Myostatin (encoded by mstn) negatively regulates skeletal muscle mass and affects lipid metabolism. To explore the regulatory effects of mstn on muscle development and lipid metabolism in Nile tilapia (Oreochromis niloticus), we used antisense RNA to transcriptionally knock-down mstn. At 180 days, the body weight and body length were significantly higher in the mstn-knock-down group than in the control group (p < 0.05). Additionally, fish with mstn-knock-down exhibited myofiber hyperplasia but not hypertrophy. Oil red O staining revealed a remarkable increase in the area of lipid droplets in muscle in the mstn-knockdown group (p < 0.05). Nutrient composition analyses of muscle tissue showed that the crude fat content was significantly increased in the mstn-knock-down group (p < 0.05). The contents of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids were all significantly increased in the mstn-knock-down group (p < 0.05). Comparative transcriptome analyses revealed 2420 significant differentially expressed genes between the mstn-knock-down group and the control group. KEGG analysis indicates that disruptions to fatty acid degradation, glycerolipid metabolism, and the PPAR signaling pathway affect muscle development and lipid metabolism in mstn-knock-down Nile tilapia: acaa2, eci1, and lepr were remarkably up-regulated, and acadvl, lpl, foxo3, myod1, myog, and myf5 were significantly down-regulated (p < 0.05). These results show that knock-down of mstn results in abnormal lipid metabolism, acceleration of skeletal muscle development, and increased adipogenesis and weight gain in Nile tilapia.

肌肉生长抑制素（由mstn编码）负向调节骨骼肌质量并影响脂质代谢。为了探讨mstn对尼罗罗非鱼（Oreochromis niloticus ）肌肉发育和脂质代谢的调节作用，我们使用反义RNA转录敲除mstn。180 天时， mstn敲低组的体重和体长显着高于对照组（ p  < 0.05）。此外，mstn敲低的鱼表现出肌纤维增生，但没有肌纤维肥大。油红O染色显示mstn敲低组肌肉中脂滴面积显着增加（p  <0.05）。肌肉组织的营养成分分析表明， mstn敲低组的粗脂肪含量显着增加（ p  < 0.05）。mstn敲低组的饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸含量均显着增加（ p  < 0.05）。比较转录组分析显示， mstn敲低组和对照组之间有 2420 个显着差异表达的基因。KEGG分析表明，脂肪酸降解、甘油脂代谢和PPAR信号通路的破坏影响了mstn敲低尼罗罗非鱼的肌肉发育和脂质代谢：acaa2、eci1和lepr显着上调，acadvl、lpl、Foxo3、myod1、myog和myf5显着下调（p  < 0.05）。这些结果表明， mstn的敲低会导致尼罗罗非鱼脂质代谢异常、骨骼肌发育加速、脂肪生成增加和体重增加。