Wang Meiqi, Feng Lin, Wu Pei, Liu Yang, Ren Hongmei, Jin Xiaowan, Zhou Xiaoqiu, Jiang Weidan
Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China.
Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
Anim Nutr. 2025 Apr 5;21:326-340. doi: 10.1016/j.aninu.2025.01.010. eCollection 2025 Jun.
Skeletal muscle constitutes the largest tissue in fish and represents the primary edible portion. Given the substantial differences in muscle growth dynamics between fish and mammals, fish serve as a crucial and distinctive model organism for investigating the fundamental mechanisms of growth regulation in vertebrates. Myo-inositol (MI), originally discovered in muscle, plays significant biological roles in growth regulation, membrane biogenesis, and transmembrane signal transduction. However, to date, no studies have investigated how MI affects adult fish growth and muscle development. A total of 450 adult grass carp () (704.84 ± 0.91 g) were randomly divided into 6 treatments with 3 replicates of 25 fish each to receive dietary MI at 35.38 (basal diet, deficient group), 98.12, 195.21, 292.30, 389.39, and 486.48 mg/kg. The trial period lasted for 8 weeks. Results indicated that compared with the 35.38 mg/kg MI group, all groups supplemented with MI improved the specific growth rate (SGR) and percent weight gain (PWG) of adult grass carp ( < 0.05). Compared with the deficient group, the sodium-myo-inositol cotransporter 2 (SMIT2) and MI content in the muscle of grass carp in the 292.30 to 486 mg/kg MI group were significantly elevated ( < 0.05). Compared with the deficient group, the dietary MI levels of 195.21 to 486.48 mg/kg lead to increased myofiber mean diameters and the frequency of myofibers with a diameter > 100 μm, while decreased myofiber diameters < 60 μm ( < 0.05). This implies that MI promotes muscle hypertrophy. The hypertrophic effect of MI was primarily ascribed to an increase in the number of myonuclear and enhanced protein synthesis, which is associated with the regulation of the skeletal muscle lysyl oxidase (LOX) and the protein kinase B (AKT)/target of rapamycin (TOR)/ribosomal protein S6 kinase 1 (S6K1) signaling pathways. Additionally, MI inhibited the myostatin (MSTN) and the forkhead box O3 (FoxO3)/muscle RING-finger protein-1 (MuRF1)/muscle atrophy F-box (MAFbx) pathways, which are involved in muscle atrophy and protein degradation. Based on PWG, the appropriate MI requirement of adult grass carp was determined to be 301.30 mg/kg. This study offers a preliminary theoretical foundation for the potential mechanism by which MI promotes muscle hypertrophy in fish and furnishes a reference for the commercial feed formulation of adult grass carp.
骨骼肌是鱼类中最大的组织，也是主要的可食用部分。鉴于鱼类和哺乳动物在肌肉生长动力学方面存在显著差异，鱼类成为研究脊椎动物生长调节基本机制的关键且独特的模式生物。肌醇（MI）最初在肌肉中被发现，在生长调节、膜生物合成和跨膜信号转导中发挥着重要的生物学作用。然而，迄今为止，尚无研究调查MI如何影响成年鱼类的生长和肌肉发育。总共450尾成年草鱼（704.84±0.91克）被随机分为6组，每组25尾鱼，设3个重复，分别投喂含35.38（基础日粮，缺乏组）、98.12、195.21、292.30、389.39和486.48毫克/千克肌醇的日粮。试验期持续8周。结果表明，与35.38毫克/千克肌醇组相比，所有补充肌醇的组均提高了成年草鱼的特定生长率（SGR）和增重百分比（PWG）（P<0.05）。与缺乏组相比，292.30至486毫克/千克肌醇组草鱼肌肉中的钠-肌醇共转运蛋白2（SMIT2）和肌醇含量显著升高（P<0.05）。与缺乏组相比，195.21至486.48毫克/千克的日粮肌醇水平导致肌纤维平均直径增加，直径>100μm的肌纤维频率增加，而直径<60μm的肌纤维直径减小（P<0.05）。这表明肌醇促进肌肉肥大。肌醇的肥大作用主要归因于肌核数量的增加和蛋白质合成的增强，这与骨骼肌赖氨酰氧化酶（LOX）和蛋白激酶B（AKT）/雷帕霉素靶蛋白（TOR）/核糖体蛋白S6激酶1（S6K1）信号通路的调节有关。此外，肌醇抑制了参与肌肉萎缩和蛋白质降解的肌肉生长抑制素（MSTN）和叉头框O3（FoxO3）/肌肉环指蛋白-1（MuRF1）/肌肉萎缩F盒（MAFbx）通路。基于PWG，确定成年草鱼的适宜肌醇需求量为301.30毫克/千克。本研究为肌醇促进鱼类肌肉肥大的潜在机制提供了初步理论基础，并为成年草鱼的商业饲料配方提供了参考。
