期刊
FISH & SHELLFISH IMMUNOLOGY
卷 45, 期 2, 页码 495-509出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.fsi.2015.05.001
关键词
Phenylalanine; Immune status; Cytokines; Tight junction proteins; TOR; Nrf
资金
- National Department Public Benefit Research Foundation (Agriculture) of China [201003020]
- National 973 Project of China [2014CB138600]
- Science and Technology Support Program of Sichuan Province of China [2014NZ0003]
- Major Scientific and Technological Achievement Transformation Project of Sichuan Province of China [2012NC0007, 2013NC0045]
The present work evaluated the effects of dietary phenylalanine (Phe) on the intestinal immune response, tight junction proteins transcript abundance, and the gene expression of immune- and antioxidant-related signalling molecules in the intestine. In addition, the dietary Phe (and Phe + Tyr) requirement of young grass carp (Ctenopharyngodon idella) was also estimated. Fish were fed fish meal -casein-gelatin based diets (302.3 g crude protein kg(-1)) containing 3.4 (basal diet), 6.1, 9.1, 11.5, 14.0 and 16.8 g Phe kg(-1), with a fixed amount of 10.7 g tyrosine kg(-1) for 8 weeks. The results showed that Phe deficiency or excess Phe reduced the lysozyme and acid phosphatase activities and complement C 3 content in the intestine (P < 0.05). Moreover, zonula occludens-1 (ZO-1), ocdudin and claudin c mRNA levels were highest in the fish fed the diet containing 11.5 g Phe kg(-1) (P < 0.05). However, claudin 12 and claudin b mRNA levels were not significantly affected by dietary Phe (P > 0.05). Gene expression of interleukin-10 (IL-10), transforming growth factor-beta 1 (TGF-beta 1), target of rapamycin (TOR) and inhibitor of nuclear factor kappa B alpha (I kappa B alpha) in proximal intestine (PI), mid intestine (MI) and distal intestine (DI) increased as dietary Phe increased up to 6.1, 9.1, 11.5 and 14.0 g kg(-1), respectively (P < 0.05). However, interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and nuclear factor-kappa B p6.5 (NF-kappa B p65) mRNA levels showed opposite tendencies. In addition, the mRNA level of superoxide dismutase (SOD) was significantly lower in the intestinal tissue of the group fed a diet with Phe levels of 16.8 g kg(-1) than in those of other groups (P < 0.05). The expression of NF-E2-related factor 2 (Nrf2) gene was increased as dietary Phe increased up to 9.1 g kg(-1) (P < 0.05). In conclusion, Phe improved intestinal immune status, and regulated gene expression of cytokines, tight junction proteins, antioxidant enzymes, NF-kappa B p65, I kappa B alpha, TOR, and Nrf2 in the fish intestine. Based on the quadratic regression analysis of lysozyme activity at a 95% maximum, the dietary Phe requirement of young grass carp (256-629 g) was estimated to be 8.31 g kg(-1), corresponding to 2.75 g 100 g(-1) protein. (C) 2015 Elsevier Ltd. All rights reserved.
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