Effects of mTOR Signaling Pathway on Growth, Antioxidant and Non-Specific Immunity of Litopenaeus vannamei

To investigate the effects of mTOR signaling pathway on the growth, antioxidant and non-specific immunity of Litopenaeus vannamei, three isonitrogen and isoenergy compound diets were designed, which were named control (Con), leucine (Leu) and rapamycin (Rap) groups, respectively. One percent of alanine (Ala) was added to the Con group, 1% of leucine to Leu group, and 0.003% of rapamycin to Rap group. Litopenaeus vannamei with initial body weight of (0.70±0.01) g was selected for culture experiment in an indoor circulating water system, 3 replicates each group, 60 shrimp each replicate. The culture cycle was 56 days. At the end of culture, the growth, antioxidant and non-specific immunity related indexes were analyzed. The results showed that the specific growth rate of Leu group was significantly higher than that of Con group, and the specific growth rate of Rap group was significantly lower than that of Con group (P < 0.01). The phosphorylation level of muscle S6 protein in prawn was the strongest at 1h after feeding, and then gradually decreased. Compared with Con group, the 1h muscle S6 protein phosphorylation level in Leu group was significantly increased, and the 1 h muscle S6 protein phosphorylation level in Rap group was significantly decreased (P < 0.05). In the serum of shrimp, the activities of alkaline phosphatase and phenoloxidase in Leu group were significantly higher than those in control group (P < 0.05), and the activities of acid phosphatase in Rap group were significantly lower than those in Con group (P < 0.05). In the hepatopancreas of shrimp, the activities of catalase, total antioxidant enzymes and phenoloxidase in Leu group were significantly higher than those in Con group (P < 0.05), and the malondialdehyde content in Leu group was significantly lower than that in Rap group (P < 0.05). The relative expression levels of Lysozyme, C-MnSOD and Lectin in Leu group were significantly higher than those in Con group (P < 0.05), and the relative expression levels of Relish and Hsp70 in Rap group were significantly lower than those in Con group (P < 0.05). The results showed that dietary leucine can effectively activate the mTOR signaling pathway, thereby improving the growth performance, antioxidant and non-specific immunity of Litopenaeus vannamei. The addition of rapamycin can effectively inhibit the mTOR signaling pathway, and inhibit the growth performance, antioxidant and immune function of Litopenaeus vannamei.