Impact of Antioxidant Feed and Growth Manipulation on the Redox Regulation of Atlantic Salmon Smolts

Abstract

Accumulating evidence indicates a close relationship between oxidative stress and growth rate in fish. However, the underlying mechanisms of this relationship remain unclear. This study evaluated the combined effect of dietary antioxidants and growth hormone (GH) on the liver and the muscle redox status of Atlantic salmon. There were two sequential experimental phases (EP) termed EP1 and EP2, each lasting for 6 weeks. In EP1, Atlantic salmon were fed either low-(L, 230 mg/kg ascorbic acid (Asc), 120 mg/kg α-tocopherol (α-TOH)), or high-(H, 380 mg/kg Asc, 210 mg/kg α-TOH)vitamin diets. The vitamins were supplemented as stable forms and the feeding was continued in EP2. In EP2, half of the fish were implanted with 3 μL per g body weight of recombinant bovine GH (Posilac®, 1 mg rbGH g BW-1) suspended in sesame oil, while the other half were held in different tanks and sham-implanted with similar volumes of the sesame oil vehicle. Here, we show that increasing high levels of vitamin C and E (diet H) increased their content in muscle and liver during EP1. GH implantation decreased vitamin C and E levels in both liver and muscle but increased malondialdehyde (MDA) levels only in the liver. GH also affected many genes and pathways of antioxidant enzymes and the redox balance. Among the most consistent were the upregulation of genes coding for the NADPH oxidase family (NOXs) and downregulation of the oxidative stress response transcription factor, nuclear factor-erythroid 2-related factor 2 (nrf2), and its downstream target genes in the liver. We verified that GH increases the growth rate until the end of the trail and induces an oxidative effect in the liver and muscle of Atlantic salmon. Dietary antioxidants do lower oxidative stress but have no effect on the growth rate. The present study is intended as a starting point to understand the potential interactions between growth and redox signaling in fish.

Dietary Resveratrol Ameliorates Hepatic Fatty Acid Metabolism and Jejunal Barrier in Offspring Induced by Maternal Oxidized Soybean Oil Challenge

“…H 2 O 2 is one of the most common types of ROS. 52 53,54 In this study, we found that the OSO challenge significantly increased the piglet liver H 2 O 2 content and markedly decreased SOD and CAT activities. This is similar to the findings in our prior research that maternal exposure to OSO resulted in higher H 2 O 2 levels and lower activity of CAT and SOD in the liver of offspring, 30 whereas Res supplementa- tion in the OSO group improved the content of H 2 O 2 and restored the CAT and SOD activities.…”

Seasonal Changes in Photoperiod: Effects on Growth and Redox Signaling Patterns in Atlantic Salmon Postsmolts

“…Activities of tSod, Gpx, Cat, and glutathione reductase (Gr) were measured in 150 mg of homogenized samples, using commercial kits (items 706002 (tSod), 703102 (Gpx), 703202 (Gr), 707002 (Cat); Cayman Chemical Co., Ann Arbor, MI, USA), as previously described [ 25 ].…”

“…The read quality checks, alignment, and differentially expressed genes (DEGs) were conducted as described by Yin et al [ 25 ]. In brief, raw RNA-seq reads were trimmed and cleaned by TrimGalore!…”

“…(Babraham Bioinformatics—Trim Galore!, version 0.6.5) and aligned to the reference genome of Atlantic salmon (ICSASG_v2; , accessed on 19 August 2022) by STAR [ 40 ] and quantified by featureCount [ 41 ]. The mRNA expression of genes chosen based on their importance within the redox system [ 21 , 22 , 23 , 25 , 42 ], oxidative stress response [ 43 , 44 , 45 ], and physiological processes including the GH–insulin-like growth factor (IGF) axis signaling [ 46 , 47 ], and cell cycle regulation [ 18 , 19 ] was studied in the liver, muscle, and brain ( Supplementary Data S1 ). DEGs was defined by 10 pair-wise comparisons: (i) Apr vs. Mar, (ii) Jun vs. Mar, (iii) Aug vs. Mar, (iv) Sep vs. Mar, (v) Jun vs. Apr, (vi) Aug vs. Apr, (vii) Sep vs. Apr, (viii) Aug vs. June, (ix) Sep vs. Jun, and (x) Sep vs. Aug, by using the DESeq2 [ 48 ].…”

“…In line with this, growing evidence links the redox environment in fish to embryonic and larval development [ 21 , 22 , 23 , 24 ]. We recently found that implantation of the growth hormone (GH) regulates the expression of redox-related genes in Atlantic salmon [ 25 ]. This indicated that redox signaling may play an important role in the growth of fish.…”