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Dietary tryptophan supplementation modulates imune status and disease resistance in senegalese sole, Solea senegalensis, reared at low or high density

2016; Frontiers Media; Volume: 3; Linguagem: Inglês

10.3389/conf.fmars.2016.04.00119

2296-7745

Rita Azeredo, Marina Machado, M. Joana, Martos-Sitcha Juan Antonio, Mancera Juan Miguel, Helena Perés, Oliva-Teles Aires, Afonso António, Benjamín Costas,

Aquaculture Nutrition and Growth

Event Abstract Back to Event Dietary tryptophan supplementation modulates imune status and disease resistance in senegalese sole, Solea senegalensis, reared at low or high density Rita Azeredo1, 2*, Marina Machado1, 3, Joana Moura3, Juan Antonio Martos-Sitcha4, 5, Juan Miguel Mancera5, Helena Peres1, Aires Oliva-Teles1, 2, António Afonso1, 3 and Benjamin Costas1, 3 1 Centro Interdisciplinar de Investigação Marinha e Ambiental, CIIMAR, Portugal 2 Faculdade de Ciências - Universidade do Porto, Biologia, Portugal 3 Instituto de Ciências Biomédicas Abel Salazar, Produção Aquática, Portugal 4 Instituto de Ciencias Marinas de Andalucía, Consejo Superior de Investigaciones Científicas (ICMAN-CSIC), Spain 5 Faculty of Marine and Environmental Sciences, University of Cádiz, Department of Biology, Spain Introduction - Besides being the building blocks of proteins, amino acids (AA) play several regulatory functions on key metabolic pathways that may be important, among other functions, to immune and neuro-endocrine responses. It has been suggested that chronic crowding stress may affect tryptophan (Trp) requirements in fish (Costas et al. 2008) and that dietary Trp supplementation counteracts such effect in chronically stressed Senegalese sole, Solea senegalensis (Costas et al. 2013a). In fish, upon activation of the hypothalamus-pituitary-interrenal (HPI) axis, several molecules are produced in order to regulate the neuro-endocrine response. Among these molecules is serotonin, which is known both to stimulate and to impair cortisol production (Lepage et al. 2002) and, therefore, to contribute to the modulation of the immune response in chronic stress situations. Serotonin is produced from Trp and in this study we hypothesized that diets supplemented above nutritional requirements with graded levels of Trp can mitigate the effects of chronic stressful conditions on fish physiology and immunity. Furthermore, we also intended to evaluate the effects of graded dietary levels of Trp on disease resistance of Senegalese sole. Material and methods - Healthy Senegalese sole juveniles with no history of photobacteriosis were obtained from a local fish farm. Fish were acclimated for two weeks to the laboratory conditions before being moved to the experimental aquaria. A practical diet was formulated to contain 45 % crude protein and 16 % crude fat (control diet) and to other diets were formulated similar to the control but supplemented with 2× and 4× the Trp requirement level (diets Trp2 and Trp4, respectively) to obtain a concentration of 0.44, 1.25 and 2.05 % of Trp (dry matter basis) in the control, Trp2 and Trp4 diets, respectively. Fish were distributed in two independent recirculating seawater systems with 9 flat-bottom aquaria each (0.05 m2; Temp.: 20±1 °C; Salinity: 24 ppm; O2 saturation: 80 %). Each aquarium contained 14 or 34 fish to achieve initial densities of 12.5 and 31 kg/m2. Fish maintained at low stocking density (12.5 kg/m2; LD) were regarded as control, while fish held at high stocking density (31 kg/m2; HD) were considered chronically stressed. Diets were randomly assigned to triplicate groups of fish in each system. The experimental period lasted for 39 days and fish were daily fed by hand, twice daily, to apparent satiety. At the end of the feeding trial, 2 fish per tank were sacrificed by overdose of 2-phenoxyethanol and thereafter hypothalamus, hypophysis, and blood were collected. Fish were then submitted to a bacterial challenge. For that purpose, fish were injected in the peritoneal cavity either with PBS (sham group) or an inoculum with Photobacterium damselae subsp. piscicida strain PC566.1 (Phdp, infected group) and distributed in four independent systems in duplicate tanks (5 fish per aquarium) according to their previous dietary and density treatments. The inoculum concentration (5 × 103 colony forming units ml-1) was prepared to match the lethal dose LD50 as described by Costas et al. (2013b). The bacterial challenge lasted for 15 days. Dead fish were removed daily and sampled to reisolate the inoculated pathogen. Results - No significant differences were observed among groups regarding corticotropin-releasing hormone gene expression in the hypothalamus and plasma cortisol concentration. Still, dietary Trp supplementation showed a trend to lower plasma cortisol levels in HD groups. In LD group, fish fed Trp2 increased alternative complement (ACH50) and bactericidal activities compared to groups held at LD, fed either Trp or Trp4, whereas in the HD group fish fed both Trp2 and Trp4 significantly augmented ACH50. Disease resistance increased in fish fed the Trp2 diet held at LD (no mortalities registered), whereas the highest mortalities at LD were observed in fish fed the Trp4 diet. In contrast, in fish maintained at HD mortalities were lower in groups fed the Trp2 or Trp4 diets, while fish fed the control diet were more susceptible to infection (Figure 1). Figure 1. Cumulative mortality (%) of Senegalese sole (Solea senegalensis) fed different dietary treatments following chronic stress and intraperitoneal (i.p.) injection with Photobacterium damselae subsp. piscicida (strain PC566.1; 5 × 103 cfu ml-1, n = 10 per treatment). LD fish fed Trp (▲), Trp2 (■) or Trp4 (●), and HD fish fed Trp (∆), Trp2 (□) or Trp4 (○). The same treatments i.p. injected with PBS (n = 10 per treatment) are not included for clarity since no mortalities were recorded. Discussion and conclusion - The main focus of Trp studies in fish has been related to its direct relationship with the neuro-endocrine system, especially relating to the stress response. The present study tested the effects of Trp on the innate immune response of Senegalese sole in an attempt to explore the links between immune and neuro-endocrine responses and to evaluate possible beneficial effects on fish health. Results suggest that a supplementation level of 2x the requirements may promote the immune status and disease resistance in both unstressed and stressed fish. However, while higher Trp levels (Trp4) may still be beneficial in stressed fish (i.e. increased disease resistance), in unstressed fish this high supplementation level seem to compromise immune status and disease resistance. Such outcomes suggest that Trp supplementation in diets for Senegalese sole should be carefully considered. Figure 1 Acknowledgements This work was partially funded by VEGICOR/AMINOAQUA project, ref. 31-03-05-FEP-43, co-financed by FEP through the IFAP/MMM (PIDDAC) and by the project PEst-C/MAR/LA0015/2013 by the European Regional Development Fund (ERDF) through the COMPETE - Operational Competitiveness Programme and national funds through FCT – Foundation for Science and Technology. R. Azeredo and B. Costas were supported by FCT (SFRH/BD/89457/2012 and SFRH/BPD/77210/2011, respectively). References Costas B., C. Aragão, J.M. Mancera, M.T. Dinis and L.E.C. Conceicao. 2008. High stocking density induces crowding stress and affects amino acid metabolism in Senegalese sole Solea senegalensis (Kaup 1858) juveniles. Aquaculture research 39:1-9. Costas B., C. Aragão, J. Dias, A. Afonso and L.E.C. Conceicao. 2013a. Interactive effects of a high-quality protein diet and high stocking density on the stress response and some innate immune parameters of Senegalese sole Solea senegalensis. Fish Physiology and Biochemistry 39: 1141-1151. Costas B., P.C.N.P. Rêgo, I. Simões, J.F. Marques, M. Castro-Cunha and A. Afonso. 2013b. Cellular and humoral immune responses of Senegalese sole (Solea senegalensis Kaup, 1858) following challenge with two Photobacterium damselae subsp. piscicida strains from different geographical origins. Journal of Fish Diseases 36: 543-553. Lepage, O., Tottmar, O. and Winberg, S. 2002. Elevated dietary intake of L-tryptophan counteracts the stress-induced elevation of plasma cortisol in rainbow trout (Oncorhynchus mykiss). Journal of Experimental Biology 205: 3679-3687 Keywords: Senegalese Sole, immune status, stress, Tryptophan, Disease Resistance Conference: IMMR | International Meeting on Marine Research 2016, Peniche, Portugal, 14 Jul - 15 Jul, 2016. Presentation Type: Oral presentation Topic: Aquaculture Citation: Azeredo R, Machado M, Moura J, Martos-Sitcha J, Mancera J, Peres H, Oliva-Teles A, Afonso A and Costas B (2016). Dietary tryptophan supplementation modulates imune status and disease resistance in senegalese sole, Solea senegalensis, reared at low or high density. Front. Mar. Sci. Conference Abstract: IMMR | International Meeting on Marine Research 2016. doi: 10.3389/conf.FMARS.2016.04.00119 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 29 Apr 2016; Published Online: 13 Jul 2016. * Correspondence: Miss. Rita Azeredo, Centro Interdisciplinar de Investigação Marinha e Ambiental, CIIMAR, Porto, 4050-123, Portugal, mleme@ciimar.up.pt Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rita Azeredo Marina Machado Joana Moura Juan Antonio Martos-Sitcha Juan Miguel Mancera Helena Peres Aires Oliva-Teles António Afonso Benjamin Costas Google Rita Azeredo Marina Machado Joana Moura Juan Antonio Martos-Sitcha Juan Miguel Mancera Helena Peres Aires Oliva-Teles António Afonso Benjamin Costas Google Scholar Rita Azeredo Marina Machado Joana Moura Juan Antonio Martos-Sitcha Juan Miguel Mancera Helena Peres Aires Oliva-Teles António Afonso Benjamin Costas PubMed Rita Azeredo Marina Machado Joana Moura Juan Antonio Martos-Sitcha Juan Miguel Mancera Helena Peres Aires Oliva-Teles António Afonso Benjamin Costas Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.