Leucine Affects Growth and Hepatic Growth‐Related Factor Gene Expression in Japanese AmberjackSeriola quinqueradiata

Abstract

We examined the effect of dietary supplementation of leucine on body weight and hepatic insulin‐like growth factor (IGF) and IGF‐binding protein (IGFBP) gene expression in juvenile Japanese Amberjack Seriola quinqueradiata. Crystalline leucine was dissolved in deionized water and added to the basal diet. Deionized water only was added to the basal diet as a control. The dietary concentration of free leucine was 0.03, 0.85, and 2.43 g/100 g diet for the control, 1% leucine‐supplemented, and 3% leucine‐supplemented diets, respectively. A growth trial was conducted for 77 d, after which the body weight was measured and the fish were then fasted for 3 d and refed. At 3, 9, and 24 h after refeeding, the liver and muscle were dissected for gene expression analysis. The mean body weight significantly increased in the 1% leucine‐supplemented group during the growth trial. The expression of hepatic IGBFP‐1 significantly increased at 3 and 9 h after refeeding in the leucine‐supplemented groups. The expression of hepatic IGF1 significantly decreased at 9 h and that of IGF2 significantly decreased at 9 and 24 h after refeeding in the 3% leucine‐supplemented group. The expression of hepatic IGFBP‐2, IGFBP‐3, and IGFBP‐5 were similar among the groups and were only affected by feeding time. In conclusion, we demonstrated for the first time that leucine supplementation increases body weight and influences the hepatic growth factor system in Japanese Amberjack.

Dietary requirements for leucine, isoleucine and valine (branched-chain amino acids) by juvenile red drumSciaenops ocellatus

“…The branched-chain amino acids (BCAAs) are a group of IAAs composed of leucine (Leu), isoleucine (Ile) and valine (Val) that are largely found in the hydrophobic interior core of globular proteins, playing important structural roles and being primarily deposited in body protein, notably in skeletal muscle (NRC, 2011). In addition, BCAAs are increasingly recognized as an anabolic nutrient signal, communicating the presence of an ingested protein-containing meal to peripheral tissues, and promoting protein synthesis in fish muscle (Kawanago, Takemura, Ishizuka, Kousaka, & Shioya, 2014;Shioya, 2015 andLansard et al, 2011). In addition, in other monogastric species (i.e., pigs and rats), BCAAs are known to be regulators of lipolysis, enhancing glucose consumption and utilization, promoting improved meat quality, benefitting embryo growth, enhancing intestinal development and intestinal AA transportation, and upregulating innate and adaptive immune responses (Zhang, Zeng, Ren, Mao, & Qiao, 2017).…”

Effects of dietary isoleucine on growth performance, enzymatic activities, antioxidant properties and expression of TOR related genes in rainbow trout,Oncorhynchus mykissfingerlings

“…Being the most extreme hydrophobic amino acids, BCAAs are generally introduced in the centre of globular proteins with significant membrane structural and functional roles (Brosnan & Brosnan, 2006; NRC, 2011; Zhao et al, 2020). BCAAs act as an anabolizing supplemental signal, advancing insulin release and synthesis of protein in fish muscle (Kawanago et al, 2014; Kawanago et al, 2015; Lansard et al, 2010). They are principally deposited in body protein, predominantly in skeletal muscle, and assume an essential role in modulating the synthesis of skeletal muscle protein (Jobgen et al, 2006; Meijer, 2003; Wu, 2013; Zhao et al, 2020).…”