New perspective on mechanism of L-arginine in promoting skeletal muscle growth of grass carp (Ctenopharyngodon Idella): Via enhancing skeletal muscle functions and regulating energy metabolism

Abstract

Meat quality has always been a main concern for both consumers and meat producers. Energy metabolism is one of the crucial factors effecting skeletal muscle quality that can be used as a key control point. L-arginine (Arg) is an essential amino acid for fish, has been observed to improves muscle quality. However, it is not clear whether Arg can improve muscle quality by regulating energy metabolism in skeletal muscle of fish. In this study, we selected 450 healthy grass carp (661.60 ± 1.00 g) randomly distributed into six groups based on varying concentrations of Arg (3.51, 7.01, 10.51, 14.01, 17.51, and 21.01 g/kg). Each group contained 3 replicates with 25 fish per replicate over a period of 9 weeks. Our findings indicated that Arg improved skeletal muscle sarcomere length, and enhanced skeletal muscle function by upregulating the expression of cytoskeleton proteins and regulating Ca²⁺ homeostasis. Optimal Arg promoted skeletal muscle energy reserves (Adenosine Triphosphate (ATP) and Na⁺-K⁺-ATP levels, glycogen), improved phosphocreatine system, glucose metabolism, and tricarboxylic acid cycling. Meanwhile, optimal Arg enhanced mitochondrial function and activate the adenosine monophosphate (AMP)-activated protein kinase (AMPK)/ Silent mating-type information regulation 2 homolog 3 (SIRT3)/ PPAR-γ coactivator 1 alpha (PGC-1α) pathway. Furthermore, Arg improved the antioxidant function of skeletal muscle via nuclear factor-erythroid 2-related factor 2 (Nrf2)/ Kelch-like ECH-associated protein 1 (Keap1) pathway. In summary, these results demonstrate that Arg supplementation promotes the skeletal muscle functions, energy metabolism, mitochondrial functions, and antioxidant capacity, helping to enhance grass carp skeletal muscle growth.