动植物蛋白对日本沼虾生长、肌肉组成、抗氧化、TOR信号通路及食欲调节相关基因表达的影响

植物蛋白替代鱼粉一直是水产研究的热点，但植物蛋白往往不能完全替代鱼粉，其潜在的原因值得进一步探索。本试验配制了3组等氮等能饲料，分别为鱼粉组（FM）、混合植物蛋白组（豆粕，菜粕，玉米蛋白粉）（PPB）和混合植物蛋白添加氨基酸组（PPB/Aa），对日本沼虾（0.123±0.03 g）进行8周的营养试验。结果发现：PPB和PPB/Aa组日本沼虾增重率显著低于FM组，而饲料系数显著高于FM组（P<0.05），各组之间成活率和肌肉必需氨基酸组成无显著差异（P>0.05）；FM组肝胰腺丙二醛（MDA）含量、超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）活性显著低于PPB组和PPB/Aa组（P<0.05），各组谷草转氨酶（AST）和谷丙转氨酶（ALT）无显著差异（P>0.05），PPB与PPB/Aa组血清碱性磷酸酶（AKP）、酸性磷酸酶（ACP）和ALT的活性均显著高于FM组（P<0.05）；与FM组相比，PPB与PPB/Aa组显著下调雷帕霉素靶蛋白（TOR）、核糖体蛋白S6激酶（S6K）及神经肽（NPY）基因的表达（P<0.05），但各组瘦素（Leptin）基因的表达无显著差异（P>0.05）。综上，鱼粉与植物蛋白对日本沼虾肌肉氨基酸组成没有影响，植物蛋白降低了日本沼虾生长并引起氧化应激，且添加氨基酸不能缓解这种负面影响，TOR信号通路与食欲调节相关基因表达的抑制可能是植物蛋白抑制日本沼虾生长的原因之一。

Effects of animal and plant proteins on growth, muscle composition, antioxidant abilities, mRNA expressions of genes related to TOR signaling pathway and appetite regulation in Macrobrachium nipponense

Substitution of fishmeal by plant proteins has been a hot topic in aquaculture research. However, plant proteins usually could not a completely replace fishmeal protein, so the underlying reasons or mechanisms deserve to further explore. Three isonitrogenous and isoenergetic diets were formulated in this experiment. A basal diet containing 58% fishmeal was used as the control(named as FM), whereas 100% of the fishmeal was replaced with a plant protein blend (soyabean meal, corn gluten meal and rapeseed meal, named as PPB) as the second diet, and lysine, threonine and methionine were added to the PPB diet to balance the amino acid content (named as PPB/Aa) as the third diet. Juvenile oriental river prawn Macrobrachium nipponense with an average weight of 0.123±0.03 g was randomly divided into three groups, and each diet was fed to prawns twice daily to apparent satiation in six replicates. The experiment lasted for 8 weeks. The growth, muscle composition, antioxidant abilities, mRNA expressions related to TOR signaling pathway and appetite regulation were evaluated. The results found that no significant difference in survival rate (SR) among three groups. The specific growth rate (SGR) and weight gain (WG) in prawns fed PPB and PPB/Aa was significantly lower than thosed fed FM (P<0.05), and the feed conversion ratio (FCR) in PPB and PPB/Aa group was significantly higher than FM group (P<0.05). The glycine content in the muscle of prawns fed FM was significantly lower than that of prawns fed PPB (P<0.05), but there was no significant differences of the other amino acids content (including lysine, threonine and methionine) among the three groups (P>0.05). The hepatopancreas content of malondialdehyde (MDA) and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in FM were significantly lower than those in PPB and PPB/Aa (P<0.05), while there was no significant differences of activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) among the three groups (P>0.05). The serum activities of alkaline phosphatase (AKP), acid phosphatase (ACP) and ALT in PPB and PPB/Aa group were significantly higher than those of FM group (P<0.05), however, no significant difference of activities of AST was observed among the three groups (P>0.05). The mRNA level of target of rapamycin (TOR), ribosomal proteins 6kinase (S6K) and neuropeptide Y (NPY) were significantly down-regulated in PPB and PPB/Aa group compared with that in FM group (P<0.05), while no significant difference was observed about mRNA expression of leptin among all groups (P>0.05). Taken together, muscle amino acids composition, except for glycine, was not affected by dietary fishmeal and plant protein blend in M. nipponense, but the antioxidant capacity of prawns was significantly decreased by plant protein blend, and the addition of amino acids could not alleviate the growth inhibition and oxidative stress caused by plant protein blend, and the mRNA levels of genes related to TOR signaling pathway and appetite regulation were inhibited in prawns fed plant protein blend, which maybe one of the reasons of growth inhibition by plant protein blendin M. nipponense.