improvement in semen quality parameters of L-lysine treated groups in terms of sperm total motility, progressive motility, progressive fast motility, average path velocity, straight linear velocity and curvilinear velocity was observed (table 3 and 4).The improvement in these aforementioned parameters may be attributed towards anti-oxidative property of lysine (Li et al, 2016)which ultimately results in decreased lipid per oxidation, lesser production of reactive oxygen species, increased glutathione peroxidase and catalase in L-lysine treated groups.…”